[FFmpeg-devel] [PATCHv2 1/5] lavu/float_dsp: add double-precision scalar product

[Rémi Denis-Courmont]

The function pointer is appended to the structure for backward binary
compatibility. Fortunately, this is allocated by libavutil, not by the
user, so increasing the structure size is safe.
---
 libavutil/float_dsp.c | 12 ++++++++++++
 libavutil/float_dsp.h | 31 ++++++++++++++++++++++++++++++-
 2 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/libavutil/float_dsp.c b/libavutil/float_dsp.c
index e9fb023466..08bbc85e3e 100644
--- a/libavutil/float_dsp.c
+++ b/libavutil/float_dsp.c
@@ -132,6 +132,17 @@ float avpriv_scalarproduct_float_c(const float *v1, const float *v2, int len)
     return p;
 }
 
+double ff_scalarproduct_double_c(const double *v1, const double *v2,
+                                 size_t len)
+{
+    double p = 0.0;
+
+    for (size_t i = 0; i < len; i++)
+        p += v1[i] * v2[i];
+
+    return p;
+}
+
 av_cold AVFloatDSPContext *avpriv_float_dsp_alloc(int bit_exact)
 {
     AVFloatDSPContext *fdsp = av_mallocz(sizeof(AVFloatDSPContext));
@@ -149,6 +160,7 @@ av_cold AVFloatDSPContext *avpriv_float_dsp_alloc(int bit_exact)
     fdsp->vector_fmul_reverse = vector_fmul_reverse_c;
     fdsp->butterflies_float = butterflies_float_c;
     fdsp->scalarproduct_float = avpriv_scalarproduct_float_c;
+    fdsp->scalarproduct_double = ff_scalarproduct_double_c;
 
 #if ARCH_AARCH64
     ff_float_dsp_init_aarch64(fdsp);
diff --git a/libavutil/float_dsp.h b/libavutil/float_dsp.h
index 342a8715c5..5053aa240d 100644
--- a/libavutil/float_dsp.h
+++ b/libavutil/float_dsp.h
@@ -19,6 +19,8 @@
 #ifndef AVUTIL_FLOAT_DSP_H
 #define AVUTIL_FLOAT_DSP_H
 
+#include <stddef.h>
+
 typedef struct AVFloatDSPContext {
     /**
      * Calculate the entry wise product of two vectors of floats and store the result in
@@ -187,19 +189,46 @@ typedef struct AVFloatDSPContext {
      */
     void (*vector_dmul)(double *dst, const double *src0, const double *src1,
                         int len);
+
+    /**
+     * Calculate the scalar product of two vectors of doubles.
+     *
+     * @param v1  first vector
+     * @param v2  second vector
+     * @param len length of vectors
+     *
+     * @return inner product of the vectors
+     */
+    double (*scalarproduct_double)(const double *v1, const double *v2,
+                                   size_t len);
 } AVFloatDSPContext;
 
 /**
- * Return the scalar product of two vectors.
+ * Return the scalar product of two vectors of floats.
  *
  * @param v1  first input vector
+ *            constraints: 32-byte aligned
  * @param v2  first input vector
+ *            constraints: 32-byte aligned
  * @param len number of elements
+ *            constraints: multiple of 16
  *
  * @return sum of elementwise products
  */
 float avpriv_scalarproduct_float_c(const float *v1, const float *v2, int len);
 
+/**
+ * Return the scalar product of two vectors of doubles.
+ *
+ * @param v1  first input vector
+ * @param v2  first input vector
+ * @param len number of elements
+ *
+ * @return inner product of the vectors
+ */
+double ff_scalarproduct_double_c(const double *v1, const double *v2,
+                                 size_t len);
+
 void ff_float_dsp_init_aarch64(AVFloatDSPContext *fdsp);
 void ff_float_dsp_init_arm(AVFloatDSPContext *fdsp);
 void ff_float_dsp_init_ppc(AVFloatDSPContext *fdsp, int strict);
-- 
2.45.1