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asterisk/codecs/mp3/src/iupL1.c
Mark Spencer 75b660551a Version 0.1.1 from FTP 
git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@95 65c4cc65-6c06-0410-ace0-fbb531ad65f3
1999-12-07 05:45:48 +00:00

331 lines
9.0 KiB
C
Executable File
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/*____________________________________________________________________________
FreeAmp - The Free MP3 Player
MP3 Decoder originally Copyright (C) 1995-1997 Xing Technology
Corp. http://www.xingtech.com
Portions Copyright (C) 1998-1999 EMusic.com
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
$Id$
____________________________________________________________________________*/
/**** iupL1.c ***************************************************
MPEG audio decoder Layer I mpeg1 and mpeg2
should be portable ANSI C, should be endian independent
icupL1 integer version of cupL1.c
******************************************************************/
/*======================================================================*/
/* Read Only */
static int bat_bit_masterL1[] =
{
0, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16};
/*======================================================================*/
static void unpack_baL1(MPEGI *m)
{
int k;
int nstereo;
int n;
m->iup.bit_skip = 0;
nstereo = m->iup.stereo_sb;
for (k = 0; k < m->iup.nbatL1; k++)
{
mac_load_check(4);
n = m->iup.ballo[k] = m->iup.samp_dispatch[k] = mac_load(4);
if (k >= m->iup.nsb_limit)
m->iup.bit_skip += bat_bit_masterL1[m->iup.samp_dispatch[k]];
m->iup.c_value[k] = m->iup.look_c_valueL1[n];
m->iup.c_shift[k] = m->iup.look_c_shiftL1[n];
if (--nstereo < 0)
{
m->iup.ballo[k + 1] = m->iup.ballo[k];
m->iup.samp_dispatch[k] += 15; /* flag as joint */
m->iup.samp_dispatch[k + 1] = m->iup.samp_dispatch[k]; /* flag for sf */
m->iup.c_value[k + 1] = m->iup.c_value[k];
m->iup.c_shift[k + 1] = m->iup.c_shift[k];
k++;
}
}
m->iup.samp_dispatch[m->iup.nsb_limit] = 31; /* terminate the dispatcher with skip */
m->iup.samp_dispatch[k] = 30; /* terminate the dispatcher */
}
/*-------------------------------------------------------------------------*/
static void unpack_sfL1(MPEGI *m) /* unpack scale factor */
{ /* combine dequant and scale factors */
int i, n;
INT32 tmp; /* only reason tmp is 32 bit is to get 32 bit mult result */
for (i = 0; i < m->iup.nbatL1; i++)
{
if (m->iup.ballo[i])
{
mac_load_check(6);
tmp = m->iup.c_value[i];
n = m->iup.c_shift[i];
m->iup.cs_factorL1[i] = (tmp * m->iup.sf_table[mac_load(6)]) >> n;
}
}
/*-- done --*/
}
/*-------------------------------------------------------------------------*/
#define UNPACKL1_N(n) s[k] = (m->iup.cs_factorL1[k]*(load(m,n)-((1 << (n-1)) -1)))>>(n-1); \
goto dispatch;
#define UNPACKL1J_N(n) tmp = (load(m,n)-((1 << (n-1)) -1)); \
s[k] = (m->iup.cs_factorL1[k]*tmp)>>(n-1); \
s[k+1] = (m->iup.cs_factorL1[k+1]*tmp)>>(n-1); \
k++; /* skip right chan dispatch */ \
goto dispatch;
/*-------------------------------------------------------------------------*/
static void unpack_sampL1(MPEGI *m) /* unpack samples */
{
int j, k;
SAMPLEINT *s;
INT32 tmp;
s = m->iup.sample;
for (j = 0; j < 12; j++)
{
k = -1;
dispatch:switch (m->iup.samp_dispatch[++k])
{
case 0:
s[k] = 0;
goto dispatch;
case 1:
UNPACKL1_N(2) /* 3 levels */
case 2:
UNPACKL1_N(3) /* 7 levels */
case 3:
UNPACKL1_N(4) /* 15 levels */
case 4:
UNPACKL1_N(5) /* 31 levels */
case 5:
UNPACKL1_N(6) /* 63 levels */
case 6:
UNPACKL1_N(7) /* 127 levels */
case 7:
UNPACKL1_N(8) /* 255 levels */
case 8:
UNPACKL1_N(9) /* 511 levels */
case 9:
UNPACKL1_N(10) /* 1023 levels */
case 10:
UNPACKL1_N(11) /* 2047 levels */
case 11:
UNPACKL1_N(12) /* 4095 levels */
case 12:
UNPACKL1_N(13) /* 8191 levels */
case 13:
UNPACKL1_N(14) /* 16383 levels */
case 14:
UNPACKL1_N(15) /* 32767 levels */
/* -- joint ---- */
case 15 + 0:
s[k + 1] = s[k] = 0;
k++; /* skip right chan dispatch */
goto dispatch;
/* -- joint ---- */
case 15 + 1:
UNPACKL1J_N(2) /* 3 levels */
case 15 + 2:
UNPACKL1J_N(3) /* 7 levels */
case 15 + 3:
UNPACKL1J_N(4) /* 15 levels */
case 15 + 4:
UNPACKL1J_N(5) /* 31 levels */
case 15 + 5:
UNPACKL1J_N(6) /* 63 levels */
case 15 + 6:
UNPACKL1J_N(7) /* 127 levels */
case 15 + 7:
UNPACKL1J_N(8) /* 255 levels */
case 15 + 8:
UNPACKL1J_N(9) /* 511 levels */
case 15 + 9:
UNPACKL1J_N(10) /* 1023 levels */
case 15 + 10:
UNPACKL1J_N(11) /* 2047 levels */
case 15 + 11:
UNPACKL1J_N(12) /* 4095 levels */
case 15 + 12:
UNPACKL1J_N(13) /* 8191 levels */
case 15 + 13:
UNPACKL1J_N(14) /* 16383 levels */
case 15 + 14:
UNPACKL1J_N(15) /* 32767 levels */
/* -- end of dispatch -- */
case 31:
skip(m, m->iup.bit_skip);
case 30:
s += 64;
} /* end switch */
} /* end j loop */
/*-- done --*/
}
/*-------------------------------------------------------------------------*/
static void unpackL1(MPEGI *m)
{
int prot;
/* at entry bit getter points at id, sync skipped by caller */
load(m,3); /* skip id and option (checked by init) */
prot = load(m,1); /* load prot bit */
load(m,6); /* skip to pad */
m->iup.pad = load(m,1) << 2;
load(m,1); /* skip to mode */
m->iup.stereo_sb = look_joint[load(m,4)];
if (prot)
load(m,4); /* skip to data */
else
load(m,20); /* skip crc */
unpack_baL1(m); /* unpack bit allocation */
unpack_sfL1(m); /* unpack scale factor */
unpack_sampL1(m); /* unpack samples */
}
/*-------------------------------------------------------------------------*/
#ifdef _MSC_VER
#pragma warning(disable: 4056)
#endif
int i_audio_decode_initL1(MPEGI *m, MPEG_HEAD * h, int framebytes_arg,
int reduction_code, int transform_code, int convert_code,
int freq_limit)
{
int i, k;
long samprate;
int limit;
int stepbit;
long step;
int bit_code;
/*--- sf table built by Layer II init ---*/
if (m->iup.first_pass_L1)
{
stepbit = 2;
step = 4;
for (i = 1; i < 16; i++)
{
m->iup.look_c_valueL1[i] = (int) (32768.0 * 2.0 / (step - 1));
m->iup.look_c_shiftL1[i] = 16 - stepbit;
stepbit++;
step <<= 1;
}
m->iup.first_pass_L1 = 0;
}
m->iup.unpack_routine = unpackL1;
transform_code = transform_code; /* not used, asm compatability */
bit_code = 0;
if (convert_code & 8)
bit_code = 1;
convert_code = convert_code & 3; /* higher bits used by dec8 freq cvt */
if (reduction_code < 0)
reduction_code = 0;
if (reduction_code > 2)
reduction_code = 2;
if (freq_limit < 1000)
freq_limit = 1000;
m->iup.framebytes = framebytes_arg;
/* check if code handles */
if (h->option != 3)
return 0; /* layer I only */
m->iup.nbatL1 = 32;
m->iup.max_sb = m->iup.nbatL1;
/*----- compute nsb_limit --------*/
samprate = sr_table[4 * h->id + h->sr_index];
m->iup.nsb_limit = (freq_limit * 64L + samprate / 2) / samprate;
/*- caller limit -*/
/*---- limit = 0.94*(32>>reduction_code); ----*/
limit = (32 >> reduction_code);
if (limit > 8)
limit--;
if (m->iup.nsb_limit > limit)
m->iup.nsb_limit = limit;
if (m->iup.nsb_limit > m->iup.max_sb)
m->iup.nsb_limit = m->iup.max_sb;
m->iup.outvalues = 384 >> reduction_code;
if (h->mode != 3)
{ /* adjust for 2 channel modes */
m->iup.nbatL1 *= 2;
m->iup.max_sb *= 2;
m->iup.nsb_limit *= 2;
}
/* set sbt function */
m->iup.nsbt = 12;
k = 1 + convert_code;
if (h->mode == 3)
{
k = 0;
}
m->iup.sbt = sbt_table[bit_code][reduction_code][k];
m->iup.outvalues *= out_chans[k];
if (bit_code != 0)
m->iup.outbytes = m->iup.outvalues;
else
m->iup.outbytes = sizeof(short) * m->iup.outvalues;
m->iup.decinfo.channels = out_chans[k];
m->iup.decinfo.outvalues = m->iup.outvalues;
m->iup.decinfo.samprate = samprate >> reduction_code;
if (bit_code != 0)
m->iup.decinfo.bits = 8;
else
m->iup.decinfo.bits = sizeof(short) * 8;
m->iup.decinfo.framebytes = m->iup.framebytes;
m->iup.decinfo.type = 0;
/* clear sample buffer, unused sub bands must be 0 */
for (i = 0; i < 768; i++)
m->iup.sample[i] = 0;
/* init sub-band transform */
i_sbt_init();
return 1;
}
#ifdef _MSC_VER
#pragma warning(default: 4056)
#endif
/*---------------------------------------------------------*/
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