swab.h 1.2 KB

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