rt-thread移植到atsamd20g18芯片，指令无法使用

发布于 2021-11-29 09:09:46 浏览：809 订阅该版

想要将rt-thread移植到microchip公司的atsamd20g18芯片上， 该芯片是cortex M0+架构，文档原文如下：
![c1be27686aa8689a949a0375a4529127.png.webp](https://oss-club.rt-thread.org/uploads/20211129/c1be27686aa8689a949a0375a4529127.png.webp)

参考了同样是m0+架构的stm32L系列芯片代码，在移植到PendSV_Handler函数时，报了以下错误，
![f5e4ffd39711dfadec574e0b3c56123f.png](https://oss-club.rt-thread.org/uploads/20211129/f5e4ffd39711dfadec574e0b3c56123f.png)

大家有遇到过嘛，这个问题该怎么解决呢？

PendSV_Handler代码如下:
```
.globl PendSV_Handler
PendSV_Handler:
	mrs     r2, PRIMASK
	cpsid   I
	
	ldr     r0, =rt_thread_switch_interrupt_flag
	ldr     r1, [r0]
	cmp		r1, #0
	beq		pendsv_exit

mov    r1, #0x00
	str    r1, [r0]

ldr    r0, =rt_interrupt_from_thread
	ldr    r1, [r0]
	cmp	   r1, #0
	beq	   switch_to_thread

mrs     r1, psp

sub 	r1, r1, #32
	ldr		r0, [r0]
	str		r1, [r0]

stmia   r1!, {r4-r7}
	mov		r4, r8
	mov		r5, r9
	mov		r6, r10
	mov		r7, r11
	stmia	r1!, {r4-r7}

switch_to_thread:
	ldr     r1, =rt_interrupt_to_thread
	ldr     r1, [r1]
	ldr     r1, [r1]
	
	ldmia   r1!, {r4 - r7}
	push	{r4	- r7}

ldmia	r1!, {r4 - r7}
	mov		r8,	 r4
	mov		r9,  r5
	mov		r10, r6
	mov		r11, r7

pop		{r4	- r7}

msr     psp, r1

pendsv_exit:
	msr     PRIMASK, r2

movs	r0, #0x4
	rsbs	r0, r0, #0x0
	bx		r0
```