From a838834b2f7cbc09b6319a1fc332c03e4d665b20 Mon Sep 17 00:00:00 2001 From: Alex Deucher Date: Tue, 30 Jul 2013 16:43:55 -0400 Subject: [PATCH] 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 --- include/drm/drm_fixed.h | 14 +++++++------- 1 file 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; }