diff options
Diffstat (limited to 'apps/os2/os2_cm3.s')
| -rw-r--r-- | apps/os2/os2_cm3.s | 42 |
1 files changed, 40 insertions, 2 deletions
diff --git a/apps/os2/os2_cm3.s b/apps/os2/os2_cm3.s index dabdfe0..aa18703 100644 --- a/apps/os2/os2_cm3.s +++ b/apps/os2/os2_cm3.s @@ -2,6 +2,15 @@ .cpu cortex-m3 .thumb +.equ PERIPH_BASE , 0x40000000 +.equ APB2PERIPH_BASE , PERIPH_BASE + 0x10000 +.equ GPIOB_BASE , APB2PERIPH_BASE + 0x0C00 + +.equ GPIO_BSRR_OFF , 0x10 +.equ GPIO_BSR_OFF , 0x14 + +# .equ GPIOB 0x40010c00 + .section .text /* @@ -18,7 +27,14 @@ do_first_context_switch: msr psp, r0 // Set CONTROL.SPSEL=1 so that we run with two stacks - mov r0, #2 + mrs r0, control + orr r0, #2 + msr control, r0 + isb + + // Set CONTROL.nPRIV=1 so that we run with in unprivileged mode + mrs r0, control + orr r0, #1 msr control, r0 isb @@ -28,6 +44,27 @@ do_first_context_switch: pop {r4, r5} bx r4 +.thumb_func +.global _ZN7trygvis3os22os10rescheduleEv +_ZN7trygvis3os22os10rescheduleEv: + svc #0 + bx lr + +// A very simple idle task, just to know exactly which registers that are used and what their values are supposed to be. +// Toggles GPIO B, pin #6 on a STM32F103 +.thumb_func +.global asm_idle_task +asm_idle_task: + ldr r0, =0x0020 + ldr r0, =0xffff + ldr r1, =GPIOB_BASE +asm_idle_task_loop: + str r0, [r1, #GPIO_BSRR_OFF] + str r0, [r1, #GPIO_BSR_OFF] + b asm_idle_task_loop +.pool +.size asm_idle_task,.-asm_idle_task + /* When this function is executed {r0-r3,r12,lr,pc} has been pushed to the stack pointed to by PSP. We push the rest of the registers to the PSP. The current stack pointer is the MSP. @@ -42,9 +79,10 @@ PendSV_Handler: // Call select_next_task_sp. after return, r0 points to a task_t bl _ZN7trygvis3os22os16select_next_taskEPh // task_t *select_next_task(uint8_t *current_stack) - // load task_t.stack and task_t.lr into r1 and lr + // load task_t.exc_return and task_t.current_stack into r1 and lr ldm r0, {r1, lr} + // Restore the registers saved on the thread's stack ldmia r1!, {r4 - r11} msr psp, r1 |