divsi3.c 1.4 KB

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  1. /* ===-- divsi3.c - Implement __divsi3 -------------------------------------===
  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 __divsi3 for the compiler_rt library.
  11. *
  12. * ===----------------------------------------------------------------------===
  13. */
  14. #include "int_lib.h"
  15. /* Returns: a / b */
  16. ARM_EABI_FNALIAS(idiv, divsi3)
  17. COMPILER_RT_ABI si_int
  18. __divsi3(si_int a, si_int b)
  19. {
  20. const int bits_in_word_m1 = (int)(sizeof(si_int) * CHAR_BIT) - 1;
  21. si_int s_a = a >> bits_in_word_m1; /* s_a = a < 0 ? -1 : 0 */
  22. si_int s_b = b >> bits_in_word_m1; /* s_b = b < 0 ? -1 : 0 */
  23. a = (a ^ s_a) - s_a; /* negate if s_a == -1 */
  24. b = (b ^ s_b) - s_b; /* negate if s_b == -1 */
  25. s_a ^= s_b; /* sign of quotient */
  26. /*
  27. * On CPUs without unsigned hardware division support,
  28. * this calls __udivsi3 (notice the cast to su_int).
  29. * On CPUs with unsigned hardware division support,
  30. * this uses the unsigned division instruction.
  31. */
  32. return ((su_int)a/(su_int)b ^ s_a) - s_a; /* negate if s_a == -1 */
  33. }