64 lines
2.4 KiB
Java
64 lines
2.4 KiB
Java
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/*
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* The Broad Institute
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* SOFTWARE COPYRIGHT NOTICE AGREEMENT
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* This software and its documentation are copyright 2009 by the
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* Broad Institute/Massachusetts Institute of Technology. All rights are reserved.
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*
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* This software is supplied without any warranty or guaranteed support whatsoever. Neither
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* the Broad Institute nor MIT can be responsible for its use, misuse, or functionality.
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*/
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package edu.mit.broad.sam.util;
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/**
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* Constants shared by BlockCompressed{Input,Output}Stream classes
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*/
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public class BlockCompressedStreamConstants {
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// Number of bytes in the gzip block before the deflated data.
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// This is not the standard header size, because we include one optional subfield,
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// but it is the standard for us.
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public static final int BLOCK_HEADER_LENGTH = 18;
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// Location in the gzip block of the total block size (actually total block size - 1)
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public static final int BLOCK_LENGTH_OFFSET = 16;
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// Number of bytes that follow the deflated data
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public static final int BLOCK_FOOTER_LENGTH = 8;
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// We require that a compressed block (including header and footer, be <= this)
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public static final int MAX_COMPRESSED_BLOCK_SIZE = 64 * 1024;
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// Push out a gzip block when this many uncompressed bytes have been accumulated.
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public static final int DEFAULT_UNCOMPRESSED_BLOCK_SIZE = 64 * 1024;
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// If after compressing a block, the compressed block is found to be >
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// MAX_COMPRESSED_BLOCK_SIZE, including overhead, then throttle back bytes to
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// be compressed by this amount and try again.
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public static final int UNCOMPRESSED_THROTTLE_AMOUNT = 1024;
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// Magic numbers
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public static final byte GZIP_ID1 = 31;
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public static final int GZIP_ID2 = 139;
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// FEXTRA flag means there are optional fields
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public static final int GZIP_FLG = 4;
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// extra flags
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public static final int GZIP_XFL = 0;
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// length of extra subfield
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public static final short GZIP_XLEN = 6;
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// The deflate compression, which is customarily used by gzip
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public static final byte GZIP_CM_DEFLATE = 8;
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// We don't care about OS because we're not doing line terminator translation
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public static final int GZIP_OS_UNKNOWN = 255;
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// The subfield ID
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public static final byte BGZF_ID1 = 66;
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public static final byte BGZF_ID2 = 67;
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// subfield length in bytes
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public static final byte BGZF_LEN = 2;
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}
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