A value of 0x80000000 and higher should round up, and
below should round down. VKMS Kunit tests for lerp_u16
showed that this is not the case. Fix it.
1 << (DRM_FIXED_POINT_HALF - 1) =
1 << 15 = 0x8000
This is not 0.5, but 0.00000762939453125.
Instead of some smart math use a simple if/else to
round up or down. This helps people like me to understand
what the function does.
Signed-off-by: Harry Wentland <harry.wentland@xxxxxxx>
---
include/drm/drm_fixed.h | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/include/drm/drm_fixed.h b/include/drm/drm_fixed.h
index cb842ba80ddd..8ee549f68537 100644
--- a/include/drm/drm_fixed.h
+++ b/include/drm/drm_fixed.h
@@ -77,6 +77,8 @@ static inline u32 dfixed_div(fixed20_12 A, fixed20_12 B)
#define DRM_FIXED_DIGITS_MASK (~DRM_FIXED_DECIMAL_MASK)
#define DRM_FIXED_EPSILON 1LL
#define DRM_FIXED_ALMOST_ONE (DRM_FIXED_ONE - DRM_FIXED_EPSILON)
+#define DRM_FIXED_FRACTIONAL 0xffffffffll
+#define DRM_FIXED_HALF 0x80000000ll
/**
* @drm_sm2fixp
@@ -106,11 +108,6 @@ static inline int drm_fixp2int(s64 a)
return ((s64)a) >> DRM_FIXED_POINT;
}
-static inline int drm_fixp2int_round(s64 a)
-{
- return drm_fixp2int(a + (1 << (DRM_FIXED_POINT_HALF - 1)));
-}
-
static inline int drm_fixp2int_ceil(s64 a)
{
if (a >= 0)
@@ -119,6 +116,14 @@ static inline int drm_fixp2int_ceil(s64 a)
return drm_fixp2int(a - DRM_FIXED_ALMOST_ONE);
}
+static inline int drm_fixp2int_round(s64 a)
+{
+ if ((a & DRM_FIXED_FRACTIONAL) < DRM_FIXED_HALF)
+ return drm_fixp2int(a);
+ else
+ return drm_fixp2int_ceil(a);
+}
+
static inline unsigned drm_fixp_msbset(s64 a)
{
unsigned shift, sign = (a >> 63) & 1;
--
2.44.0
