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
__bswap_variable_16(uint16_t x)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
__bswap_variable_32(uint32_t x)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
__bswap_variable_64(uint64_t x)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 */
44