1 | INSTALLATION INSTRUCTIONS for the Independent JPEG Group's JPEG software |
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2 | |
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3 | Copyright (C) 1991-2009, Thomas G. Lane, Guido Vollbeding. |
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4 | This file is part of the Independent JPEG Group's software. |
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5 | For conditions of distribution and use, see the accompanying README file. |
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6 | |
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7 | |
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8 | This file explains how to configure and install the IJG software. We have |
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9 | tried to make this software extremely portable and flexible, so that it can be |
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10 | adapted to almost any environment. The downside of this decision is that the |
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11 | installation process is complicated. We have provided shortcuts to simplify |
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12 | the task on common systems. But in any case, you will need at least a little |
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13 | familiarity with C programming and program build procedures for your system. |
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14 | |
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15 | If you are only using this software as part of a larger program, the larger |
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16 | program's installation procedure may take care of configuring the IJG code. |
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17 | For example, Ghostscript's installation script will configure the IJG code. |
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18 | You don't need to read this file if you just want to compile Ghostscript. |
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19 | |
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20 | If you are on a Unix machine, you may not need to read this file at all. |
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21 | Try doing |
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22 | ./configure |
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23 | make |
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24 | make test |
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25 | If that doesn't complain, do |
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26 | make install |
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27 | (better do "make -n install" first to see if the makefile will put the files |
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28 | where you want them). Read further if you run into snags or want to customize |
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29 | the code for your system. |
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30 | |
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31 | |
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32 | TABLE OF CONTENTS |
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33 | ----------------- |
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34 | |
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35 | Before you start |
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36 | Configuring the software: |
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37 | using the automatic "configure" script |
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38 | using one of the supplied jconfig and makefile files |
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39 | by hand |
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40 | Building the software |
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41 | Testing the software |
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42 | Installing the software |
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43 | Optional stuff |
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44 | Optimization |
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45 | Hints for specific systems |
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46 | |
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47 | |
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48 | BEFORE YOU START |
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49 | ================ |
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50 | |
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51 | Before installing the software you must unpack the distributed source code. |
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52 | Since you are reading this file, you have probably already succeeded in this |
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53 | task. However, there is a potential for error if you needed to convert the |
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54 | files to the local standard text file format (for example, if you are on |
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55 | MS-DOS you may have converted LF end-of-line to CR/LF). You must apply |
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56 | such conversion to all the files EXCEPT those whose names begin with "test". |
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57 | The test files contain binary data; if you change them in any way then the |
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58 | self-test will give bad results. |
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59 | |
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60 | Please check the last section of this file to see if there are hints for the |
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61 | specific machine or compiler you are using. |
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62 | |
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63 | |
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64 | CONFIGURING THE SOFTWARE |
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65 | ======================== |
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66 | |
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67 | To configure the IJG code for your system, you need to create two files: |
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68 | * jconfig.h: contains values for system-dependent #define symbols. |
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69 | * Makefile: controls the compilation process. |
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70 | (On a non-Unix machine, you may create "project files" or some other |
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71 | substitute for a Makefile. jconfig.h is needed in any environment.) |
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72 | |
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73 | We provide three different ways to generate these files: |
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74 | * On a Unix system, you can just run the "configure" script. |
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75 | * We provide sample jconfig files and makefiles for popular machines; |
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76 | if your machine matches one of the samples, just copy the right sample |
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77 | files to jconfig.h and Makefile. |
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78 | * If all else fails, read the instructions below and make your own files. |
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79 | |
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80 | |
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81 | Configuring the software using the automatic "configure" script |
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82 | --------------------------------------------------------------- |
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83 | |
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84 | If you are on a Unix machine, you can just type |
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85 | ./configure |
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86 | and let the configure script construct appropriate configuration files. |
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87 | If you're using "csh" on an old version of System V, you might need to type |
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88 | sh configure |
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89 | instead to prevent csh from trying to execute configure itself. |
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90 | Expect configure to run for a few minutes, particularly on slower machines; |
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91 | it works by compiling a series of test programs. |
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92 | |
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93 | Configure was created with GNU Autoconf and it follows the usual conventions |
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94 | for GNU configure scripts. It makes a few assumptions that you may want to |
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95 | override. You can do this by providing optional switches to configure: |
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96 | |
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97 | * Configure will build both static and shared libraries, if possible. |
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98 | If you want to build libjpeg only as a static library, say |
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99 | ./configure --disable-shared |
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100 | If you want to build libjpeg only as a shared library, say |
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101 | ./configure --disable-static |
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102 | Configure uses GNU libtool to take care of system-dependent shared library |
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103 | building methods. |
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104 | |
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105 | * Configure will use gcc (GNU C compiler) if it's available, otherwise cc. |
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106 | To force a particular compiler to be selected, use the CC option, for example |
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107 | ./configure CC='cc' |
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108 | The same method can be used to include any unusual compiler switches. |
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109 | For example, on HP-UX you probably want to say |
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110 | ./configure CC='cc -Aa' |
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111 | to get HP's compiler to run in ANSI mode. |
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112 | |
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113 | * The default CFLAGS setting is "-g" for non-gcc compilers, "-g -O2" for gcc. |
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114 | You can override this by saying, for example, |
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115 | ./configure CFLAGS='-O2' |
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116 | if you want to compile without debugging support. |
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117 | |
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118 | * Configure will set up the makefile so that "make install" will install files |
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119 | into /usr/local/bin, /usr/local/man, etc. You can specify an installation |
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120 | prefix other than "/usr/local" by giving configure the option "--prefix=PATH". |
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121 | |
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122 | * If you don't have a lot of swap space, you may need to enable the IJG |
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123 | software's internal virtual memory mechanism. To do this, give the option |
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124 | "--enable-maxmem=N" where N is the default maxmemory limit in megabytes. |
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125 | This is discussed in more detail under "Selecting a memory manager", below. |
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126 | You probably don't need to worry about this on reasonably-sized Unix machines, |
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127 | unless you plan to process very large images. |
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128 | |
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129 | Configure has some other features that are useful if you are cross-compiling |
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130 | or working in a network of multiple machine types; but if you need those |
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131 | features, you probably already know how to use them. |
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132 | |
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133 | |
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134 | Configuring the software using one of the supplied jconfig and makefile files |
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135 | ----------------------------------------------------------------------------- |
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136 | |
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137 | If you have one of these systems, you can just use the provided configuration |
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138 | files: |
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139 | |
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140 | Makefile jconfig file System and/or compiler |
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141 | |
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142 | makefile.manx jconfig.manx Amiga, Manx Aztec C |
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143 | makefile.sas jconfig.sas Amiga, SAS C |
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144 | makeproj.mac jconfig.mac Apple Macintosh, Metrowerks CodeWarrior |
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145 | mak*jpeg.st jconfig.st Atari ST/STE/TT, Pure C or Turbo C |
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146 | makefile.bcc jconfig.bcc MS-DOS or OS/2, Borland C |
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147 | makefile.dj jconfig.dj MS-DOS, DJGPP (Delorie's port of GNU C) |
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148 | makefile.mc6 jconfig.mc6 MS-DOS, Microsoft C (16-bit only) |
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149 | makefile.wat jconfig.wat MS-DOS, OS/2, or Windows NT, Watcom C |
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150 | makefile.vc jconfig.vc Windows NT/95, MS Visual C++ |
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151 | make*.vc6 jconfig.vc Windows NT/95, MS Visual C++ 6 |
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152 | make*.vc9 jconfig.vc Windows NT/95, MS Visual C++ 2008 (v9) |
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153 | makefile.mms jconfig.vms Digital VMS, with MMS software |
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154 | makefile.vms jconfig.vms Digital VMS, without MMS software |
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155 | |
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156 | Copy the proper jconfig file to jconfig.h and the makefile to Makefile (or |
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157 | whatever your system uses as the standard makefile name). For more info see |
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158 | the appropriate system-specific hints section near the end of this file. |
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159 | |
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160 | |
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161 | Configuring the software by hand |
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162 | -------------------------------- |
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163 | |
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164 | First, generate a jconfig.h file. If you are moderately familiar with C, |
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165 | the comments in jconfig.txt should be enough information to do this; just |
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166 | copy jconfig.txt to jconfig.h and edit it appropriately. Otherwise, you may |
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167 | prefer to use the ckconfig.c program. You will need to compile and execute |
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168 | ckconfig.c by hand --- we hope you know at least enough to do that. |
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169 | ckconfig.c may not compile the first try (in fact, the whole idea is for it |
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170 | to fail if anything is going to). If you get compile errors, fix them by |
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171 | editing ckconfig.c according to the directions given in ckconfig.c. Once |
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172 | you get it to run, it will write a suitable jconfig.h file, and will also |
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173 | print out some advice about which makefile to use. |
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174 | |
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175 | You may also want to look at the canned jconfig files, if there is one for a |
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176 | system similar to yours. |
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177 | |
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178 | Second, select a makefile and copy it to Makefile (or whatever your system |
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179 | uses as the standard makefile name). The most generic makefiles we provide |
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180 | are |
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181 | makefile.ansi: if your C compiler supports function prototypes |
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182 | makefile.unix: if not. |
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183 | (You have function prototypes if ckconfig.c put "#define HAVE_PROTOTYPES" |
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184 | in jconfig.h.) You may want to start from one of the other makefiles if |
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185 | there is one for a system similar to yours. |
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186 | |
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187 | Look over the selected Makefile and adjust options as needed. In particular |
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188 | you may want to change the CC and CFLAGS definitions. For instance, if you |
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189 | are using GCC, set CC=gcc. If you had to use any compiler switches to get |
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190 | ckconfig.c to work, make sure the same switches are in CFLAGS. |
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191 | |
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192 | If you are on a system that doesn't use makefiles, you'll need to set up |
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193 | project files (or whatever you do use) to compile all the source files and |
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194 | link them into executable files cjpeg, djpeg, jpegtran, rdjpgcom, and wrjpgcom. |
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195 | See the file lists in any of the makefiles to find out which files go into |
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196 | each program. Note that the provided makefiles all make a "library" file |
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197 | libjpeg first, but you don't have to do that if you don't want to; the file |
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198 | lists identify which source files are actually needed for compression, |
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199 | decompression, or both. As a last resort, you can make a batch script that |
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200 | just compiles everything and links it all together; makefile.vms is an example |
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201 | of this (it's for VMS systems that have no make-like utility). |
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202 | |
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203 | Here are comments about some specific configuration decisions you'll |
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204 | need to make: |
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205 | |
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206 | Command line style |
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207 | ------------------ |
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208 | |
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209 | These programs can use a Unix-like command line style which supports |
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210 | redirection and piping, like this: |
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211 | cjpeg inputfile >outputfile |
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212 | cjpeg <inputfile >outputfile |
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213 | source program | cjpeg >outputfile |
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214 | The simpler "two file" command line style is just |
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215 | cjpeg inputfile outputfile |
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216 | You may prefer the two-file style, particularly if you don't have pipes. |
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217 | |
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218 | You MUST use two-file style on any system that doesn't cope well with binary |
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219 | data fed through stdin/stdout; this is true for some MS-DOS compilers, for |
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220 | example. If you're not on a Unix system, it's safest to assume you need |
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221 | two-file style. (But if your compiler provides either the Posix-standard |
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222 | fdopen() library routine or a Microsoft-compatible setmode() routine, you |
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223 | can safely use the Unix command line style, by defining USE_FDOPEN or |
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224 | USE_SETMODE respectively.) |
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225 | |
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226 | To use the two-file style, make jconfig.h say "#define TWO_FILE_COMMANDLINE". |
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227 | |
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228 | Selecting a memory manager |
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229 | -------------------------- |
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230 | |
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231 | The IJG code is capable of working on images that are too big to fit in main |
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232 | memory; data is swapped out to temporary files as necessary. However, the |
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233 | code to do this is rather system-dependent. We provide five different |
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234 | memory managers: |
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235 | |
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236 | * jmemansi.c This version uses the ANSI-standard library routine tmpfile(), |
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237 | which not all non-ANSI systems have. On some systems |
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238 | tmpfile() may put the temporary file in a non-optimal |
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239 | location; if you don't like what it does, use jmemname.c. |
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240 | |
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241 | * jmemname.c This version creates named temporary files. For anything |
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242 | except a Unix machine, you'll need to configure the |
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243 | select_file_name() routine appropriately; see the comments |
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244 | near the head of jmemname.c. If you use this version, define |
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245 | NEED_SIGNAL_CATCHER in jconfig.h to make sure the temp files |
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246 | are removed if the program is aborted. |
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247 | |
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248 | * jmemnobs.c (That stands for No Backing Store :-).) This will compile on |
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249 | almost any system, but it assumes you have enough main memory |
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250 | or virtual memory to hold the biggest images you work with. |
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251 | |
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252 | * jmemdos.c This should be used with most 16-bit MS-DOS compilers. |
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253 | See the system-specific notes about MS-DOS for more info. |
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254 | IMPORTANT: if you use this, define USE_MSDOS_MEMMGR in |
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255 | jconfig.h, and include the assembly file jmemdosa.asm in the |
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256 | programs. The supplied makefiles and jconfig files for |
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257 | 16-bit MS-DOS compilers already do both. |
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258 | |
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259 | * jmemmac.c Custom version for Apple Macintosh; see the system-specific |
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260 | notes for Macintosh for more info. |
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261 | |
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262 | To use a particular memory manager, change the SYSDEPMEM variable in your |
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263 | makefile to equal the corresponding object file name (for example, jmemansi.o |
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264 | or jmemansi.obj for jmemansi.c). |
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265 | |
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266 | If you have plenty of (real or virtual) main memory, just use jmemnobs.c. |
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267 | "Plenty" means about ten bytes for every pixel in the largest images |
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268 | you plan to process, so a lot of systems don't meet this criterion. |
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269 | If yours doesn't, try jmemansi.c first. If that doesn't compile, you'll have |
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270 | to use jmemname.c; be sure to adjust select_file_name() for local conditions. |
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271 | You may also need to change unlink() to remove() in close_backing_store(). |
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272 | |
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273 | Except with jmemnobs.c or jmemmac.c, you need to adjust the DEFAULT_MAX_MEM |
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274 | setting to a reasonable value for your system (either by adding a #define for |
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275 | DEFAULT_MAX_MEM to jconfig.h, or by adding a -D switch to the Makefile). |
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276 | This value limits the amount of data space the program will attempt to |
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277 | allocate. Code and static data space isn't counted, so the actual memory |
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278 | needs for cjpeg or djpeg are typically 100 to 150Kb more than the max-memory |
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279 | setting. Larger max-memory settings reduce the amount of I/O needed to |
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280 | process a large image, but too large a value can result in "insufficient |
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281 | memory" failures. On most Unix machines (and other systems with virtual |
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282 | memory), just set DEFAULT_MAX_MEM to several million and forget it. At the |
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283 | other end of the spectrum, for MS-DOS machines you probably can't go much |
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284 | above 300K to 400K. (On MS-DOS the value refers to conventional memory only. |
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285 | Extended/expanded memory is handled separately by jmemdos.c.) |
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286 | |
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287 | |
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288 | BUILDING THE SOFTWARE |
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289 | ===================== |
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290 | |
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291 | Now you should be able to compile the software. Just say "make" (or |
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292 | whatever's necessary to start the compilation). Have a cup of coffee. |
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293 | |
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294 | Here are some things that could go wrong: |
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295 | |
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296 | If your compiler complains about undefined structures, you should be able to |
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297 | shut it up by putting "#define INCOMPLETE_TYPES_BROKEN" in jconfig.h. |
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298 | |
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299 | If you have trouble with missing system include files or inclusion of the |
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300 | wrong ones, read jinclude.h. This shouldn't happen if you used configure |
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301 | or ckconfig.c to set up jconfig.h. |
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302 | |
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303 | There are a fair number of routines that do not use all of their parameters; |
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304 | some compilers will issue warnings about this, which you can ignore. There |
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305 | are also a few configuration checks that may give "unreachable code" warnings. |
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306 | Any other warning deserves investigation. |
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307 | |
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308 | If you don't have a getenv() library routine, define NO_GETENV. |
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309 | |
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310 | Also see the system-specific hints, below. |
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311 | |
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312 | |
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313 | TESTING THE SOFTWARE |
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314 | ==================== |
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315 | |
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316 | As a quick test of functionality we've included a small sample image in |
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317 | several forms: |
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318 | testorig.jpg Starting point for the djpeg tests. |
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319 | testimg.ppm The output of djpeg testorig.jpg |
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320 | testimg.bmp The output of djpeg -bmp -colors 256 testorig.jpg |
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321 | testimg.jpg The output of cjpeg testimg.ppm |
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322 | testprog.jpg Progressive-mode equivalent of testorig.jpg. |
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323 | testimgp.jpg The output of cjpeg -progressive -optimize testimg.ppm |
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324 | (The first- and second-generation .jpg files aren't identical since JPEG is |
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325 | lossy.) If you can generate duplicates of the testimg* files then you |
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326 | probably have working programs. |
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327 | |
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328 | With most of the makefiles, "make test" will perform the necessary |
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329 | comparisons. |
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330 | |
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331 | If you're using a makefile that doesn't provide the test option, run djpeg |
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332 | and cjpeg by hand and compare the output files to testimg* with whatever |
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333 | binary file comparison tool you have. The files should be bit-for-bit |
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334 | identical. |
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335 | |
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336 | If the programs complain "MAX_ALLOC_CHUNK is wrong, please fix", then you |
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337 | need to reduce MAX_ALLOC_CHUNK to a value that fits in type size_t. |
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338 | Try adding "#define MAX_ALLOC_CHUNK 65520L" to jconfig.h. A less likely |
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339 | configuration error is "ALIGN_TYPE is wrong, please fix": defining ALIGN_TYPE |
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340 | as long should take care of that one. |
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341 | |
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342 | If the cjpeg test run fails with "Missing Huffman code table entry", it's a |
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343 | good bet that you needed to define RIGHT_SHIFT_IS_UNSIGNED. Go back to the |
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344 | configuration step and run ckconfig.c. (This is a good plan for any other |
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345 | test failure, too.) |
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346 | |
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347 | If you are using Unix (one-file) command line style on a non-Unix system, |
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348 | it's a good idea to check that binary I/O through stdin/stdout actually |
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349 | works. You should get the same results from "djpeg <testorig.jpg >out.ppm" |
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350 | as from "djpeg -outfile out.ppm testorig.jpg". Note that the makefiles all |
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351 | use the latter style and therefore do not exercise stdin/stdout! If this |
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352 | check fails, try recompiling with USE_SETMODE or USE_FDOPEN defined. |
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353 | If it still doesn't work, better use two-file style. |
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354 | |
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355 | If you chose a memory manager other than jmemnobs.c, you should test that |
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356 | temporary-file usage works. Try "djpeg -bmp -colors 256 -max 0 testorig.jpg" |
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357 | and make sure its output matches testimg.bmp. If you have any really large |
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358 | images handy, try compressing them with -optimize and/or decompressing with |
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359 | -colors 256 to make sure your DEFAULT_MAX_MEM setting is not too large. |
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360 | |
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361 | NOTE: this is far from an exhaustive test of the JPEG software; some modules, |
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362 | such as 1-pass color quantization, are not exercised at all. It's just a |
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363 | quick test to give you some confidence that you haven't missed something |
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364 | major. |
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365 | |
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366 | |
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367 | INSTALLING THE SOFTWARE |
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368 | ======================= |
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369 | |
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370 | Once you're done with the above steps, you can install the software by |
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371 | copying the executable files (cjpeg, djpeg, jpegtran, rdjpgcom, and wrjpgcom) |
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372 | to wherever you normally install programs. On Unix systems, you'll also want |
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373 | to put the man pages (cjpeg.1, djpeg.1, jpegtran.1, rdjpgcom.1, wrjpgcom.1) |
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374 | in the man-page directory. The pre-fab makefiles don't support this step |
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375 | since there's such a wide variety of installation procedures on different |
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376 | systems. |
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377 | |
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378 | If you generated a Makefile with the "configure" script, you can just say |
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379 | make install |
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380 | to install the programs and their man pages into the standard places. |
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381 | (You'll probably need to be root to do this.) We recommend first saying |
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382 | make -n install |
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383 | to see where configure thought the files should go. You may need to edit |
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384 | the Makefile, particularly if your system's conventions for man page |
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385 | filenames don't match what configure expects. |
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386 | |
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387 | If you want to install the IJG library itself, for use in compiling other |
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388 | programs besides ours, then you need to put the four include files |
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389 | jpeglib.h jerror.h jconfig.h jmorecfg.h |
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390 | into your include-file directory, and put the library file libjpeg.a |
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391 | (extension may vary depending on system) wherever library files go. |
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392 | If you generated a Makefile with "configure", it will do what it thinks |
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393 | is the right thing if you say |
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394 | make install-lib |
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395 | |
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396 | |
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397 | OPTIONAL STUFF |
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398 | ============== |
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399 | |
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400 | Progress monitor: |
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401 | |
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402 | If you like, you can #define PROGRESS_REPORT (in jconfig.h) to enable display |
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403 | of percent-done progress reports. The routine provided in cdjpeg.c merely |
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404 | prints percentages to stderr, but you can customize it to do something |
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405 | fancier. |
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406 | |
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407 | Utah RLE file format support: |
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408 | |
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409 | We distribute the software with support for RLE image files (Utah Raster |
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410 | Toolkit format) disabled, because the RLE support won't compile without the |
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411 | Utah library. If you have URT version 3.1 or later, you can enable RLE |
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412 | support as follows: |
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413 | 1. #define RLE_SUPPORTED in jconfig.h. |
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414 | 2. Add a -I option to CFLAGS in the Makefile for the directory |
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415 | containing the URT .h files (typically the "include" |
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416 | subdirectory of the URT distribution). |
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417 | 3. Add -L... -lrle to LDLIBS in the Makefile, where ... specifies |
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418 | the directory containing the URT "librle.a" file (typically the |
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419 | "lib" subdirectory of the URT distribution). |
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420 | |
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421 | Support for 12-bit-deep pixel data: |
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422 | |
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423 | The JPEG standard allows either 8-bit or 12-bit data precision. (For color, |
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424 | this means 8 or 12 bits per channel, of course.) If you need to work with |
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425 | deeper than 8-bit data, you can compile the IJG code for 12-bit operation. |
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426 | To do so: |
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427 | 1. In jmorecfg.h, define BITS_IN_JSAMPLE as 12 rather than 8. |
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428 | 2. In jconfig.h, undefine BMP_SUPPORTED, RLE_SUPPORTED, and TARGA_SUPPORTED, |
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429 | because the code for those formats doesn't handle 12-bit data and won't |
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430 | even compile. (The PPM code does work, as explained below. The GIF |
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431 | code works too; it scales 8-bit GIF data to and from 12-bit depth |
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432 | automatically.) |
---|
433 | 3. Compile. Don't expect "make test" to pass, since the supplied test |
---|
434 | files are for 8-bit data. |
---|
435 | |
---|
436 | Currently, 12-bit support does not work on 16-bit-int machines. |
---|
437 | |
---|
438 | Note that a 12-bit version will not read 8-bit JPEG files, nor vice versa; |
---|
439 | so you'll want to keep around a regular 8-bit compilation as well. |
---|
440 | (Run-time selection of data depth, to allow a single copy that does both, |
---|
441 | is possible but would probably slow things down considerably; it's very low |
---|
442 | on our to-do list.) |
---|
443 | |
---|
444 | The PPM reader (rdppm.c) can read 12-bit data from either text-format or |
---|
445 | binary-format PPM and PGM files. Binary-format PPM/PGM files which have a |
---|
446 | maxval greater than 255 are assumed to use 2 bytes per sample, MSB first |
---|
447 | (big-endian order). As of early 1995, 2-byte binary format is not |
---|
448 | officially supported by the PBMPLUS library, but it is expected that a |
---|
449 | future release of PBMPLUS will support it. Note that the PPM reader will |
---|
450 | read files of any maxval regardless of the BITS_IN_JSAMPLE setting; incoming |
---|
451 | data is automatically rescaled to either maxval=255 or maxval=4095 as |
---|
452 | appropriate for the cjpeg bit depth. |
---|
453 | |
---|
454 | The PPM writer (wrppm.c) will normally write 2-byte binary PPM or PGM |
---|
455 | format, maxval 4095, when compiled with BITS_IN_JSAMPLE=12. Since this |
---|
456 | format is not yet widely supported, you can disable it by compiling wrppm.c |
---|
457 | with PPM_NORAWWORD defined; then the data is scaled down to 8 bits to make a |
---|
458 | standard 1-byte/sample PPM or PGM file. (Yes, this means still another copy |
---|
459 | of djpeg to keep around. But hopefully you won't need it for very long. |
---|
460 | Poskanzer's supposed to get that new PBMPLUS release out Real Soon Now.) |
---|
461 | |
---|
462 | Of course, if you are working with 12-bit data, you probably have it stored |
---|
463 | in some other, nonstandard format. In that case you'll probably want to |
---|
464 | write your own I/O modules to read and write your format. |
---|
465 | |
---|
466 | Note that a 12-bit version of cjpeg always runs in "-optimize" mode, in |
---|
467 | order to generate valid Huffman tables. This is necessary because our |
---|
468 | default Huffman tables only cover 8-bit data. |
---|
469 | |
---|
470 | Removing code: |
---|
471 | |
---|
472 | If you need to make a smaller version of the JPEG software, some optional |
---|
473 | functions can be removed at compile time. See the xxx_SUPPORTED #defines in |
---|
474 | jconfig.h and jmorecfg.h. If at all possible, we recommend that you leave in |
---|
475 | decoder support for all valid JPEG files, to ensure that you can read anyone's |
---|
476 | output. Taking out support for image file formats that you don't use is the |
---|
477 | most painless way to make the programs smaller. Another possibility is to |
---|
478 | remove some of the DCT methods: in particular, the "IFAST" method may not be |
---|
479 | enough faster than the others to be worth keeping on your machine. (If you |
---|
480 | do remove ISLOW or IFAST, be sure to redefine JDCT_DEFAULT or JDCT_FASTEST |
---|
481 | to a supported method, by adding a #define in jconfig.h.) |
---|
482 | |
---|
483 | |
---|
484 | OPTIMIZATION |
---|
485 | ============ |
---|
486 | |
---|
487 | Unless you own a Cray, you'll probably be interested in making the JPEG |
---|
488 | software go as fast as possible. This section covers some machine-dependent |
---|
489 | optimizations you may want to try. We suggest that before trying any of |
---|
490 | this, you first get the basic installation to pass the self-test step. |
---|
491 | Repeat the self-test after any optimization to make sure that you haven't |
---|
492 | broken anything. |
---|
493 | |
---|
494 | The integer DCT routines perform a lot of multiplications. These |
---|
495 | multiplications must yield 32-bit results, but none of their input values |
---|
496 | are more than 16 bits wide. On many machines, notably the 680x0 and 80x86 |
---|
497 | CPUs, a 16x16=>32 bit multiply instruction is faster than a full 32x32=>32 |
---|
498 | bit multiply. Unfortunately there is no portable way to specify such a |
---|
499 | multiplication in C, but some compilers can generate one when you use the |
---|
500 | right combination of casts. See the MULTIPLYxxx macro definitions in |
---|
501 | jdct.h. If your compiler makes "int" be 32 bits and "short" be 16 bits, |
---|
502 | defining SHORTxSHORT_32 is fairly likely to work. When experimenting with |
---|
503 | alternate definitions, be sure to test not only whether the code still works |
---|
504 | (use the self-test), but also whether it is actually faster --- on some |
---|
505 | compilers, alternate definitions may compute the right answer, yet be slower |
---|
506 | than the default. Timing cjpeg on a large PGM (grayscale) input file is the |
---|
507 | best way to check this, as the DCT will be the largest fraction of the runtime |
---|
508 | in that mode. (Note: some of the distributed compiler-specific jconfig files |
---|
509 | already contain #define switches to select appropriate MULTIPLYxxx |
---|
510 | definitions.) |
---|
511 | |
---|
512 | If your machine has sufficiently fast floating point hardware, you may find |
---|
513 | that the float DCT method is faster than the integer DCT methods, even |
---|
514 | after tweaking the integer multiply macros. In that case you may want to |
---|
515 | make the float DCT be the default method. (The only objection to this is |
---|
516 | that float DCT results may vary slightly across machines.) To do that, add |
---|
517 | "#define JDCT_DEFAULT JDCT_FLOAT" to jconfig.h. Even if you don't change |
---|
518 | the default, you should redefine JDCT_FASTEST, which is the method selected |
---|
519 | by djpeg's -fast switch. Don't forget to update the documentation files |
---|
520 | (usage.txt and/or cjpeg.1, djpeg.1) to agree with what you've done. |
---|
521 | |
---|
522 | If access to "short" arrays is slow on your machine, it may be a win to |
---|
523 | define type JCOEF as int rather than short. This will cost a good deal of |
---|
524 | memory though, particularly in some multi-pass modes, so don't do it unless |
---|
525 | you have memory to burn and short is REALLY slow. |
---|
526 | |
---|
527 | If your compiler can compile function calls in-line, make sure the INLINE |
---|
528 | macro in jmorecfg.h is defined as the keyword that marks a function |
---|
529 | inline-able. Some compilers have a switch that tells the compiler to inline |
---|
530 | any function it thinks is profitable (e.g., -finline-functions for gcc). |
---|
531 | Enabling such a switch is likely to make the compiled code bigger but faster. |
---|
532 | |
---|
533 | In general, it's worth trying the maximum optimization level of your compiler, |
---|
534 | and experimenting with any optional optimizations such as loop unrolling. |
---|
535 | (Unfortunately, far too many compilers have optimizer bugs ... be prepared to |
---|
536 | back off if the code fails self-test.) If you do any experimentation along |
---|
537 | these lines, please report the optimal settings to jpeg-info@jpegclub.org so |
---|
538 | we can mention them in future releases. Be sure to specify your machine and |
---|
539 | compiler version. |
---|
540 | |
---|
541 | |
---|
542 | HINTS FOR SPECIFIC SYSTEMS |
---|
543 | ========================== |
---|
544 | |
---|
545 | We welcome reports on changes needed for systems not mentioned here. Submit |
---|
546 | 'em to jpeg-info@jpegclub.org. Also, if configure or ckconfig.c is wrong |
---|
547 | about how to configure the JPEG software for your system, please let us know. |
---|
548 | |
---|
549 | |
---|
550 | Acorn RISC OS: |
---|
551 | |
---|
552 | (Thanks to Simon Middleton for these hints on compiling with Desktop C.) |
---|
553 | After renaming the files according to Acorn conventions, take a copy of |
---|
554 | makefile.ansi, change all occurrences of 'libjpeg.a' to 'libjpeg.o' and |
---|
555 | change these definitions as indicated: |
---|
556 | |
---|
557 | CFLAGS= -throwback -IC: -Wn |
---|
558 | LDLIBS=C:o.Stubs |
---|
559 | SYSDEPMEM=jmemansi.o |
---|
560 | LN=Link |
---|
561 | AR=LibFile -c -o |
---|
562 | |
---|
563 | Also add a new line '.c.o:; $(cc) $< $(cflags) -c -o $@'. Remove the |
---|
564 | lines '$(RM) libjpeg.o' and '$(AR2) libjpeg.o' and the 'jconfig.h' |
---|
565 | dependency section. |
---|
566 | |
---|
567 | Copy jconfig.txt to jconfig.h. Edit jconfig.h to define TWO_FILE_COMMANDLINE |
---|
568 | and CHAR_IS_UNSIGNED. |
---|
569 | |
---|
570 | Run the makefile using !AMU not !Make. If you want to use the 'clean' and |
---|
571 | 'test' makefile entries then you will have to fiddle with the syntax a bit |
---|
572 | and rename the test files. |
---|
573 | |
---|
574 | |
---|
575 | Amiga: |
---|
576 | |
---|
577 | SAS C 6.50 reportedly is too buggy to compile the IJG code properly. |
---|
578 | A patch to update to 6.51 is available from SAS or AmiNet FTP sites. |
---|
579 | |
---|
580 | The supplied config files are set up to use jmemname.c as the memory |
---|
581 | manager, with temporary files being created on the device named by |
---|
582 | "JPEGTMP:". |
---|
583 | |
---|
584 | |
---|
585 | Atari ST/STE/TT: |
---|
586 | |
---|
587 | Copy the project files makcjpeg.st, makdjpeg.st, maktjpeg.st, and makljpeg.st |
---|
588 | to cjpeg.prj, djpeg.prj, jpegtran.prj, and libjpeg.prj respectively. The |
---|
589 | project files should work as-is with Pure C. For Turbo C, change library |
---|
590 | filenames "pc..." to "tc..." in each project file. Note that libjpeg.prj |
---|
591 | selects jmemansi.c as the recommended memory manager. You'll probably want to |
---|
592 | adjust the DEFAULT_MAX_MEM setting --- you want it to be a couple hundred K |
---|
593 | less than your normal free memory. Put "#define DEFAULT_MAX_MEM nnnn" into |
---|
594 | jconfig.h to do this. |
---|
595 | |
---|
596 | To use the 68881/68882 coprocessor for the floating point DCT, add the |
---|
597 | compiler option "-8" to the project files and replace pcfltlib.lib with |
---|
598 | pc881lib.lib in cjpeg.prj and djpeg.prj. Or if you don't have a |
---|
599 | coprocessor, you may prefer to remove the float DCT code by undefining |
---|
600 | DCT_FLOAT_SUPPORTED in jmorecfg.h (since without a coprocessor, the float |
---|
601 | code will be too slow to be useful). In that case, you can delete |
---|
602 | pcfltlib.lib from the project files. |
---|
603 | |
---|
604 | Note that you must make libjpeg.lib before making cjpeg.ttp, djpeg.ttp, |
---|
605 | or jpegtran.ttp. You'll have to perform the self-test by hand. |
---|
606 | |
---|
607 | We haven't bothered to include project files for rdjpgcom and wrjpgcom. |
---|
608 | Those source files should just be compiled by themselves; they don't |
---|
609 | depend on the JPEG library. You can use the default.prj project file |
---|
610 | of the Pure C distribution to make the programs. |
---|
611 | |
---|
612 | There is a bug in some older versions of the Turbo C library which causes the |
---|
613 | space used by temporary files created with "tmpfile()" not to be freed after |
---|
614 | an abnormal program exit. If you check your disk afterwards, you will find |
---|
615 | cluster chains that are allocated but not used by a file. This should not |
---|
616 | happen in cjpeg/djpeg/jpegtran, since we enable a signal catcher to explicitly |
---|
617 | close temp files before exiting. But if you use the JPEG library with your |
---|
618 | own code, be sure to supply a signal catcher, or else use a different |
---|
619 | system-dependent memory manager. |
---|
620 | |
---|
621 | |
---|
622 | Cray: |
---|
623 | |
---|
624 | Should you be so fortunate as to be running JPEG on a Cray YMP, there is a |
---|
625 | compiler bug in old versions of Cray's Standard C (prior to 3.1). If you |
---|
626 | still have an old compiler, you'll need to insert a line reading |
---|
627 | "#pragma novector" just before the loop |
---|
628 | for (i = 1; i <= (int) htbl->bits[l]; i++) |
---|
629 | huffsize[p++] = (char) l; |
---|
630 | in fix_huff_tbl (in V5beta1, line 204 of jchuff.c and line 176 of jdhuff.c). |
---|
631 | [This bug may or may not still occur with the current IJG code, but it's |
---|
632 | probably a dead issue anyway...] |
---|
633 | |
---|
634 | |
---|
635 | HP-UX: |
---|
636 | |
---|
637 | If you have HP-UX 7.05 or later with the "software development" C compiler, |
---|
638 | you should run the compiler in ANSI mode. If using the configure script, |
---|
639 | say |
---|
640 | ./configure CC='cc -Aa' |
---|
641 | (or -Ae if you prefer). If configuring by hand, use makefile.ansi and add |
---|
642 | "-Aa" to the CFLAGS line in the makefile. |
---|
643 | |
---|
644 | If you have a pre-7.05 system, or if you are using the non-ANSI C compiler |
---|
645 | delivered with a minimum HP-UX system, then you must use makefile.unix |
---|
646 | (and do NOT add -Aa); or just run configure without the CC option. |
---|
647 | |
---|
648 | On HP 9000 series 800 machines, the HP C compiler is buggy in revisions prior |
---|
649 | to A.08.07. If you get complaints about "not a typedef name", you'll have to |
---|
650 | use makefile.unix, or run configure without the CC option. |
---|
651 | |
---|
652 | |
---|
653 | Macintosh, generic comments: |
---|
654 | |
---|
655 | The supplied user-interface files (cjpeg.c, djpeg.c, etc) are set up to |
---|
656 | provide a Unix-style command line interface. You can use this interface on |
---|
657 | the Mac by means of the ccommand() library routine provided by Metrowerks |
---|
658 | CodeWarrior or Think C. This is only appropriate for testing the library, |
---|
659 | however; to make a user-friendly equivalent of cjpeg/djpeg you'd really want |
---|
660 | to develop a Mac-style user interface. There isn't a complete example |
---|
661 | available at the moment, but there are some helpful starting points: |
---|
662 | 1. Sam Bushell's free "To JPEG" applet provides drag-and-drop conversion to |
---|
663 | JPEG under System 7 and later. This only illustrates how to use the |
---|
664 | compression half of the library, but it does a very nice job of that part. |
---|
665 | The CodeWarrior source code is available from http://www.pobox.com/~jsam. |
---|
666 | 2. Jim Brunner prepared a Mac-style user interface for both compression and |
---|
667 | decompression. Unfortunately, it hasn't been updated since IJG v4, and |
---|
668 | the library's API has changed considerably since then. Still it may be of |
---|
669 | some help, particularly as a guide to compiling the IJG code under Think C. |
---|
670 | Jim's code is available from the Info-Mac archives, at sumex-aim.stanford.edu |
---|
671 | or mirrors thereof; see file /info-mac/dev/src/jpeg-convert-c.hqx. |
---|
672 | |
---|
673 | jmemmac.c is the recommended memory manager back end for Macintosh. It uses |
---|
674 | NewPtr/DisposePtr instead of malloc/free, and has a Mac-specific |
---|
675 | implementation of jpeg_mem_available(). It also creates temporary files that |
---|
676 | follow Mac conventions. (That part of the code relies on System-7-or-later OS |
---|
677 | functions. See the comments in jmemmac.c if you need to run it on System 6.) |
---|
678 | NOTE that USE_MAC_MEMMGR must be defined in jconfig.h to use jmemmac.c. |
---|
679 | |
---|
680 | You can also use jmemnobs.c, if you don't care about handling images larger |
---|
681 | than available memory. If you use any memory manager back end other than |
---|
682 | jmemmac.c, we recommend replacing "malloc" and "free" by "NewPtr" and |
---|
683 | "DisposePtr", because Mac C libraries often have peculiar implementations of |
---|
684 | malloc/free. (For instance, free() may not return the freed space to the |
---|
685 | Mac Memory Manager. This is undesirable for the IJG code because jmemmgr.c |
---|
686 | already clumps space requests.) |
---|
687 | |
---|
688 | |
---|
689 | Macintosh, Metrowerks CodeWarrior: |
---|
690 | |
---|
691 | The Unix-command-line-style interface can be used by defining USE_CCOMMAND. |
---|
692 | You'll also need to define TWO_FILE_COMMANDLINE to avoid stdin/stdout. |
---|
693 | This means that when using the cjpeg/djpeg programs, you'll have to type the |
---|
694 | input and output file names in the "Arguments" text-edit box, rather than |
---|
695 | using the file radio buttons. (Perhaps USE_FDOPEN or USE_SETMODE would |
---|
696 | eliminate the problem, but I haven't heard from anyone who's tried it.) |
---|
697 | |
---|
698 | On 680x0 Macs, Metrowerks defines type "double" as a 10-byte IEEE extended |
---|
699 | float. jmemmgr.c won't like this: it wants sizeof(ALIGN_TYPE) to be a power |
---|
700 | of 2. Add "#define ALIGN_TYPE long" to jconfig.h to eliminate the complaint. |
---|
701 | |
---|
702 | The supplied configuration file jconfig.mac can be used for your jconfig.h; |
---|
703 | it includes all the recommended symbol definitions. If you have AppleScript |
---|
704 | installed, you can run the supplied script makeproj.mac to create CodeWarrior |
---|
705 | project files for the library and the testbed applications, then build the |
---|
706 | library and applications. (Thanks to Dan Sears and Don Agro for this nifty |
---|
707 | hack, which saves us from trying to maintain CodeWarrior project files as part |
---|
708 | of the IJG distribution...) |
---|
709 | |
---|
710 | |
---|
711 | Macintosh, Think C: |
---|
712 | |
---|
713 | The documentation in Jim Brunner's "JPEG Convert" source code (see above) |
---|
714 | includes detailed build instructions for Think C; it's probably somewhat |
---|
715 | out of date for the current release, but may be helpful. |
---|
716 | |
---|
717 | If you want to build the minimal command line version, proceed as follows. |
---|
718 | You'll have to prepare project files for the programs; we don't include any |
---|
719 | in the distribution since they are not text files. Use the file lists in |
---|
720 | any of the supplied makefiles as a guide. Also add the ANSI and Unix C |
---|
721 | libraries in a separate segment. You may need to divide the JPEG files into |
---|
722 | more than one segment; we recommend dividing compression and decompression |
---|
723 | modules. Define USE_CCOMMAND in jconfig.h so that the ccommand() routine is |
---|
724 | called. You must also define TWO_FILE_COMMANDLINE because stdin/stdout |
---|
725 | don't handle binary data correctly. |
---|
726 | |
---|
727 | On 680x0 Macs, Think C defines type "double" as a 12-byte IEEE extended float. |
---|
728 | jmemmgr.c won't like this: it wants sizeof(ALIGN_TYPE) to be a power of 2. |
---|
729 | Add "#define ALIGN_TYPE long" to jconfig.h to eliminate the complaint. |
---|
730 | |
---|
731 | jconfig.mac should work as a jconfig.h configuration file for Think C, |
---|
732 | but the makeproj.mac AppleScript script is specific to CodeWarrior. Sorry. |
---|
733 | |
---|
734 | |
---|
735 | MIPS R3000: |
---|
736 | |
---|
737 | MIPS's cc version 1.31 has a rather nasty optimization bug. Don't use -O |
---|
738 | if you have that compiler version. (Use "cc -V" to check the version.) |
---|
739 | Note that the R3000 chip is found in workstations from DEC and others. |
---|
740 | |
---|
741 | |
---|
742 | MS-DOS, generic comments for 16-bit compilers: |
---|
743 | |
---|
744 | The IJG code is designed to work well in 80x86 "small" or "medium" memory |
---|
745 | models (i.e., data pointers are 16 bits unless explicitly declared "far"; |
---|
746 | code pointers can be either size). You may be able to use small model to |
---|
747 | compile cjpeg or djpeg by itself, but you will probably have to use medium |
---|
748 | model for any larger application. This won't make much difference in |
---|
749 | performance. You *will* take a noticeable performance hit if you use a |
---|
750 | large-data memory model, and you should avoid "huge" model if at all |
---|
751 | possible. Be sure that NEED_FAR_POINTERS is defined in jconfig.h if you use |
---|
752 | a small-data memory model; be sure it is NOT defined if you use a large-data |
---|
753 | model. (The supplied makefiles and jconfig files for Borland and Microsoft C |
---|
754 | compile in medium model and define NEED_FAR_POINTERS.) |
---|
755 | |
---|
756 | The DOS-specific memory manager, jmemdos.c, should be used if possible. |
---|
757 | It needs some assembly-code routines which are in jmemdosa.asm; make sure |
---|
758 | your makefile assembles that file and includes it in the library. If you |
---|
759 | don't have a suitable assembler, you can get pre-assembled object files for |
---|
760 | jmemdosa by FTP from ftp.uu.net:/graphics/jpeg/jdosaobj.zip. (DOS-oriented |
---|
761 | distributions of the IJG source code often include these object files.) |
---|
762 | |
---|
763 | When using jmemdos.c, jconfig.h must define USE_MSDOS_MEMMGR and must set |
---|
764 | MAX_ALLOC_CHUNK to less than 64K (65520L is a typical value). If your |
---|
765 | C library's far-heap malloc() can't allocate blocks that large, reduce |
---|
766 | MAX_ALLOC_CHUNK to whatever it can handle. |
---|
767 | |
---|
768 | If you can't use jmemdos.c for some reason --- for example, because you |
---|
769 | don't have an assembler to assemble jmemdosa.asm --- you'll have to fall |
---|
770 | back to jmemansi.c or jmemname.c. You'll probably still need to set |
---|
771 | MAX_ALLOC_CHUNK in jconfig.h, because most DOS C libraries won't malloc() |
---|
772 | more than 64K at a time. IMPORTANT: if you use jmemansi.c or jmemname.c, |
---|
773 | you will have to compile in a large-data memory model in order to get the |
---|
774 | right stdio library. Too bad. |
---|
775 | |
---|
776 | wrjpgcom needs to be compiled in large model, because it malloc()s a 64KB |
---|
777 | work area to hold the comment text. If your C library's malloc can't |
---|
778 | handle that, reduce MAX_COM_LENGTH as necessary in wrjpgcom.c. |
---|
779 | |
---|
780 | Most MS-DOS compilers treat stdin/stdout as text files, so you must use |
---|
781 | two-file command line style. But if your compiler has either fdopen() or |
---|
782 | setmode(), you can use one-file style if you like. To do this, define |
---|
783 | USE_SETMODE or USE_FDOPEN so that stdin/stdout will be set to binary mode. |
---|
784 | (USE_SETMODE seems to work with more DOS compilers than USE_FDOPEN.) You |
---|
785 | should test that I/O through stdin/stdout produces the same results as I/O |
---|
786 | to explicitly named files... the "make test" procedures in the supplied |
---|
787 | makefiles do NOT use stdin/stdout. |
---|
788 | |
---|
789 | |
---|
790 | MS-DOS, generic comments for 32-bit compilers: |
---|
791 | |
---|
792 | None of the above comments about memory models apply if you are using a |
---|
793 | 32-bit flat-memory-space environment, such as DJGPP or Watcom C. (And you |
---|
794 | should use one if you have it, as performance will be much better than |
---|
795 | 8086-compatible code!) For flat-memory-space compilers, do NOT define |
---|
796 | NEED_FAR_POINTERS, and do NOT use jmemdos.c. Use jmemnobs.c if the |
---|
797 | environment supplies adequate virtual memory, otherwise use jmemansi.c or |
---|
798 | jmemname.c. |
---|
799 | |
---|
800 | You'll still need to be careful about binary I/O through stdin/stdout. |
---|
801 | See the last paragraph of the previous section. |
---|
802 | |
---|
803 | |
---|
804 | MS-DOS, Borland C: |
---|
805 | |
---|
806 | Be sure to convert all the source files to DOS text format (CR/LF newlines). |
---|
807 | Although Borland C will often work OK with unmodified Unix (LF newlines) |
---|
808 | source files, sometimes it will give bogus compile errors. |
---|
809 | "Illegal character '#'" is the most common such error. (This is true with |
---|
810 | Borland C 3.1, but perhaps is fixed in newer releases.) |
---|
811 | |
---|
812 | If you want one-file command line style, just undefine TWO_FILE_COMMANDLINE. |
---|
813 | jconfig.bcc already includes #define USE_SETMODE to make this work. |
---|
814 | (fdopen does not work correctly.) |
---|
815 | |
---|
816 | |
---|
817 | MS-DOS, Microsoft C: |
---|
818 | |
---|
819 | makefile.mc6 works with Microsoft C, DOS Visual C++, etc. It should only |
---|
820 | be used if you want to build a 16-bit (small or medium memory model) program. |
---|
821 | |
---|
822 | If you want one-file command line style, just undefine TWO_FILE_COMMANDLINE. |
---|
823 | jconfig.mc6 already includes #define USE_SETMODE to make this work. |
---|
824 | (fdopen does not work correctly.) |
---|
825 | |
---|
826 | Note that this makefile assumes that the working copy of itself is called |
---|
827 | "makefile". If you want to call it something else, say "makefile.mak", |
---|
828 | be sure to adjust the dependency line that reads "$(RFILE) : makefile". |
---|
829 | Otherwise the make will fail because it doesn't know how to create "makefile". |
---|
830 | Worse, some releases of Microsoft's make utilities give an incorrect error |
---|
831 | message in this situation. |
---|
832 | |
---|
833 | Old versions of MS C fail with an "out of macro expansion space" error |
---|
834 | because they can't cope with the macro TRACEMS8 (defined in jerror.h). |
---|
835 | If this happens to you, the easiest solution is to change TRACEMS8 to |
---|
836 | expand to nothing. You'll lose the ability to dump out JPEG coefficient |
---|
837 | tables with djpeg -debug -debug, but at least you can compile. |
---|
838 | |
---|
839 | Original MS C 6.0 is very buggy; it compiles incorrect code unless you turn |
---|
840 | off optimization entirely (remove -O from CFLAGS). 6.00A is better, but it |
---|
841 | still generates bad code if you enable loop optimizations (-Ol or -Ox). |
---|
842 | |
---|
843 | MS C 8.0 crashes when compiling jquant1.c with optimization switch /Oo ... |
---|
844 | which is on by default. To work around this bug, compile that one file |
---|
845 | with /Oo-. |
---|
846 | |
---|
847 | |
---|
848 | Microsoft Windows (all versions), generic comments: |
---|
849 | |
---|
850 | Some Windows system include files define typedef boolean as "unsigned char". |
---|
851 | The IJG code also defines typedef boolean, but we make it "int" by default. |
---|
852 | This doesn't affect the IJG programs because we don't import those Windows |
---|
853 | include files. But if you use the JPEG library in your own program, and some |
---|
854 | of your program's files import one definition of boolean while some import the |
---|
855 | other, you can get all sorts of mysterious problems. A good preventive step |
---|
856 | is to make the IJG library use "unsigned char" for boolean. To do that, |
---|
857 | add something like this to your jconfig.h file: |
---|
858 | /* Define "boolean" as unsigned char, not int, per Windows custom */ |
---|
859 | #ifndef __RPCNDR_H__ /* don't conflict if rpcndr.h already read */ |
---|
860 | typedef unsigned char boolean; |
---|
861 | #endif |
---|
862 | #define HAVE_BOOLEAN /* prevent jmorecfg.h from redefining it */ |
---|
863 | (This is already in jconfig.vc, by the way.) |
---|
864 | |
---|
865 | windef.h contains the declarations |
---|
866 | #define far |
---|
867 | #define FAR far |
---|
868 | Since jmorecfg.h tries to define FAR as empty, you may get a compiler |
---|
869 | warning if you include both jpeglib.h and windef.h (which windows.h |
---|
870 | includes). To suppress the warning, you can put "#ifndef FAR"/"#endif" |
---|
871 | around the line "#define FAR" in jmorecfg.h. |
---|
872 | (Something like this is already in jmorecfg.h, by the way.) |
---|
873 | |
---|
874 | When using the library in a Windows application, you will almost certainly |
---|
875 | want to modify or replace the error handler module jerror.c, since our |
---|
876 | default error handler does a couple of inappropriate things: |
---|
877 | 1. it tries to write error and warning messages on stderr; |
---|
878 | 2. in event of a fatal error, it exits by calling exit(). |
---|
879 | |
---|
880 | A simple stopgap solution for problem 1 is to replace the line |
---|
881 | fprintf(stderr, "%s\n", buffer); |
---|
882 | (in output_message in jerror.c) with |
---|
883 | MessageBox(GetActiveWindow(),buffer,"JPEG Error",MB_OK|MB_ICONERROR); |
---|
884 | It's highly recommended that you at least do that much, since otherwise |
---|
885 | error messages will disappear into nowhere. (Beginning with IJG v6b, this |
---|
886 | code is already present in jerror.c; just define USE_WINDOWS_MESSAGEBOX in |
---|
887 | jconfig.h to enable it.) |
---|
888 | |
---|
889 | The proper solution for problem 2 is to return control to your calling |
---|
890 | application after a library error. This can be done with the setjmp/longjmp |
---|
891 | technique discussed in libjpeg.txt and illustrated in example.c. (NOTE: |
---|
892 | some older Windows C compilers provide versions of setjmp/longjmp that |
---|
893 | don't actually work under Windows. You may need to use the Windows system |
---|
894 | functions Catch and Throw instead.) |
---|
895 | |
---|
896 | The recommended memory manager under Windows is jmemnobs.c; in other words, |
---|
897 | let Windows do any virtual memory management needed. You should NOT use |
---|
898 | jmemdos.c nor jmemdosa.asm under Windows. |
---|
899 | |
---|
900 | For Windows 3.1, we recommend compiling in medium or large memory model; |
---|
901 | for newer Windows versions, use a 32-bit flat memory model. (See the MS-DOS |
---|
902 | sections above for more info about memory models.) In the 16-bit memory |
---|
903 | models only, you'll need to put |
---|
904 | #define MAX_ALLOC_CHUNK 65520L /* Maximum request to malloc() */ |
---|
905 | into jconfig.h to limit allocation chunks to 64Kb. (Without that, you'd |
---|
906 | have to use huge memory model, which slows things down unnecessarily.) |
---|
907 | jmemnobs.c works without modification in large or flat memory models, but to |
---|
908 | use medium model, you need to modify its jpeg_get_large and jpeg_free_large |
---|
909 | routines to allocate far memory. In any case, you might like to replace |
---|
910 | its calls to malloc and free with direct calls on Windows memory allocation |
---|
911 | functions. |
---|
912 | |
---|
913 | You may also want to modify jdatasrc.c and jdatadst.c to use Windows file |
---|
914 | operations rather than fread/fwrite. This is only necessary if your C |
---|
915 | compiler doesn't provide a competent implementation of C stdio functions. |
---|
916 | |
---|
917 | You might want to tweak the RGB_xxx macros in jmorecfg.h so that the library |
---|
918 | will accept or deliver color pixels in BGR sample order, not RGB; BGR order |
---|
919 | is usually more convenient under Windows. Note that this change will break |
---|
920 | the sample applications cjpeg/djpeg, but the library itself works fine. |
---|
921 | |
---|
922 | |
---|
923 | Many people want to convert the IJG library into a DLL. This is reasonably |
---|
924 | straightforward, but watch out for the following: |
---|
925 | |
---|
926 | 1. Don't try to compile as a DLL in small or medium memory model; use |
---|
927 | large model, or even better, 32-bit flat model. Many places in the IJG code |
---|
928 | assume the address of a local variable is an ordinary (not FAR) pointer; |
---|
929 | that isn't true in a medium-model DLL. |
---|
930 | |
---|
931 | 2. Microsoft C cannot pass file pointers between applications and DLLs. |
---|
932 | (See Microsoft Knowledge Base, PSS ID Number Q50336.) So jdatasrc.c and |
---|
933 | jdatadst.c don't work if you open a file in your application and then pass |
---|
934 | the pointer to the DLL. One workaround is to make jdatasrc.c/jdatadst.c |
---|
935 | part of your main application rather than part of the DLL. |
---|
936 | |
---|
937 | 3. You'll probably need to modify the macros GLOBAL() and EXTERN() to |
---|
938 | attach suitable linkage keywords to the exported routine names. Similarly, |
---|
939 | you'll want to modify METHODDEF() and JMETHOD() to ensure function pointers |
---|
940 | are declared in a way that lets application routines be called back through |
---|
941 | the function pointers. These macros are in jmorecfg.h. Typical definitions |
---|
942 | for a 16-bit DLL are: |
---|
943 | #define GLOBAL(type) type _far _pascal _loadds _export |
---|
944 | #define EXTERN(type) extern type _far _pascal _loadds |
---|
945 | #define METHODDEF(type) static type _far _pascal |
---|
946 | #define JMETHOD(type,methodname,arglist) \ |
---|
947 | type (_far _pascal *methodname) arglist |
---|
948 | For a 32-bit DLL you may want something like |
---|
949 | #define GLOBAL(type) __declspec(dllexport) type |
---|
950 | #define EXTERN(type) extern __declspec(dllexport) type |
---|
951 | Although not all the GLOBAL routines are actually intended to be called by |
---|
952 | the application, the performance cost of making them all DLL entry points is |
---|
953 | negligible. |
---|
954 | |
---|
955 | The unmodified IJG library presents a very C-specific application interface, |
---|
956 | so the resulting DLL is only usable from C or C++ applications. There has |
---|
957 | been some talk of writing wrapper code that would present a simpler interface |
---|
958 | usable from other languages, such as Visual Basic. This is on our to-do list |
---|
959 | but hasn't been very high priority --- any volunteers out there? |
---|
960 | |
---|
961 | |
---|
962 | Microsoft Windows, Borland C: |
---|
963 | |
---|
964 | The provided jconfig.bcc should work OK in a 32-bit Windows environment, |
---|
965 | but you'll need to tweak it in a 16-bit environment (you'd need to define |
---|
966 | NEED_FAR_POINTERS and MAX_ALLOC_CHUNK). Beware that makefile.bcc will need |
---|
967 | alteration if you want to use it for Windows --- in particular, you should |
---|
968 | use jmemnobs.c not jmemdos.c under Windows. |
---|
969 | |
---|
970 | Borland C++ 4.5 fails with an internal compiler error when trying to compile |
---|
971 | jdmerge.c in 32-bit mode. If enough people complain, perhaps Borland will fix |
---|
972 | it. In the meantime, the simplest known workaround is to add a redundant |
---|
973 | definition of the variable range_limit in h2v1_merged_upsample(), at the head |
---|
974 | of the block that handles odd image width (about line 268 in v6 jdmerge.c): |
---|
975 | /* If image width is odd, do the last output column separately */ |
---|
976 | if (cinfo->output_width & 1) { |
---|
977 | register JSAMPLE * range_limit = cinfo->sample_range_limit; /* ADD THIS */ |
---|
978 | cb = GETJSAMPLE(*inptr1); |
---|
979 | Pretty bizarre, especially since the very similar routine h2v2_merged_upsample |
---|
980 | doesn't trigger the bug. |
---|
981 | Recent reports suggest that this bug does not occur with "bcc32a" (the |
---|
982 | Pentium-optimized version of the compiler). |
---|
983 | |
---|
984 | Another report from a user of Borland C 4.5 was that incorrect code (leading |
---|
985 | to a color shift in processed images) was produced if any of the following |
---|
986 | optimization switch combinations were used: |
---|
987 | -Ot -Og |
---|
988 | -Ot -Op |
---|
989 | -Ot -Om |
---|
990 | So try backing off on optimization if you see such a problem. (Are there |
---|
991 | several different releases all numbered "4.5"??) |
---|
992 | |
---|
993 | |
---|
994 | Microsoft Windows, Microsoft Visual C++: |
---|
995 | |
---|
996 | jconfig.vc should work OK with any Microsoft compiler for a 32-bit memory |
---|
997 | model. makefile.vc is intended for command-line use. (If you are using |
---|
998 | the Developer Studio environment, you may prefer the DevStudio project |
---|
999 | files; see below.) |
---|
1000 | |
---|
1001 | v7 adds extern "C" to jpeglib.h. This avoids the need to put extern "C" |
---|
1002 | { ... } around #include "jpeglib.h" in your C++ application. |
---|
1003 | You can also force VC++ to treat the library as C++ code by renaming |
---|
1004 | all the *.c files to *.cpp (and adjusting the makefile to match). |
---|
1005 | In this case you also need to define the symbol DONT_USE_EXTERN_C in |
---|
1006 | the configuration to prevent jpeglib.h from using extern "C". |
---|
1007 | |
---|
1008 | |
---|
1009 | Microsoft Windows, Microsoft Visual C++ 6 Developer Studio: |
---|
1010 | |
---|
1011 | We include makefiles that should work as project files in DevStudio 6.0 or |
---|
1012 | later. There is a library makefile that builds the IJG library as a static |
---|
1013 | Win32 library, and application makefiles that build the sample applications |
---|
1014 | as Win32 console applications. (Even if you only want the library, we |
---|
1015 | recommend building the applications so that you can run the self-test.) |
---|
1016 | |
---|
1017 | To use: |
---|
1018 | 1. Copy jconfig.vc to jconfig.h, makejdsw.vc6 to jpeg.dsw, |
---|
1019 | makeadsw.vc6 to apps.dsw, makejmak.vc6 to jpeg.mak, |
---|
1020 | makejdep.vc6 to jpeg.dep, makejdsp.vc6 to jpeg.dsp, |
---|
1021 | makecmak.vc6 to cjpeg.mak, makecdep.vc6 to cjpeg.dep, |
---|
1022 | makecdsp.vc6 to cjpeg.dsp, makedmak.vc6 to djpeg.mak, |
---|
1023 | makeddep.vc6 to djpeg.dep, makeddsp.vc6 to djpeg.dsp, |
---|
1024 | maketmak.vc6 to jpegtran.mak, maketdep.vc6 to jpegtran.dep, |
---|
1025 | maketdsp.vc6 to jpegtran.dsp, makermak.vc6 to rdjpgcom.mak, |
---|
1026 | makerdep.vc6 to rdjpgcom.dep, makerdsp.vc6 to rdjpgcom.dsp, |
---|
1027 | makewmak.vc6 to wrjpgcom.mak, makewdep.vc6 to wrjpgcom.dep, and |
---|
1028 | makewdsp.vc6 to wrjpgcom.dsp. (Note that the renaming is critical!) |
---|
1029 | 2. Click on jpeg.dsw and apps.dsw to load the project workspaces. |
---|
1030 | (If you are using DevStudio more recent than 6.0, you'll probably |
---|
1031 | get a message saying that the project files are being updated.) |
---|
1032 | 3. Build the library project, then the applications project. |
---|
1033 | 4. Move the application .exe files from `app`\Release to an |
---|
1034 | appropriate location on your path. |
---|
1035 | 5. To perform the self-test, execute the command line |
---|
1036 | NMAKE /f makefile.vc test |
---|
1037 | |
---|
1038 | |
---|
1039 | Microsoft Windows, Microsoft Visual C++ 2008 Developer Studio (v9): |
---|
1040 | |
---|
1041 | We include makefiles that should work as project files in Visual Studio |
---|
1042 | 2008 or later. There is a library makefile that builds the IJG library |
---|
1043 | as a static Win32 library, and application makefiles that build the sample |
---|
1044 | applications as Win32 console applications. (Even if you only want the |
---|
1045 | library, we recommend building the applications so that you can run the |
---|
1046 | self-test.) |
---|
1047 | |
---|
1048 | To use: |
---|
1049 | 1. Copy jconfig.vc to jconfig.h, makejsln.vc9 to jpeg.sln, |
---|
1050 | makeasln.vc9 to apps.sln, makejvcp.vc9 to jpeg.vcproj, |
---|
1051 | makecvcp.vc9 to cjpeg.vcproj, makedvcp.vc9 to djpeg.vcproj, |
---|
1052 | maketvcp.vc9 to jpegtran.vcproj, makervcp.vc9 to rdjpgcom.vcproj, and |
---|
1053 | makewvcp.vc9 to wrjpgcom.vcproj. (Note that the renaming is critical!) |
---|
1054 | 2. Click on jpeg.sln and apps.sln to load the project solutions. |
---|
1055 | (If you are using Visual Studio more recent than 2008 (v9), you'll |
---|
1056 | probably get a message saying that the project files are being |
---|
1057 | updated.) |
---|
1058 | 3. Build the library project, then the applications project. |
---|
1059 | 4. Move the application .exe files from `app`\Release to an |
---|
1060 | appropriate location on your path. |
---|
1061 | 5. To perform the self-test, execute the command line |
---|
1062 | NMAKE /f makefile.vc test |
---|
1063 | |
---|
1064 | |
---|
1065 | OS/2, Borland C++: |
---|
1066 | |
---|
1067 | Watch out for optimization bugs in older Borland compilers; you may need |
---|
1068 | to back off the optimization switch settings. See the comments in |
---|
1069 | makefile.bcc. |
---|
1070 | |
---|
1071 | |
---|
1072 | SGI: |
---|
1073 | |
---|
1074 | On some SGI systems, you may need to set "AR2= ar -ts" in the Makefile. |
---|
1075 | If you are using configure, you can do this by saying |
---|
1076 | ./configure RANLIB='ar -ts' |
---|
1077 | This change is not needed on all SGIs. Use it only if the make fails at the |
---|
1078 | stage of linking the completed programs. |
---|
1079 | |
---|
1080 | On the MIPS R4000 architecture (Indy, etc.), the compiler option "-mips2" |
---|
1081 | reportedly speeds up the float DCT method substantially, enough to make it |
---|
1082 | faster than the default int method (but still slower than the fast int |
---|
1083 | method). If you use -mips2, you may want to alter the default DCT method to |
---|
1084 | be float. To do this, put "#define JDCT_DEFAULT JDCT_FLOAT" in jconfig.h. |
---|
1085 | |
---|
1086 | |
---|
1087 | VMS: |
---|
1088 | |
---|
1089 | On an Alpha/VMS system with MMS, be sure to use the "/Marco=Alpha=1" |
---|
1090 | qualifier with MMS when building the JPEG package. |
---|
1091 | |
---|
1092 | VAX/VMS v5.5-1 may have problems with the test step of the build procedure |
---|
1093 | reporting differences when it compares the original and test images. If the |
---|
1094 | error points to the last block of the files, it is most likely bogus and may |
---|
1095 | be safely ignored. It seems to be because the files are Stream_LF and |
---|
1096 | Backup/Compare has difficulty with the (presumably) null padded files. |
---|
1097 | This problem was not observed on VAX/VMS v6.1 or AXP/VMS v6.1. |
---|