74 lines
2.3 KiB
C
74 lines
2.3 KiB
C
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/**
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* @file
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* Common code for Vorbis I encoder and decoder
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* @author Denes Balatoni ( dbalatoni programozo hu )
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/* render_line and friend taken from ffmpeg (libavcodec/vorbis.c) */
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static inline void render_line_unrolled(int x, int y, int x1,
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int sy, int ady, int adx,
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ogg_int32_t *buf)
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{
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int err = -adx;
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x -= x1 - 1;
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buf += x1 - 1;
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while (++x < 0) {
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err += ady;
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if (err >= 0) {
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err += ady - adx;
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y += sy;
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buf[x] = MULT31_SHIFT15(buf[x],FLOOR_fromdB_LOOKUP[y]);
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x++;
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}
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buf[x] = MULT31_SHIFT15(buf[x],FLOOR_fromdB_LOOKUP[y]);
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}
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if (x <= 0) {
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if (err + ady >= 0)
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y += sy;
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buf[x] = MULT31_SHIFT15(buf[x],FLOOR_fromdB_LOOKUP[y]);
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}
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}
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static void render_line(int x0, int y0, int x1, int y1, ogg_int32_t *buf)
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{
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int dy = y1 - y0;
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int adx = x1 - x0;
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int ady = abs(dy);
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int sy = dy < 0 ? -1 : 1;
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buf[x0] = MULT31_SHIFT15(buf[x0],FLOOR_fromdB_LOOKUP[y0]);
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if (ady*2 <= adx) { // optimized common case
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render_line_unrolled(x0, y0, x1, sy, ady, adx, buf);
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} else {
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int base = dy / adx;
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int x = x0;
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int y = y0;
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int err = -adx;
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ady -= abs(base) * adx;
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while (++x < x1) {
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y += base;
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err += ady;
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if (err >= 0) {
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err -= adx;
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y += sy;
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}
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buf[x] = MULT31_SHIFT15(buf[x],FLOOR_fromdB_LOOKUP[y]);
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}
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}
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}
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