84 lines
2.2 KiB
C
84 lines
2.2 KiB
C
#include <stdlib.h>
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#include <stm32f4xx_hal.h>
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#include "misc.h"
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#include "mpconfig.h"
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#include "qstr.h"
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#include "obj.h"
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#include "pendsv.h"
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static void *pendsv_object = NULL;
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void pendsv_init(void) {
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// set PendSV interrupt at lowest priority
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HAL_NVIC_SetPriority(PendSV_IRQn, 0xf, 0xf);
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}
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// call this function to raise a pending exception during an interrupt
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// it will wait until all interrupts are finished then raise the given
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// exception object using nlr_jump in the context of the top-level thread
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void pendsv_nlr_jump(void *o) {
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pendsv_object = o;
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SCB->ICSR = SCB_ICSR_PENDSVSET_Msk;
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}
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// since we play tricks with the stack, the compiler must not generate a
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// prelude for this function
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void pendsv_isr_handler(void) __attribute__((naked));
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void pendsv_isr_handler(void) {
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// re-jig the stack so that when we return from this interrupt handler
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// it returns instead to nlr_jump with argument pendsv_object
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// note that stack has a different layout if DEBUG is enabled
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//
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// on entry to this (naked) function, stack has the following layout:
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//
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// stack layout with DEBUG disabled:
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// sp[6]: pc
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// sp[5]: ?
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// sp[4]: ?
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// sp[3]: ?
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// sp[2]: ?
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// sp[1]: ?
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// sp[0]: r0
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//
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// stack layout with DEBUG enabled:
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// sp[8]: pc
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// sp[7]: lr
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// sp[6]: ?
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// sp[5]: ?
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// sp[4]: ?
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// sp[3]: ?
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// sp[2]: r0
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// sp[1]: 0xfffffff9
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// sp[0]: ?
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__asm volatile (
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"ldr r0, pendsv_object_ptr\n"
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"ldr r0, [r0]\n"
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#if defined(PENDSV_DEBUG)
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"str r0, [sp, #8]\n"
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#else
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"str r0, [sp, #0]\n"
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#endif
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"ldr r0, nlr_jump_ptr\n"
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#if defined(PENDSV_DEBUG)
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"str r0, [sp, #32]\n"
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#else
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"str r0, [sp, #24]\n"
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#endif
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"bx lr\n"
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".align 2\n"
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"pendsv_object_ptr: .word pendsv_object\n"
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"nlr_jump_ptr: .word nlr_jump\n"
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);
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/*
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uint32_t x[2] = {0x424242, 0xdeaddead};
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printf("PendSV: %p\n", x);
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for (uint32_t *p = (uint32_t*)(((uint32_t)x - 15) & 0xfffffff0), i = 64; i > 0; p += 4, i -= 4) {
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printf(" %p: %08x %08x %08x %08x\n", p, (uint)p[0], (uint)p[1], (uint)p[2], (uint)p[3]);
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}
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*/
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}
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