深入理解计算机系统 家庭作业 2.63

/* subst.c -- 在字符串中替换 */
#include <stdio.h>

unsigned srl(unsigned x,int k);
int sra(int x,int k);

int main(void)
{

    printf("xsra = %d\n",srl(-1,1));
     printf("xsrl = %d\n",sra(-1,1));
  return 0;
}

unsigned srl(unsigned x,int k){
    unsigned xsra = (int) x>>k;
    xsra = (~(-1<<(sizeof(int)*4-k))) & xsra;
    return xsra;
}

int sra(int x,int k){
    int xsrl = (unsigned) x>>k;
    xsrl = ((-1<<(sizeof(int)*4-k))) | xsrl;
    return xsrl;
}