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ffmpeg / libavcodec / vorbis.c @ 2912e87a

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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 02110-1301 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, uint_fast32_t 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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    uint_fast8_t i, j;
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    uint_fast32_t code, p;
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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, " %d. of %d code len %d code %d - ", p, num, 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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    ++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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}