判断cpu大小端的算法程序

// 摘自sha源码
static inline void setEndian(int *littleEndianp)
{
  union {
    uint32_t w;
    uint8_t b[4];
  } endian;

  endian.w = 1L;
  *littleEndianp = endian.b[0] != 0;
}