1 | /*-------------------------------------------------------------------------+ |
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2 | | timer.c v1.1 - PC386 BSP - 1997/08/07 |
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3 | +--------------------------------------------------------------------------+ |
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4 | | This file contains the PC386 timer package. |
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5 | +--------------------------------------------------------------------------+ |
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6 | | NOTE: It is important that the timer start/stop overhead be determined |
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7 | | when porting or modifying this code. |
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8 | +--------------------------------------------------------------------------+ |
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9 | | (C) Copyright 1997 - |
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10 | | - NavIST Group - Real-Time Distributed Systems and Industrial Automation |
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11 | | |
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12 | | http://pandora.ist.utl.pt |
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13 | | |
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14 | | Instituto Superior Tecnico * Lisboa * PORTUGAL |
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15 | +--------------------------------------------------------------------------+ |
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16 | | Disclaimer: |
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17 | | |
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18 | | This file is provided "AS IS" without warranty of any kind, either |
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19 | | expressed or implied. |
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20 | +--------------------------------------------------------------------------+ |
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21 | | This code is base on: |
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22 | | timer.c,v 1.7 1995/12/19 20:07:43 joel Exp - go32 BSP |
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23 | | With the following copyright notice: |
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24 | | ************************************************************************** |
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25 | | * COPYRIGHT (c) 1989, 1990, 1991, 1992, 1993, 1994. * |
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26 | | * On-Line Applications Research Corporation (OAR). * |
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27 | | * All rights assigned to U.S. Government, 1994. * |
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28 | | * * |
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29 | | * This material may be reproduced by or for the U.S. Government pursuant * |
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30 | | * to the copyright license under the clause at DFARS 252.227-7013. This * |
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31 | | * notice must appear in all copies of this file and its derivatives. * |
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32 | | ************************************************************************** |
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33 | +--------------------------------------------------------------------------*/ |
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34 | |
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35 | |
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36 | #include <stdlib.h> |
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37 | |
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38 | #include <bsp.h> |
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39 | #include <irq.h> |
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40 | |
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41 | /*-------------------------------------------------------------------------+ |
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42 | | Constants |
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43 | +--------------------------------------------------------------------------*/ |
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44 | #define TIMER_IRQ 0x00 /* Timer IRQ. */ |
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45 | #define AVG_OVERHEAD 0 /* 0.1 microseconds to start/stop timer. */ |
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46 | #define LEAST_VALID 1 /* Don't trust a value lower than this. */ |
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47 | |
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48 | /*-------------------------------------------------------------------------+ |
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49 | | Global Variables |
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50 | +--------------------------------------------------------------------------*/ |
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51 | volatile rtems_unsigned32 Ttimer_val; |
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52 | rtems_boolean Timer_driver_Find_average_overhead = TRUE; |
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53 | |
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54 | /*-------------------------------------------------------------------------+ |
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55 | | Pentium optimized timer handling. |
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56 | +--------------------------------------------------------------------------*/ |
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57 | #if defined(pentium) |
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58 | |
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59 | /*-------------------------------------------------------------------------+ |
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60 | | Function: rdtsc |
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61 | | Description: Read the value of PENTIUM on-chip cycle counter. |
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62 | | Global Variables: None. |
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63 | | Arguments: None. |
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64 | | Returns: Value of PENTIUM on-chip cycle counter. |
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65 | +--------------------------------------------------------------------------*/ |
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66 | static inline unsigned long long |
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67 | rdtsc(void) |
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68 | { |
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69 | /* Return the value of the on-chip cycle counter. */ |
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70 | unsigned long long result; |
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71 | asm volatile(".byte 0x0F, 0x31" : "=A" (result)); |
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72 | return result; |
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73 | } /* rdtsc */ |
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74 | |
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75 | |
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76 | /*-------------------------------------------------------------------------+ |
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77 | | Function: Timer_exit |
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78 | | Description: Timer cleanup routine at RTEMS exit. NOTE: This routine is |
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79 | | not really necessary, since there will be a reset at exit. |
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80 | | Global Variables: None. |
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81 | | Arguments: None. |
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82 | | Returns: Nothing. |
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83 | +--------------------------------------------------------------------------*/ |
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84 | void |
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85 | Timer_exit(void) |
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86 | { |
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87 | PC386_disableIrq(TIMER_IRQ); |
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88 | } /* Timer_exit */ |
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89 | |
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90 | |
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91 | /*-------------------------------------------------------------------------+ |
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92 | | Function: Timer_initialize |
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93 | | Description: Timer initialization routine. |
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94 | | Global Variables: Ttimer_val. |
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95 | | Arguments: None. |
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96 | | Returns: Nothing. |
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97 | +--------------------------------------------------------------------------*/ |
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98 | void |
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99 | Timer_initialize(void) |
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100 | { |
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101 | static rtems_boolean First = TRUE; |
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102 | |
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103 | if (First) |
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104 | { |
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105 | First = FALSE; |
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106 | |
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107 | atexit(Timer_exit); /* Try not to hose the system at exit. */ |
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108 | PC386_enableIrq(TIMER_IRQ); |
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109 | /* Disable the programmable timer so ticks don't interfere. */ |
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110 | } |
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111 | Ttimer_val = rdtsc(); /* read starting time */ |
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112 | } /* Timer_initialize */ |
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113 | |
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114 | |
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115 | /*-------------------------------------------------------------------------+ |
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116 | | Function: Read_timer |
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117 | | Description: Read hardware timer value. |
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118 | | Global Variables: Ttimer_val, Timer_driver_Find_average_overhead. |
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119 | | Arguments: None. |
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120 | | Returns: Nothing. |
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121 | +--------------------------------------------------------------------------*/ |
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122 | rtems_unsigned32 |
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123 | Read_timer(void) |
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124 | { |
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125 | register rtems_unsigned32 total; |
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126 | |
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127 | total = (rtems_unsigned32)(rdtsc() - Ttimer_val); |
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128 | |
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129 | if (Timer_driver_Find_average_overhead) |
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130 | return total; |
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131 | else if (total < LEAST_VALID) |
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132 | return 0; /* below timer resolution */ |
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133 | else |
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134 | return (total - AVG_OVERHEAD); |
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135 | } /* Read_timer */ |
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136 | |
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137 | #else /* pentium */ |
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138 | |
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139 | /*-------------------------------------------------------------------------+ |
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140 | | Non-Pentium timer handling. |
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141 | +--------------------------------------------------------------------------*/ |
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142 | #define US_PER_ISR 250 /* Number of micro-seconds per timer interruption */ |
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143 | |
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144 | /*-------------------------------------------------------------------------+ |
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145 | | External Prototypes |
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146 | +--------------------------------------------------------------------------*/ |
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147 | extern rtems_isr timerisr(rtems_vector_number); |
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148 | /* timer (int 08h) Interrupt Service Routine (defined in 'timerisr.s') */ |
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149 | |
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150 | /*-------------------------------------------------------------------------+ |
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151 | | Function: Timer_exit |
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152 | | Description: Timer cleanup routine at RTEMS exit. NOTE: This routine is |
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153 | | not really necessary, since there will be a reset at exit. |
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154 | | Global Variables: None. |
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155 | | Arguments: None. |
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156 | | Returns: Nothing. |
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157 | +--------------------------------------------------------------------------*/ |
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158 | void |
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159 | Timer_exit(void) |
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160 | { |
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161 | /* reset timer mode to standard (DOS) value */ |
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162 | outport_byte(TIMER_MODE, TIMER_SEL0|TIMER_16BIT|TIMER_RATEGEN); |
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163 | outport_byte(TIMER_CNTR0, 0); |
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164 | outport_byte(TIMER_CNTR0, 0); |
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165 | } /* Timer_exit */ |
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166 | |
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167 | |
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168 | /*-------------------------------------------------------------------------+ |
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169 | | Function: Timer_initialize |
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170 | | Description: Timer initialization routine. |
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171 | | Global Variables: Ttimer_val. |
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172 | | Arguments: None. |
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173 | | Returns: Nothing. |
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174 | +--------------------------------------------------------------------------*/ |
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175 | void |
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176 | Timer_initialize(void) |
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177 | { |
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178 | static rtems_boolean First = TRUE; |
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179 | |
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180 | if (First) |
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181 | { |
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182 | First = FALSE; |
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183 | |
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184 | atexit(Timer_exit); /* Try not to hose the system at exit. */ |
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185 | |
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186 | /* install a raw interrupt handler for timer */ |
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187 | PC386_installRawIrqHandler(TIMER_IRQ, timerisr); |
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188 | |
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189 | /* load timer for US_PER_ISR microsecond period */ |
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190 | outport_byte(TIMER_MODE, TIMER_SEL0|TIMER_16BIT|TIMER_RATEGEN); |
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191 | outport_byte(TIMER_CNTR0, US_TO_TICK(US_PER_ISR) >> 0 & 0xff); |
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192 | outport_byte(TIMER_CNTR0, US_TO_TICK(US_PER_ISR) >> 8 & 0xff); |
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193 | } |
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194 | /* wait for ISR to be called at least once */ |
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195 | Ttimer_val = 0; |
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196 | while (Ttimer_val == 0) |
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197 | continue; |
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198 | Ttimer_val = 0; |
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199 | } /* Timer_initialize */ |
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200 | |
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201 | |
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202 | /*-------------------------------------------------------------------------+ |
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203 | | Function: Read_timer |
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204 | | Description: Read hardware timer value. |
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205 | | Global Variables: Ttimer_val, Timer_driver_Find_average_overhead. |
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206 | | Arguments: None. |
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207 | | Returns: Nothing. |
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208 | +--------------------------------------------------------------------------*/ |
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209 | rtems_unsigned32 |
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210 | Read_timer(void) |
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211 | { |
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212 | register rtems_unsigned32 total, clicks; |
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213 | register rtems_unsigned8 lsb, msb; |
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214 | |
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215 | outport_byte(TIMER_MODE, TIMER_SEL0|TIMER_LATCH); |
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216 | inport_byte(TIMER_CNTR0, lsb); |
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217 | inport_byte(TIMER_CNTR0, msb); |
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218 | clicks = (msb << 8) | lsb; |
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219 | total = (Ttimer_val * US_PER_ISR) + (US_PER_ISR - TICK_TO_US(clicks)); |
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220 | |
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221 | if (Timer_driver_Find_average_overhead) |
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222 | return total; |
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223 | else if (total < LEAST_VALID) |
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224 | return 0; /* below timer resolution */ |
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225 | else |
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226 | return (total - AVG_OVERHEAD); |
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227 | } |
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228 | |
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229 | #endif /* pentium */ |
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230 | |
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231 | |
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232 | /*-------------------------------------------------------------------------+ |
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233 | | Function: Empty_function |
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234 | | Description: Empty function used in time tests. |
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235 | | Global Variables: None. |
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236 | | Arguments: None. |
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237 | | Returns: Nothing. |
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238 | +--------------------------------------------------------------------------*/ |
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239 | rtems_status_code Empty_function(void) |
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240 | { |
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241 | return RTEMS_SUCCESSFUL; |
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242 | } /* Empty function */ |
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243 | |
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244 | |
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245 | /*-------------------------------------------------------------------------+ |
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246 | | Function: Set_find_average_overhead |
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247 | | Description: Set internal Timer_driver_Find_average_overhead flag value. |
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248 | | Global Variables: Timer_driver_Find_average_overhead. |
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249 | | Arguments: find_flag - new value of the flag. |
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250 | | Returns: Nothing. |
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251 | +--------------------------------------------------------------------------*/ |
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252 | void |
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253 | Set_find_average_overhead(rtems_boolean find_flag) |
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254 | { |
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255 | Timer_driver_Find_average_overhead = find_flag; |
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256 | } /* Set_find_average_overhead */ |
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