2 * FreeRTOS Kernel V10.2.1
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3 * Copyright (C) 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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5 * Permission is hereby granted, free of charge, to any person obtaining a copy of
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6 * this software and associated documentation files (the "Software"), to deal in
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7 * the Software without restriction, including without limitation the rights to
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8 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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9 * the Software, and to permit persons to whom the Software is furnished to do so,
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10 * subject to the following conditions:
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12 * The above copyright notice and this permission notice shall be included in all
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13 * copies or substantial portions of the Software.
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15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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17 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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18 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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19 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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20 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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22 * http://www.FreeRTOS.org
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23 * http://aws.amazon.com/freertos
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25 * 1 tab == 4 spaces!
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27 /* Including FreeRTOSConfig.h here will cause build errors if the header file
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28 contains code not understood by the assembler - for example the 'extern' keyword.
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29 To avoid errors place any such code inside a #ifdef __ICCARM__/#endif block so
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30 the code is included in C files but excluded by the preprocessor in assembly
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31 files (__ICCARM__ is defined by the IAR C compiler but not by the IAR assembler. */
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32 #include <FreeRTOSConfig.h>
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38 EXTERN vTaskSwitchContext
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39 EXTERN vPortSVCHandler_C
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41 PUBLIC xPortPendSVHandler
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42 PUBLIC vPortSVCHandler
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43 PUBLIC vPortStartFirstTask
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44 PUBLIC vPortEnableVFP
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45 PUBLIC vPortRestoreContextOfFirstTask
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46 PUBLIC xIsPrivileged
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47 PUBLIC vResetPrivilege
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49 /*-----------------------------------------------------------*/
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54 /* Get the location of the current TCB. */
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55 ldr r3, =pxCurrentTCB
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58 /* Is the task using the FPU context? If so, push high vfp registers. */
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61 vstmdbeq r0!, {s16-s31}
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63 /* Save the core registers. */
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65 stmdb r0!, {r1, r4-r11, r14}
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67 /* Save the new top of stack into the first member of the TCB. */
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71 mov r0, #configMAX_SYSCALL_INTERRUPT_PRIORITY
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75 bl vTaskSwitchContext
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80 /* The first item in pxCurrentTCB is the task top of stack. */
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83 /* Move onto the second item in the TCB... */
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86 dmb /* Complete outstanding transfers before disabling MPU. */
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87 ldr r2, =0xe000ed94 /* MPU_CTRL register. */
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88 ldr r3, [r2] /* Read the value of MPU_CTRL. */
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89 bic r3, r3, #1 /* r3 = r3 & ~1 i.e. Clear the bit 0 in r3. */
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90 str r3, [r2] /* Disable MPU. */
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92 /* Region Base Address register. */
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94 /* Read 4 sets of MPU registers. */
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96 /* Write 4 sets of MPU registers. */
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99 ldr r2, =0xe000ed94 /* MPU_CTRL register. */
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100 ldr r3, [r2] /* Read the value of MPU_CTRL. */
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101 orr r3, r3, #1 /* r3 = r3 | 1 i.e. Set the bit 0 in r3. */
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102 str r3, [r2] /* Enable MPU. */
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103 dsb /* Force memory writes before continuing. */
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105 /* Pop the registers that are not automatically saved on exception entry. */
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106 ldmia r0!, {r3-r11, r14}
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109 /* Is the task using the FPU context? If so, pop the high vfp registers
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113 vldmiaeq r0!, {s16-s31}
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121 /*-----------------------------------------------------------*/
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124 #ifndef USE_PROCESS_STACK /* Code should not be required if a main() is using the process stack. */
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132 b vPortSVCHandler_C
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134 /*-----------------------------------------------------------*/
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136 vPortStartFirstTask:
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137 /* Use the NVIC offset register to locate the stack. */
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138 ldr r0, =0xE000ED08
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141 /* Set the msp back to the start of the stack. */
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143 /* Clear the bit that indicates the FPU is in use in case the FPU was used
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144 before the scheduler was started - which would otherwise result in the
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145 unnecessary leaving of space in the SVC stack for lazy saving of FPU
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149 /* Call SVC to start the first task. */
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156 /*-----------------------------------------------------------*/
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158 vPortRestoreContextOfFirstTask:
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159 /* Use the NVIC offset register to locate the stack. */
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160 ldr r0, =0xE000ED08
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163 /* Set the msp back to the start of the stack. */
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165 /* Restore the context. */
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166 ldr r3, =pxCurrentTCB
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168 /* The first item in the TCB is the task top of stack. */
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170 /* Move onto the second item in the TCB... */
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173 dmb /* Complete outstanding transfers before disabling MPU. */
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174 ldr r2, =0xe000ed94 /* MPU_CTRL register. */
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175 ldr r3, [r2] /* Read the value of MPU_CTRL. */
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176 bic r3, r3, #1 /* r3 = r3 & ~1 i.e. Clear the bit 0 in r3. */
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177 str r3, [r2] /* Disable MPU. */
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179 /* Region Base Address register. */
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180 ldr r2, =0xe000ed9c
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181 /* Read 4 sets of MPU registers. */
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182 ldmia r1!, {r4-r11}
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183 /* Write 4 sets of MPU registers. */
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184 stmia r2!, {r4-r11}
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186 ldr r2, =0xe000ed94 /* MPU_CTRL register. */
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187 ldr r3, [r2] /* Read the value of MPU_CTRL. */
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188 orr r3, r3, #1 /* r3 = r3 | 1 i.e. Set the bit 0 in r3. */
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189 str r3, [r2] /* Enable MPU. */
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190 dsb /* Force memory writes before continuing. */
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192 /* Pop the registers that are not automatically saved on exception entry. */
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193 ldmia r0!, {r3-r11, r14}
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195 /* Restore the task stack pointer. */
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201 /*-----------------------------------------------------------*/
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204 /* The FPU enable bits are in the CPACR. */
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205 ldr.w r0, =0xE000ED88
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208 /* Enable CP10 and CP11 coprocessors, then save back. */
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209 orr r1, r1, #( 0xf << 20 )
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213 /*-----------------------------------------------------------*/
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216 mrs r0, control /* r0 = CONTROL. */
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217 tst r0, #1 /* Perform r0 & 1 (bitwise AND) and update the conditions flag. */
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219 movne r0, #0 /* CONTROL[0]!=0. Return false to indicate that the processor is not privileged. */
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220 moveq r0, #1 /* CONTROL[0]==0. Return true to indicate that the processor is privileged. */
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221 bx lr /* Return. */
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222 /*-----------------------------------------------------------*/
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225 mrs r0, control /* r0 = CONTROL. */
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226 orr r0, r0, #1 /* r0 = r0 | 1. */
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227 msr control, r0 /* CONTROL = r0. */
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228 bx lr /* Return to the caller. */
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229 /*-----------------------------------------------------------*/
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