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| author | Alex Deucher <alexander.deucher@amd.com> | 2013-07-30 16:43:55 -0400 |
|---|---|---|
| committer | Alex Deucher <alexander.deucher@amd.com> | 2013-07-30 17:24:13 -0400 |
| commit | a838834b2f7cbc09b6319a1fc332c03e4d665b20 (patch) | |
| tree | 548865f29964a44d9f62b51f88586832e58aba08 /include | |
| parent | 42a21826dc54583cdb79cc8477732e911ac9c376 (diff) | |
| download | lwn-a838834b2f7cbc09b6319a1fc332c03e4d665b20.tar.gz lwn-a838834b2f7cbc09b6319a1fc332c03e4d665b20.zip | |
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>
Diffstat (limited to 'include')
| -rw-r--r-- | include/drm/drm_fixed.h | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/include/drm/drm_fixed.h b/include/drm/drm_fixed.h index f5e1168c7647..d639049a613d 100644 --- a/include/drm/drm_fixed.h +++ b/include/drm/drm_fixed.h @@ -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; } |