76 lines
2.1 KiB
C
76 lines
2.1 KiB
C
// Copyright 2010 Google Inc. All Rights Reserved.
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//
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// Use of this source code is governed by a BSD-style license
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// that can be found in the COPYING file in the root of the source
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// tree. An additional intellectual property rights grant can be found
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// in the file PATENTS. All contributing project authors may
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// be found in the AUTHORS file in the root of the source tree.
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// -----------------------------------------------------------------------------
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//
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// YUV->RGB conversion function
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//
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// Author: Skal (pascal.massimino@gmail.com)
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#include "./yuv.h"
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#if defined(__cplusplus) || defined(c_plusplus)
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extern "C" {
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#endif
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#ifdef WEBP_YUV_USE_TABLE
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int16_t VP8kVToR[256], VP8kUToB[256];
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int32_t VP8kVToG[256], VP8kUToG[256];
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uint8_t VP8kClip[YUV_RANGE_MAX - YUV_RANGE_MIN];
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uint8_t VP8kClip4Bits[YUV_RANGE_MAX - YUV_RANGE_MIN];
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static int done = 0;
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static WEBP_INLINE uint8_t clip(int v, int max_value) {
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return v < 0 ? 0 : v > max_value ? max_value : v;
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}
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void VP8YUVInit(void) {
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int i;
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if (done) {
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return;
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}
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#ifndef USE_YUVj
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for (i = 0; i < 256; ++i) {
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VP8kVToR[i] = (89858 * (i - 128) + YUV_HALF) >> YUV_FIX;
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VP8kUToG[i] = -22014 * (i - 128) + YUV_HALF;
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VP8kVToG[i] = -45773 * (i - 128);
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VP8kUToB[i] = (113618 * (i - 128) + YUV_HALF) >> YUV_FIX;
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}
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for (i = YUV_RANGE_MIN; i < YUV_RANGE_MAX; ++i) {
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const int k = ((i - 16) * 76283 + YUV_HALF) >> YUV_FIX;
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VP8kClip[i - YUV_RANGE_MIN] = clip(k, 255);
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VP8kClip4Bits[i - YUV_RANGE_MIN] = clip((k + 8) >> 4, 15);
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}
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#else
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for (i = 0; i < 256; ++i) {
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VP8kVToR[i] = (91881 * (i - 128) + YUV_HALF) >> YUV_FIX;
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VP8kUToG[i] = -22554 * (i - 128) + YUV_HALF;
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VP8kVToG[i] = -46802 * (i - 128);
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VP8kUToB[i] = (116130 * (i - 128) + YUV_HALF) >> YUV_FIX;
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}
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for (i = YUV_RANGE_MIN; i < YUV_RANGE_MAX; ++i) {
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const int k = i;
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VP8kClip[i - YUV_RANGE_MIN] = clip(k, 255);
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VP8kClip4Bits[i - YUV_RANGE_MIN] = clip((k + 8) >> 4, 15);
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}
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#endif
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done = 1;
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}
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#else
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void VP8YUVInit(void) {}
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#endif // WEBP_YUV_USE_TABLE
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#if defined(__cplusplus) || defined(c_plusplus)
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} // extern "C"
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#endif
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