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////////////////////////////////////////////////////////////////////////////
// **** WAVPACK **** //
// Hybrid Lossless Wavefile Compressor //
// Copyright (c) 1998 - 2004 Conifer Software. //
// All Rights Reserved. //
// Distributed under the BSD Software License (see license.txt) //
////////////////////////////////////////////////////////////////////////////
// bits.c
// This module provides utilities to support the BitStream structure which is
// used to read and write all WavPack audio data streams. It also contains a
// wrapper for the stream I/O functions and a set of functions dealing with
// endian-ness, both for enhancing portability. Finally, a debug wrapper for
// the malloc() system is provided.
#include "wavpack.h"
#include <string.h>
////////////////////////// Bitstream functions ////////////////////////////////
// Open the specified BitStream and associate with the specified buffer.
static void bs_read (Bitstream *bs);
void bs_open_read (Bitstream *bs, uchar *buffer_start, uchar *buffer_end, read_stream file, ulong file_bytes)
{
CLEAR (*bs);
bs->buf = buffer_start;
bs->end = buffer_end;
if (file) {
bs->ptr = bs->end - 1;
bs->file_bytes = file_bytes;
bs->file = file;
}
else
bs->ptr = bs->buf - 1;
bs->wrap = bs_read;
}
// This function is only called from the getbit() and getbits() macros when
// the BitStream has been exhausted and more data is required. Sinve these
// bistreams no longer access files, this function simple sets an error and
// resets the buffer.
static void bs_read (Bitstream *bs)
{
if (bs->file && bs->file_bytes) {
ulong bytes_read, bytes_to_read = bs->end - bs->buf;
if (bytes_to_read > bs->file_bytes)
bytes_to_read = bs->file_bytes;
bytes_read = bs->file (bs->buf, bytes_to_read);
if (bytes_read) {
bs->end = bs->buf + bytes_read;
bs->file_bytes -= bytes_read;
}
else {
memset (bs->buf, -1, bs->end - bs->buf);
bs->error = 1;
}
}
else
bs->error = 1;
if (bs->error)
memset (bs->buf, -1, bs->end - bs->buf);
bs->ptr = bs->buf;
}
// Open the specified BitStream using the specified buffer pointers. It is
// assumed that enough buffer space has been allocated for all data that will
// be written, otherwise an error will be generated.
static void bs_write (Bitstream *bs);
void bs_open_write (Bitstream *bs, uchar *buffer_start, uchar *buffer_end)
{
bs->error = bs->sr = bs->bc = 0;
bs->ptr = bs->buf = buffer_start;
bs->end = buffer_end;
bs->wrap = bs_write;
}
// This function is only called from the putbit() and putbits() macros when
// the buffer is full, which is now flagged as an error.
static void bs_write (Bitstream *bs)
{
bs->ptr = bs->buf;
bs->error = 1;
}
// This function forces a flushing write of the specified BitStream, and
// returns the total number of bytes written into the buffer.
ulong bs_close_write (Bitstream *bs)
{
ulong bytes_written;
if (bs->error)
return (ulong) -1;
while (bs->bc || ((bs->ptr - bs->buf) & 1)) putbit_1 (bs);
bytes_written = bs->ptr - bs->buf;
CLEAR (*bs);
return bytes_written;
}
/////////////////////// Endian Correction Routines ////////////////////////////
void little_endian_to_native (void *data, char *format)
{
uchar *cp = (uchar *) data;
long temp;
while (*format) {
switch (*format) {
case 'L':
temp = cp [0] + ((long) cp [1] << 8) + ((long) cp [2] << 16) + ((long) cp [3] << 24);
* (long *) cp = temp;
cp += 4;
break;
case 'S':
temp = cp [0] + (cp [1] << 8);
* (short *) cp = (short) temp;
cp += 2;
break;
default:
if (*format >= '0' && *format <= '9')
cp += *format - '0';
break;
}
format++;
}
}
void native_to_little_endian (void *data, char *format)
{
uchar *cp = (uchar *) data;
long temp;
while (*format) {
switch (*format) {
case 'L':
temp = * (long *) cp;
*cp++ = (uchar) temp;
*cp++ = (uchar) (temp >> 8);
*cp++ = (uchar) (temp >> 16);
*cp++ = (uchar) (temp >> 24);
break;
case 'S':
temp = * (short *) cp;
*cp++ = (uchar) temp;
*cp++ = (uchar) (temp >> 8);
break;
default:
if (*format >= '0' && *format <= '9')
cp += *format - '0';
break;
}
format++;
}
}
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