--- src/3rdparty/chromium/third_party/libpng/powerpc/filter_vsx_intrinsics.c.orig	2019-10-27 17:23:52 UTC
+++ src/3rdparty/chromium/third_party/libpng/powerpc/filter_vsx_intrinsics.c
@@ -0,0 +1,767 @@
+/* filter_vsx_intrinsics.c - PowerPC optimised filter functions
+ *
+ * Copyright (c) 2017 Glenn Randers-Pehrson
+ * Written by Vadim Barkov, 2017.
+ * Last changed in libpng 1.6.29 [March 16, 2017]
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ */
+#include <stdio.h>
+#include <stdint.h>
+#include "../pngpriv.h"
+
+#ifdef PNG_READ_SUPPORTED
+
+/* This code requires -maltivec and -mvsx on the command line: */
+#if PNG_POWERPC_VSX_IMPLEMENTATION == 1 /* intrinsics code from pngpriv.h */
+
+#include <altivec.h>
+
+#if PNG_POWERPC_VSX_OPT > 0
+
+#ifndef __VSX__
+#  error "This code requires VSX support (POWER7 and later). Please provide -mvsx compiler flag."
+#endif
+
+#define vec_ld_unaligned(vec,data) vec = vec_vsx_ld(0,data)
+#define vec_st_unaligned(vec,data) vec_vsx_st(vec,0,data)
+
+
+/* Functions in this file look at most 3 pixels (a,b,c) to predict the 4th (d).
+ * They're positioned like this:
+ *    prev:  c b
+ *    row:   a d
+ * The Sub filter predicts d=a, Avg d=(a+b)/2, and Paeth predicts d to be
+ * whichever of a, b, or c is closest to p=a+b-c.
+ * ( this is taken from ../intel/filter_sse2_intrinsics.c )
+ */
+
+#define vsx_declare_common_vars(row_info,row,prev_row,offset) \
+   png_byte i;\
+   png_bytep rp = row + offset;\
+   png_const_bytep pp = prev_row;\
+   png_size_t unaligned_top = 16 - (((png_size_t)rp % 16));\
+   png_size_t istop;\
+   if(unaligned_top == 16)\
+      unaligned_top = 0;\
+   istop = row_info->rowbytes;\
+   if((unaligned_top < istop))\
+      istop -= unaligned_top;\
+   else{\
+      unaligned_top = istop;\
+      istop = 0;\
+   }
+
+void png_read_filter_row_up_vsx(png_row_infop row_info, png_bytep row,
+                                png_const_bytep prev_row)
+{
+   vector unsigned char rp_vec;
+   vector unsigned char pp_vec;
+   vsx_declare_common_vars(row_info,row,prev_row,0)
+
+   /* Altivec operations require 16-byte aligned data
+    * but input can be unaligned. So we calculate
+    * unaligned part as usual.
+    */
+   for (i = 0; i < unaligned_top; i++)
+   {
+      *rp = (png_byte)(((int)(*rp) + (int)(*pp++)) & 0xff);
+      rp++;
+   }
+
+   /* Using SIMD while we can */
+   while( istop >= 16 )
+   {
+      rp_vec = vec_ld(0,rp);
+      vec_ld_unaligned(pp_vec,pp);
+
+      rp_vec = vec_add(rp_vec,pp_vec);
+
+      vec_st(rp_vec,0,rp);
+
+      pp += 16;
+      rp += 16;
+      istop -= 16;
+   }
+
+   if(istop > 0)
+   {
+      /* If byte count of row is not divisible by 16
+       * we will process remaining part as usual
+       */
+      for (i = 0; i < istop; i++)
+      {
+         *rp = (png_byte)(((int)(*rp) + (int)(*pp++)) & 0xff);
+         rp++;
+      }
+}
+
+}
+
+static const vector unsigned char VSX_LEFTSHIFTED1_4 = {16,16,16,16, 0, 1, 2, 3,16,16,16,16,16,16,16,16};
+static const vector unsigned char VSX_LEFTSHIFTED2_4 = {16,16,16,16,16,16,16,16, 4, 5, 6, 7,16,16,16,16};
+static const vector unsigned char VSX_LEFTSHIFTED3_4 = {16,16,16,16,16,16,16,16,16,16,16,16, 8, 9,10,11};
+
+static const vector unsigned char VSX_LEFTSHIFTED1_3 = {16,16,16, 0, 1, 2,16,16,16,16,16,16,16,16,16,16};
+static const vector unsigned char VSX_LEFTSHIFTED2_3 = {16,16,16,16,16,16, 3, 4, 5,16,16,16,16,16,16,16};
+static const vector unsigned char VSX_LEFTSHIFTED3_3 = {16,16,16,16,16,16,16,16,16, 6, 7, 8,16,16,16,16};
+static const vector unsigned char VSX_LEFTSHIFTED4_3 = {16,16,16,16,16,16,16,16,16,16,16,16, 9,10,11,16};
+
+static const vector unsigned char VSX_NOT_SHIFTED1_4 = {16,16,16,16, 4, 5, 6, 7,16,16,16,16,16,16,16,16};
+static const vector unsigned char VSX_NOT_SHIFTED2_4 = {16,16,16,16,16,16,16,16, 8, 9,10,11,16,16,16,16};
+static const vector unsigned char VSX_NOT_SHIFTED3_4 = {16,16,16,16,16,16,16,16,16,16,16,16,12,13,14,15};
+
+static const vector unsigned char VSX_NOT_SHIFTED1_3 = {16,16,16, 3, 4, 5,16,16,16,16,16,16,16,16,16,16};
+static const vector unsigned char VSX_NOT_SHIFTED2_3 = {16,16,16,16,16,16, 6, 7, 8,16,16,16,16,16,16,16};
+static const vector unsigned char VSX_NOT_SHIFTED3_3 = {16,16,16,16,16,16,16,16,16, 9,10,11,16,16,16,16};
+static const vector unsigned char VSX_NOT_SHIFTED4_3 = {16,16,16,16,16,16,16,16,16,16,16,16,12,13,14,16};
+
+static const vector unsigned char VSX_CHAR_ZERO = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
+#ifdef __LITTLE_ENDIAN__
+
+static const vector unsigned char VSX_CHAR_TO_SHORT1_4 = { 4,16, 5,16, 6,16, 7,16,16,16,16,16,16,16,16,16};
+static const vector unsigned char VSX_CHAR_TO_SHORT2_4 = { 8,16, 9,16,10,16,11,16,16,16,16,16,16,16,16,16};
+static const vector unsigned char VSX_CHAR_TO_SHORT3_4 = {12,16,13,16,14,16,15,16,16,16,16,16,16,16,16,16};
+
+static const vector unsigned char VSX_SHORT_TO_CHAR1_4 = {16,16,16,16, 0, 2, 4, 6,16,16,16,16,16,16,16,16};
+static const vector unsigned char VSX_SHORT_TO_CHAR2_4 = {16,16,16,16,16,16,16,16, 0, 2, 4, 6,16,16,16,16};
+static const vector unsigned char VSX_SHORT_TO_CHAR3_4 = {16,16,16,16,16,16,16,16,16,16,16,16, 0, 2, 4, 6};
+
+static const vector unsigned char VSX_CHAR_TO_SHORT1_3 = { 3,16, 4,16, 5,16,16,16,16,16,16,16,16,16,16,16};
+static const vector unsigned char VSX_CHAR_TO_SHORT2_3 = { 6,16, 7,16, 8,16,16,16,16,16,16,16,16,16,16,16};
+static const vector unsigned char VSX_CHAR_TO_SHORT3_3 = { 9,16,10,16,11,16,16,16,16,16,16,16,16,16,16,16};
+static const vector unsigned char VSX_CHAR_TO_SHORT4_3 = {12,16,13,16,14,16,16,16,16,16,16,16,16,16,16,16};
+
+static const vector unsigned char VSX_SHORT_TO_CHAR1_3 = {16,16,16, 0, 2, 4,16,16,16,16,16,16,16,16,16,16};
+static const vector unsigned char VSX_SHORT_TO_CHAR2_3 = {16,16,16,16,16,16, 0, 2, 4,16,16,16,16,16,16,16};
+static const vector unsigned char VSX_SHORT_TO_CHAR3_3 = {16,16,16,16,16,16,16,16,16, 0, 2, 4,16,16,16,16};
+static const vector unsigned char VSX_SHORT_TO_CHAR4_3 = {16,16,16,16,16,16,16,16,16,16,16,16, 0, 2, 4,16};
+
+#elif defined(__BIG_ENDIAN__)
+
+static const vector unsigned char VSX_CHAR_TO_SHORT1_4 = {16, 4,16, 5,16, 6,16, 7,16,16,16,16,16,16,16,16};
+static const vector unsigned char VSX_CHAR_TO_SHORT2_4 = {16, 8,16, 9,16,10,16,11,16,16,16,16,16,16,16,16};
+static const vector unsigned char VSX_CHAR_TO_SHORT3_4 = {16,12,16,13,16,14,16,15,16,16,16,16,16,16,16,16};
+
+static const vector unsigned char VSX_SHORT_TO_CHAR1_4 = {16,16,16,16, 1, 3, 5, 7,16,16,16,16,16,16,16,16};
+static const vector unsigned char VSX_SHORT_TO_CHAR2_4 = {16,16,16,16,16,16,16,16, 1, 3, 5, 7,16,16,16,16};
+static const vector unsigned char VSX_SHORT_TO_CHAR3_4 = {16,16,16,16,16,16,16,16,16,16,16,16, 1, 3, 5, 7};
+
+static const vector unsigned char VSX_CHAR_TO_SHORT1_3 = {16, 3,16, 4,16, 5,16,16,16,16,16,16,16,16,16,16};
+static const vector unsigned char VSX_CHAR_TO_SHORT2_3 = {16, 6,16, 7,16, 8,16,16,16,16,16,16,16,16,16,16};
+static const vector unsigned char VSX_CHAR_TO_SHORT3_3 = {16, 9,16,10,16,11,16,16,16,16,16,16,16,16,16,16};
+static const vector unsigned char VSX_CHAR_TO_SHORT4_3 = {16,12,16,13,16,14,16,16,16,16,16,16,16,16,16,16};
+
+static const vector unsigned char VSX_SHORT_TO_CHAR1_3 = {16,16,16, 1, 3, 5,16,16,16,16,16,16,16,16,16,16};
+static const vector unsigned char VSX_SHORT_TO_CHAR2_3 = {16,16,16,16,16,16, 1, 3, 5,16,16,16,16,16,16,16};
+static const vector unsigned char VSX_SHORT_TO_CHAR3_3 = {16,16,16,16,16,16,16,16,16, 1, 3, 5,16,16,16,16};
+static const vector unsigned char VSX_SHORT_TO_CHAR4_3 = {16,16,16,16,16,16,16,16,16,16,16,16, 1, 3, 5,16};
+
+#endif
+
+#define vsx_char_to_short(vec,offset,bpp) (vector unsigned short)vec_perm((vec),VSX_CHAR_ZERO,VSX_CHAR_TO_SHORT##offset##_##bpp)
+#define vsx_short_to_char(vec,offset,bpp) vec_perm(((vector unsigned char)(vec)),VSX_CHAR_ZERO,VSX_SHORT_TO_CHAR##offset##_##bpp)
+
+#ifdef PNG_USE_ABS
+#  define vsx_abs(number) abs(number)
+#else
+#  define vsx_abs(number) (number > 0) ? (number) : -(number)
+#endif
+
+void png_read_filter_row_sub4_vsx(png_row_infop row_info, png_bytep row,
+                                  png_const_bytep prev_row)
+{
+   const png_byte bpp = 4;
+
+   vector unsigned char rp_vec;
+   vector unsigned char part_vec;
+
+   vsx_declare_common_vars(row_info,row,prev_row,bpp)
+
+   PNG_UNUSED(pp)
+
+   /* Altivec operations require 16-byte aligned data
+    * but input can be unaligned. So we calculate
+    * unaligned part as usual.
+    */
+   for (i = 0; i < unaligned_top; i++)
+   {
+      *rp = (png_byte)(((int)(*rp) + (int)(*(rp-bpp))) & 0xff);
+      rp++;
+   }
+
+   /* Using SIMD while we can */
+   while( istop >= 16 )
+   {
+      for(i=0;i < bpp ; i++)
+      {
+         *rp = (png_byte)(((int)(*rp) + (int)(*(rp-bpp))) & 0xff);
+         rp++;
+      }
+      rp -= bpp;
+
+      rp_vec = vec_ld(0,rp);
+      part_vec = vec_perm(rp_vec,VSX_CHAR_ZERO,VSX_LEFTSHIFTED1_4);
+      rp_vec = vec_add(rp_vec,part_vec);
+
+      part_vec = vec_perm(rp_vec,VSX_CHAR_ZERO,VSX_LEFTSHIFTED2_4);
+      rp_vec = vec_add(rp_vec,part_vec);
+
+      part_vec = vec_perm(rp_vec,VSX_CHAR_ZERO,VSX_LEFTSHIFTED3_4);
+      rp_vec = vec_add(rp_vec,part_vec);
+
+      vec_st(rp_vec,0,rp);
+
+      rp += 16;
+      istop -= 16;
+   }
+
+   if(istop > 0)
+      for (i = 0; i < istop % 16; i++)
+      {
+         *rp = (png_byte)(((int)(*rp) + (int)(*(rp - bpp))) & 0xff);
+         rp++;
+      }
+
+}
+
+void png_read_filter_row_sub3_vsx(png_row_infop row_info, png_bytep row,
+                                  png_const_bytep prev_row)
+{
+   const png_byte bpp = 3;
+
+   vector unsigned char rp_vec;
+   vector unsigned char part_vec;
+
+   vsx_declare_common_vars(row_info,row,prev_row,bpp)
+
+   PNG_UNUSED(pp)
+
+   /* Altivec operations require 16-byte aligned data
+    * but input can be unaligned. So we calculate
+    * unaligned part as usual.
+    */
+   for (i = 0; i < unaligned_top; i++)
+   {
+      *rp = (png_byte)(((int)(*rp) + (int)(*(rp-bpp))) & 0xff);
+      rp++;
+   }
+
+   /* Using SIMD while we can */
+   while( istop >= 16 )
+   {
+      for(i=0;i < bpp ; i++)
+      {
+         *rp = (png_byte)(((int)(*rp) + (int)(*(rp-bpp))) & 0xff);
+         rp++;
+      }
+      rp -= bpp;
+
+      rp_vec = vec_ld(0,rp);
+      part_vec = vec_perm(rp_vec,VSX_CHAR_ZERO,VSX_LEFTSHIFTED1_3);
+      rp_vec = vec_add(rp_vec,part_vec);
+
+      part_vec = vec_perm(rp_vec,VSX_CHAR_ZERO,VSX_LEFTSHIFTED2_3);
+      rp_vec = vec_add(rp_vec,part_vec);
+
+      part_vec = vec_perm(rp_vec,VSX_CHAR_ZERO,VSX_LEFTSHIFTED3_3);
+      rp_vec = vec_add(rp_vec,part_vec);
+
+      part_vec = vec_perm(rp_vec,VSX_CHAR_ZERO,VSX_LEFTSHIFTED4_3);
+      rp_vec = vec_add(rp_vec,part_vec);
+
+      vec_st(rp_vec,0,rp);
+      rp += 15;
+      istop -= 16;
+
+      /* Since 16 % bpp = 16 % 3 = 1, last element of array must
+       * be proceeded manually
+       */
+      *rp = (png_byte)(((int)(*rp) + (int)(*(rp-bpp))) & 0xff);
+      rp++;
+   }
+
+   if(istop > 0)
+      for (i = 0; i < istop % 16; i++)
+      {
+         *rp = (png_byte)(((int)(*rp) + (int)(*(rp-bpp))) & 0xff);
+         rp++;
+      }
+}
+
+void png_read_filter_row_avg4_vsx(png_row_infop row_info, png_bytep row,
+                                  png_const_bytep prev_row)
+{
+   const png_byte bpp = 4;
+
+   vector unsigned char rp_vec;
+   vector unsigned char pp_vec;
+   vector unsigned char pp_part_vec;
+   vector unsigned char rp_part_vec;
+   vector unsigned char avg_vec;
+
+   vsx_declare_common_vars(row_info,row,prev_row,bpp)
+   rp -= bpp;
+   if(istop >= bpp)
+      istop -= bpp;
+
+   for (i = 0; i < bpp; i++)
+   {
+      *rp = (png_byte)(((int)(*rp) +
+         ((int)(*pp++) / 2 )) & 0xff);
+
+      rp++;
+   }
+
+   /* Altivec operations require 16-byte aligned data
+    * but input can be unaligned. So we calculate
+    * unaligned part as usual.
+    */
+   for (i = 0; i < unaligned_top; i++)
+   {
+      *rp = (png_byte)(((int)(*rp) +
+         (int)(*pp++ + *(rp-bpp)) / 2 ) & 0xff);
+
+      rp++;
+   }
+
+   /* Using SIMD while we can */
+   while( istop >= 16 )
+   {
+      for(i=0;i < bpp ; i++)
+      {
+         *rp = (png_byte)(((int)(*rp) +
+            (int)(*pp++ + *(rp-bpp)) / 2 ) & 0xff);
+
+         rp++;
+      }
+      rp -= bpp;
+      pp -= bpp;
+
+      vec_ld_unaligned(pp_vec,pp);
+      rp_vec = vec_ld(0,rp);
+
+      rp_part_vec = vec_perm(rp_vec,VSX_CHAR_ZERO,VSX_LEFTSHIFTED1_4);
+      pp_part_vec = vec_perm(pp_vec,VSX_CHAR_ZERO,VSX_NOT_SHIFTED1_4);
+      avg_vec = vec_avg(rp_part_vec,pp_part_vec);
+      avg_vec = vec_sub(avg_vec, vec_and(vec_xor(rp_part_vec,pp_part_vec),vec_splat_u8(1)));
+      rp_vec = vec_add(rp_vec,avg_vec);
+
+      rp_part_vec = vec_perm(rp_vec,VSX_CHAR_ZERO,VSX_LEFTSHIFTED2_4);
+      pp_part_vec = vec_perm(pp_vec,VSX_CHAR_ZERO,VSX_NOT_SHIFTED2_4);
+      avg_vec = vec_avg(rp_part_vec,pp_part_vec);
+      avg_vec = vec_sub(avg_vec, vec_and(vec_xor(rp_part_vec,pp_part_vec),vec_splat_u8(1)));
+      rp_vec = vec_add(rp_vec,avg_vec);
+
+      rp_part_vec = vec_perm(rp_vec,VSX_CHAR_ZERO,VSX_LEFTSHIFTED3_4);
+      pp_part_vec = vec_perm(pp_vec,VSX_CHAR_ZERO,VSX_NOT_SHIFTED3_4);
+      avg_vec = vec_avg(rp_part_vec,pp_part_vec);
+      avg_vec = vec_sub(avg_vec, vec_and(vec_xor(rp_part_vec,pp_part_vec),vec_splat_u8(1)));
+      rp_vec = vec_add(rp_vec,avg_vec);
+
+      vec_st(rp_vec,0,rp);
+
+      rp += 16;
+      pp += 16;
+      istop -= 16;
+   }
+
+   if(istop  > 0)
+      for (i = 0; i < istop % 16; i++)
+      {
+         *rp = (png_byte)(((int)(*rp) +
+            (int)(*pp++ + *(rp-bpp)) / 2 ) & 0xff);
+
+         rp++;
+      }
+}
+
+void png_read_filter_row_avg3_vsx(png_row_infop row_info, png_bytep row,
+                                  png_const_bytep prev_row)
+{
+  const png_byte bpp = 3;
+
+  vector unsigned char rp_vec;
+  vector unsigned char pp_vec;
+  vector unsigned char pp_part_vec;
+  vector unsigned char rp_part_vec;
+  vector unsigned char avg_vec;
+
+  vsx_declare_common_vars(row_info,row,prev_row,bpp)
+  rp -= bpp;
+  if(istop >= bpp)
+     istop -= bpp;
+
+  for (i = 0; i < bpp; i++)
+  {
+     *rp = (png_byte)(((int)(*rp) +
+        ((int)(*pp++) / 2 )) & 0xff);
+
+     rp++;
+  }
+
+  /* Altivec operations require 16-byte aligned data
+   * but input can be unaligned. So we calculate
+   * unaligned part as usual.
+   */
+  for (i = 0; i < unaligned_top; i++)
+  {
+     *rp = (png_byte)(((int)(*rp) +
+        (int)(*pp++ + *(rp-bpp)) / 2 ) & 0xff);
+
+     rp++;
+  }
+
+  /* Using SIMD while we can */
+  while( istop >= 16 )
+  {
+     for(i=0;i < bpp ; i++)
+     {
+        *rp = (png_byte)(((int)(*rp) +
+           (int)(*pp++ + *(rp-bpp)) / 2 ) & 0xff);
+
+        rp++;
+     }
+     rp -= bpp;
+     pp -= bpp;
+
+     vec_ld_unaligned(pp_vec,pp);
+     rp_vec = vec_ld(0,rp);
+
+     rp_part_vec = vec_perm(rp_vec,VSX_CHAR_ZERO,VSX_LEFTSHIFTED1_3);
+     pp_part_vec = vec_perm(pp_vec,VSX_CHAR_ZERO,VSX_NOT_SHIFTED1_3);
+     avg_vec = vec_avg(rp_part_vec,pp_part_vec);
+     avg_vec = vec_sub(avg_vec, vec_and(vec_xor(rp_part_vec,pp_part_vec),vec_splat_u8(1)));
+     rp_vec = vec_add(rp_vec,avg_vec);
+
+     rp_part_vec = vec_perm(rp_vec,VSX_CHAR_ZERO,VSX_LEFTSHIFTED2_3);
+     pp_part_vec = vec_perm(pp_vec,VSX_CHAR_ZERO,VSX_NOT_SHIFTED2_3);
+     avg_vec = vec_avg(rp_part_vec,pp_part_vec);
+     avg_vec = vec_sub(avg_vec, vec_and(vec_xor(rp_part_vec,pp_part_vec),vec_splat_u8(1)));
+     rp_vec = vec_add(rp_vec,avg_vec);
+
+     rp_part_vec = vec_perm(rp_vec,VSX_CHAR_ZERO,VSX_LEFTSHIFTED3_3);
+     pp_part_vec = vec_perm(pp_vec,VSX_CHAR_ZERO,VSX_NOT_SHIFTED3_3);
+     avg_vec = vec_avg(rp_part_vec,pp_part_vec);
+     avg_vec = vec_sub(avg_vec, vec_and(vec_xor(rp_part_vec,pp_part_vec),vec_splat_u8(1)));
+     rp_vec = vec_add(rp_vec,avg_vec);
+
+     rp_part_vec = vec_perm(rp_vec,VSX_CHAR_ZERO,VSX_LEFTSHIFTED4_3);
+     pp_part_vec = vec_perm(pp_vec,VSX_CHAR_ZERO,VSX_NOT_SHIFTED4_3);
+     avg_vec = vec_avg(rp_part_vec,pp_part_vec);
+     avg_vec = vec_sub(avg_vec, vec_and(vec_xor(rp_part_vec,pp_part_vec),vec_splat_u8(1)));
+     rp_vec = vec_add(rp_vec,avg_vec);
+
+     vec_st(rp_vec,0,rp);
+
+     rp += 15;
+     pp += 15;
+     istop -= 16;
+
+     /* Since 16 % bpp = 16 % 3 = 1, last element of array must
+      * be proceeded manually
+      */
+     *rp = (png_byte)(((int)(*rp) +
+        (int)(*pp++ + *(rp-bpp)) / 2 ) & 0xff);
+     rp++;
+  }
+
+  if(istop  > 0)
+     for (i = 0; i < istop % 16; i++)
+     {
+        *rp = (png_byte)(((int)(*rp) +
+           (int)(*pp++ + *(rp-bpp)) / 2 ) & 0xff);
+
+        rp++;
+     }
+}
+
+/* Bytewise c ? t : e. */
+#define if_then_else(c,t,e) vec_sel(e,t,c)
+
+#define vsx_paeth_process(rp,pp,a,b,c,pa,pb,pc,bpp) {\
+      c = *(pp - bpp);\
+      a = *(rp - bpp);\
+      b = *pp++;\
+      p = b - c;\
+      pc = a - c;\
+      pa = vsx_abs(p);\
+      pb = vsx_abs(pc);\
+      pc = vsx_abs(p + pc);\
+      if (pb < pa) pa = pb, a = b;\
+      if (pc < pa) a = c;\
+      a += *rp;\
+      *rp++ = (png_byte)a;\
+      }
+
+void png_read_filter_row_paeth4_vsx(png_row_infop row_info, png_bytep row,
+   png_const_bytep prev_row)
+{
+   const png_byte bpp = 4;
+
+   int a, b, c, pa, pb, pc, p;
+   vector unsigned char rp_vec;
+   vector unsigned char pp_vec;
+   vector unsigned short a_vec,b_vec,c_vec,nearest_vec;
+   vector signed short pa_vec,pb_vec,pc_vec,smallest_vec;
+
+   vsx_declare_common_vars(row_info,row,prev_row,bpp)
+   rp -= bpp;
+   if(istop >= bpp)
+      istop -= bpp;
+
+   /* Process the first pixel in the row completely (this is the same as 'up'
+    * because there is only one candidate predictor for the first row).
+    */
+   for(i = 0; i < bpp ; i++)
+   {
+      *rp = (png_byte)( *rp + *pp);
+      rp++;
+      pp++;
+   }
+
+   for(i = 0; i < unaligned_top ; i++)
+   {
+      vsx_paeth_process(rp,pp,a,b,c,pa,pb,pc,bpp)
+   }
+
+   while( istop >= 16)
+   {
+      for(i = 0; i < bpp ; i++)
+      {
+         vsx_paeth_process(rp,pp,a,b,c,pa,pb,pc,bpp)
+      }
+
+      rp -= bpp;
+      pp -= bpp;
+      rp_vec = vec_ld(0,rp);
+      vec_ld_unaligned(pp_vec,pp);
+
+      a_vec = vsx_char_to_short(vec_perm(rp_vec , VSX_CHAR_ZERO , VSX_LEFTSHIFTED1_4),1,4);
+      b_vec = vsx_char_to_short(vec_perm(pp_vec , VSX_CHAR_ZERO , VSX_NOT_SHIFTED1_4),1,4);
+      c_vec = vsx_char_to_short(vec_perm(pp_vec , VSX_CHAR_ZERO , VSX_LEFTSHIFTED1_4),1,4);
+      pa_vec = (vector signed short) vec_sub(b_vec,c_vec);
+      pb_vec = (vector signed short) vec_sub(a_vec , c_vec);
+      pc_vec = vec_add(pa_vec,pb_vec);
+      pa_vec = vec_abs(pa_vec);
+      pb_vec = vec_abs(pb_vec);
+      pc_vec = vec_abs(pc_vec);
+      smallest_vec = vec_min(pc_vec, vec_min(pa_vec,pb_vec));
+      nearest_vec =  if_then_else(
+            vec_cmpeq(pa_vec,smallest_vec),
+            a_vec,
+            if_then_else(
+              vec_cmpeq(pb_vec,smallest_vec),
+              b_vec,
+              c_vec
+              )
+            );
+      rp_vec = vec_add(rp_vec,(vsx_short_to_char(nearest_vec,1,4)));
+
+      a_vec = vsx_char_to_short(vec_perm(rp_vec , VSX_CHAR_ZERO , VSX_LEFTSHIFTED2_4),2,4);
+      b_vec = vsx_char_to_short(vec_perm(pp_vec , VSX_CHAR_ZERO , VSX_NOT_SHIFTED2_4),2,4);
+      c_vec = vsx_char_to_short(vec_perm(pp_vec , VSX_CHAR_ZERO , VSX_LEFTSHIFTED2_4),2,4);
+      pa_vec = (vector signed short) vec_sub(b_vec,c_vec);
+      pb_vec = (vector signed short) vec_sub(a_vec , c_vec);
+      pc_vec = vec_add(pa_vec,pb_vec);
+      pa_vec = vec_abs(pa_vec);
+      pb_vec = vec_abs(pb_vec);
+      pc_vec = vec_abs(pc_vec);
+      smallest_vec = vec_min(pc_vec, vec_min(pa_vec,pb_vec));
+      nearest_vec =  if_then_else(
+            vec_cmpeq(pa_vec,smallest_vec),
+            a_vec,
+            if_then_else(
+              vec_cmpeq(pb_vec,smallest_vec),
+              b_vec,
+              c_vec
+              )
+            );
+      rp_vec = vec_add(rp_vec,(vsx_short_to_char(nearest_vec,2,4)));
+
+      a_vec = vsx_char_to_short(vec_perm(rp_vec , VSX_CHAR_ZERO , VSX_LEFTSHIFTED3_4),3,4);
+      b_vec = vsx_char_to_short(vec_perm(pp_vec , VSX_CHAR_ZERO , VSX_NOT_SHIFTED3_4),3,4);
+      c_vec = vsx_char_to_short(vec_perm(pp_vec , VSX_CHAR_ZERO , VSX_LEFTSHIFTED3_4),3,4);
+      pa_vec = (vector signed short) vec_sub(b_vec,c_vec);
+      pb_vec = (vector signed short) vec_sub(a_vec , c_vec);
+      pc_vec = vec_add(pa_vec,pb_vec);
+      pa_vec = vec_abs(pa_vec);
+      pb_vec = vec_abs(pb_vec);
+      pc_vec = vec_abs(pc_vec);
+      smallest_vec = vec_min(pc_vec, vec_min(pa_vec,pb_vec));
+      nearest_vec =  if_then_else(
+            vec_cmpeq(pa_vec,smallest_vec),
+            a_vec,
+            if_then_else(
+              vec_cmpeq(pb_vec,smallest_vec),
+              b_vec,
+              c_vec
+              )
+            );
+      rp_vec = vec_add(rp_vec,(vsx_short_to_char(nearest_vec,3,4)));
+
+      vec_st(rp_vec,0,rp);
+
+      rp += 16;
+      pp += 16;
+      istop -= 16;
+   }
+
+   if(istop > 0)
+      for (i = 0; i < istop % 16; i++)
+      {
+         vsx_paeth_process(rp,pp,a,b,c,pa,pb,pc,bpp)
+      }
+}
+
+void png_read_filter_row_paeth3_vsx(png_row_infop row_info, png_bytep row,
+   png_const_bytep prev_row)
+{
+  const png_byte bpp = 3;
+
+  int a, b, c, pa, pb, pc, p;
+  vector unsigned char rp_vec;
+  vector unsigned char pp_vec;
+  vector unsigned short a_vec,b_vec,c_vec,nearest_vec;
+  vector signed short pa_vec,pb_vec,pc_vec,smallest_vec;
+
+  vsx_declare_common_vars(row_info,row,prev_row,bpp)
+  rp -= bpp;
+  if(istop >= bpp)
+     istop -= bpp;
+
+  /* Process the first pixel in the row completely (this is the same as 'up'
+   * because there is only one candidate predictor for the first row).
+   */
+  for(i = 0; i < bpp ; i++)
+  {
+     *rp = (png_byte)( *rp + *pp);
+     rp++;
+     pp++;
+  }
+
+  for(i = 0; i < unaligned_top ; i++)
+  {
+     vsx_paeth_process(rp,pp,a,b,c,pa,pb,pc,bpp)
+  }
+
+  while( istop >= 16)
+  {
+     for(i = 0; i < bpp ; i++)
+     {
+        vsx_paeth_process(rp,pp,a,b,c,pa,pb,pc,bpp)
+     }
+
+     rp -= bpp;
+     pp -= bpp;
+     rp_vec = vec_ld(0,rp);
+     vec_ld_unaligned(pp_vec,pp);
+
+     a_vec = vsx_char_to_short(vec_perm(rp_vec , VSX_CHAR_ZERO , VSX_LEFTSHIFTED1_3),1,3);
+     b_vec = vsx_char_to_short(vec_perm(pp_vec , VSX_CHAR_ZERO , VSX_NOT_SHIFTED1_3),1,3);
+     c_vec = vsx_char_to_short(vec_perm(pp_vec , VSX_CHAR_ZERO , VSX_LEFTSHIFTED1_3),1,3);
+     pa_vec = (vector signed short) vec_sub(b_vec,c_vec);
+     pb_vec = (vector signed short) vec_sub(a_vec , c_vec);
+     pc_vec = vec_add(pa_vec,pb_vec);
+     pa_vec = vec_abs(pa_vec);
+     pb_vec = vec_abs(pb_vec);
+     pc_vec = vec_abs(pc_vec);
+     smallest_vec = vec_min(pc_vec, vec_min(pa_vec,pb_vec));
+     nearest_vec =  if_then_else(
+           vec_cmpeq(pa_vec,smallest_vec),
+           a_vec,
+           if_then_else(
+             vec_cmpeq(pb_vec,smallest_vec),
+             b_vec,
+             c_vec
+             )
+           );
+     rp_vec = vec_add(rp_vec,(vsx_short_to_char(nearest_vec,1,3)));
+
+     a_vec = vsx_char_to_short(vec_perm(rp_vec , VSX_CHAR_ZERO , VSX_LEFTSHIFTED2_3),2,3);
+     b_vec = vsx_char_to_short(vec_perm(pp_vec , VSX_CHAR_ZERO , VSX_NOT_SHIFTED2_3),2,3);
+     c_vec = vsx_char_to_short(vec_perm(pp_vec , VSX_CHAR_ZERO , VSX_LEFTSHIFTED2_3),2,3);
+     pa_vec = (vector signed short) vec_sub(b_vec,c_vec);
+     pb_vec = (vector signed short) vec_sub(a_vec , c_vec);
+     pc_vec = vec_add(pa_vec,pb_vec);
+     pa_vec = vec_abs(pa_vec);
+     pb_vec = vec_abs(pb_vec);
+     pc_vec = vec_abs(pc_vec);
+     smallest_vec = vec_min(pc_vec, vec_min(pa_vec,pb_vec));
+     nearest_vec =  if_then_else(
+           vec_cmpeq(pa_vec,smallest_vec),
+           a_vec,
+           if_then_else(
+             vec_cmpeq(pb_vec,smallest_vec),
+             b_vec,
+             c_vec
+             )
+           );
+     rp_vec = vec_add(rp_vec,(vsx_short_to_char(nearest_vec,2,3)));
+
+     a_vec = vsx_char_to_short(vec_perm(rp_vec , VSX_CHAR_ZERO , VSX_LEFTSHIFTED3_3),3,3);
+     b_vec = vsx_char_to_short(vec_perm(pp_vec , VSX_CHAR_ZERO , VSX_NOT_SHIFTED3_3),3,3);
+     c_vec = vsx_char_to_short(vec_perm(pp_vec , VSX_CHAR_ZERO , VSX_LEFTSHIFTED3_3),3,3);
+     pa_vec = (vector signed short) vec_sub(b_vec,c_vec);
+     pb_vec = (vector signed short) vec_sub(a_vec , c_vec);
+     pc_vec = vec_add(pa_vec,pb_vec);
+     pa_vec = vec_abs(pa_vec);
+     pb_vec = vec_abs(pb_vec);
+     pc_vec = vec_abs(pc_vec);
+     smallest_vec = vec_min(pc_vec, vec_min(pa_vec,pb_vec));
+     nearest_vec =  if_then_else(
+           vec_cmpeq(pa_vec,smallest_vec),
+           a_vec,
+           if_then_else(
+             vec_cmpeq(pb_vec,smallest_vec),
+             b_vec,
+             c_vec
+             )
+           );
+     rp_vec = vec_add(rp_vec,(vsx_short_to_char(nearest_vec,3,3)));
+
+     a_vec = vsx_char_to_short(vec_perm(rp_vec , VSX_CHAR_ZERO , VSX_LEFTSHIFTED4_3),4,3);
+     b_vec = vsx_char_to_short(vec_perm(pp_vec , VSX_CHAR_ZERO , VSX_NOT_SHIFTED4_3),4,3);
+     c_vec = vsx_char_to_short(vec_perm(pp_vec , VSX_CHAR_ZERO , VSX_LEFTSHIFTED4_3),4,3);
+     pa_vec = (vector signed short) vec_sub(b_vec,c_vec);
+     pb_vec = (vector signed short) vec_sub(a_vec , c_vec);
+     pc_vec = vec_add(pa_vec,pb_vec);
+     pa_vec = vec_abs(pa_vec);
+     pb_vec = vec_abs(pb_vec);
+     pc_vec = vec_abs(pc_vec);
+     smallest_vec = vec_min(pc_vec, vec_min(pa_vec,pb_vec));
+     nearest_vec =  if_then_else(
+           vec_cmpeq(pa_vec,smallest_vec),
+           a_vec,
+           if_then_else(
+             vec_cmpeq(pb_vec,smallest_vec),
+             b_vec,
+             c_vec
+             )
+           );
+     rp_vec = vec_add(rp_vec,(vsx_short_to_char(nearest_vec,4,3)));
+
+     vec_st(rp_vec,0,rp);
+
+     rp += 15;
+     pp += 15;
+     istop -= 16;
+
+     /* Since 16 % bpp = 16 % 3 = 1, last element of array must
+      * be proceeded manually
+      */
+     vsx_paeth_process(rp,pp,a,b,c,pa,pb,pc,bpp)
+  }
+
+  if(istop > 0)
+     for (i = 0; i < istop % 16; i++)
+     {
+        vsx_paeth_process(rp,pp,a,b,c,pa,pb,pc,bpp)
+     }
+}
+
+#endif /* PNG_POWERPC_VSX_OPT > 0 */
+#endif /* PNG_POWERPC_VSX_IMPLEMENTATION == 1 (intrinsics) */
+#endif /* READ */
