[PATCH] Fix remainder calculating bug in single floating point division
From: Liu Yu <hidden>
Date: 2008-01-06 14:17:15
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Linus Torvalds
This bug exists in the emulation of floating point division for powerpc. The original code cannot count the remainder correctly. I can provide a test case to trigger this bug. When use fdiv to count 1.1754941e-38f / 0.9999999f, the result is expected to be 1.175494e-38f, but we will get 1.174921e-38f in the original case. Comments are always welcomed! Signed-off-by: Liu Yu <redacted> --- arch/powerpc/math-emu/sfp-machine.h | 11 +++++------ 1 files changed, 5 insertions(+), 6 deletions(-)
diff --git a/arch/powerpc/math-emu/sfp-machine.h b/arch/powerpc/math-emu/sfp-machine.h
index 4b17d83..644cee2 100644
--- a/arch/powerpc/math-emu/sfp-machine.h
+++ b/arch/powerpc/math-emu/sfp-machine.h@@ -324,10 +324,10 @@ extern int fp_pack_ds(void *, long, unsigned long, unsigned long, long, long); __r1 = __r1 * __ll_B | __ll_highpart (n0); \ if (__r1 < __m) \ { \ - __q1--, __r1 += (d); \ - if (__r1 >= (d)) /* we didn't get carry when adding to __r1 */ \ - if (__r1 < __m) \ + do { \ __q1--, __r1 += (d); \ + /* we didn't get carry when adding to __r1 */ \ + } while (__r1 >= (d) && __r1 < __m); \ } \ __r1 -= __m; \ \
@@ -337,10 +337,9 @@ extern int fp_pack_ds(void *, long, unsigned long, unsigned long, long, long); __r0 = __r0 * __ll_B | __ll_lowpart (n0); \ if (__r0 < __m) \ { \ - __q0--, __r0 += (d); \ - if (__r0 >= (d)) \ - if (__r0 < __m) \ + do { \ __q0--, __r0 += (d); \ + } while (__r0 >= (d) && __r0 < __m); \ } \ __r0 -= __m; \ \
--
1.5.2