lshrti3.c 1.2 KB

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  1. /* ===-- lshrti3.c - Implement __lshrti3 -----------------------------------===
  2. *
  3. * The LLVM Compiler Infrastructure
  4. *
  5. * This file is dual licensed under the MIT and the University of Illinois Open
  6. * Source Licenses. See LICENSE.TXT for details.
  7. *
  8. * ===----------------------------------------------------------------------===
  9. *
  10. * This file implements __lshrti3 for the compiler_rt library.
  11. *
  12. * ===----------------------------------------------------------------------===
  13. */
  14. #include "int_lib.h"
  15. #ifdef CRT_HAS_128BIT
  16. /* Returns: logical a >> b */
  17. /* Precondition: 0 <= b < bits_in_tword */
  18. COMPILER_RT_ABI ti_int
  19. __lshrti3(ti_int a, si_int b)
  20. {
  21. const int bits_in_dword = (int)(sizeof(di_int) * CHAR_BIT);
  22. utwords input;
  23. utwords result;
  24. input.all = a;
  25. if (b & bits_in_dword) /* bits_in_dword <= b < bits_in_tword */
  26. {
  27. result.s.high = 0;
  28. result.s.low = input.s.high >> (b - bits_in_dword);
  29. }
  30. else /* 0 <= b < bits_in_dword */
  31. {
  32. if (b == 0)
  33. return a;
  34. result.s.high = input.s.high >> b;
  35. result.s.low = (input.s.high << (bits_in_dword - b)) | (input.s.low >> b);
  36. }
  37. return result.all;
  38. }
  39. #endif /* CRT_HAS_128BIT */