[PATCH] drm/amd/display: Remove use of division operator for long longs

[PATCH] drm/amd/display: Remove use of division operator for long longs

[sunpeng.li-5C7GfCeVMHo]

From: David Francis <David.Francis@amd.com>

In fixed31_32.h, in dc_fixpt_shl,'/' was used for division of one long
long int by another long long int.  As there is no inbuilt long long
int division function in c, gcc inserted its own.  However, gcc does not
link the library that contains this function.  To avoid this, use
bitwise operators instead of /

Signed-off-by: David Francis <David.Francis@amd.com>
Reviewed-by: Dmytro Laktyushkin <Dmytro.Laktyushkin@amd.com>
---
 drivers/gpu/drm/amd/display/include/fixed31_32.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/include/fixed31_32.h b/drivers/gpu/drm/amd/display/include/fixed31_32.h
index 76f64e9..bb0d4eb 100644
--- a/drivers/gpu/drm/amd/display/include/fixed31_32.h
+++ b/drivers/gpu/drm/amd/display/include/fixed31_32.h
@@ -209,7 +209,7 @@ static inline struct fixed31_32 dc_fixpt_clamp(
 static inline struct fixed31_32 dc_fixpt_shl(struct fixed31_32 arg, unsigned char shift)
 {
 	ASSERT(((arg.value >= 0) && (arg.value <= LLONG_MAX >> shift)) ||
-		((arg.value < 0) && (arg.value >= (LLONG_MIN / (1LL << shift)))));
+		((arg.value < 0) && (arg.value >= ~(LLONG_MAX >> shift))));
 
 	arg.value = arg.value << shift;
 
-- 
2.7.4

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Re: [PATCH] drm/amd/display: Remove use of division operator for long longs

[Alex Deucher]

On Thu, May 24, 2018 at 10:40 AM,  <sunpeng.li@amd.com> wrote:
> From: David Francis <David.Francis@amd.com>
>
> In fixed31_32.h, in dc_fixpt_shl,'/' was used for division of one long
> long int by another long long int.  As there is no inbuilt long long
> int division function in c, gcc inserted its own.  However, gcc does not
> link the library that contains this function.  To avoid this, use
> bitwise operators instead of /
>
> Signed-off-by: David Francis <David.Francis@amd.com>
> Reviewed-by: Dmytro Laktyushkin <Dmytro.Laktyushkin@amd.com>

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>

> ---
>  drivers/gpu/drm/amd/display/include/fixed31_32.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/display/include/fixed31_32.h b/drivers/gpu/drm/amd/display/include/fixed31_32.h
> index 76f64e9..bb0d4eb 100644
> --- a/drivers/gpu/drm/amd/display/include/fixed31_32.h
> +++ b/drivers/gpu/drm/amd/display/include/fixed31_32.h
> @@ -209,7 +209,7 @@ static inline struct fixed31_32 dc_fixpt_clamp(
>  static inline struct fixed31_32 dc_fixpt_shl(struct fixed31_32 arg, unsigned char shift)
>  {
>         ASSERT(((arg.value >= 0) && (arg.value <= LLONG_MAX >> shift)) ||
> -               ((arg.value < 0) && (arg.value >= (LLONG_MIN / (1LL << shift)))));
> +               ((arg.value < 0) && (arg.value >= ~(LLONG_MAX >> shift))));
>
>         arg.value = arg.value << shift;
>
> --
> 2.7.4
>
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