From: Harry Wentland <harry.wentland@xxxxxxx>
CTM values are defined as signed-magnitude values. Add
a helper that converts from CTM signed-magnitude fixed
point value to the twos-complement value used by
drm_fixed.
Signed-off-by: Harry Wentland <harry.wentland@xxxxxxx>
---
include/drm/drm_fixed.h | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/include/drm/drm_fixed.h b/include/drm/drm_fixed.h
index 1922188f00e8..0b44f2f294ce 100644
--- a/include/drm/drm_fixed.h
+++ b/include/drm/drm_fixed.h
@@ -78,6 +78,24 @@ static inline u32 dfixed_div(fixed20_12 A, fixed20_12 B)
#define DRM_FIXED_EPSILON 1LL
#define DRM_FIXED_ALMOST_ONE (DRM_FIXED_ONE - DRM_FIXED_EPSILON)
+/**
+ * @drm_sm2fixp
+ *
+ * Convert a 1.31.32 signed-magnitude fixed point to 32.32
+ * 2s-complement fixed point
+ *
+ * @return s64 2s-complement fixed point
+ */
+static inline s64 drm_sm2fixp(__u64 a)
+{
+ if ((a & (1LL << 63))) {
+ return -(a & 0x7fffffffffffffffll);
+ } else {
+ return a;
+ }
+
+}
+
static inline s64 drm_int2fixp(int a)
{
return ((s64)a) << DRM_FIXED_POINT;
--
2.43.0
