ffmpeg / libavcodec / vorbis.c @ cf3ac543
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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 Libav.

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*

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* Libav 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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* Libav 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 Libav; if not, write to the Free Software

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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 021101301 USA

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*/

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#undef V_DEBUG

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//#define V_DEBUG

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#define ALT_BITSTREAM_READER_LE

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#include "avcodec.h" 
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#include "get_bits.h" 
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#include "vorbis.h" 
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/* Helper functions */

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// x^(1/n)

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unsigned int ff_vorbis_nth_root(unsigned int x, unsigned int n) 
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{ 
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unsigned int ret = 0, i, j; 
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do {

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++ret; 
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for (i = 0, j = ret; i < n  1; i++) 
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j *= ret; 
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} while (j <= x);

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return ret  1; 
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} 
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// Generate vlc codes from vorbis huffman code lengths

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// the two bits[p] > 32 checks should be redundant, all calling code should

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// already ensure that, but since it allows overwriting the stack it seems

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// reasonable to check redundantly.

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int ff_vorbis_len2vlc(uint8_t *bits, uint32_t *codes, unsigned num) 
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{ 
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uint_fast32_t exit_at_level[33] = {

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404, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }; 
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unsigned i, j, p, code;

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#ifdef V_DEBUG

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GetBitContext gb; 
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#endif

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for (p = 0; (bits[p] == 0) && (p < num); ++p) 
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; 
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if (p == num) {

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// av_log(vc>avccontext, AV_LOG_INFO, "An empty codebook. Heh?! \n");

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return 0; 
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} 
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codes[p] = 0;

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if (bits[p] > 32) 
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return 1; 
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for (i = 0; i < bits[p]; ++i) 
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exit_at_level[i+1] = 1 << i; 
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#ifdef V_DEBUG

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av_log(NULL, AV_LOG_INFO, " %u. of %u code len %d code %d  ", p, num, bits[p], codes[p]); 
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init_get_bits(&gb, (uint8_t *)&codes[p], bits[p]); 
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for (i = 0; i < bits[p]; ++i) 
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av_log(NULL, AV_LOG_INFO, "%s", get_bits1(&gb) ? "1" : "0"); 
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av_log(NULL, AV_LOG_INFO, "\n"); 
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#endif

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++p; 
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for (; p < num; ++p) {

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if (bits[p] > 32) 
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return 1; 
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if (bits[p] == 0) 
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continue;

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// find corresponding exit(node which the tree can grow further from)

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for (i = bits[p]; i > 0; i) 
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if (exit_at_level[i])

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break;

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if (!i) // overspecified tree 
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return 1; 
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code = exit_at_level[i]; 
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exit_at_level[i] = 0;

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// construct code (append 0s to end) and introduce new exits

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for (j = i + 1 ;j <= bits[p]; ++j) 
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exit_at_level[j] = code + (1 << (j  1)); 
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codes[p] = code; 
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#ifdef V_DEBUG

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av_log(NULL, AV_LOG_INFO, " %d. code len %d code %d  ", p, bits[p], codes[p]); 
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init_get_bits(&gb, (uint_fast8_t *)&codes[p], bits[p]); 
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for (i = 0; i < bits[p]; ++i) 
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av_log(NULL, AV_LOG_INFO, "%s", get_bits1(&gb) ? "1" : "0"); 
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av_log(NULL, AV_LOG_INFO, "\n"); 
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#endif

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} 
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//no exits should be left (underspecified tree  ie. unused valid vlcs  not allowed by SPEC)

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for (p = 1; p < 33; p++) 
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if (exit_at_level[p])

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return 1; 
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return 0; 
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} 
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void ff_vorbis_ready_floor1_list(vorbis_floor1_entry * list, int values) 
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{ 
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int i;

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list[0].sort = 0; 
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list[1].sort = 1; 
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for (i = 2; i < values; i++) { 
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int j;

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list[i].low = 0;

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list[i].high = 1;

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list[i].sort = i; 
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for (j = 2; j < i; j++) { 
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int tmp = list[j].x;

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if (tmp < list[i].x) {

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if (tmp > list[list[i].low].x)

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list[i].low = j; 
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} else {

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if (tmp < list[list[i].high].x)

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list[i].high = j; 
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} 
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} 
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} 
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for (i = 0; i < values  1; i++) { 
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int j;

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for (j = i + 1; j < values; j++) { 
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if (list[list[i].sort].x > list[list[j].sort].x) {

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int tmp = list[i].sort;

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list[i].sort = list[j].sort; 
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list[j].sort = tmp; 
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} 
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} 
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} 
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} 
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static inline void render_line_unrolled(intptr_t x, intptr_t y, int x1, 
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intptr_t sy, int ady, int adx, 
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float *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++] = ff_vorbis_floor1_inverse_db_table[y]; 
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} 
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buf[x] = ff_vorbis_floor1_inverse_db_table[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] = ff_vorbis_floor1_inverse_db_table[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, float *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 = FFABS(dy);

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int sy = dy < 0 ? 1 : 1; 
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buf[x0] = ff_vorbis_floor1_inverse_db_table[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 = FFABS(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] = ff_vorbis_floor1_inverse_db_table[y]; 
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} 
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} 
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} 
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void ff_vorbis_floor1_render_list(vorbis_floor1_entry * list, int values, 
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uint_fast16_t *y_list, int *flag,

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int multiplier, float *out, int samples) 
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{ 
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int lx, ly, i;

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lx = 0;

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ly = y_list[0] * multiplier;

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for (i = 1; i < values; i++) { 
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int pos = list[i].sort;

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if (flag[pos]) {

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int x1 = list[pos].x;

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int y1 = y_list[pos] * multiplier;

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if (lx < samples)

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render_line(lx, ly, FFMIN(x1,samples), y1, out); 
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lx = x1; 
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ly = y1; 
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} 
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if (lx >= samples)

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break;

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} 
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if (lx < samples)

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render_line(lx, ly, samples, ly, out); 
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} 