135 lines
5.9 KiB
C
135 lines
5.9 KiB
C
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/*
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* FreeRTOS Kernel V10.0.0
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* Copyright (C) 2017 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy of
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* this software and associated documentation files (the "Software"), to deal in
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* the Software without restriction, including without limitation the rights to
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* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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* the Software, and to permit persons to whom the Software is furnished to do so,
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* subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software. If you wish to use our Amazon
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* FreeRTOS name, please do so in a fair use way that does not cause confusion.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*
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* http://www.FreeRTOS.org
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* http://aws.amazon.com/freertos
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*
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* 1 tab == 4 spaces!
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*/
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/*-----------------------------------------------------------
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* Implementation of functions defined in portable.h for the ARM CM0 port.
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*----------------------------------------------------------*/
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/* Scheduler includes. */
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#include "FreeRTOS.h"
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#include "task.h"
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/*
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* Start first task is a separate function so it can be tested in isolation.
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*/
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void vPortStartFirstTask( void ) __attribute__ (( naked ));
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/*
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* Exception handlers.
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*/
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void vPortSVCHandler( void );
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void xPortPendSVHandler( void ) __attribute__ (( naked ));
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/*-----------------------------------------------------------*/
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void vPortStartFirstTask( void )
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{
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__asm volatile(
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" .syntax unified \n"
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" \n"
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#if defined(__SES_ARM)
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" ldr r0, =_vectors \n" /* Locate the stack using _vectors table. */
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#else
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" ldr r0, =__isr_vector \n" /* Locate the stack using __isr_vector table. */
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#endif
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" ldr r0, [r0] \n"
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" msr msp, r0 \n" /* Set the msp back to the start of the stack. */
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" \n"
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" ldr r3, =pxCurrentTCB \n" /* Obtain location of pxCurrentTCB. */
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" ldr r1, [r3] \n"
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" ldr r0, [r1] \n" /* The first item in pxCurrentTCB is the task top of stack. */
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" adds r0, #32 \n" /* Discard everything up to r0 */
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" msr psp, r0 \n" /* This is now the new top of stack to use in the task. */
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" movs r0, #2 \n" /* Switch to the psp stack. */
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" msr CONTROL, r0 \n"
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" pop {r0-r5} \n" /* Pop the registers that are saved automatically. */
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" mov lr, r5 \n" /* lr is now in r5. */
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" cpsie i \n" /* The first task has its context and interrupts can be enabled. */
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" pop {pc} \n" /* Finally, pop the PC to jump to the user defined task code. */
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" \n"
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" .align 2 \n"
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);
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}
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/*-----------------------------------------------------------*/
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void vPortSVCHandler( void )
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{
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/* This function is no longer used, but retained for backward
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compatibility. */
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}
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/*-----------------------------------------------------------*/
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void xPortPendSVHandler( void )
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{
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/* This is a naked function. */
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__asm volatile
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(
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" .syntax unified \n"
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" \n"
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" mrs r0, psp \n"
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" \n"
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" ldr r3, =pxCurrentTCB \n" /* Get the location of the current TCB. */
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" ldr r2, [r3] \n"
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" \n"
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" subs r0, #32 \n" /* Make space for the remaining low registers. */
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" str r0, [r2] \n" /* Save the new top of stack. */
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" stmia r0!, {r4-r7} \n" /* Store the low registers that are not saved automatically. */
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" mov r4, r8 \n" /* Store the high registers. */
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" mov r5, r9 \n"
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" mov r6, r10 \n"
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" mov r7, r11 \n"
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" stmia r0!, {r4-r7} \n"
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" \n"
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" push {r3, r14} \n"
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" bl vPortSafeTaskSwitchContext \n"
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" pop {r2, r3} \n" /* lr goes in r3. r2 now holds tcb pointer. */
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" \n"
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" ldr r1, [r2] \n"
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" ldr r0, [r1] \n" /* The first item in pxCurrentTCB is the task top of stack. */
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" adds r0, #16 \n" /* Move to the high registers. */
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" ldmia r0!, {r4-r7} \n" /* Pop the high registers. */
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" mov r8, r4 \n"
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" mov r9, r5 \n"
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" mov r10, r6 \n"
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" mov r11, r7 \n"
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" \n"
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" msr psp, r0 \n" /* Remember the new top of stack for the task. */
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" \n"
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" subs r0, #32 \n" /* Go back for the low registers that are not automatically restored. */
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" ldmia r0!, {r4-r7} \n" /* Pop low registers. */
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" \n"
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" bx r3 \n"
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" \n"
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" .align 2 \n"
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);
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}
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