1 | /* m68k-stub.c |
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2 | * |
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3 | * $Id$ |
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4 | */ |
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5 | |
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6 | #include <efi68k.h> |
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7 | #include <rtems.h> |
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8 | |
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9 | m68k_isr_entry set_vector( |
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10 | rtems_isr_entry handler, |
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11 | rtems_vector_number vector, |
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12 | int type |
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13 | ); |
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14 | |
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15 | |
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16 | void (*exceptionHook)() = 0; |
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17 | |
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18 | void outbyte(char c); |
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19 | char putDebugChar( char c) |
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20 | { |
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21 | outbyte(c); |
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22 | return c; |
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23 | } |
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24 | |
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25 | char inbyte(void); |
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26 | char getDebugChar(void) |
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27 | { |
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28 | return inbyte(); |
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29 | } |
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30 | |
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31 | void flush_i_cache(void) |
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32 | { |
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33 | return; |
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34 | } |
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35 | |
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36 | void *memset(void *p, int c, int n) |
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37 | { |
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38 | register int i; |
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39 | void *s=p; |
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40 | |
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41 | for (i=0;i<n;i++) *((char *)p)++=(char)c; |
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42 | return s; |
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43 | } |
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44 | |
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45 | char *db_strcpy(char *s, const char *t) |
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46 | { |
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47 | char *save=s; |
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48 | while((*s++ = *t++) != '\0'); |
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49 | return save; |
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50 | } |
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51 | |
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52 | int db_strlen(const char *s) |
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53 | { |
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54 | int n; |
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55 | |
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56 | for (n=0; *s!='\0'; s++) n++; |
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57 | return n; |
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58 | } |
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59 | |
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60 | /************************************************************************ |
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61 | * |
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62 | * external low-level support routines |
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63 | */ |
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64 | typedef void (*ExceptionHook)(int); /* pointer to function with int parm */ |
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65 | typedef void (*Function)(); /* pointer to a function */ |
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66 | |
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67 | /* extern Function exceptionHandler(); */ /* assign an exception handler */ |
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68 | extern ExceptionHook exceptionHook; /* hook variable for errors/exceptions */ |
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69 | /* extern void exceptionHandler(int vect, void (*function)()); */ |
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70 | |
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71 | /************************/ |
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72 | /* FORWARD DECLARATIONS */ |
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73 | /************************/ |
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74 | static void initializeRemcomErrorFrame(); |
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75 | |
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76 | /************************************************************************/ |
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77 | /* BUFMAX defines the maximum number of characters in inbound/outbound buffers*/ |
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78 | /* at least NUMREGBYTES*2 are needed for register packets */ |
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79 | #define BUFMAX 400 |
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80 | |
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81 | static char initialized; /* boolean flag. != 0 means we've been initialized */ |
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82 | |
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83 | int remote_debug; |
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84 | /* debug > 0 prints ill-formed commands in valid packets & checksum errors */ |
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85 | |
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86 | static const char hexchars[]="0123456789abcdef"; |
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87 | |
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88 | /* there are 180 bytes of registers on a 68020 w/68881 */ |
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89 | /* many of the fpa registers are 12 byte (96 bit) registers */ |
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90 | #define NUMREGBYTES 180 |
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91 | enum regnames {D0,D1,D2,D3,D4,D5,D6,D7, |
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92 | A0,A1,A2,A3,A4,A5,A6,A7, |
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93 | PS,PC, |
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94 | FP0,FP1,FP2,FP3,FP4,FP5,FP6,FP7, |
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95 | FPCONTROL,FPSTATUS,FPIADDR |
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96 | }; |
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97 | |
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98 | |
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99 | |
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100 | typedef struct FrameStruct |
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101 | { |
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102 | struct FrameStruct *previous; |
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103 | int exceptionPC; /* pc value when this frame created */ |
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104 | int exceptionVector; /* cpu vector causing exception */ |
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105 | short frameSize; /* size of cpu frame in words */ |
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106 | short sr; /* for 68000, this not always sr */ |
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107 | int pc; |
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108 | short format; |
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109 | int fsaveHeader; |
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110 | int morejunk[0]; /* exception frame, fp save... */ |
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111 | } Frame; |
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112 | |
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113 | #define FRAMESIZE 10 |
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114 | int gdbFrameStack[FRAMESIZE]; |
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115 | static Frame *lastFrame; |
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116 | |
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117 | /* |
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118 | * these should not be static cuz they can be used outside this module |
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119 | */ |
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120 | int registers[NUMREGBYTES/4]; |
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121 | int superStack; |
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122 | |
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123 | #define STACKSIZE 600 |
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124 | int remcomStack[STACKSIZE/sizeof(int)]; |
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125 | static int* stackPtr = &remcomStack[STACKSIZE/sizeof(int) - 1]; |
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126 | |
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127 | static ExceptionHook oldExceptionHook; |
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128 | |
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129 | #define SAVE_FP_REGS() |
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130 | #define RESTORE_FP_REGS() |
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131 | |
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132 | void return_to_super(); |
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133 | void return_to_user(); |
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134 | |
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135 | asm(" |
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136 | .text |
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137 | .align 2 |
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138 | .globl return_to_super |
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139 | return_to_super: |
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140 | oriw #0x0700,%sr |
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141 | movel registers+60,%sp /* get new stack pointer */ |
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142 | movel lastFrame,%a0 /* get last frame info */ |
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143 | bra return_to_any |
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144 | |
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145 | .globl return_to_user |
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146 | return_to_user: |
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147 | oriw #0x0700,%sr |
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148 | movel registers+60,%a0 /* get usp */ |
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149 | movel %a0,%usp /* set usp */ |
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150 | movel superStack,%sp /* get original stack pointer */ |
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151 | |
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152 | return_to_any: |
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153 | movel lastFrame,%a0 /* get last frame info */ |
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154 | movel %a0@+,lastFrame /* link in previous frame */ |
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155 | addql #8,%a0 /* skip over pc, vector#*/ |
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156 | movew %a0@+,%d0 /* get # of words in cpu frame */ |
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157 | addw %d0,%a0 /* point to end of data */ |
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158 | addw %d0,%a0 /* point to end of data */ |
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159 | movel %a0,%a1 |
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160 | # |
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161 | # copy the stack frame |
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162 | subql #1,%d0 |
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163 | copyUserLoop: |
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164 | movew %a1@-,%sp@- |
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165 | dbf %d0,copyUserLoop |
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166 | "); |
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167 | RESTORE_FP_REGS() |
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168 | asm(" moveml registers,%d0-%d7/%a0-%a6"); |
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169 | asm(" rte"); /* pop and go! */ |
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170 | |
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171 | #define DISABLE_INTERRUPTS() asm(" oriw #0x0700,%sr"); |
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172 | #define BREAKPOINT() asm(" trap #1"); |
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173 | |
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174 | /* this function is called immediately when a level 7 interrupt occurs */ |
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175 | /* if the previous interrupt level was 7 then we're already servicing */ |
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176 | /* this interrupt and an rte is in order to return to the debugger. */ |
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177 | /* For the 68000, the offset for sr is 6 due to the jsr return address */ |
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178 | asm(" |
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179 | .text |
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180 | .align 2 |
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181 | .globl _debug_level7 |
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182 | _debug_level7: |
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183 | movew %d0,%sp@-"); |
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184 | asm(" movew %sp@(6),%d0"); |
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185 | |
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186 | asm(" andiw #0x700,%d0 |
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187 | cmpiw #0x700,%d0 |
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188 | beq already7 |
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189 | movew %sp@+,%d0 |
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190 | bra _catchException |
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191 | already7: |
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192 | movew %sp@+,%d0"); |
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193 | asm(" lea %sp@(4),%sp"); /* pull off 68000 return address */ |
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194 | |
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195 | asm(" rte"); |
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196 | |
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197 | extern void _catchException (); |
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198 | |
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199 | /* This function is called when an exception occurs. It translates the |
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200 | * return address found on the stack into an exception vector # which |
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201 | * is then handled by either handle_exception or a system handler. |
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202 | * _catchException provides a front end for both. |
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203 | * |
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204 | * stack on entry: stack on exit: |
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205 | * Program counter MSWord exception # MSWord |
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206 | * Program counter LSWord exception # MSWord |
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207 | * Status Register |
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208 | * Return Address MSWord |
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209 | * Return Address LSWord |
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210 | */ |
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211 | |
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212 | asm(" |
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213 | .text |
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214 | .align 2 |
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215 | .globl _catchException |
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216 | _catchException: |
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217 | "); |
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218 | DISABLE_INTERRUPTS(); |
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219 | asm(" |
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220 | moveml %d0-%d7/%a0-%a6,registers /* save registers */ |
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221 | movel lastFrame,%a0 /* last frame pointer */ |
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222 | |
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223 | move.b #64,(0x00600001) |
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224 | move.b (0x00600007),%d0 |
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225 | andib #-64,%d0 |
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226 | move.b %d0,(0x00600007) |
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227 | |
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228 | "); |
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229 | SAVE_FP_REGS(); |
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230 | asm(" |
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231 | lea registers,%a5 /* get address of registers */ |
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232 | movel %sp@+,%d2 /* pop return address */ |
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233 | addq.l #6,%d2 |
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234 | sub.l #0x200000,%d2 |
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235 | divs #6,%d2 |
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236 | /* addl #1530,%d2 */ /* convert return addr to */ |
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237 | /* divs #6,%d2 */ /* exception number */ |
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238 | extl %d2 |
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239 | |
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240 | moveql #3,%d3 /* assume a three word frame */ |
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241 | |
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242 | cmpiw #3,%d2 /* bus error or address error ? */ |
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243 | bgt normal /* if >3 then normal error */ |
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244 | movel %sp@+,%a0@- /* copy error info to frame buff*/ |
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245 | movel %sp@+,%a0@- /* these are never used */ |
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246 | moveql #7,%d3 /* this is a 7 word frame */ |
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247 | |
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248 | normal: |
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249 | movew %sp@+,%d1 /* pop status register */ |
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250 | movel %sp@+,%a4 /* pop program counter */ |
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251 | movew %d1,%a5@(66) /* save sr */ |
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252 | movel %a4,%a5@(68) /* save pc in _regisers[] */ |
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253 | movel %a4,%a0@- /* copy pc to frame buffer */ |
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254 | movew %d1,%a0@- /* copy sr to frame buffer */ |
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255 | |
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256 | movel %sp,superStack /* save supervisor sp */ |
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257 | |
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258 | andiw #0x2000,%d1 /* were we in supervisor mode ? */ |
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259 | beq userMode |
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260 | movel %a7,%a5@(60) /* save a7 */ |
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261 | bra saveDone |
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262 | userMode: |
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263 | movel %usp,%a1 /* save user stack pointer */ |
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264 | movel %a1,%a5@(60) /* save user stack pointer */ |
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265 | saveDone: |
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266 | |
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267 | movew %d3,%a0@- /* push frame size in words */ |
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268 | movel %d2,%a0@- /* push vector number */ |
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269 | movel %a4,%a0@- /* push exception pc */ |
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270 | |
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271 | # |
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272 | # save old frame link and set the new value |
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273 | movel lastFrame,%a1 /* last frame pointer */ |
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274 | movel %a1,%a0@- /* save pointer to prev frame */ |
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275 | movel %a0,lastFrame |
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276 | |
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277 | movel %d2,%sp@- /* push exception num */ |
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278 | movel exceptionHook,%a0 /* get address of handler */ |
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279 | jbsr %a0@ /* and call it */ |
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280 | clrl %sp@ /* replace exception num parm with frame ptr*/ |
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281 | jbsr _returnFromException /* jbsr, but never returns */ |
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282 | "); |
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283 | |
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284 | |
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285 | /* |
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286 | * remcomHandler is a front end for handle_exception. It moves the |
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287 | * stack pointer into an area reserved for debugger use in case the |
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288 | * breakpoint happened in supervisor mode. |
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289 | */ |
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290 | asm("remcomHandler:"); |
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291 | asm(" addl #4,%sp"); /* pop off return address */ |
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292 | asm(" movel %sp@+,%d0"); /* get the exception number */ |
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293 | asm(" movel stackPtr,%sp"); /* move to remcom stack area */ |
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294 | asm(" movel %d0,%sp@-"); /* push exception onto stack */ |
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295 | asm(" andiw #0xf8ff,%sr"); |
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296 | asm(" jbsr handle_exception"); /* this never returns */ |
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297 | asm(" rts"); /* return */ |
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298 | |
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299 | void _returnFromException( Frame *frame ) |
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300 | { |
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301 | /* if no passed in frame, use the last one */ |
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302 | if (! frame) |
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303 | { |
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304 | frame = lastFrame; |
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305 | frame->frameSize = 4; |
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306 | frame->format = 0; |
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307 | frame->fsaveHeader = -1; /* restore regs, but we dont have fsave info*/ |
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308 | } |
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309 | |
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310 | |
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311 | /* a 68000 cannot use the internal info pushed onto a bus error |
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312 | * or address error frame when doing an RTE so don't put this info |
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313 | * onto the stack or the stack will creep every time this happens. |
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314 | */ |
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315 | frame->frameSize=3; |
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316 | |
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317 | |
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318 | /* throw away any frames in the list after this frame */ |
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319 | lastFrame = frame; |
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320 | |
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321 | frame->sr = registers[(int) PS]; |
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322 | frame->pc = registers[(int) PC]; |
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323 | |
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324 | if (registers[(int) PS] & 0x2000) |
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325 | { |
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326 | /* return to supervisor mode... */ |
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327 | return_to_super(); |
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328 | } |
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329 | else |
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330 | { /* return to user mode */ |
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331 | return_to_user(); |
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332 | } |
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333 | } |
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334 | |
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335 | int hex(ch) |
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336 | char ch; |
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337 | { |
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338 | if ((ch >= 'a') && (ch <= 'f')) return (ch-'a'+10); |
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339 | if ((ch >= '0') && (ch <= '9')) return (ch-'0'); |
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340 | if ((ch >= 'A') && (ch <= 'F')) return (ch-'A'+10); |
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341 | return (-1); |
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342 | } |
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343 | |
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344 | |
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345 | /* scan for the sequence $<data>#<checksum> */ |
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346 | void getpacket(buffer) |
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347 | char * buffer; |
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348 | { |
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349 | unsigned char checksum; |
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350 | unsigned char xmitcsum; |
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351 | int i; |
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352 | int count; |
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353 | char ch; |
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354 | |
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355 | do { |
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356 | /* wait around for the start character, ignore all other characters */ |
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357 | while ((ch = getDebugChar()) != '$'); |
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358 | checksum = 0; |
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359 | xmitcsum = -1; |
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360 | |
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361 | count = 0; |
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362 | |
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363 | /* now, read until a # or end of buffer is found */ |
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364 | while (count < BUFMAX) { |
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365 | ch = getDebugChar(); |
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366 | if (ch == '#') break; |
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367 | checksum = checksum + ch; |
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368 | buffer[count] = ch; |
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369 | count = count + 1; |
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370 | } |
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371 | buffer[count] = 0; |
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372 | |
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373 | if (ch == '#') { |
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374 | xmitcsum = hex(getDebugChar()) << 4; |
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375 | xmitcsum += hex(getDebugChar()); |
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376 | |
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377 | if (checksum != xmitcsum) putDebugChar('-'); /* failed checksum */ |
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378 | else { |
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379 | putDebugChar('+'); /* successful transfer */ |
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380 | /* if a sequence char is present, reply the sequence ID */ |
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381 | if (buffer[2] == ':') { |
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382 | putDebugChar( buffer[0] ); |
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383 | putDebugChar( buffer[1] ); |
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384 | /* remove sequence chars from buffer */ |
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385 | count = db_strlen(buffer); |
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386 | for (i=3; i <= count; i++) buffer[i-3] = buffer[i]; |
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387 | } |
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388 | } |
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389 | } |
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390 | } while (checksum != xmitcsum); |
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391 | |
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392 | } |
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393 | |
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394 | /* send the packet in buffer. The host get's one chance to read it. |
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395 | This routine does not wait for a positive acknowledge. */ |
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396 | |
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397 | |
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398 | void putpacket(buffer) |
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399 | char * buffer; |
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400 | { |
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401 | unsigned char checksum; |
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402 | int count; |
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403 | char ch; |
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404 | |
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405 | /* $<packet info>#<checksum>. */ |
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406 | do { |
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407 | putDebugChar('$'); |
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408 | checksum = 0; |
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409 | count = 0; |
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410 | |
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411 | while ((ch=buffer[count])) { |
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412 | if (! putDebugChar(ch)) return; |
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413 | checksum += ch; |
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414 | count += 1; |
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415 | } |
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416 | |
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417 | putDebugChar('#'); |
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418 | putDebugChar(hexchars[checksum >> 4]); |
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419 | putDebugChar(hexchars[checksum % 16]); |
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420 | |
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421 | } while (1 == 0); /* (getDebugChar() != '+'); */ |
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422 | |
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423 | } |
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424 | |
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425 | char remcomInBuffer[BUFMAX]; |
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426 | char remcomOutBuffer[BUFMAX]; |
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427 | static short error; |
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428 | |
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429 | |
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430 | void debug_error(format, parm) |
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431 | char * format; |
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432 | char * parm; |
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433 | { |
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434 | return; |
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435 | } |
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436 | |
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437 | /* convert the memory pointed to by mem into hex, placing result in buf */ |
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438 | /* return a pointer to the last char put in buf (null) */ |
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439 | char* mem2hex(mem, buf, count) |
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440 | char* mem; |
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441 | char* buf; |
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442 | int count; |
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443 | { |
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444 | int i; |
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445 | unsigned char ch; |
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446 | for (i=0;i<count;i++) { |
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447 | ch = *mem++; |
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448 | *buf++ = hexchars[ch >> 4]; |
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449 | *buf++ = hexchars[ch % 16]; |
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450 | } |
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451 | *buf = 0; |
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452 | return(buf); |
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453 | } |
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454 | |
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455 | /* convert the hex array pointed to by buf into binary to be placed in mem */ |
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456 | /* return a pointer to the character AFTER the last byte written */ |
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457 | char* hex2mem(buf, mem, count) |
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458 | char* buf; |
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459 | char* mem; |
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460 | int count; |
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461 | { |
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462 | int i; |
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463 | unsigned char ch; |
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464 | for (i=0;i<count;i++) { |
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465 | ch = hex(*buf++) << 4; |
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466 | ch = ch + hex(*buf++); |
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467 | *mem++ = ch; |
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468 | } |
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469 | return(mem); |
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470 | } |
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471 | |
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472 | /* this function takes the 68000 exception number and attempts to |
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473 | translate this number into a unix compatible signal value */ |
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474 | int computeSignal( exceptionVector ) |
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475 | int exceptionVector; |
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476 | { |
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477 | int sigval; |
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478 | switch (exceptionVector) { |
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479 | case 2 : sigval = 10; break; /* bus error */ |
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480 | case 3 : sigval = 10; break; /* address error */ |
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481 | case 4 : sigval = 4; break; /* illegal instruction */ |
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482 | case 5 : sigval = 8; break; /* zero divide */ |
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483 | case 6 : sigval = 8; break; /* chk instruction */ |
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484 | case 7 : sigval = 8; break; /* trapv instruction */ |
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485 | case 8 : sigval = 11; break; /* privilege violation */ |
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486 | case 9 : sigval = 5; break; /* trace trap */ |
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487 | case 10: sigval = 4; break; /* line 1010 emulator */ |
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488 | case 11: sigval = 4; break; /* line 1111 emulator */ |
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489 | |
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490 | /* Coprocessor protocol violation. Using a standard MMU or FPU |
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491 | this cannot be triggered by software. Call it a SIGBUS. */ |
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492 | case 13: sigval = 10; break; |
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493 | |
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494 | case 31: sigval = 2; break; /* interrupt */ |
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495 | case 33: sigval = 5; break; /* breakpoint */ |
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496 | |
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497 | /* This is a trap #8 instruction. Apparently it is someone's software |
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498 | convention for some sort of SIGFPE condition. Whose? How many |
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499 | people are being screwed by having this code the way it is? |
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500 | Is there a clean solution? */ |
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501 | case 40: sigval = 8; break; /* floating point err */ |
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502 | |
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503 | case 48: sigval = 8; break; /* floating point err */ |
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504 | case 49: sigval = 8; break; /* floating point err */ |
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505 | case 50: sigval = 8; break; /* zero divide */ |
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506 | case 51: sigval = 8; break; /* underflow */ |
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507 | case 52: sigval = 8; break; /* operand error */ |
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508 | case 53: sigval = 8; break; /* overflow */ |
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509 | case 54: sigval = 8; break; /* NAN */ |
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510 | default: |
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511 | sigval = 7; /* "software generated"*/ |
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512 | } |
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513 | return (sigval); |
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514 | } |
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515 | |
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516 | /**********************************************/ |
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517 | /* WHILE WE FIND NICE HEX CHARS, BUILD AN INT */ |
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518 | /* RETURN NUMBER OF CHARS PROCESSED */ |
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519 | /**********************************************/ |
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520 | int hexToInt(char **ptr, int *intValue) |
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521 | { |
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522 | int numChars = 0; |
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523 | int hexValue; |
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524 | |
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525 | *intValue = 0; |
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526 | |
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527 | while (**ptr) |
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528 | { |
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529 | hexValue = hex(**ptr); |
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530 | if (hexValue >=0) |
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531 | { |
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532 | *intValue = (*intValue <<4) | hexValue; |
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533 | numChars ++; |
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534 | } |
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535 | else |
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536 | break; |
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537 | |
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538 | (*ptr)++; |
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539 | } |
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540 | |
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541 | return (numChars); |
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542 | } |
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543 | |
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544 | /* |
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545 | * This function does all command procesing for interfacing to gdb. |
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546 | */ |
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547 | void handle_exception(int exceptionVector) |
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548 | { |
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549 | int sigval; |
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550 | int addr, length; |
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551 | char * ptr; |
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552 | int newPC; |
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553 | Frame *frame; |
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554 | |
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555 | /* reply to host that an exception has occurred */ |
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556 | sigval = computeSignal( exceptionVector ); |
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557 | remcomOutBuffer[0] = 'S'; |
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558 | remcomOutBuffer[1] = hexchars[sigval >> 4]; |
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559 | remcomOutBuffer[2] = hexchars[sigval % 16]; |
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560 | remcomOutBuffer[3] = 0; |
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561 | |
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562 | putpacket(remcomOutBuffer); |
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563 | |
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564 | while (1==1) { |
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565 | error = 0; |
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566 | remcomOutBuffer[0] = 0; |
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567 | getpacket(remcomInBuffer); |
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568 | switch (remcomInBuffer[0]) { |
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569 | case '?' : remcomOutBuffer[0] = 'S'; |
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570 | remcomOutBuffer[1] = hexchars[sigval >> 4]; |
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571 | remcomOutBuffer[2] = hexchars[sigval % 16]; |
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572 | remcomOutBuffer[3] = 0; |
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573 | break; |
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574 | case 'd' : remote_debug = !(remote_debug); /* toggle debug flag */ |
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575 | break; |
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576 | case 'g' : /* return the value of the CPU registers */ |
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577 | mem2hex((char*) registers, remcomOutBuffer, NUMREGBYTES); |
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578 | break; |
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579 | case 'G' : /* set the value of the CPU registers - return OK */ |
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580 | hex2mem(&remcomInBuffer[1], (char*) registers, NUMREGBYTES); |
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581 | db_strcpy(remcomOutBuffer,"OK"); |
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582 | break; |
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583 | |
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584 | /* mAA..AA,LLLL Read LLLL bytes at address AA..AA */ |
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585 | case 'm' : |
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586 | /* TRY TO READ %x,%x. IF SUCCEED, SET PTR = 0 */ |
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587 | ptr = &remcomInBuffer[1]; |
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588 | if (hexToInt(&ptr,&addr)) |
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589 | if (*(ptr++) == ',') |
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590 | if (hexToInt(&ptr,&length)) |
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591 | { |
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592 | ptr = 0; |
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593 | mem2hex((char*) addr, remcomOutBuffer, length); |
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594 | } |
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595 | |
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596 | if (ptr) |
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597 | { |
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598 | db_strcpy(remcomOutBuffer,"E01"); |
---|
599 | debug_error("malformed read memory command: %s",remcomInBuffer); |
---|
600 | } |
---|
601 | break; |
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602 | |
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603 | /* MAA..AA,LLLL: Write LLLL bytes at address AA.AA return OK */ |
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604 | case 'M' : |
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605 | /* TRY TO READ '%x,%x:'. IF SUCCEED, SET PTR = 0 */ |
---|
606 | ptr = &remcomInBuffer[1]; |
---|
607 | if (hexToInt(&ptr,&addr)) |
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608 | if (*(ptr++) == ',') |
---|
609 | if (hexToInt(&ptr,&length)) |
---|
610 | if (*(ptr++) == ':') |
---|
611 | { |
---|
612 | hex2mem(ptr, (char*) addr, length); |
---|
613 | ptr = 0; |
---|
614 | db_strcpy(remcomOutBuffer,"OK"); |
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615 | } |
---|
616 | if (ptr) |
---|
617 | { |
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618 | db_strcpy(remcomOutBuffer,"E02"); |
---|
619 | debug_error("malformed write memory command: %s",remcomInBuffer); |
---|
620 | } |
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621 | break; |
---|
622 | |
---|
623 | /* cAA..AA Continue at address AA..AA(optional) */ |
---|
624 | /* sAA..AA Step one instruction from AA..AA(optional) */ |
---|
625 | case 'c' : |
---|
626 | case 's' : |
---|
627 | /* try to read optional parameter, pc unchanged if no parm */ |
---|
628 | ptr = &remcomInBuffer[1]; |
---|
629 | if (hexToInt(&ptr,&addr)) |
---|
630 | registers[ PC ] = addr; |
---|
631 | |
---|
632 | newPC = registers[ PC]; |
---|
633 | |
---|
634 | /* clear the trace bit */ |
---|
635 | registers[ PS ] &= 0x7fff; |
---|
636 | |
---|
637 | /* set the trace bit if we're stepping */ |
---|
638 | if (remcomInBuffer[0] == 's') registers[ PS ] |= 0x8000; |
---|
639 | |
---|
640 | /* |
---|
641 | * look for newPC in the linked list of exception frames. |
---|
642 | * if it is found, use the old frame it. otherwise, |
---|
643 | * fake up a dummy frame in returnFromException(). |
---|
644 | */ |
---|
645 | frame = lastFrame; |
---|
646 | while (frame) |
---|
647 | { |
---|
648 | if (frame->exceptionPC == newPC) break; /* bingo! a match */ |
---|
649 | /* |
---|
650 | * for a breakpoint instruction, the saved pc may |
---|
651 | * be off by two due to re-executing the instruction |
---|
652 | * replaced by the trap instruction. Check for this. |
---|
653 | */ |
---|
654 | if ((frame->exceptionVector == 33) && |
---|
655 | (frame->exceptionPC == (newPC+2))) break; |
---|
656 | if (frame == frame->previous) |
---|
657 | { |
---|
658 | frame = 0; /* no match found */ |
---|
659 | break; |
---|
660 | } |
---|
661 | frame = frame->previous; |
---|
662 | } |
---|
663 | |
---|
664 | /* |
---|
665 | * If we found a match for the PC AND we are not returning |
---|
666 | * as a result of a breakpoint (33), |
---|
667 | * trace exception (9), nmi (31), jmp to |
---|
668 | * the old exception handler as if this code never ran. |
---|
669 | */ |
---|
670 | if (frame) |
---|
671 | { |
---|
672 | if ((frame->exceptionVector != 9) && |
---|
673 | (frame->exceptionVector != 31) && |
---|
674 | (frame->exceptionVector != 33)) |
---|
675 | { |
---|
676 | /* |
---|
677 | * invoke the previous handler. |
---|
678 | */ |
---|
679 | if (oldExceptionHook) |
---|
680 | (*oldExceptionHook) (frame->exceptionVector); |
---|
681 | newPC = registers[ PC ]; /* pc may have changed */ |
---|
682 | if (newPC != frame->exceptionPC) |
---|
683 | { |
---|
684 | /* re-use the last frame, we're skipping it (longjump?)*/ |
---|
685 | frame = (Frame *) 0; |
---|
686 | _returnFromException( frame ); /* this is a jump */ |
---|
687 | } |
---|
688 | } |
---|
689 | } |
---|
690 | |
---|
691 | /* if we couldn't find a frame, create one */ |
---|
692 | if (frame == 0) |
---|
693 | { |
---|
694 | frame = lastFrame -1 ; |
---|
695 | |
---|
696 | /* by using a bunch of print commands with breakpoints, |
---|
697 | it's possible for the frame stack to creep down. If it creeps |
---|
698 | too far, give up and reset it to the top. Normal use should |
---|
699 | not see this happen. |
---|
700 | */ |
---|
701 | if ((unsigned int) (frame-2) < (unsigned int) &gdbFrameStack) |
---|
702 | { |
---|
703 | initializeRemcomErrorFrame(); |
---|
704 | frame = lastFrame; |
---|
705 | } |
---|
706 | frame->previous = lastFrame; |
---|
707 | lastFrame = frame; |
---|
708 | frame = 0; /* null so _return... will properly initialize it */ |
---|
709 | } |
---|
710 | |
---|
711 | _returnFromException( frame ); /* this is a jump */ |
---|
712 | |
---|
713 | break; |
---|
714 | |
---|
715 | /* kill the program */ |
---|
716 | case 'k' : /* do nothing */ |
---|
717 | break; |
---|
718 | } /* switch */ |
---|
719 | |
---|
720 | /* reply to the request */ |
---|
721 | putpacket(remcomOutBuffer); |
---|
722 | } |
---|
723 | } |
---|
724 | |
---|
725 | |
---|
726 | void |
---|
727 | initializeRemcomErrorFrame() |
---|
728 | { |
---|
729 | lastFrame = ((Frame *) &gdbFrameStack[FRAMESIZE-1]) - 1; |
---|
730 | lastFrame->previous = lastFrame; |
---|
731 | } |
---|
732 | |
---|
733 | /* this function is used to set up exception handlers for tracing and |
---|
734 | breakpoints */ |
---|
735 | void set_debug_traps() |
---|
736 | { |
---|
737 | extern void _debug_level7(); |
---|
738 | extern void remcomHandler(); |
---|
739 | int exception; |
---|
740 | |
---|
741 | initializeRemcomErrorFrame(); |
---|
742 | stackPtr = &remcomStack[STACKSIZE/sizeof(int) - 1]; |
---|
743 | |
---|
744 | for (exception = 2; exception <= 23; exception++) |
---|
745 | set_vector(_catchException,exception,0); |
---|
746 | |
---|
747 | /* level 7 interrupt */ |
---|
748 | set_vector(_debug_level7,31,0); |
---|
749 | |
---|
750 | /* breakpoint exception (trap #1) */ |
---|
751 | set_vector(_catchException,33,0); |
---|
752 | |
---|
753 | /* This is a trap #8 instruction. Apparently it is someone's software |
---|
754 | convention for some sort of SIGFPE condition. Whose? How many |
---|
755 | people are being screwed by having this code the way it is? |
---|
756 | Is there a clean solution? */ |
---|
757 | set_vector(_catchException,40,0); |
---|
758 | |
---|
759 | /* 48 to 54 are floating point coprocessor errors */ |
---|
760 | for (exception = 48; exception <= 54; exception++) |
---|
761 | set_vector(_catchException,exception,0); |
---|
762 | |
---|
763 | if (oldExceptionHook != remcomHandler) |
---|
764 | { |
---|
765 | oldExceptionHook = exceptionHook; |
---|
766 | exceptionHook = remcomHandler; |
---|
767 | } |
---|
768 | |
---|
769 | initialized = 1; |
---|
770 | |
---|
771 | } |
---|
772 | |
---|
773 | /* This function will generate a breakpoint exception. It is used at the |
---|
774 | beginning of a program to sync up with a debugger and can be used |
---|
775 | otherwise as a quick means to stop program execution and "break" into |
---|
776 | the debugger. */ |
---|
777 | |
---|
778 | void breakpoint() |
---|
779 | { |
---|
780 | if (initialized) BREAKPOINT(); |
---|
781 | } |
---|
782 | |
---|