Odd width variation of scale down by 2 for subsampling

source/scale_any.cc

 /*
  *  Copyright 2015 The LibYuv Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS. All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 37 matching lines @@
                  uint8* dst_ptr, int dst_width) {                              \
       int r = (int)((unsigned int)dst_width % (MASK + 1));                     \
       int n = dst_width - r;                                                   \
       if (n > 0) {                                                             \
         SCALEROWDOWN_SIMD(src_ptr, src_stride, dst_ptr, n);                    \
       }                                                                        \
       SCALEROWDOWN_C(src_ptr + (n * FACTOR) * BPP, src_stride,                 \
                      dst_ptr + n * BPP, r);                                    \
     }
 
+// Fixed scale down for odd source width.  Used by I420Blend subsampling.
+// Since dst_width is (width + 1) / 2, this function scales one less pixel
+// and copies the last pixel.
+#define SDODD(NAMEANY, SCALEROWDOWN_SIMD, SCALEROWDOWN_C, FACTOR, BPP, MASK)   \
+    void NAMEANY(const uint8* src_ptr, ptrdiff_t src_stride,                   \
+                 uint8* dst_ptr, int dst_width) {                              \
+      int r = (int)((unsigned int)(dst_width - 1) % (MASK + 1));               \
+      int n = dst_width - r;                                                   \
+      if (n > 0) {                                                             \
+        SCALEROWDOWN_SIMD(src_ptr, src_stride, dst_ptr, n);                    \
+      }                                                                        \
+      SCALEROWDOWN_C(src_ptr + (n * FACTOR) * BPP, src_stride,                 \
+                     dst_ptr + n * BPP, r);                                    \
+    }
+
 #ifdef HAS_SCALEROWDOWN2_SSSE3
 SDANY(ScaleRowDown2_Any_SSSE3, ScaleRowDown2_SSSE3, ScaleRowDown2_C, 2, 1, 15)
 SDANY(ScaleRowDown2Linear_Any_SSSE3, ScaleRowDown2Linear_SSSE3,
       ScaleRowDown2Linear_C, 2, 1, 15)
 SDANY(ScaleRowDown2Box_Any_SSSE3, ScaleRowDown2Box_SSSE3, ScaleRowDown2Box_C,
       2, 1, 15)
+SDODD(ScaleRowDown2Box_Odd_SSSE3, ScaleRowDown2Box_SSSE3,
+      ScaleRowDown2Box_Odd_C, 2, 1, 15)
 #endif
 #ifdef HAS_SCALEROWDOWN2_AVX2
 SDANY(ScaleRowDown2_Any_AVX2, ScaleRowDown2_AVX2, ScaleRowDown2_C, 2, 1, 31)
 SDANY(ScaleRowDown2Linear_Any_AVX2, ScaleRowDown2Linear_AVX2,
       ScaleRowDown2Linear_C, 2, 1, 31)
 SDANY(ScaleRowDown2Box_Any_AVX2, ScaleRowDown2Box_AVX2, ScaleRowDown2Box_C,
       2, 1, 31)
+SDODD(ScaleRowDown2Box_Odd_AVX2, ScaleRowDown2Box_AVX2, ScaleRowDown2Box_Odd_C,
+      2, 1, 31)
 #endif
 #ifdef HAS_SCALEROWDOWN2_NEON
 SDANY(ScaleRowDown2_Any_NEON, ScaleRowDown2_NEON, ScaleRowDown2_C, 2, 1, 15)
 SDANY(ScaleRowDown2Linear_Any_NEON, ScaleRowDown2Linear_NEON,
       ScaleRowDown2Linear_C, 2, 1, 15)
 SDANY(ScaleRowDown2Box_Any_NEON, ScaleRowDown2Box_NEON,
       ScaleRowDown2Box_C, 2, 1, 15)
+SDODD(ScaleRowDown2Box_Odd_NEON, ScaleRowDown2Box_NEON,
+      ScaleRowDown2Box_Odd_C, 2, 1, 15)
 #endif
 #ifdef HAS_SCALEROWDOWN4_SSSE3
 SDANY(ScaleRowDown4_Any_SSSE3, ScaleRowDown4_SSSE3, ScaleRowDown4_C, 4, 1, 7)
 SDANY(ScaleRowDown4Box_Any_SSSE3, ScaleRowDown4Box_SSSE3, ScaleRowDown4Box_C,
       4, 1, 7)
 #endif
 #ifdef HAS_SCALEROWDOWN4_AVX2
 SDANY(ScaleRowDown4_Any_AVX2, ScaleRowDown4_AVX2, ScaleRowDown4_C, 4, 1, 15)
 SDANY(ScaleRowDown4Box_Any_AVX2, ScaleRowDown4Box_AVX2, ScaleRowDown4Box_C,
       4, 1, 15)
@@ skipping 103 matching lines @@
 
 #ifdef __cplusplus
 }  // extern "C"
 }  // namespace libyuv
 #endif