2.63 shift 32 bits error

[swy20190]

unsigned srl(unsigned x, int k) {
  unsigned xsra = (int) x >> k;

  int w = sizeof(int) << 3;
  //原来这句代码在k==0时会出左移32位的问题：int mask = (int) -1 << (w - k); ，改为以下这句
  int mask;
  ((k==0)&&(mask=(int)-1<<(w-k-1)<<1))||((k)&&(mask=(int)-1<<(w-k)));
  int mask = (int)-1<<(w-k
  return xsra & ~mask;
}

[userheng]

unsigned srl(unsigned x, int k){
	//算术右移 
	unsigned xsra = (int)x >> k;
	int w =  sizeof(x) <<  3;
       //以2来作为移位的基数是比较简单的解决边界问题的一种方式，这样 k=0 代码也可以正常工作
	int mask = (2 << (w - k - 1)) + (-1);
	return mask & xsra;
} 

int sra(int x, int k){
	//逻辑右移 
	int xsrl = (unsigned)x >> k; 	
	int w =  sizeof(x) <<  3;
	int mask = -2 << (w - k - 1);
	return mask | xsrl;
}

[geethubccc]

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