详细MSPM0库函数之delay_cycles()

1万 · 2023-3-22 22:37

本帖最后由 xyz549040622 于 2023-3-22 22:40 编辑

MSPM0的库函数中有一个延时函数，delay_cycles（cycles）
这个函数在dl_core.h中进行了宏定义

#define delay_cycles(cycles) DL_Common_delayCycles(cycles)

DL_Common_delayCycles(cycles)这个函数其实在dl_common.c中进行了定义

复制

#include <stdint.h>



#include <ti/driverlib/dl_common.h>



void DL_Common_delayCycles(uint32_t cycles)

{

    /* There will be a 2 cycle delay here to fetch & decode instructions

     * if branch and linking to this function */



    /* Subtract 2 net cycles for constant offset: +2 cycles for entry jump,

     * +2 cycles for exit, -1 cycle for a shorter loop cycle on the last loop,

     * -1 for this instruction */



#ifdef __GNUC__

    __asm(".syntax unified");

#endif

    __asm volatile(

        "SUBS     r0, r0, #2; \n"

        "DL_Common_delayCyclesLoop: \n"

        "SUBS     r0, r0, #4; \n"

        "NOP; \n"

        "BHS     DL_Common_delayCyclesLoop; \n"

        /* Return: 2 cycles */



    );

}