在網(wǎng)絡編程里,網(wǎng)絡字節(jié)序是big-endian的,而大部分的PC的系統(tǒng)都是X86處理器系列,X86采用的是little-endian,所以需要將
網(wǎng)絡數(shù)據(jù)流轉(zhuǎn)換成本地數(shù)據(jù)流的話,需要進行字節(jié)序的轉(zhuǎn)換。
標準庫里提供了hlton()和nthl()兩個函數(shù)來支持轉(zhuǎn)換。
hston(unsigned short), hlton(unsigned long) 將本地字節(jié)序轉(zhuǎn)換為網(wǎng)絡字節(jié)序
ntohl(unsigned long), ntohs(unsigned short) 將網(wǎng)絡字節(jié)序轉(zhuǎn)換為本地字節(jié)序
但是對于64位的整數(shù)進行轉(zhuǎn)換,標準庫并沒有提供相應的轉(zhuǎn)換函數(shù),本文將給出個人原創(chuàng)的64位字節(jié)序轉(zhuǎn)換函數(shù)。
#ifndef ULONG64
#define unsigned long long ULONG64
#endif
// host long 64 to network
ULONG64 hl64ton(ULONG64 host)
{
ULONG64 ret = 0;
ULONG high,low;
low = host & 0xFFFFFFFF;
high = (host >> 32) & 0xFFFFFFFF;
low = htonl(low);
high = htonl(high);
ret = low;
ret <<= 32;
ret |= high;
return ret;
}
//network to host long 64
ULONG64 ntohl64(ULONG64 host)
{
ULONG64 ret = 0;
ULONG high,low;
low = host & 0xFFFFFFFF;
high = (host >> 32) & 0xFFFFFFFF;
low = ntohl(low);
high = ntohl(high);
ret = low;
ret <<= 32;
ret |= high;
return ret;
}
關(guān)于little endian和big endian的詳細信息,網(wǎng)上的資料太多了,本文就不詳述了。