请教怎么制定位开始位移 - 编程论坛

#2

自由而无用2021-08-22 13:14

//online parser: https://www.bccn.net/run/
#include <stdio.h>

typedef unsigned char reg;

#define BIT_MASK4  (reg)0xEF
#define BIT_CLR567  (reg)0x1F
#define BIT_SET567(_r)  (reg)(_r & 0xE0)
#define BIT_MASK4SR(_r, _c)  (reg)((_r & BIT_CLR567) >> _c)
#define BIT_BAOBAO(_r, _c)  (reg)(BIT_SET567(_r) | BIT_MASK4SR(_r, _c))

#define FR_FLAG
#define BIT4  (reg)(1 << 2)
#define BIT_CLRX(_idx)  (reg)(0xFF >> (_idx - 1))
#define BIT_SETX(_r, _idx)  (reg)(_r & (0xFF << (_idx + 1)))
#define BIT_MASKXSR(_r, _idx, _c)  (reg)((_r & BIT_CLRX(_idx)) >> _c)
#define BIT_FR(_r, _idx, _c)  (reg)(BIT_SETX(_r,_idx) | BIT_MASKXSR(_r, _idx, _c))

int main(int argc, char *argv[])
{
    reg r, *vreg = (char *)main;

    for (int i = 0; i < 125; i++) {
       r = vreg[i];
#ifndef FR_FLAG
       printf("%02d: r = 0x%x, r(%d) = 0x%x\n",
       (i + 1), r, 2, BIT_BAOBAO(r, 2));
#else
       printf("%02d: r = 0x%x, r(%d) = 0x%x\n",
       (i + 1), r, 2, BIT_FR(r, BIT4, 2));
#endif
    }

    return 0;
}

[此贴子已经被作者于2021-8-22 14:23编辑过]

#3

吹水佬2021-08-22 17:32

从第5位起右移1位
unsigned char a=0x95; //10010101
printf("%.2x",(a&0xE0)|((a&0x1F)>>1)); //0x8A ‭10001010

#4

我善治鬼2021-08-22 18:22

你想要的结果

程序代码：

#include <stdio.h>

int main()
{
    unsigned char a = 1 << 4;
    printf("%u", a >> 1);
    return 0;
}

[此贴子已经被作者于2021-8-22 18:24编辑过]

#5

llsh772021-08-22 19:30

回复 3楼吹水佬

学到了

#6

s484065032021-08-24 08:21

学到了

#7

l33920665302022-10-29 13:57

学到了