open watcom学习记录之——字节序交换,另一帖回复满了
int swap32_1(int i){return ((i&0xff000000)>>24)|((i&0xff0000)>>8)|((i&0xff00)<<8)|((i&0xff)<<24);}int swap(int x){int out,i;char *p_in=(char*)&x,*p_out=(char*)&out;while (i<sizeof(int))p_out[i++]=p_in[sizeof(int)-1-i];/*赋值运算先算右面，所以要把i++放在左面*/return out;}int bswap(int x){ int ret; /*psrc指向x首字节,pdst指向ret之后*/ char *psrc=(char*)&x,*pdst=(char*)(&ret+1); while(pdst>(char*)&ret) *--pdst=*psrc++; return ret;}main(){int a=0x12345678;printf("a=%x\n",a);a=swap32_1(a);printf("swap32_1--->%x\n",a);a=0x12345678;a=swap(a);printf("swap--->%x\n",a);a=0x12345678;a=bswap(a);printf("bswap--->%x",a);}#include <stdio.h>#include <stdlib.h>#include <string.h>int v;int bitrev1(const int b) { register int n; n=b; n=((n>> 1)&0x55555555)|((n<< 1)&0xaaaaaaaa); n=((n>> 2)&0x33333333)|((n<< 2)&0xcccccccc); n=((n>> 4)&0x0f0f0f0f)|((n<< 4)&0xf0f0f0f0); n=((n>> 8)&0x00ff00ff)|((n<< 8)&0xff00ff00); n=((n>>16)&0x0000ffff)|((n<<16)&0xffff0000); return n;}int bitrev2(const int b) { __asm { push ebx push ecx mov ebx,b mov ecx,32 nextbit: rcl ebx,1 rcr eax,1 loop nextbit pop ecx pop ebx }}int bitrev3(const int b) { char bs[33],bs1[33],*ep; itoa(b,bs1,2); sprintf(bs,"%032s",bs1); strrev(bs); return strtol(bs,&ep,2);}void main() { v=0x12345678;//0001 0010 0011 0100 0101 0110 0111 1000 printf("%08x\n",bitrev1(v)); printf("%08x\n",bitrev2(v)); printf("%08x\n",bitrev3(v));}//1e6a2c48//1e6a2c48//1e6a2c48