synth_8bit.h

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/*
    synth_8bit.h: Wrappers over optimized synth_xtoy for converting signed short to 8bit.
 
    copyright 1995-2008 by the mpg123 project - free software under the terms of the LGPL 2.1
    see COPYING and AUTHORS files in distribution or http://mpg123.org
    initially written by Michael Hipp, code generalized to the wrapper by Thomas Orgis
 
    Only variable is the BLOCK size to choose 1to1, 2to1 or 4to1.
    Oh, and the names: BASE_SYNTH_NAME, SYNTH_NAME, MONO_NAME, MONO2STEREO_NAME
    (p.ex. opt_synth_1to1(fr), synth_1to1_8bit, synth_1to1_8bit_mono, ...).
*/
 
int SYNTH_NAME(real *bandPtr, int channel, mpg123_handle *fr, int final)
{
    short samples_tmp[BLOCK];
    short *tmp1 = samples_tmp + channel;
    int i,ret;
 
    unsigned char *samples = fr->buffer.data;
    int pnt = fr->buffer.fill;
    fr->buffer.data = (unsigned char*) samples_tmp;
    fr->buffer.fill = 0;
    ret = BASE_SYNTH_NAME(bandPtr, channel, fr , 0);
    fr->buffer.data = samples;
 
    samples += channel + pnt;
    for(i=0;i<(BLOCK/2);i++)
    {
        *samples = fr->conv16to8[*tmp1>>AUSHIFT];
        samples += 2;
        tmp1 += 2;
    }
    fr->buffer.fill = pnt + (final ? BLOCK : 0 );
 
    return ret;
}
 
int MONO_NAME(real *bandPtr, mpg123_handle *fr)
{
    short samples_tmp[BLOCK];
    short *tmp1 = samples_tmp;
    int i,ret;
 
    unsigned char *samples = fr->buffer.data;
    int pnt = fr->buffer.fill;
    fr->buffer.data = (unsigned char*) samples_tmp;
    fr->buffer.fill = 0;
    ret = BASE_SYNTH_NAME(bandPtr, 0, fr, 0);
    fr->buffer.data = samples;
 
    samples += pnt;
    for(i=0;i<(BLOCK/2);i++)
    {
        *samples++ = fr->conv16to8[*tmp1>>AUSHIFT];
        tmp1+=2;
    }
    fr->buffer.fill = pnt + BLOCK/2;
 
    return ret;
}
 
int MONO2STEREO_NAME(real *bandPtr, mpg123_handle *fr)
{
    short samples_tmp[BLOCK];
    short *tmp1 = samples_tmp;
    int i,ret;
 
    unsigned char *samples = fr->buffer.data;
    int pnt = fr->buffer.fill;
    fr->buffer.data = (unsigned char*) samples_tmp;
    fr->buffer.fill = 0;
    ret = BASE_SYNTH_NAME(bandPtr, 0, fr, 0);
    fr->buffer.data = samples;
 
    samples += pnt;
    for(i=0;i<(BLOCK/2);i++)
    {
        *samples++ = fr->conv16to8[*tmp1>>AUSHIFT];
        *samples++ = fr->conv16to8[*tmp1>>AUSHIFT];
        tmp1 += 2;
    }
    fr->buffer.fill = pnt + BLOCK;
 
    return ret;
}