[Qemu-devel] [PATCH] target-arm: Fix GE bits for v6media signed modulo arithmetic

[Qemu-devel] [PATCH] target-arm: Fix GE bits for v6media signed modulo arithmetic

[Peter Maydell]

Fix the signed modulo arithmetic helpers for the v6media
instructions (SADD8, SSUB8, SADD16, SSUB16, SASX, SSAX) to set
the GE bits correctly (based on the result of the add or subtract
before it is truncated to 16 bits, not after).

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 target-arm/helper.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/target-arm/helper.c b/target-arm/helper.c
index d360121..4f2b440 100644
--- a/target-arm/helper.c
+++ b/target-arm/helper.c
@@ -2171,7 +2171,7 @@ static inline uint8_t sub8_usat(uint8_t a, uint8_t b)
 /* Signed modulo arithmetic.  */
 #define SARITH16(a, b, n, op) do { \
     int32_t sum; \
-    sum = (int16_t)((uint16_t)(a) op (uint16_t)(b)); \
+    sum = (int32_t)(int16_t)(a) op (int32_t)(int16_t)(b); \
     RESULT(sum, n, 16); \
     if (sum >= 0) \
         ge |= 3 << (n * 2); \
@@ -2179,7 +2179,7 @@ static inline uint8_t sub8_usat(uint8_t a, uint8_t b)
 
 #define SARITH8(a, b, n, op) do { \
     int32_t sum; \
-    sum = (int8_t)((uint8_t)(a) op (uint8_t)(b)); \
+    sum = (int32_t)(int8_t)(a) op (int32_t)(int8_t)(b); \
     RESULT(sum, n, 8); \
     if (sum >= 0) \
         ge |= 1 << n; \
-- 
1.7.1

Re: [Qemu-devel] [PATCH] target-arm: Fix GE bits for v6media signed modulo arithmetic

[Aurelien Jarno]

On Thu, Mar 10, 2011 at 06:51:49PM +0000, Peter Maydell wrote:
> Fix the signed modulo arithmetic helpers for the v6media
> instructions (SADD8, SSUB8, SADD16, SSUB16, SASX, SSAX) to set
> the GE bits correctly (based on the result of the add or subtract
> before it is truncated to 16 bits, not after).
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>  target-arm/helper.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)

Thanks, applied.

> diff --git a/target-arm/helper.c b/target-arm/helper.c
> index d360121..4f2b440 100644
> --- a/target-arm/helper.c
> +++ b/target-arm/helper.c
> @@ -2171,7 +2171,7 @@ static inline uint8_t sub8_usat(uint8_t a, uint8_t b)
>  /* Signed modulo arithmetic.  */
>  #define SARITH16(a, b, n, op) do { \
>      int32_t sum; \
> -    sum = (int16_t)((uint16_t)(a) op (uint16_t)(b)); \
> +    sum = (int32_t)(int16_t)(a) op (int32_t)(int16_t)(b); \
>      RESULT(sum, n, 16); \
>      if (sum >= 0) \
>          ge |= 3 << (n * 2); \
> @@ -2179,7 +2179,7 @@ static inline uint8_t sub8_usat(uint8_t a, uint8_t b)
>  
>  #define SARITH8(a, b, n, op) do { \
>      int32_t sum; \
> -    sum = (int8_t)((uint8_t)(a) op (uint8_t)(b)); \
> +    sum = (int32_t)(int8_t)(a) op (int32_t)(int8_t)(b); \
>      RESULT(sum, n, 8); \
>      if (sum >= 0) \
>          ge |= 1 << n; \
> -- 
> 1.7.1
> 
> 
> 

-- 
Aurelien Jarno                          GPG: 1024D/F1BCDB73
aurelien@aurel32.net                 http://www.aurel32.net