On 03/12/2017 22:33, Andrew D'Addesio wrote:
Add av_sat_sub32 and av_sat_dsub32 as the subtraction analogues to
av_sat_add32/av_sat_dadd32.
Also clarify the formulas for dadd32/dsub32.
Signed-off-by: Andrew D'Addesio <[email protected]>
---
libavutil/arm/intmath.h | 16 ++++++++++++++++
libavutil/common.h | 32 +++++++++++++++++++++++++++++++-
2 files changed, 47 insertions(+), 1 deletion(-)
diff --git a/libavutil/arm/intmath.h b/libavutil/arm/intmath.h
index 2b15ba0..a14337f 100644
--- a/libavutil/arm/intmath.h
+++ b/libavutil/arm/intmath.h
@@ -94,6 +94,22 @@ static av_always_inline int av_sat_dadd32_arm(int a, int b)
return r;
}
+#define av_sat_sub32 av_sat_sub32_arm
+static av_always_inline int av_sat_sub32_arm(int a, int b)
+{
+ int r;
+ __asm__ ("qsub %0, %1, %2" : "=r"(r) : "r"(a), "r"(b));
+ return r;
+}
+
+#define av_sat_dsub32 av_sat_dsub32_arm
+static av_always_inline int av_sat_dsub32_arm(int a, int b)
+{
+ int r;
+ __asm__ ("qdsub %0, %1, %2" : "=r"(r) : "r"(a), "r"(b));
+ return r;
+}
+
#endif /* HAVE_ARMV6_INLINE */
#if HAVE_ASM_MOD_Q
diff --git a/libavutil/common.h b/libavutil/common.h
index 3832f10..63ea18d 100644
--- a/libavutil/common.h
+++ b/libavutil/common.h
@@ -210,13 +210,37 @@ static av_always_inline int av_sat_add32_c(int a, int b)
*
* @param a first value
* @param b value doubled and added to a
- * @return sum with signed saturation
+ * @return sum sat(a + sat(2*b)) with signed saturation
*/
static av_always_inline int av_sat_dadd32_c(int a, int b)
{
return av_sat_add32(a, av_sat_add32(b, b));
}
+/**
+ * Subtract two signed 32-bit values with saturation.
+ *
+ * @param a one value
+ * @param b another value
+ * @return difference with signed saturation
+ */
+static av_always_inline int av_sat_sub32_c(int a, int b)
+{
+ return av_clipl_int32((int64_t)a - b);
+}
+
+/**
+ * Subtract a doubled value from another value with saturation at both stages.
+ *
+ * @param a first value
+ * @param b value doubled and subtracted from a
+ * @return difference sat(a - sat(2*b)) with signed saturation
+ */
+static av_always_inline int av_sat_dsub32_c(int a, int b)
+{
+ return av_sat_sub32(a, av_sat_add32(b, b));
+}
+
/**
* Clip a float value into the amin-amax range.
* @param a value to clip
@@ -430,6 +454,12 @@ static av_always_inline av_const int
av_popcount64_c(uint64_t x)
#ifndef av_sat_dadd32
# define av_sat_dadd32 av_sat_dadd32_c
#endif
+#ifndef av_sat_sub32
+# define av_sat_sub32 av_sat_sub32_c
+#endif
+#ifndef av_sat_dsub32
+# define av_sat_dsub32 av_sat_dsub32_c
+#endif
#ifndef av_clipf
# define av_clipf av_clipf_c
#endif
Ok.
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