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- /*
- * FreeRTOS Kernel V10.0.0
- * Copyright (C) 2017 Amazon.com, Inc. or its affiliates. All Rights Reserved.
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy of
- * this software and associated documentation files (the "Software"), to deal in
- * the Software without restriction, including without limitation the rights to
- * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
- * the Software, and to permit persons to whom the Software is furnished to do so,
- * subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in all
- * copies or substantial portions of the Software. If you wish to use our Amazon
- * FreeRTOS name, please do so in a fair use way that does not cause confusion.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
- * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
- * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
- * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
- * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
- *
- * http://www.FreeRTOS.org
- * http://aws.amazon.com/freertos
- *
- * 1 tab == 4 spaces!
- */
- /*-----------------------------------------------------------
- * Implementation of functions defined in portable.h for the ARM CM0 port.
- *----------------------------------------------------------*/
- /* Scheduler includes. */
- #include "FreeRTOS.h"
- #include "task.h"
- /*
- * Start first task is a separate function so it can be tested in isolation.
- */
- void vPortStartFirstTask( void );
- /*
- * Exception handlers.
- */
- void xPortPendSVHandler( void );
- void vPortSVCHandler( void );
- /*-----------------------------------------------------------*/
- __asm void vPortSVCHandler( void )
- {
- /* This function is no longer used, but retained for backward
- compatibility. */
- }
- /*-----------------------------------------------------------*/
- __asm void vPortStartFirstTask( void )
- {
- PRESERVE8
- EXTERN __Vectors
- /* Use the NVIC offset register to locate the stack. */
- ldr r0, =__Vectors
- ldr r0, [r0]
- /* Set the msp back to the start of the stack. */
- msr msp, r0
- ldr r3, =pxCurrentTCB /* Obtain location of pxCurrentTCB. */
- ldr r1, [r3]
- ldr r0, [r1] /* The first item in pxCurrentTCB is the task top of stack. */
- adds r0, #32 /* Discard everything up to r0. */
- msr psp, r0 /* This is now the new top of stack to use in the task. */
- movs r0, #2 /* Switch to the psp stack. */
- msr CONTROL, r0
- pop {r0-r5} /* Pop the registers that are saved automatically. */
- mov lr, r5 /* lr is now in r5. */
- cpsie i /* The first task has its context and interrupts can be enabled. */
- pop {pc} /* Finally, pop the PC to jump to the user defined task code. */
- ALIGN
- }
- /*-----------------------------------------------------------*/
- __asm void xPortPendSVHandler( void )
- {
- extern vPortSafeTaskSwitchContext
- extern pxCurrentTCB
- PRESERVE8
- mrs r0, psp
- ldr r3, =pxCurrentTCB /* Get the location of the current TCB. */
- ldr r2, [r3]
- subs r0, #32 /* Make space for the remaining low registers. */
- str r0, [r2] /* Save the new top of stack. */
- stmia r0!, {r4-r7} /* Store the low registers that are not saved automatically. */
- mov r4, r8 /* Store the high registers. */
- mov r5, r9
- mov r6, r10
- mov r7, r11
- stmia r0!, {r4-r7}
- push {r3, r14}
- bl vPortSafeTaskSwitchContext
- pop {r2, r3} /* lr goes in r3. r2 now holds tcb pointer. */
- ldr r1, [r2]
- ldr r0, [r1] /* The first item in pxCurrentTCB is the task top of stack. */
- adds r0, #16 /* Move to the high registers. */
- ldmia r0!, {r4-r7} /* Pop the high registers. */
- mov r8, r4
- mov r9, r5
- mov r10, r6
- mov r11, r7
- msr psp, r0 /* Remember the new top of stack for the task. */
- subs r0, #32 /* Go back for the low registers that are not automatically restored. */
- ldmia r0!, {r4-r7} /* Pop low registers. */
- bx r3
- ALIGN
- }
- /*-----------------------------------------------------------*/
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