mirror of
https://github.com/webmproject/libwebp.git
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ab66becaae
so that we keep the details of WebPRescaler in utils/rescaler.c when possible. Change-Id: Ib6c1029a09b84cbc7a7d2f70dafa4d4d9132cecc
116 lines
3.8 KiB
C
116 lines
3.8 KiB
C
// Copyright 2014 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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// Rescaling functions
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#include "./dsp.h"
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#include "../utils/rescaler.h"
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//------------------------------------------------------------------------------
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// Implementations of critical functions ImportRow / ExportRow
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#define ROUNDER (1 << (WEBP_RESCALER_RFIX - 1))
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#define MULT_FIX(x, y) (((int64_t)(x) * (y) + ROUNDER) >> WEBP_RESCALER_RFIX)
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static void ImportRowC(WebPRescaler* const wrk,
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const uint8_t* const src, int channel) {
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const int x_stride = wrk->num_channels;
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const int x_out_max = wrk->dst_width * wrk->num_channels;
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int x_in = channel;
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int x_out;
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int accum = 0;
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if (!wrk->x_expand) {
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int sum = 0;
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for (x_out = channel; x_out < x_out_max; x_out += x_stride) {
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accum += wrk->x_add;
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for (; accum > 0; accum -= wrk->x_sub) {
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sum += src[x_in];
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x_in += x_stride;
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}
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{ // Emit next horizontal pixel.
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const int32_t base = src[x_in];
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const int32_t frac = base * (-accum);
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x_in += x_stride;
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wrk->frow[x_out] = (sum + base) * wrk->x_sub - frac;
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// fresh fractional start for next pixel
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sum = (int)MULT_FIX(frac, wrk->fx_scale);
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}
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}
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} else { // simple bilinear interpolation
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int left = src[channel], right = src[channel];
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for (x_out = channel; x_out < x_out_max; x_out += x_stride) {
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if (accum < 0) {
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left = right;
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x_in += x_stride;
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right = src[x_in];
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accum += wrk->x_add;
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}
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wrk->frow[x_out] = right * wrk->x_add + (left - right) * accum;
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accum -= wrk->x_sub;
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}
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}
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// Accumulate the contribution of the new row.
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for (x_out = channel; x_out < x_out_max; x_out += x_stride) {
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wrk->irow[x_out] += wrk->frow[x_out];
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}
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}
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static void ExportRowC(WebPRescaler* const wrk, int x_out) {
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if (wrk->y_accum <= 0) {
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uint8_t* const dst = wrk->dst;
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int32_t* const irow = wrk->irow;
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const int32_t* const frow = wrk->frow;
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const int yscale = wrk->fy_scale * (-wrk->y_accum);
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const int x_out_max = wrk->dst_width * wrk->num_channels;
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for (; x_out < x_out_max; ++x_out) {
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const int frac = (int)MULT_FIX(frow[x_out], yscale);
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const int v = (int)MULT_FIX(irow[x_out] - frac, wrk->fxy_scale);
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dst[x_out] = (!(v & ~0xff)) ? v : (v < 0) ? 0 : 255;
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irow[x_out] = frac; // new fractional start
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}
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wrk->y_accum += wrk->y_add;
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wrk->dst += wrk->dst_stride;
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}
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}
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#undef MULT_FIX
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#undef ROUNDER
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//------------------------------------------------------------------------------
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void (*WebPRescalerImportRow)(struct WebPRescaler* const wrk,
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const uint8_t* const src, int channel);
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void (*WebPRescalerExportRow)(struct WebPRescaler* const wrk, int x_out);
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extern void WebPRescalerDspInitMIPS32(void);
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extern void WebPRescalerDspInitMIPSdspR2(void);
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static volatile VP8CPUInfo rescaler_last_cpuinfo_used =
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(VP8CPUInfo)&rescaler_last_cpuinfo_used;
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WEBP_TSAN_IGNORE_FUNCTION void WebPRescalerDspInit(void) {
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if (rescaler_last_cpuinfo_used == VP8GetCPUInfo) return;
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WebPRescalerImportRow = ImportRowC;
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WebPRescalerExportRow = ExportRowC;
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if (VP8GetCPUInfo != NULL) {
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#if defined(WEBP_USE_MIPS32)
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if (VP8GetCPUInfo(kMIPS32)) {
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WebPRescalerDspInitMIPS32();
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}
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#endif
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#if defined(WEBP_USE_MIPS_DSP_R2)
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if (VP8GetCPUInfo(kMIPSdspR2)) {
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WebPRescalerDspInitMIPSdspR2();
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}
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#endif
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}
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rescaler_last_cpuinfo_used = VP8GetCPUInfo;
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}
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