From: Andrzej Zaborowski <balrogg@gmail.com>
To: qemu-devel@nongnu.org
Subject: [Qemu-devel] [4900] ARMv6: fix SIMD add/sub carry flags (Vincent Palatin).
Date: Sat, 19 Jul 2008 10:46:14 +0000 [thread overview]
Message-ID: <E1KK9x8-0002mS-2Z@cvs.savannah.gnu.org> (raw)
Revision: 4900
http://svn.sv.gnu.org/viewvc/?view=rev&root=qemu&revision=4900
Author: balrog
Date: 2008-07-19 10:46:13 +0000 (Sat, 19 Jul 2008)
Log Message:
-----------
ARMv6: fix SIMD add/sub carry flags (Vincent Palatin).
After a quick code review, it seems to be a bad cut-n-paste between
16-bit and 8-bit UADD/USUB, indeed UADD8/USUB8 tries to set GE bits by
pair instead of one at a time.
Besides, the addition operations (UADD8/UADD16) set GE bits to "NOT
carry" instead of "carry" (probably once again due to a copy of the
substraction code which sets flags to "NOT borrow")
Modified Paths:
--------------
trunk/target-arm/helper.c
Modified: trunk/target-arm/helper.c
===================================================================
--- trunk/target-arm/helper.c 2008-07-19 10:34:35 UTC (rev 4899)
+++ trunk/target-arm/helper.c 2008-07-19 10:46:13 UTC (rev 4900)
@@ -2059,7 +2059,7 @@
uint32_t sum; \
sum = (uint32_t)(uint16_t)(a) + (uint32_t)(uint16_t)(b); \
RESULT(sum, n, 16); \
- if ((sum >> 16) == 0) \
+ if ((sum >> 16) == 1) \
ge |= 3 << (n * 2); \
} while(0)
@@ -2067,8 +2067,8 @@
uint32_t sum; \
sum = (uint32_t)(uint8_t)(a) + (uint32_t)(uint8_t)(b); \
RESULT(sum, n, 8); \
- if ((sum >> 8) == 0) \
- ge |= 3 << (n * 2); \
+ if ((sum >> 8) == 1) \
+ ge |= 1 << n; \
} while(0)
#define SUB16(a, b, n) do { \
@@ -2084,7 +2084,7 @@
sum = (uint32_t)(uint8_t)(a) - (uint32_t)(uint8_t)(b); \
RESULT(sum, n, 8); \
if ((sum >> 8) == 0) \
- ge |= 3 << (n * 2); \
+ ge |= 1 << n; \
} while(0)
#define PFX u
reply other threads:[~2008-07-19 10:46 UTC|newest]
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