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drm: fix 64 bit drm fixed point helpers 

Sign bit wasn't handled properly and a small typo.

Thanks to Christian for helping me sort this out.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Alex Deucher 2013-07-30 16:43:55 -04:00
parent 42a21826dc
commit a838834b2f
1 changed files with 7 additions and 7 deletions
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14
include/drm/drm_fixed.h
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@ -84,12 +84,12 @@ static inline int drm_fixp2int(int64_t a)
return ((s64)a) >> DRM_FIXED_POINT;
}
static inline s64 drm_fixp_msbset(int64_t a)
static inline unsigned drm_fixp_msbset(int64_t a)
{
unsigned shift, sign = (a >> 63) & 1;
for (shift = 62; shift > 0; --shift)
if ((a >> shift) != sign)
if (((a >> shift) & 1) != sign)
return shift;
return 0;
@ -100,9 +100,9 @@ static inline s64 drm_fixp_mul(s64 a, s64 b)
unsigned shift = drm_fixp_msbset(a) + drm_fixp_msbset(b);
s64 result;
if (shift > 63) {
shift = shift - 63;
a >>= shift >> 1;
if (shift > 61) {
shift = shift - 61;
a >>= (shift >> 1) + (shift & 1);
b >>= shift >> 1;
} else
shift = 0;
@ -120,7 +120,7 @@ static inline s64 drm_fixp_mul(s64 a, s64 b)
static inline s64 drm_fixp_div(s64 a, s64 b)
{
unsigned shift = 63 - drm_fixp_msbset(a);
unsigned shift = 62 - drm_fixp_msbset(a);
s64 result;
a <<= shift;
@ -154,7 +154,7 @@ static inline s64 drm_fixp_exp(s64 x)
}
if (x < 0)
sum = drm_fixp_div(1, sum);
sum = drm_fixp_div(DRM_FIXED_ONE, sum);
return sum;
}