arch/alpha/include/uapi/asm/swab.h

   1 /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
   2 #ifndef _ALPHA_SWAB_H
   3 #define _ALPHA_SWAB_H
   4
   5 #include <linux/types.h>
   6 #include <linux/compiler.h>
   7 #include <asm/compiler.h>
   8
   9 #ifdef __GNUC__
  10
  11 static inline __attribute_const__ __u32 __arch_swab32(__u32 x)
  12 {
  13         /*
  14          * Unfortunately, we can't use the 6 instruction sequence
  15          * on ev6 since the latency of the UNPKBW is 3, which is
  16          * pretty hard to hide.  Just in case a future implementation
  17          * has a lower latency, here's the sequence (also by Mike Burrows)
  18          *
  19          * UNPKBW a0, v0       v0: 00AA00BB00CC00DD
  20          * SLL v0, 24, a0      a0: BB00CC00DD000000
  21          * BIS v0, a0, a0      a0: BBAACCBBDDCC00DD
  22          * EXTWL a0, 6, v0     v0: 000000000000BBAA
  23          * ZAP a0, 0xf3, a0    a0: 00000000DDCC0000
  24          * ADDL a0, v0, v0     v0: ssssssssDDCCBBAA
  25          */
  26
  27         __u64 t0, t1, t2, t3;
  28
  29         t0 = __kernel_inslh(x, 7);      /* t0 : 0000000000AABBCC */
  30         t1 = __kernel_inswl(x, 3);      /* t1 : 000000CCDD000000 */
  31         t1 |= t0;                       /* t1 : 000000CCDDAABBCC */
  32         t2 = t1 >> 16;                  /* t2 : 0000000000CCDDAA */
  33         t0 = t1 & 0xFF00FF00;           /* t0 : 00000000DD00BB00 */
  34         t3 = t2 & 0x00FF00FF;           /* t3 : 0000000000CC00AA */
  35         t1 = t0 + t3;                   /* t1 : ssssssssDDCCBBAA */
  36
  37         return t1;
  38 }
  39 #define __arch_swab32 __arch_swab32
  40
  41 #endif /* __GNUC__ */
  42
  43 #endif /* _ALPHA_SWAB_H */