Linux Kernel  3.7.1
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
swab.h
Go to the documentation of this file.
1 #ifndef _ALPHA_SWAB_H
2 #define _ALPHA_SWAB_H
3 
4 #include <linux/types.h>
5 #include <linux/compiler.h>
6 #include <asm/compiler.h>
7 
8 #ifdef __GNUC__
9 
11 {
12  /*
13  * Unfortunately, we can't use the 6 instruction sequence
14  * on ev6 since the latency of the UNPKBW is 3, which is
15  * pretty hard to hide. Just in case a future implementation
16  * has a lower latency, here's the sequence (also by Mike Burrows)
17  *
18  * UNPKBW a0, v0 v0: 00AA00BB00CC00DD
19  * SLL v0, 24, a0 a0: BB00CC00DD000000
20  * BIS v0, a0, a0 a0: BBAACCBBDDCC00DD
21  * EXTWL a0, 6, v0 v0: 000000000000BBAA
22  * ZAP a0, 0xf3, a0 a0: 00000000DDCC0000
23  * ADDL a0, v0, v0 v0: ssssssssDDCCBBAA
24  */
25 
26  __u64 t0, t1, t2, t3;
27 
28  t0 = __kernel_inslh(x, 7); /* t0 : 0000000000AABBCC */
29  t1 = __kernel_inswl(x, 3); /* t1 : 000000CCDD000000 */
30  t1 |= t0; /* t1 : 000000CCDDAABBCC */
31  t2 = t1 >> 16; /* t2 : 0000000000CCDDAA */
32  t0 = t1 & 0xFF00FF00; /* t0 : 00000000DD00BB00 */
33  t3 = t2 & 0x00FF00FF; /* t3 : 0000000000CC00AA */
34  t1 = t0 + t3; /* t1 : ssssssssDDCCBBAA */
35 
36  return t1;
37 }
38 #define __arch_swab32 __arch_swab32
39 
40 #endif /* __GNUC__ */
41 
42 #endif /* _ALPHA_SWAB_H */