_lshrdi3.S 1.1 KB

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  1. /*
  2. * This code was copied from arch/powerpc/kernel/misc_32.S in the Linux
  3. * kernel sources (commit 85e2efbb1db9a18d218006706d6e4fbeb0216213, also
  4. * known as 2.6.38-rc5). The source file copyrights are as follows:
  5. *
  6. * (C) Copyright 1995-1996 Gary Thomas (gdt@linuxppc.org)
  7. *
  8. * Largely rewritten by Cort Dougan (cort@cs.nmt.edu)
  9. * and Paul Mackerras.
  10. *
  11. * SPDX-License-Identifier: GPL-2.0+
  12. */
  13. #include <ppc_asm.tmpl>
  14. #include <ppc_defs.h>
  15. #include <config.h>
  16. /*
  17. * Extended precision shifts.
  18. *
  19. * Updated to be valid for shift counts from 0 to 63 inclusive.
  20. * -- Gabriel
  21. *
  22. * R3/R4 has 64 bit value
  23. * R5 has shift count
  24. * result in R3/R4
  25. *
  26. * ashrdi3: arithmetic right shift (sign propagation)
  27. * lshrdi3: logical right shift
  28. * ashldi3: left shift
  29. */
  30. .globl __lshrdi3
  31. __lshrdi3:
  32. subfic r6,r5,32
  33. srw r4,r4,r5 # LSW = count > 31 ? 0 : LSW >> count
  34. addi r7,r5,32 # could be xori, or addi with -32
  35. slw r6,r3,r6 # t1 = count > 31 ? 0 : MSW << (32-count)
  36. srw r7,r3,r7 # t2 = count < 32 ? 0 : MSW >> (count-32)
  37. or r4,r4,r6 # LSW |= t1
  38. srw r3,r3,r5 # MSW = MSW >> count
  39. or r4,r4,r7 # LSW |= t2
  40. blr