ref: 455880cdb3e12f68ba06b025898442f0917a8483
dir: /src/lpc10.c/
/*
* libSoX lpc-10 format.
*
* Copyright 2007 Reuben Thomas <rrt@sc3d.org>
*
* This library 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 of the License, or (at your option) any later version.
*
* This library 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 this library. If not, write to the Free Software
* Foundation, Fifth Floor, 51 Franklin Street, Boston, MA 02111-1301,
* USA. */
#include "sox_i.h"
#include "../lpc10/lpc10.h"
/* Private data */
typedef struct lpcpriv {
struct lpc10_encoder_state *encst;
float speech[LPC10_SAMPLES_PER_FRAME];
unsigned samples;
struct lpc10_decoder_state *decst;
} *lpcpriv_t;
/*
Write the bits in bits[0] through bits[len-1] to file f, in "packed"
format.
bits is expected to be an array of len integer values, where each
integer is 0 to represent a 0 bit, and any other value represents a
1 bit. This bit string is written to the file f in the form of
several 8 bit characters. If len is not a multiple of 8, then the
last character is padded with 0 bits -- the padding is in the least
significant bits of the last byte. The 8 bit characters are "filled"
in order from most significant bit to least significant.
*/
static void write_bits(sox_format_t * ft, INT32 *bits, int len)
{
int i;
uint8_t mask; /* The next bit position within the variable "data" to
place the next bit. */
uint8_t data; /* The contents of the next byte to place in the
output. */
/* Fill in the array bits.
* The first compressed output bit will be the most significant
* bit of the byte, so initialize mask to 0x80. The next byte of
* compressed data is initially 0, and the desired bits will be
* turned on below.
*/
mask = 0x80;
data = 0;
for (i = 0; i < len; i++) {
/* Turn on the next bit of output data, if necessary. */
if (bits[i]) {
data |= mask;
}
/*
* If the byte data is full, determined by mask becoming 0,
* then write the byte to the output file, and reinitialize
* data and mask for the next output byte. Also add the byte
* if (i == len-1), because if len is not a multiple of 8,
* then mask won't yet be 0. */
mask >>= 1;
if ((mask == 0) || (i == len-1)) {
sox_writeb(ft, data);
data = 0;
mask = 0x80;
}
}
}
/*
Read bits from file f into bits[0] through bits[len-1], in "packed"
format.
Read ceiling(len/8) characters from file f, if that many are
available to read, otherwise read to the end of the file. The first
character's 8 bits, in order from MSB to LSB, are used to fill
bits[0] through bits[7]. The second character's bits are used to
fill bits[8] through bits[15], and so on. If ceiling(len/8)
characters are available to read, and len is not a multiple of 8,
then some of the least significant bits of the last character read
are completely ignored. Every entry of bits[] that is modified is
changed to either a 0 or a 1.
The number of bits successfully read is returned, and is always in
the range 0 to len, inclusive. If it is less than len, it will
always be a multiple of 8.
*/
static int read_bits(sox_format_t * ft, INT32 *bits, int len)
{
int i;
uint8_t c;
/* Unpack the array bits into coded_frame. */
for (i = 0; i < len; i++) {
if (i % 8 == 0) {
sox_readb(ft, &c);
if (sox_eof(ft)) {
return (i);
}
}
if (c & (0x80 >> (i & 7))) {
bits[i] = 1;
} else {
bits[i] = 0;
}
}
return (len);
}
static int startread(sox_format_t * ft)
{
lpcpriv_t lpc = (lpcpriv_t)ft->priv;
if ((lpc->decst = create_lpc10_decoder_state()) == NULL) {
fprintf(stderr, "lpc10 could not allocate decoder state");
return SOX_EOF;
}
lpc->samples = LPC10_SAMPLES_PER_FRAME;
return SOX_SUCCESS;
}
static int startwrite(sox_format_t * ft)
{
lpcpriv_t lpc = (lpcpriv_t)ft->priv;
if ((lpc->encst = create_lpc10_encoder_state()) == NULL) {
fprintf(stderr, "lpc10 could not allocate encoder state");
return SOX_EOF;
}
lpc->samples = 0;
return SOX_SUCCESS;
}
static sox_size_t read(sox_format_t * ft, sox_ssample_t *buf, sox_size_t len)
{
lpcpriv_t lpc = (lpcpriv_t)ft->priv;
sox_size_t nread = 0;
while (nread < len) {
/* Read more data if buffer is empty */
if (lpc->samples == LPC10_SAMPLES_PER_FRAME) {
INT32 bits[LPC10_BITS_IN_COMPRESSED_FRAME];
if (read_bits(ft, bits, LPC10_BITS_IN_COMPRESSED_FRAME) !=
LPC10_BITS_IN_COMPRESSED_FRAME)
break;
lpc10_decode(bits, lpc->speech, lpc->decst);
lpc->samples = 0;
}
while (nread < len && lpc->samples < LPC10_SAMPLES_PER_FRAME)
buf[nread++] = SOX_FLOAT_32BIT_TO_SAMPLE(lpc->speech[lpc->samples++], ft->clips);
}
return nread;
}
static sox_size_t write(sox_format_t * ft, const sox_ssample_t *buf, sox_size_t len)
{
lpcpriv_t lpc = (lpcpriv_t)ft->priv;
sox_size_t nwritten = 0;
while (len + lpc->samples >= LPC10_SAMPLES_PER_FRAME) {
INT32 bits[LPC10_BITS_IN_COMPRESSED_FRAME];
while (lpc->samples < LPC10_SAMPLES_PER_FRAME) {
lpc->speech[lpc->samples++] = SOX_SAMPLE_TO_FLOAT_32BIT(buf[nwritten++], ft->clips);
len--;
}
lpc10_encode(lpc->speech, bits, lpc->encst);
write_bits(ft, bits, LPC10_BITS_IN_COMPRESSED_FRAME);
lpc->samples = 0;
}
return nwritten;
}
static int stopread(sox_format_t * ft)
{
lpcpriv_t lpc = (lpcpriv_t)ft->priv;
free(lpc->decst);
return SOX_SUCCESS;
}
static int stopwrite(sox_format_t * ft)
{
lpcpriv_t lpc = (lpcpriv_t)ft->priv;
free(lpc->encst);
return SOX_SUCCESS;
}
/* LPC-10 */
static const char *lpc10names[] = {
"lpc",
"lpc10",
NULL
};
static sox_format_handler_t sox_lpc10_format = {
lpc10names,
0,
startread,
read,
stopread,
startwrite,
write,
stopwrite,
sox_format_nothing_seek
};
const sox_format_handler_t *sox_lpc10_format_fn(void);
const sox_format_handler_t *sox_lpc10_format_fn(void)
{
return &sox_lpc10_format;
}