1 | /* cpu_asm.c ===> cpu_asm.S or cpu_asm.s |
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2 | * |
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3 | * This file contains the basic algorithms for all assembly code used |
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4 | * in an specific CPU port of RTEMS. These algorithms must be implemented |
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5 | * in assembly language |
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6 | * |
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7 | * NOTE: This is supposed to be a .S or .s file NOT a C file. |
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8 | * |
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9 | * COPYRIGHT (c) 1989-1999. |
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10 | * On-Line Applications Research Corporation (OAR). |
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11 | * |
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12 | * The license and distribution terms for this file may be |
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13 | * found in the file LICENSE in this distribution or at |
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14 | * http://www.OARcorp.com/rtems/license.html. |
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15 | * |
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16 | * $Id$ |
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17 | */ |
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18 | |
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19 | /* |
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20 | * This is supposed to be an assembly file. This means that system.h |
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21 | * and cpu.h should not be included in a "real" cpu_asm file. An |
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22 | * implementation in assembly should include "cpu_asm.h> |
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23 | */ |
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24 | |
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25 | #include <rtems/system.h> |
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26 | #include <rtems/score/cpu.h> |
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27 | /* #include "cpu_asm.h> */ |
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28 | |
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29 | /* |
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30 | * _CPU_Context_save_fp_context |
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31 | * |
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32 | * This routine is responsible for saving the FP context |
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33 | * at *fp_context_ptr. If the point to load the FP context |
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34 | * from is changed then the pointer is modified by this routine. |
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35 | * |
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36 | * Sometimes a macro implementation of this is in cpu.h which dereferences |
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37 | * the ** and a similarly named routine in this file is passed something |
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38 | * like a (Context_Control_fp *). The general rule on making this decision |
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39 | * is to avoid writing assembly language. |
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40 | * |
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41 | * NO_CPU Specific Information: |
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42 | * |
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43 | * XXX document implementation including references if appropriate |
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44 | */ |
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45 | |
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46 | void _CPU_Context_save_fp( |
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47 | void **fp_context_ptr |
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48 | ) |
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49 | { |
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50 | } |
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51 | |
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52 | /* |
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53 | * _CPU_Context_restore_fp_context |
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54 | * |
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55 | * This routine is responsible for restoring the FP context |
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56 | * at *fp_context_ptr. If the point to load the FP context |
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57 | * from is changed then the pointer is modified by this routine. |
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58 | * |
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59 | * Sometimes a macro implementation of this is in cpu.h which dereferences |
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60 | * the ** and a similarly named routine in this file is passed something |
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61 | * like a (Context_Control_fp *). The general rule on making this decision |
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62 | * is to avoid writing assembly language. |
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63 | * |
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64 | * NO_CPU Specific Information: |
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65 | * |
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66 | * XXX document implementation including references if appropriate |
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67 | */ |
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68 | |
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69 | void _CPU_Context_restore_fp( |
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70 | void **fp_context_ptr |
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71 | ) |
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72 | { |
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73 | } |
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74 | |
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75 | /* _CPU_Context_switch |
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76 | * |
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77 | * This routine performs a normal non-FP context switch. |
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78 | * |
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79 | * NO_CPU Specific Information: |
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80 | * |
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81 | * XXX document implementation including references if appropriate |
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82 | */ |
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83 | |
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84 | void _CPU_Context_switch( |
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85 | Context_Control *run, |
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86 | Context_Control *heir |
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87 | ) |
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88 | { |
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89 | } |
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90 | |
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91 | /* |
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92 | * _CPU_Context_restore |
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93 | * |
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94 | * This routine is generally used only to restart self in an |
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95 | * efficient manner. It may simply be a label in _CPU_Context_switch. |
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96 | * |
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97 | * NOTE: May be unnecessary to reload some registers. |
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98 | * |
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99 | * NO_CPU Specific Information: |
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100 | * |
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101 | * XXX document implementation including references if appropriate |
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102 | */ |
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103 | |
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104 | void _CPU_Context_restore( |
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105 | Context_Control *new_context |
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106 | ) |
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107 | { |
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108 | } |
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109 | |
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110 | /* void __ISR_Handler() |
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111 | * |
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112 | * This routine provides the RTEMS interrupt management. |
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113 | * |
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114 | * NO_CPU Specific Information: |
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115 | * |
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116 | * XXX document implementation including references if appropriate |
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117 | */ |
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118 | |
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119 | void _ISR_Handler() |
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120 | { |
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121 | /* |
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122 | * This discussion ignores a lot of the ugly details in a real |
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123 | * implementation such as saving enough registers/state to be |
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124 | * able to do something real. Keep in mind that the goal is |
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125 | * to invoke a user's ISR handler which is written in C and |
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126 | * uses a certain set of registers. |
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127 | * |
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128 | * Also note that the exact order is to a large extent flexible. |
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129 | * Hardware will dictate a sequence for a certain subset of |
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130 | * _ISR_Handler while requirements for setting |
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131 | */ |
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132 | |
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133 | /* |
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134 | * At entry to "common" _ISR_Handler, the vector number must be |
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135 | * available. On some CPUs the hardware puts either the vector |
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136 | * number or the offset into the vector table for this ISR in a |
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137 | * known place. If the hardware does not give us this information, |
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138 | * then the assembly portion of RTEMS for this port will contain |
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139 | * a set of distinct interrupt entry points which somehow place |
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140 | * the vector number in a known place (which is safe if another |
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141 | * interrupt nests this one) and branches to _ISR_Handler. |
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142 | * |
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143 | * save some or all context on stack |
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144 | * may need to save some special interrupt information for exit |
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145 | * |
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146 | * #if ( CPU_HAS_SOFTWARE_INTERRUPT_STACK == TRUE ) |
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147 | * if ( _ISR_Nest_level == 0 ) |
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148 | * switch to software interrupt stack |
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149 | * #endif |
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150 | * |
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151 | * _ISR_Nest_level++; |
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152 | * |
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153 | * _Thread_Dispatch_disable_level++; |
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154 | * |
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155 | * (*_ISR_Vector_table[ vector ])( vector ); |
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156 | * |
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157 | * --_ISR_Nest_level; |
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158 | * |
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159 | * if ( _ISR_Nest_level ) |
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160 | * goto the label "exit interrupt (simple case)" |
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161 | * |
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162 | * #if ( CPU_HAS_SOFTWARE_INTERRUPT_STACK == TRUE ) |
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163 | * restore stack |
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164 | * #endif |
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165 | * |
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166 | * if ( !_Context_Switch_necessary ) |
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167 | * goto the label "exit interrupt (simple case)" |
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168 | * |
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169 | * if ( !_ISR_Signals_to_thread_executing ) |
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170 | * _ISR_Signals_to_thread_executing = FALSE; |
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171 | * goto the label "exit interrupt (simple case)" |
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172 | * |
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173 | * call _Thread_Dispatch() or prepare to return to _ISR_Dispatch |
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174 | * |
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175 | * prepare to get out of interrupt |
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176 | * return from interrupt (maybe to _ISR_Dispatch) |
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177 | * |
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178 | * LABEL "exit interrupt (simple case): |
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179 | * prepare to get out of interrupt |
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180 | * return from interrupt |
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181 | */ |
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182 | } |
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183 | |
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