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141 lines
3.9 KiB
C
141 lines
3.9 KiB
C
////////////////////////////////////////////////////////////////////////////
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// **** WAVPACK **** //
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// Hybrid Lossless Wavefile Compressor //
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// Copyright (c) 1998 - 2006 Conifer Software. //
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// All Rights Reserved. //
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// Distributed under the BSD Software License (see license.txt) //
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////////////////////////////////////////////////////////////////////////////
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// bits.c
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// This module provides utilities to support the BitStream structure which is
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// used to read and write all WavPack audio data streams. It also contains a
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// wrapper for the stream I/O functions and a set of functions dealing with
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// endian-ness, both for enhancing portability. Finally, a debug wrapper for
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// the malloc() system is provided.
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#include "wavpack.h"
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#include <string.h>
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#include <ctype.h>
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////////////////////////// Bitstream functions ////////////////////////////////
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// Open the specified BitStream and associate with the specified buffer.
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static void bs_read (Bitstream *bs);
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void bs_open_read (Bitstream *bs, uchar *buffer_start, uchar *buffer_end, read_stream file, uint32_t file_bytes)
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{
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CLEAR (*bs);
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bs->buf = buffer_start;
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bs->end = buffer_end;
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if (file) {
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bs->ptr = bs->end - 1;
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bs->file_bytes = file_bytes;
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bs->file = file;
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}
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else
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bs->ptr = bs->buf - 1;
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bs->wrap = bs_read;
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}
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// This function is only called from the getbit() and getbits() macros when
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// the BitStream has been exhausted and more data is required. Sinve these
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// bistreams no longer access files, this function simple sets an error and
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// resets the buffer.
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static void bs_read (Bitstream *bs)
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{
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if (bs->file && bs->file_bytes) {
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uint32_t bytes_read, bytes_to_read = bs->end - bs->buf;
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if (bytes_to_read > bs->file_bytes)
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bytes_to_read = bs->file_bytes;
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bytes_read = bs->file (bs->buf, bytes_to_read);
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if (bytes_read) {
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bs->end = bs->buf + bytes_read;
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bs->file_bytes -= bytes_read;
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}
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else {
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memset (bs->buf, -1, bs->end - bs->buf);
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bs->error = 1;
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}
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}
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else
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bs->error = 1;
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if (bs->error)
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memset (bs->buf, -1, bs->end - bs->buf);
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bs->ptr = bs->buf;
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}
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/////////////////////// Endian Correction Routines ////////////////////////////
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void little_endian_to_native (void *data, char *format)
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{
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uchar *cp = (uchar *) data;
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int32_t temp;
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while (*format) {
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switch (*format) {
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case 'L':
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temp = cp [0] + ((int32_t) cp [1] << 8) + ((int32_t) cp [2] << 16) + ((int32_t) cp [3] << 24);
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* (int32_t *) cp = temp;
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cp += 4;
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break;
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case 'S':
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temp = cp [0] + (cp [1] << 8);
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* (short *) cp = (short) temp;
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cp += 2;
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break;
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default:
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if (isdigit (*format))
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cp += *format - '0';
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break;
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}
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format++;
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}
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}
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void native_to_little_endian (void *data, char *format)
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{
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uchar *cp = (uchar *) data;
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int32_t temp;
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while (*format) {
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switch (*format) {
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case 'L':
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temp = * (int32_t *) cp;
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*cp++ = (uchar) temp;
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*cp++ = (uchar) (temp >> 8);
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*cp++ = (uchar) (temp >> 16);
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*cp++ = (uchar) (temp >> 24);
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break;
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case 'S':
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temp = * (short *) cp;
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*cp++ = (uchar) temp;
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*cp++ = (uchar) (temp >> 8);
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break;
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default:
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if (isdigit (*format))
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cp += *format - '0';
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break;
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}
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format++;
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}
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}
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