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BGZF.cpp
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BGZF.cpp
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// ***************************************************************************
// BGZF.cpp (c) 2009 Derek Barnett, Michael Str�mberg
// Marth Lab, Department of Biology, Boston College
// All rights reserved.
// ---------------------------------------------------------------------------
// Last modified: 16 August 2010 (DB)
// ---------------------------------------------------------------------------
// BGZF routines were adapted from the bgzf.c code developed at the Broad
// Institute.
// ---------------------------------------------------------------------------
// Provides the basic functionality for reading & writing BGZF files
// ***************************************************************************
#include <algorithm>
#include "BGZF.h"
using namespace BamTools;
using std::string;
using std::min;
BgzfData::BgzfData(void)
: UncompressedBlockSize(DEFAULT_BLOCK_SIZE)
, CompressedBlockSize(MAX_BLOCK_SIZE)
, BlockLength(0)
, BlockOffset(0)
, BlockAddress(0)
, IsOpen(false)
, IsWriteOnly(false)
, IsWriteUncompressed(false)
, Stream(NULL)
, UncompressedBlock(NULL)
, CompressedBlock(NULL)
{
try {
CompressedBlock = new char[CompressedBlockSize];
UncompressedBlock = new char[UncompressedBlockSize];
} catch( std::bad_alloc& ba ) {
fprintf(stderr, "BGZF ERROR: unable to allocate memory for our BGZF object.\n");
exit(1);
}
}
// destructor
BgzfData::~BgzfData(void) {
if( CompressedBlock ) delete[] CompressedBlock;
if( UncompressedBlock ) delete[] UncompressedBlock;
}
// closes BGZF file
void BgzfData::Close(void) {
// skip if file not open, otherwise set flag
if ( !IsOpen ) return;
// if writing to file, flush the current BGZF block,
// then write an empty block (as EOF marker)
if ( IsWriteOnly ) {
FlushBlock();
int blockLength = DeflateBlock();
fwrite(CompressedBlock, 1, blockLength, Stream);
}
// flush and close
fflush(Stream);
fclose(Stream);
IsWriteUncompressed = false;
IsOpen = false;
}
// compresses the current block
int BgzfData::DeflateBlock(void) {
// initialize the gzip header
char* buffer = CompressedBlock;
memset(buffer, 0, 18);
buffer[0] = GZIP_ID1;
buffer[1] = (char)GZIP_ID2;
buffer[2] = CM_DEFLATE;
buffer[3] = FLG_FEXTRA;
buffer[9] = (char)OS_UNKNOWN;
buffer[10] = BGZF_XLEN;
buffer[12] = BGZF_ID1;
buffer[13] = BGZF_ID2;
buffer[14] = BGZF_LEN;
// set compression level
const int compressionLevel = ( IsWriteUncompressed ? 0 : Z_DEFAULT_COMPRESSION );
// loop to retry for blocks that do not compress enough
int inputLength = BlockOffset;
int compressedLength = 0;
unsigned int bufferSize = CompressedBlockSize;
while ( true ) {
// initialize zstream values
z_stream zs;
zs.zalloc = NULL;
zs.zfree = NULL;
zs.next_in = (Bytef*)UncompressedBlock;
zs.avail_in = inputLength;
zs.next_out = (Bytef*)&buffer[BLOCK_HEADER_LENGTH];
zs.avail_out = bufferSize - BLOCK_HEADER_LENGTH - BLOCK_FOOTER_LENGTH;
// initialize the zlib compression algorithm
if ( deflateInit2(&zs, compressionLevel, Z_DEFLATED, GZIP_WINDOW_BITS, Z_DEFAULT_MEM_LEVEL, Z_DEFAULT_STRATEGY) != Z_OK ) {
fprintf(stderr, "BGZF ERROR: zlib deflate initialization failed.\n");
exit(1);
}
// compress the data
int status = deflate(&zs, Z_FINISH);
if ( status != Z_STREAM_END ) {
deflateEnd(&zs);
// reduce the input length and try again
if ( status == Z_OK ) {
inputLength -= 1024;
if( inputLength < 0 ) {
fprintf(stderr, "BGZF ERROR: input reduction failed.\n");
exit(1);
}
continue;
}
fprintf(stderr, "BGZF ERROR: zlib::deflateEnd() failed.\n");
exit(1);
}
// finalize the compression routine
if ( deflateEnd(&zs) != Z_OK ) {
fprintf(stderr, "BGZF ERROR: zlib::deflateEnd() failed.\n");
exit(1);
}
compressedLength = zs.total_out;
compressedLength += BLOCK_HEADER_LENGTH + BLOCK_FOOTER_LENGTH;
if ( compressedLength > MAX_BLOCK_SIZE ) {
fprintf(stderr, "BGZF ERROR: deflate overflow.\n");
exit(1);
}
break;
}
// store the compressed length
BgzfData::PackUnsignedShort(&buffer[16], (unsigned short)(compressedLength - 1));
// store the CRC32 checksum
unsigned int crc = crc32(0, NULL, 0);
crc = crc32(crc, (Bytef*)UncompressedBlock, inputLength);
BgzfData::PackUnsignedInt(&buffer[compressedLength - 8], crc);
BgzfData::PackUnsignedInt(&buffer[compressedLength - 4], inputLength);
// ensure that we have less than a block of data left
int remaining = BlockOffset - inputLength;
if ( remaining > 0 ) {
if ( remaining > inputLength ) {
fprintf(stderr, "BGZF ERROR: after deflate, remainder too large.\n");
exit(1);
}
memcpy(UncompressedBlock, UncompressedBlock + inputLength, remaining);
}
BlockOffset = remaining;
return compressedLength;
}
// flushes the data in the BGZF block
void BgzfData::FlushBlock(void) {
// flush all of the remaining blocks
while ( BlockOffset > 0 ) {
// compress the data block
int blockLength = DeflateBlock();
// flush the data to our output stream
int numBytesWritten = fwrite(CompressedBlock, 1, blockLength, Stream);
if ( numBytesWritten != blockLength ) {
fprintf(stderr, "BGZF ERROR: expected to write %u bytes during flushing, but wrote %u bytes.\n", blockLength, numBytesWritten);
exit(1);
}
BlockAddress += blockLength;
}
}
// de-compresses the current block
int BgzfData::InflateBlock(const int& blockLength) {
// Inflate the block in m_BGZF.CompressedBlock into m_BGZF.UncompressedBlock
z_stream zs;
zs.zalloc = NULL;
zs.zfree = NULL;
zs.next_in = (Bytef*)CompressedBlock + 18;
zs.avail_in = blockLength - 16;
zs.next_out = (Bytef*)UncompressedBlock;
zs.avail_out = UncompressedBlockSize;
int status = inflateInit2(&zs, GZIP_WINDOW_BITS);
if ( status != Z_OK ) {
fprintf(stderr, "BGZF ERROR: could not decompress block - zlib::inflateInit() failed\n");
return -1;
}
status = inflate(&zs, Z_FINISH);
if ( status != Z_STREAM_END ) {
inflateEnd(&zs);
fprintf(stderr, "BGZF ERROR: could not decompress block - zlib::inflate() failed\n");
return -1;
}
status = inflateEnd(&zs);
if ( status != Z_OK ) {
fprintf(stderr, "BGZF ERROR: could not decompress block - zlib::inflateEnd() failed\n");
return -1;
}
return zs.total_out;
}
// opens the BGZF file for reading (mode is either "rb" for reading, or "wb" for writing)
bool BgzfData::Open(const string& filename, const char* mode, bool isWriteUncompressed ) {
// determine open mode
if ( strcmp(mode, "rb") == 0 )
IsWriteOnly = false;
else if ( strcmp(mode, "wb") == 0)
IsWriteOnly = true;
else {
fprintf(stderr, "BGZF ERROR: unknown file mode: %s\n", mode);
return false;
}
// ----------------------------------------------------------------
// open Stream to read to/write from file, stdin, or stdout
// stdin/stdout option contributed by Aaron Quinlan (2010-Jan-03)
// read/write BGZF data to/from a file
if ( (filename != "stdin") && (filename != "stdout") )
Stream = fopen(filename.c_str(), mode);
// read BGZF data from stdin
else if ( (filename == "stdin") && (strcmp(mode, "rb") == 0 ) )
Stream = freopen(NULL, mode, stdin);
// write BGZF data to stdout
else if ( (filename == "stdout") && (strcmp(mode, "wb") == 0) )
Stream = freopen(NULL, mode, stdout);
if ( !Stream ) {
fprintf(stderr, "BGZF ERROR: unable to open file %s\n", filename.c_str() );
return false;
}
// set flags, return success
IsOpen = true;
IsWriteUncompressed = isWriteUncompressed;
return true;
}
// reads BGZF data into a byte buffer
int BgzfData::Read(char* data, const unsigned int dataLength) {
if ( !IsOpen || IsWriteOnly || dataLength == 0 ) return 0;
char* output = data;
unsigned int numBytesRead = 0;
while ( numBytesRead < dataLength ) {
int bytesAvailable = BlockLength - BlockOffset;
if ( bytesAvailable <= 0 ) {
if ( !ReadBlock() ) return -1;
bytesAvailable = BlockLength - BlockOffset;
if ( bytesAvailable <= 0 ) break;
}
char* buffer = UncompressedBlock;
int copyLength = min( (int)(dataLength-numBytesRead), bytesAvailable );
memcpy(output, buffer + BlockOffset, copyLength);
BlockOffset += copyLength;
output += copyLength;
numBytesRead += copyLength;
}
if ( BlockOffset == BlockLength ) {
BlockAddress = ftell64(Stream);
BlockOffset = 0;
BlockLength = 0;
}
return numBytesRead;
}
// reads a BGZF block
bool BgzfData::ReadBlock(void) {
char header[BLOCK_HEADER_LENGTH];
int64_t blockAddress = ftell64(Stream);
int count = fread(header, 1, sizeof(header), Stream);
if ( count == 0 ) {
BlockLength = 0;
return true;
}
if ( count != sizeof(header) ) {
fprintf(stderr, "BGZF ERROR: read block failed - could not read block header\n");
return false;
}
if ( !BgzfData::CheckBlockHeader(header) ) {
fprintf(stderr, "BGZF ERROR: read block failed - invalid block header\n");
return false;
}
int blockLength = BgzfData::UnpackUnsignedShort(&header[16]) + 1;
char* compressedBlock = CompressedBlock;
memcpy(compressedBlock, header, BLOCK_HEADER_LENGTH);
int remaining = blockLength - BLOCK_HEADER_LENGTH;
count = fread(&compressedBlock[BLOCK_HEADER_LENGTH], 1, remaining, Stream);
if ( count != remaining ) {
fprintf(stderr, "BGZF ERROR: read block failed - could not read data from block\n");
return false;
}
count = InflateBlock(blockLength);
if ( count < 0 ) {
fprintf(stderr, "BGZF ERROR: read block failed - could not decompress block data\n");
return false;
}
if ( BlockLength != 0 )
BlockOffset = 0;
BlockAddress = blockAddress;
BlockLength = count;
return true;
}
// seek to position in BGZF file
bool BgzfData::Seek(int64_t position) {
if ( !IsOpen ) return false;
int blockOffset = (position & 0xFFFF);
int64_t blockAddress = (position >> 16) & 0xFFFFFFFFFFFFLL;
if ( fseek64(Stream, blockAddress, SEEK_SET) != 0 ) {
fprintf(stderr, "BGZF ERROR: unable to seek in file\n");
return false;
}
BlockLength = 0;
BlockAddress = blockAddress;
BlockOffset = blockOffset;
return true;
}
// get file position in BGZF file
int64_t BgzfData::Tell(void) {
if ( !IsOpen )
return false;
else
return ( (BlockAddress << 16) | (BlockOffset & 0xFFFF) );
}
// writes the supplied data into the BGZF buffer
unsigned int BgzfData::Write(const char* data, const unsigned int dataLen) {
if ( !IsOpen || !IsWriteOnly ) return false;
// initialize
unsigned int numBytesWritten = 0;
const char* input = data;
unsigned int blockLength = UncompressedBlockSize;
// copy the data to the buffer
while ( numBytesWritten < dataLen ) {
unsigned int copyLength = min(blockLength - BlockOffset, dataLen - numBytesWritten);
char* buffer = UncompressedBlock;
memcpy(buffer + BlockOffset, input, copyLength);
BlockOffset += copyLength;
input += copyLength;
numBytesWritten += copyLength;
if ( BlockOffset == blockLength )
FlushBlock();
}
return numBytesWritten;
}