Some microoptimizations in combine_two_samples(). Saves about 4% in ResampleEffect...

[movit] / resample_effect.cpp

diff --git a/resample_effect.cpp b/resample_effect.cpp
index ba8a71c0241443c0730a5ce99d68a2fa7c014ad3..30c40c4145fdd73903a7ce485d8ca75f7b28c783 100644 (file)
--- a/resample_effect.cpp
+++ b/resample_effect.cpp
@@ -109,7 +109,7 @@ unsigned gcd(unsigned a, unsigned b)
 }
 
 template<class DestFloat>
-unsigned combine_samples(const Tap<float> *src, Tap<DestFloat> *dst, float num_subtexels, float inv_num_subtexels, unsigned num_src_samples, unsigned max_samples_saved)
+unsigned combine_samples(const Tap<float> *src, Tap<DestFloat> *dst, float num_subtexels, float inv_num_subtexels, unsigned num_src_samples, unsigned max_samples_saved, float pos1_pos2_diff, float inv_pos1_pos2_diff)
 {
        // Cut off near-zero values at both sides.
        unsigned num_samples_saved = 0;
@@ -157,7 +157,7 @@ unsigned combine_samples(const Tap<float> *src, Tap<DestFloat> *dst, float num_s
 
                DestFloat pos, total_weight;
                float sum_sq_error;
-               combine_two_samples(w1, w2, pos1, pos2, num_subtexels, inv_num_subtexels, &pos, &total_weight, &sum_sq_error);
+               combine_two_samples(w1, w2, pos1, pos1_pos2_diff, inv_pos1_pos2_diff, num_subtexels, inv_num_subtexels, &pos, &total_weight, &sum_sq_error);
 
                // If the interpolation error is larger than that of about sqrt(2) of
                // a level at 8-bit precision, don't combine. (You'd think 1.0 was enough,
@@ -210,10 +210,12 @@ unsigned combine_many_samples(const Tap<float> *weights, unsigned src_size, unsi
 {
        float num_subtexels = src_size / movit_texel_subpixel_precision;
        float inv_num_subtexels = movit_texel_subpixel_precision / src_size;
+       float pos1_pos2_diff = 1.0f / src_size;
+       float inv_pos1_pos2_diff = src_size;
 
        unsigned max_samples_saved = UINT_MAX;
        for (unsigned y = 0; y < dst_samples && max_samples_saved > 0; ++y) {
-               unsigned num_samples_saved = combine_samples<DestFloat>(weights + y * src_samples, NULL, num_subtexels, inv_num_subtexels, src_samples, max_samples_saved);
+               unsigned num_samples_saved = combine_samples<DestFloat>(weights + y * src_samples, NULL, num_subtexels, inv_num_subtexels, src_samples, max_samples_saved, pos1_pos2_diff, inv_pos1_pos2_diff);
                max_samples_saved = min(max_samples_saved, num_samples_saved);
        }
 
@@ -228,7 +230,9 @@ unsigned combine_many_samples(const Tap<float> *weights, unsigned src_size, unsi
                        num_subtexels,
                        inv_num_subtexels,
                        src_samples,
-                       max_samples_saved);
+                       max_samples_saved,
+                       pos1_pos2_diff,
+                       inv_pos1_pos2_diff);
                assert(num_samples_saved == max_samples_saved);
                normalize_sum(bilinear_weights_ptr, src_bilinear_samples);
        }