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#include <task.h>
#include <heap.h>
#include <stm32l476xx.h>
typedef struct {
void *next;
uint32_t *stack;
uint32_t *sp;
} task_t;
static task_t *current;
static uint8_t task_disable = 0;
void task_hold(uint8_t hold)
{
if (hold != 0)
task_disable++;
else if (task_disable > 0)
task_disable--;
}
void task_exit(void)
{
// TODO free stack?
// TODO remove from chain
// hopefully current is preserved..?
while (1); // bye
}
task_t *task_create(void (*code)(void), uint32_t stackSize)
{
task_t *t = (task_t *)malloc(sizeof(task_t));
t->next = 0;
t->stack = (uint32_t *)malloc(stackSize);
t->sp = (void *)t->stack + stackSize - 64;//16;
t->sp[13] = (uint32_t)task_exit;
t->sp[14] = (uint32_t)code;
t->sp[15] = 0x01000000;
return t;
}
void task_init(void (*init)(void))
{
current = task_create(init, 4096);
current->next = current;
// bit 0 - priv, bit 1 - psp/msp
asm("\
msr psp, %0; \
mrs r0, control; \
orr r0, r0, #2; \
msr control, r0; \
isb; \
" :: "r" (current->sp));
task_disable = 0;
init();
/*asm("\
cpsie i; \
mov pc, %0; \
" :: "r" (init + 4));*/
}
void task_start(void (*task)(void), uint16_t stackSize)
{
task_hold(1);
task_t *t = task_create(task, stackSize);
t->next = current->next;
current->next = t;
task_hold(0);
}
__attribute__ ((naked))
void PendSV_Handler(void)
{
if (task_disable != 0)
asm("bx lr");
// save state
asm("\
cpsid i; \
isb; \
dsb; \
mrs r0, psp; \
stmdb r0!, {r4-r11}; \
mov %0, r0; \
" : "=r" (current->sp));
current = current->next;
// restore
asm("\
mov r0, %0; \
ldmia r0!, {r4-r11}; \
msr psp, r0; \
isb; \
dsb; \
cpsie i; \
bx lr; \
" :: "r" (current->sp));
}
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