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