1 files changed, 137 insertions, 0 deletions
diff --git a/third_party/libpng16/arm/palette_neon_intrinsics.c b/third_party/libpng16/arm/palette_neon_intrinsics.c
new file mode 100644
index 0000000000..703b9ff250
--- /dev/null
+++ b/third_party/libpng16/arm/palette_neon_intrinsics.c
@@ -0,0 +1,137 @@
+/* palette_neon_intrinsics.c - NEON optimised palette expansion functions
+ *
+ * Copyright (c) 2017 The Chromium Authors. All rights reserved.
+ * Written by Richard Townsend <Richard.Townsend@arm.com>, February 2017.
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ */
+
+#include "../pngpriv.h"
+
+#if PNG_ARM_NEON_IMPLEMENTATION == 1
+
+#include <arm_neon.h>
+
+/* Build an RGBA palette from the RGB and separate alpha palettes. */
+void
+png_riffle_palette_rgba(png_structrp png_ptr, png_row_infop row_info)
+{
+   png_const_colorp palette = png_ptr->palette;
+   png_bytep riffled_palette = png_ptr->riffled_palette;
+   png_const_bytep trans_alpha = png_ptr->trans_alpha;
+   int num_trans = png_ptr->num_trans;
+
+   if (row_info->bit_depth != 8) {
+      png_error(png_ptr, "bit_depth must be 8 for png_riffle_palette_rgba");
+      return;
+   }
+
+   /* Initially black, opaque. */
+   uint8x16x4_t w = {{
+      vdupq_n_u8(0x00),
+      vdupq_n_u8(0x00),
+      vdupq_n_u8(0x00),
+      vdupq_n_u8(0xff),
+   }};
+
+   int i;
+   /* First, riffle the RGB colours into a RGBA palette, the A value is
+    * set to opaque for now. */
+   for (i = 0; i < (1 << row_info->bit_depth); i += 16) {
+      uint8x16x3_t v = vld3q_u8((png_const_bytep)(palette + i));
+      w.val[0] = v.val[0];
+      w.val[1] = v.val[1];
+      w.val[2] = v.val[2];
+      vst4q_u8(riffled_palette + (i << 2), w);
+   }
+
+   /* Fix up the missing transparency values. */
+   for (i = 0; i < num_trans; i++) {
+      riffled_palette[(i << 2) + 3] = trans_alpha[i];
+   }
+}
+
+
+/* Expands a palettized row into RGBA. */
+int
+png_do_expand_palette_neon_rgba(png_structrp png_ptr, png_row_infop row_info,
+   png_const_bytep row, const png_bytepp ssp, const png_bytepp ddp)
+{
+
+   png_uint_32 row_width = row_info->width;
+   const png_uint_32 *riffled_palette = (const png_uint_32*)png_ptr->riffled_palette;
+   const png_int_32 pixels_per_chunk = 4;
+
+   if (row_width < pixels_per_chunk) {
+      return 0;
+   }
+
+   /* This function originally gets the last byte of the output row.
+      The NEON part writes forward from a given position, so we have
+      to seek this back by 4 pixels x 4 bytes. */
+   *ddp = *ddp - ((pixels_per_chunk * sizeof(png_uint_32)) - 1);
+
+   int i;
+   for (i = 0; i < row_width; i += pixels_per_chunk) {
+      uint32x4_t cur;
+      png_bytep sp = *ssp - i, dp = *ddp - (i << 2);
+      cur = vld1q_dup_u32 (riffled_palette + *(sp - 3));
+      cur = vld1q_lane_u32(riffled_palette + *(sp - 2), cur, 1);
+      cur = vld1q_lane_u32(riffled_palette + *(sp - 1), cur, 2);
+      cur = vld1q_lane_u32(riffled_palette + *(sp - 0), cur, 3);
+      vst1q_u32((void *)dp, cur);
+   }
+   if (i != row_width) {
+      i -= pixels_per_chunk; /* Remove the amount that wasn't processed. */
+   }
+
+   /* Decrement output pointers. */
+   *ssp = *ssp - i;
+   *ddp = *ddp - (i << 2);
+   return i;
+}
+
+/* Expands a palettized row into RGB format. */
+int
+png_do_expand_palette_neon_rgb(png_structrp png_ptr, png_row_infop row_info,
+   png_const_bytep row, const png_bytepp ssp, const png_bytepp ddp)
+{
+   png_uint_32 row_width = row_info->width;
+   png_const_bytep palette = (png_const_bytep)png_ptr->palette;
+   const png_uint_32 pixels_per_chunk = 8;
+
+   if (row_width <= pixels_per_chunk) {
+      return 0;
+   }
+
+   /* Seeking this back by 8 pixels x 3 bytes. */
+   *ddp = *ddp - ((pixels_per_chunk * sizeof(png_color)) - 1);
+
+   int i;
+   for (i = 0; i < row_width; i += pixels_per_chunk) {
+      uint8x8x3_t cur;
+      png_bytep sp = *ssp - i, dp = *ddp - ((i << 1) + i);
+      cur = vld3_dup_u8(palette + sizeof(png_color) * (*(sp - 7)));
+      cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 6)), cur, 1);
+      cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 5)), cur, 2);
+      cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 4)), cur, 3);
+      cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 3)), cur, 4);
+      cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 2)), cur, 5);
+      cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 1)), cur, 6);
+      cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 0)), cur, 7);
+      vst3_u8((void *)dp, cur);
+   }
+
+   if (i != row_width) {
+      i -= pixels_per_chunk; /* Remove the amount that wasn't processed. */
+   }
+
+   /* Decrement output pointers. */
+   *ssp = *ssp - i;
+   *ddp = *ddp - ((i << 1) + i);
+   return i;
+}
+
+#endif /* PNG_ARM_NEON_IMPLEMENTATION */