From: Liu Yu <Yu.Liu@freescale.com>
To: linuxppc-dev@ozlabs.org
Cc: Liu Yu <Yu.Liu@freescale.com>
Subject: [PATCH] Fix remainder calculating bug in single floating point division
Date: Sun, 6 Jan 2008 22:26:53 +0800 [thread overview]
Message-ID: <11996296134110-git-send-email-Yu.Liu@freescale.com> (raw)
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 <Yu.Liu@freescale.com>
---
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
next reply other threads:[~2008-01-06 14:17 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-01-06 14:26 Liu Yu [this message]
2008-01-06 20:07 ` [PATCH] Fix remainder calculating bug in single floating point division Benjamin Herrenschmidt
2008-01-06 20:44 ` Dan Malek
2008-01-06 20:49 ` Benjamin Herrenschmidt
2008-01-07 1:09 ` Josh Boyer
2008-01-08 6:20 ` Kumar Gala
2008-01-09 15:38 ` [PATCH] Fix remainder calculating bug in single floating pointdivision Liu Yu
2008-01-09 16:19 ` Kumar Gala
2008-01-08 6:22 ` [PATCH] Fix remainder calculating bug in single floating point division Kumar Gala
2008-01-09 1:24 ` Liu Yu
2008-01-09 23:48 ` David Gibson
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