www.pudn.com > XvidQP.rar > ibitstr.cpp
/* ibitstr.cpp
Input bitstream class implementation
Changes by Jeff Tsay:
01/26/96 : Modified for Windows file handles.
11/29/96 : Added syncword detection for compatibility with streams produced
by DALET. Changed at the request of Wilfried Solbach, thanks for the
donation in advance! However Layer I MPP files playback jerkily.
03/09/97 : Added a routine to read layer III side info. Also not mentioned
previously are several routines that allow seeking in a stream.
04/14/97 : Moved the side info routine to the layer III decoder object.
Revamped the seeking mechanism and also included better syncword detection.
Moved the original file reading mechanisms back for better
portability, and used John Fehr's implementations of the seeking routines
for non-Win32 file reading. */
/*
* @(#) ibitstream.cc 1.8, last edit: 6/15/94 16:51:45
* @(#) Copyright (C) 1993, 1994 Tobias Bading (bading@cs.tu-berlin.de)
* @(#) Berlin University of Technology
*
* 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.
*/
/*
* Changes from version 1.1 to 1.2:
* - third argument in open syscall added
* - minor bug in get_header() fixed
*/
#define __WIN32__
#ifdef __WIN32__
#include
#else
#include
#include
#include
#include
#include
#endif // __WIN32__
#ifndef GUI
#include
#endif // GUI
#include "all.h"
#include "ibitstr.h"
#include "header.h"
#ifdef DAMN_INTEL_BYTE_ORDER
#define swap_int32(int_32) (((int_32) << 24) | (((int_32) << 8) & 0x00ff0000) | \
(((int_32) >> 8) & 0x0000ff00) | ((int_32) >> 24))
#endif // DAMN_INTEL_BYTE_ORDER
Ibitstream::Ibitstream(const char *filename)
{
#ifdef __WIN32__
SECURITY_ATTRIBUTES security;
security.nLength = sizeof(SECURITY_ATTRIBUTES);
security.lpSecurityDescriptor = NULL;
security.bInheritHandle = FALSE;
fd = CreateFile(filename, GENERIC_READ, FILE_SHARE_READ,
&security, OPEN_EXISTING, NULL, NULL);
if (fd == INVALID_HANDLE_VALUE) {
char bad_file_msg[256];
lstrcpy(bad_file_msg, "Error opening file: ");
#ifdef WIN32GUI
MessageBox(NULL, lstrcat(bad_file_msg, filename) , "Invalid handle", MB_OK);
#else
cerr << "Error opening file: " << filename << endl;
#endif // WIN32GUI
return;
}
#else
// copy any arguments you need, open the file, and check for error
if ((fd = open(filename, O_RDONLY)) == -1)
{
#ifndef GUI
cerr << "Error opening file: " << filename << endl;
#endif
return;
}
#endif // __WIN32__
wordpointer = buffer;
bitindex = 0;
// Seeking variables
current_frame_number = -1;
#ifdef SEEK_STOP
last_frame_number = -1;
#endif
copy = false;
}
Ibitstream::Ibitstream(const Ibitstream &s0)
{
int32 i;
fd = s0.fd;
for (i=0; i (bufferintsize << 2))
{
cerr << "Internal error: framelength > bufferlength?!\n";
exit (1);
} */
wordpointer = buffer;
bitindex = 0;
framesize = bytesize;
#ifdef DAMN_INTEL_BYTE_ORDER
uint32 *wordp;
for (wordp = buffer + ((bytesize - 1) >> 2); wordp >= buffer; --wordp)
{
#ifdef INTEL386
// inline 386 assembly doesn't work on Borland compiler
__asm {
mov eax, wordp
mov ebx, [eax]
bswap ebx
mov [eax], ebx
}
#else
uint32 word = *wordp;
*wordp = swap_int32(word);
#endif // INTEL386
} // for (wordp ...
#endif // DAMN_INTEL_BYTE_ORDER
return((bool) (result && (numread == framesize)));
}
uint32 Ibitstream::get_bits(uint32 number_of_bits)
{
static uint32 bitmask[18] =
{
0, // dummy
0x00000001, 0x00000003, 0x00000007, 0x0000000F,
0x0000001F, 0x0000003F, 0x0000007F, 0x000000FF,
0x000001FF, 0x000003FF, 0x000007FF, 0x00000FFF,
0x00001FFF, 0x00003FFF, 0x00007FFF, 0x0000FFFF,
0x0001FFFF
};
uint32 returnvalue;
uint32 sum = bitindex + number_of_bits;
if (sum <= 32)
{
// all bits contained in *wordpointer
returnvalue = (*wordpointer >> (32 - sum)) & bitmask[number_of_bits];
if ((bitindex += number_of_bits) == 32)
{
bitindex = 0;
/* if ((char *)++wordpointer > (char *)buffer + framesize)
{
cerr << "Ibitstream::get_bits(): no more bits in buffer!\n";
exit (1);
} */
wordpointer++; // added by me!
}
return returnvalue;
}
#ifdef DAMN_INTEL_BYTE_ORDER
*((int16 *)&returnvalue + 1) = *(int16 *)wordpointer;
wordpointer++; // Added by me!
*(int16 *)&returnvalue = *((int16 *)wordpointer + 1);
#else
*(int16 *)&returnvalue = *((int16 *)wordpointer + 1);
wordpointer++; // Added by me!
*((int16 *)&returnvalue + 1) = *(int16 *)wordpointer;
#endif // DAMN_INTEL_BYTE_ORDER
returnvalue >>= 48 - sum; // returnvalue >>= 16 - (number_of_bits - (32 - bitindex))
returnvalue &= bitmask[number_of_bits];
bitindex = sum - 32;
return returnvalue;
}
void Ibitstream::set_syncword(uint32 syncword0)
{
#ifdef DAMN_INTEL_BYTE_ORDER
syncword = swap_int32(syncword0 & 0xFFFFFF3F);
#else
syncword = syncword0 & 0xFFFFFF3F;
#endif // DAMN_INTEL_BYTE_ORDER
single_ch_mode = ((syncword0 & 0x000000C0) == 0x000000C0);
}
uint32 Ibitstream::file_size() const
// return the file size of the file
{
#ifdef __WIN32__
return GetFileSize(fd, NULL);
#else
// hmm. I think this should work -- John Fehr
off_t o_off;
off_t len;
o_off = lseek(fd, 0, SEEK_CUR);
len = lseek(fd, 0, SEEK_END);
lseek(fd, o_off, SEEK_SET);
return len;
#endif // __WIN32__
}
uint32 Ibitstream::file_pos() const
{
return SetFilePointer(fd, 0, NULL, FILE_CURRENT);
}
#ifdef SEEK_STOP
bool Ibitstream::seek(int32 frame, int32 frame_size)
// set the file pointer to frame * (frame_size + 4) bytes after the
// beginning of the file and return true if successful
{
current_frame_number = frame - 1;
#ifdef __WIN32__
return(SetFilePointer(fd, frame * (frame_size + 4), NULL, FILE_BEGIN)
!= 0xFFFFFFFF);
#else
return lseek(fd, frame * (frame_size + 4), SEEK_SET);
#endif // __WIN32__
}
bool Ibitstream::seek_pad(int32 frame, int32 base_frame_size,
Header *header, uint32 *offset)
{
// base_frame_size is the frame size _without_ padding.
Crc16 *crc = NULL;
int32 total_frame_size = base_frame_size + 4;
int32 diff;
if (last_frame_number < frame) {
diff = (last_frame_number >= 0) ? offset[last_frame_number] : 0;
// set the file pointer to ((last_frame_number+1) * total_frame_size)
// bytes after the beginning of the file
#ifdef __WIN32__
SetFilePointer(fd, (last_frame_number + 1) * total_frame_size +
diff, NULL, FILE_BEGIN);
#else
lseek(fd, (last_frame_number + 1) * total_frame_size + diff, SEEK_SET);
#endif // __WIN32__
current_frame_number = last_frame_number;
do {
if (!header->read_header(this, &crc)) // will increment last_frame_number
return false;
} while (last_frame_number < frame);
return true;
} else {
diff = (frame > 0) ? offset[frame - 1] : 0;
// set the file pointer to (frame * total_frame_size + diff) bytes
// after the beginning of the file
#ifdef __WIN32__
SetFilePointer(fd, frame * total_frame_size + diff, NULL, FILE_BEGIN);
#else
lseek(fd, frame * total_frame_size + diff, SEEK_SET);
#endif // __WIN32__
current_frame_number = frame - 1;
return header->read_header(this, &crc);
}
}
#endif // SEEK_STOP