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kernel
os
linux
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>
+7
-7
+7
-7
include/drm/drm_fixed.h
+7
-7
include/drm/drm_fixed.h
···
84
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return ((s64)a) >> DRM_FIXED_POINT;
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}
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-
static inline s64 drm_fixp_msbset(int64_t a)
87
+
static inline unsigned drm_fixp_msbset(int64_t a)
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{
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unsigned shift, sign = (a >> 63) & 1;
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for (shift = 62; shift > 0; --shift)
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-
if ((a >> shift) != sign)
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+
if (((a >> shift) & 1) != sign)
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return shift;
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return 0;
···
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unsigned shift = drm_fixp_msbset(a) + drm_fixp_msbset(b);
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s64 result;
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103
-
if (shift > 63) {
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-
shift = shift - 63;
105
-
a >>= shift >> 1;
103
+
if (shift > 61) {
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+
shift = shift - 61;
105
+
a >>= (shift >> 1) + (shift & 1);
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b >>= shift >> 1;
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} else
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shift = 0;
···
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static inline s64 drm_fixp_div(s64 a, s64 b)
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{
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-
unsigned shift = 63 - drm_fixp_msbset(a);
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+
unsigned shift = 62 - drm_fixp_msbset(a);
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s64 result;
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a <<= shift;
···
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}
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if (x < 0)
157
-
sum = drm_fixp_div(1, sum);
157
+
sum = drm_fixp_div(DRM_FIXED_ONE, sum);
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return sum;
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}