diff options
Diffstat (limited to 'stm/pendsv.c')
| -rw-r--r-- | stm/pendsv.c | 40 |
1 files changed, 37 insertions, 3 deletions
diff --git a/stm/pendsv.c b/stm/pendsv.c index e8e5b840c6..216bb4db09 100644 --- a/stm/pendsv.c +++ b/stm/pendsv.c @@ -22,15 +22,51 @@ void pendsv_nlr_jump(mp_obj_t o) { SCB->ICSR = SCB_ICSR_PENDSVSET_Msk; } +// since we play tricks with the stack, the compiler must not generate a +// prelude for this function +void pendsv_isr_handler(void) __attribute__((naked)); + void pendsv_isr_handler(void) { // re-jig the stack so that when we return from this interrupt handler // it returns instead to nlr_jump with argument pendsv_object + // note that stack has a different layout if DEBUG is enabled + // + // on entry to this (naked) function, stack has the following layout: + // + // stack layout with DEBUG disabled: + // sp[6]: pc + // sp[5]: ? + // sp[4]: ? + // sp[3]: ? + // sp[2]: ? + // sp[1]: ? + // sp[0]: r0 + // + // stack layout with DEBUG enabled: + // sp[8]: pc + // sp[7]: lr + // sp[6]: ? + // sp[5]: ? + // sp[4]: ? + // sp[3]: ? + // sp[2]: r0 + // sp[1]: 0xfffffff9 + // sp[0]: ? + __asm volatile ( "ldr r0, pendsv_object_ptr\n" "ldr r0, [r0]\n" +#if defined(PENDSV_DEBUG) + "str r0, [sp, #8]\n" +#else "str r0, [sp, #0]\n" +#endif "ldr r0, nlr_jump_ptr\n" +#if defined(PENDSV_DEBUG) + "str r0, [sp, #32]\n" +#else "str r0, [sp, #24]\n" +#endif "bx lr\n" ".align 2\n" "pendsv_object_ptr: .word pendsv_object\n" @@ -38,12 +74,10 @@ void pendsv_isr_handler(void) { ); /* - sp[0] = r0 = exception to raise - sp[6] = pc = nlr_jump uint32_t x[2] = {0x424242, 0xdeaddead}; printf("PendSV: %p\n", x); for (uint32_t *p = (uint32_t*)(((uint32_t)x - 15) & 0xfffffff0), i = 64; i > 0; p += 4, i -= 4) { - printf(" %p: %08x %08x %08x %08x\n", p, p[0], p[1], p[2], p[3]); + printf(" %p: %08x %08x %08x %08x\n", p, (uint)p[0], (uint)p[1], (uint)p[2], (uint)p[3]); } */ } |