/*
* The Broad Institute
* SOFTWARE COPYRIGHT NOTICE AGREEMENT
* This software and its documentation are copyright 2009 by the
* Broad Institute/Massachusetts Institute of Technology. All rights are reserved.
*
* This software is supplied without any warranty or guaranteed support whatsoever. Neither
* the Broad Institute nor MIT can be responsible for its use, misuse, or functionality.
*/
package edu.mit.broad.sam.util;

/**
 * Constants shared by BlockCompressed{Input,Output}Stream classes
 */
public class BlockCompressedStreamConstants {
    // Number of bytes in the gzip block before the deflated data.
    // This is not the standard header size, because we include one optional subfield,
    // but it is the standard for us.
    public static final int BLOCK_HEADER_LENGTH = 18;

    // Location in the gzip block of the total block size (actually total block size - 1)
    public static final int BLOCK_LENGTH_OFFSET = 16;

    // Number of bytes that follow the deflated data
    public static final int BLOCK_FOOTER_LENGTH = 8;

    // We require that a compressed block (including header and footer, be <= this)
    public static final int MAX_COMPRESSED_BLOCK_SIZE = 64 * 1024;

    // Push out a gzip block when this many uncompressed bytes have been accumulated.
    public static final int DEFAULT_UNCOMPRESSED_BLOCK_SIZE = 64 * 1024;

    // If after compressing a block, the compressed block is found to be >
    // MAX_COMPRESSED_BLOCK_SIZE, including overhead, then throttle back bytes to
    // be compressed by this amount and try again.
    public static final int UNCOMPRESSED_THROTTLE_AMOUNT = 1024;

    // Magic numbers
    public static final byte GZIP_ID1 = 31;
    public static final int GZIP_ID2 = 139;

    // FEXTRA flag means there are optional fields
    public static final int GZIP_FLG = 4;

    // extra flags
    public static final int GZIP_XFL = 0;

    // length of extra subfield
    public static final short GZIP_XLEN = 6;

    // The deflate compression, which is customarily used by gzip
    public static final byte GZIP_CM_DEFLATE = 8;

    // We don't care about OS because we're not doing line terminator translation
    public static final int GZIP_OS_UNKNOWN = 255;

    // The subfield ID
    public static final byte BGZF_ID1 = 66;
    public static final byte BGZF_ID2 = 67;

    // subfield length in bytes
    public static final byte BGZF_LEN = 2;
}