src/arch/i386/include/bits/byteswap.h

   1 #ifndef ETHERBOOT_BITS_BYTESWAP_H
   2 #define ETHERBOOT_BITS_BYTESWAP_H
   3
   4 FILE_LICENCE ( GPL2_OR_LATER );
   5
   6 static inline __attribute__ ((always_inline, const)) uint16_t
   7 __bswap_variable_16(uint16_t x)
   8 {
   9         __asm__("xchgb %b0,%h0\n\t"
  10                 : "=q" (x)
  11                 : "0" (x));
  12         return x;
  13 }
  14
  15 static inline __attribute__ ((always_inline, const)) uint32_t
  16 __bswap_variable_32(uint32_t x)
  17 {
  18         __asm__("xchgb %b0,%h0\n\t"
  19                 "rorl $16,%0\n\t"
  20                 "xchgb %b0,%h0"
  21                 : "=q" (x)
  22                 : "0" (x));
  23         return x;
  24 }
  25
  26 static inline __attribute__ ((always_inline, const)) uint64_t
  27 __bswap_variable_64(uint64_t x)
  28 {
  29         union {
  30                 uint64_t qword;
  31                 uint32_t dword[2];
  32         } u;
  33
  34         u.qword = x;
  35         u.dword[0] = __bswap_variable_32(u.dword[0]);
  36         u.dword[1] = __bswap_variable_32(u.dword[1]);
  37         __asm__("xchgl %0,%1"
  38                 : "=r" ( u.dword[0] ), "=r" ( u.dword[1] )
  39                 : "0" ( u.dword[0] ), "1" ( u.dword[1] ) );
  40         return u.qword;
  41 }
  42
  43 #endif /* ETHERBOOT_BITS_BYTESWAP_H */