Chromium Code Reviews
chromiumcodereview-hr@appspot.gserviceaccount.com (chromiumcodereview-hr) | Please choose your nickname with Settings | Help | Chromium Project | Gerrit Changes | Sign out
(44)

Unified Diff: src/opts/SkSwizzler_opts.h

Issue 1577703006: Optimized premultiplying swizzles for NEON (Closed) Base URL: https://skia.googlesource.com/skia.git@master
Patch Set: Remove unnecessary if statement Created 4 years, 11 months ago
Use n/p to move between diff chunks; N/P to move between comments. Draft comments are only viewable by you.
Jump to:
View side-by-side diff with in-line comments
Download patch
« no previous file with comments | « src/opts/SkOpts_neon.cpp ('k') | no next file » | no next file with comments »
Expand Comments ('e') | Collapse Comments ('c') | Show Comments Hide Comments ('s')
Index: src/opts/SkSwizzler_opts.h
diff --git a/src/opts/SkSwizzler_opts.h b/src/opts/SkSwizzler_opts.h
new file mode 100644
index 0000000000000000000000000000000000000000..467e5d1940624d6571c7561cafc26e6c8a776fa0
--- /dev/null
+++ b/src/opts/SkSwizzler_opts.h
@@ -0,0 +1,153 @@
+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkSwizzler_opts_DEFINED
+#define SkSwizzler_opts_DEFINED
+
+#include "SkColorPriv.h"
+
+namespace SK_OPTS_NS {
+
+// These variable names in these functions just pretend the input is BGRA.
+// They work fine with both RGBA and BGRA.
+
+static void premul_xxxa_portable(uint32_t dst[], const uint32_t src[], int count) {
+ for (int i = 0; i < count; i++) {
+ uint8_t a = src[i] >> 24,
+ r = src[i] >> 16,
+ g = src[i] >> 8,
+ b = src[i] >> 0;
+ r = (r*a+127)/255;
+ g = (g*a+127)/255;
+ b = (b*a+127)/255;
+ dst[i] = (uint32_t)a << 24
+ | (uint32_t)r << 16
+ | (uint32_t)g << 8
+ | (uint32_t)b << 0;
+ }
+}
+
+static void premul_swaprb_xxxa_portable(uint32_t dst[], const uint32_t src[], int count) {
+ for (int i = 0; i < count; i++) {
+ uint8_t a = src[i] >> 24,
+ r = src[i] >> 16,
+ g = src[i] >> 8,
+ b = src[i] >> 0;
+ r = (r*a+127)/255;
+ g = (g*a+127)/255;
+ b = (b*a+127)/255;
+ dst[i] = (uint32_t)a << 24
+ | (uint32_t)b << 16
+ | (uint32_t)g << 8
+ | (uint32_t)r << 0;
+ }
+}
+
+#if defined(SK_ARM_HAS_NEON)
+
+// Rounded divide by 255, (x + 127) / 255
+static uint8x8_t div255_round(uint16x8_t x) {
+ // result = (x + 127) / 255
+ // result = (x + 127) / 256 + error1
+ //
+ // error1 = (x + 127) / (255 * 256)
+ // error1 = (x + 127) / (256 * 256) + error2
+ //
+ // error2 = (x + 127) / (255 * 256 * 256)
+ //
+ // The maximum value of error2 is too small to matter. Thus:
+ // result = (x + 127) / 256 + (x + 127) / (256 * 256)
+ // result = ((x + 127) / 256 + x + 127) / 256
+ // result = ((x + 127) >> 8 + x + 127) >> 8
+ //
+ // Use >>> to represent "rounded right shift" which, conveniently,
+ // NEON supports in one instruction.
+ // result = ((x >>> 8) + x) >>> 8
+ //
+ // Note that the second right shift is actually performed as an
+ // "add, round, and narrow back to 8-bits" instruction.
+ return vraddhn_u16(x, vrshrq_n_u16(x, 8));
+}
+
+// Scale a byte by another, (x * y + 127) / 255
+static uint8x8_t scale(uint8x8_t x, uint8x8_t y) {
+ return div255_round(vmull_u8(x, y));
+}
+
+template <bool kSwapRB>
+static void premul_xxxa_should_swaprb(uint32_t dst[], const uint32_t src[], int count) {
+ while (count >= 8) {
+ // Load 8 pixels.
+ uint8x8x4_t bgra = vld4_u8((const uint8_t*) src);
+
+ uint8x8_t a = bgra.val[3],
+ r = bgra.val[2],
+ g = bgra.val[1],
+ b = bgra.val[0];
+
+ // Premultiply.
+ r = scale(r, a);
+ g = scale(g, a);
+ b = scale(b, a);
+
+ // Store 8 premultiplied pixels.
+ if (kSwapRB) {
+ bgra.val[2] = b;
+ bgra.val[1] = g;
+ bgra.val[0] = r;
+ } else {
+ bgra.val[2] = r;
+ bgra.val[1] = g;
+ bgra.val[0] = b;
+ }
+ vst4_u8((uint8_t*) dst, bgra);
+ src += 8;
+ dst += 8;
+ count -= 8;
+ }
+
+ // Call portable code to finish up the tail of [0,8) pixels.
+ auto proc = kSwapRB ? premul_swaprb_xxxa_portable : premul_xxxa_portable;
+ proc(dst, src, count);
+}
+
+static void premul_xxxa(uint32_t dst[], const uint32_t src[], int count) {
+ premul_xxxa_should_swaprb<false>(dst, src, count);
+}
+
+static void premul_swaprb_xxxa(uint32_t dst[], const uint32_t src[], int count) {
+ premul_xxxa_should_swaprb<true>(dst, src, count);
+}
+
+#else
+
+static void premul_xxxa(uint32_t dst[], const uint32_t src[], int count) {
+ premul_xxxa_portable(dst, src, count);
+}
+
+static void premul_swaprb_xxxa(uint32_t dst[], const uint32_t src[], int count) {
+ premul_swaprb_xxxa_portable(dst, src, count);
+}
+
+#endif
+
+static void swaprb_xxxa(uint32_t dst[], const uint32_t src[], int count) {
+ for (int i = 0; i < count; i++) {
+ uint8_t a = src[i] >> 24,
+ r = src[i] >> 16,
+ g = src[i] >> 8,
+ b = src[i] >> 0;
+ dst[i] = (uint32_t)a << 24
+ | (uint32_t)b << 16
+ | (uint32_t)g << 8
+ | (uint32_t)r << 0;
+ }
+}
+
+}
+
+#endif // SkSwizzler_opts_DEFINED
« no previous file with comments | « src/opts/SkOpts_neon.cpp ('k') | no next file » | no next file with comments »

Powered by Google App Engine
This is Rietveld 408576698