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1086 lines
24 KiB
1086 lines
24 KiB
/////////////////////////////////////////////////////////////////////////// |
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// |
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// Copyright (c) 2002, Industrial Light & Magic, a division of Lucas |
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// Digital Ltd. LLC |
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// |
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// All rights reserved. |
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// |
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// Redistribution and use in source and binary forms, with or without |
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// modification, are permitted provided that the following conditions are |
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// met: |
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// * Redistributions of source code must retain the above copyright |
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// notice, this list of conditions and the following disclaimer. |
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// * Redistributions in binary form must reproduce the above |
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// copyright notice, this list of conditions and the following disclaimer |
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// in the documentation and/or other materials provided with the |
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// distribution. |
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// * Neither the name of Industrial Light & Magic nor the names of |
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// its contributors may be used to endorse or promote products derived |
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// from this software without specific prior written permission. |
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// |
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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// |
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/////////////////////////////////////////////////////////////////////////// |
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//----------------------------------------------------------------------------- |
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// |
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// 16-bit Huffman compression and decompression. |
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// |
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// The source code in this file is derived from the 8-bit |
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// Huffman compression and decompression routines written |
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// by Christian Rouet for his PIZ image file format. |
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// |
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//----------------------------------------------------------------------------- |
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#include <ImfHuf.h> |
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#include <ImfInt64.h> |
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#include <ImfAutoArray.h> |
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#include "Iex.h" |
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#include <string.h> |
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#include <assert.h> |
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#include <algorithm> |
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using namespace std; |
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using namespace Iex; |
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namespace Imf { |
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namespace { |
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const int HUF_ENCBITS = 16; // literal (value) bit length |
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const int HUF_DECBITS = 14; // decoding bit size (>= 8) |
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const int HUF_ENCSIZE = (1 << HUF_ENCBITS) + 1; // encoding table size |
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const int HUF_DECSIZE = 1 << HUF_DECBITS; // decoding table size |
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const int HUF_DECMASK = HUF_DECSIZE - 1; |
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struct HufDec |
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{ // short code long code |
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//------------------------------- |
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int len:8; // code length 0 |
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int lit:24; // lit p size |
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int * p; // 0 lits |
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}; |
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void |
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invalidNBits () |
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{ |
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throw InputExc ("Error in header for Huffman-encoded data " |
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"(invalid number of bits)."); |
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} |
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void |
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tooMuchData () |
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{ |
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throw InputExc ("Error in Huffman-encoded data " |
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"(decoded data are longer than expected)."); |
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} |
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void |
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notEnoughData () |
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{ |
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throw InputExc ("Error in Huffman-encoded data " |
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"(decoded data are shorter than expected)."); |
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} |
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void |
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invalidCode () |
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{ |
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throw InputExc ("Error in Huffman-encoded data " |
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"(invalid code)."); |
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} |
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void |
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invalidTableSize () |
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{ |
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throw InputExc ("Error in Huffman-encoded data " |
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"(invalid code table size)."); |
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} |
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void |
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unexpectedEndOfTable () |
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{ |
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throw InputExc ("Error in Huffman-encoded data " |
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"(unexpected end of code table data)."); |
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} |
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void |
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tableTooLong () |
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{ |
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throw InputExc ("Error in Huffman-encoded data " |
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"(code table is longer than expected)."); |
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} |
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void |
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invalidTableEntry () |
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{ |
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throw InputExc ("Error in Huffman-encoded data " |
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"(invalid code table entry)."); |
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} |
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inline Int64 |
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hufLength (Int64 code) |
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{ |
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return code & 63; |
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} |
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inline Int64 |
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hufCode (Int64 code) |
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{ |
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return code >> 6; |
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} |
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inline void |
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outputBits (int nBits, Int64 bits, Int64 &c, int &lc, char *&out) |
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{ |
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c <<= nBits; |
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lc += nBits; |
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c |= bits; |
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while (lc >= 8) |
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*out++ = (c >> (lc -= 8)); |
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} |
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inline Int64 |
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getBits (int nBits, Int64 &c, int &lc, const char *&in) |
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{ |
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while (lc < nBits) |
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{ |
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c = (c << 8) | *(unsigned char *)(in++); |
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lc += 8; |
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} |
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lc -= nBits; |
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return (c >> lc) & ((1 << nBits) - 1); |
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} |
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// |
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// ENCODING TABLE BUILDING & (UN)PACKING |
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// |
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// |
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// Build a "canonical" Huffman code table: |
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// - for each (uncompressed) symbol, hcode contains the length |
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// of the corresponding code (in the compressed data) |
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// - canonical codes are computed and stored in hcode |
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// - the rules for constructing canonical codes are as follows: |
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// * shorter codes (if filled with zeroes to the right) |
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// have a numerically higher value than longer codes |
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// * for codes with the same length, numerical values |
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// increase with numerical symbol values |
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// - because the canonical code table can be constructed from |
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// symbol lengths alone, the code table can be transmitted |
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// without sending the actual code values |
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// - see http://www.compressconsult.com/huffman/ |
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// |
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void |
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hufCanonicalCodeTable (Int64 hcode[HUF_ENCSIZE]) |
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{ |
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Int64 n[59]; |
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// |
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// For each i from 0 through 58, count the |
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// number of different codes of length i, and |
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// store the count in n[i]. |
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// |
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for (int i = 0; i <= 58; ++i) |
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n[i] = 0; |
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for (int i = 0; i < HUF_ENCSIZE; ++i) |
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n[hcode[i]] += 1; |
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// |
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// For each i from 58 through 1, compute the |
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// numerically lowest code with length i, and |
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// store that code in n[i]. |
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// |
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Int64 c = 0; |
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for (int i = 58; i > 0; --i) |
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{ |
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Int64 nc = ((c + n[i]) >> 1); |
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n[i] = c; |
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c = nc; |
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} |
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// |
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// hcode[i] contains the length, l, of the |
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// code for symbol i. Assign the next available |
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// code of length l to the symbol and store both |
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// l and the code in hcode[i]. |
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// |
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for (int i = 0; i < HUF_ENCSIZE; ++i) |
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{ |
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int l = hcode[i]; |
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if (l > 0) |
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hcode[i] = l | (n[l]++ << 6); |
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} |
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} |
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// |
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// Compute Huffman codes (based on frq input) and store them in frq: |
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// - code structure is : [63:lsb - 6:msb] | [5-0: bit length]; |
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// - max code length is 58 bits; |
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// - codes outside the range [im-iM] have a null length (unused values); |
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// - original frequencies are destroyed; |
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// - encoding tables are used by hufEncode() and hufBuildDecTable(); |
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// |
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struct FHeapCompare |
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{ |
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bool operator () (Int64 *a, Int64 *b) {return *a > *b;} |
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}; |
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void |
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hufBuildEncTable |
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(Int64* frq, // io: input frequencies [HUF_ENCSIZE], output table |
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int* im, // o: min frq index |
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int* iM) // o: max frq index |
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{ |
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// |
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// This function assumes that when it is called, array frq |
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// indicates the frequency of all possible symbols in the data |
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// that are to be Huffman-encoded. (frq[i] contains the number |
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// of occurrences of symbol i in the data.) |
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// |
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// The loop below does three things: |
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// |
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// 1) Finds the minimum and maximum indices that point |
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// to non-zero entries in frq: |
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// |
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// frq[im] != 0, and frq[i] == 0 for all i < im |
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// frq[iM] != 0, and frq[i] == 0 for all i > iM |
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// |
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// 2) Fills array fHeap with pointers to all non-zero |
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// entries in frq. |
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// |
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// 3) Initializes array hlink such that hlink[i] == i |
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// for all array entries. |
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// |
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AutoArray <int, HUF_ENCSIZE> hlink; |
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AutoArray <Int64 *, HUF_ENCSIZE> fHeap; |
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*im = 0; |
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while (!frq[*im]) |
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(*im)++; |
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int nf = 0; |
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for (int i = *im; i < HUF_ENCSIZE; i++) |
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{ |
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hlink[i] = i; |
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if (frq[i]) |
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{ |
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fHeap[nf] = &frq[i]; |
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nf++; |
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*iM = i; |
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} |
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} |
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// |
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// Add a pseudo-symbol, with a frequency count of 1, to frq; |
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// adjust the fHeap and hlink array accordingly. Function |
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// hufEncode() uses the pseudo-symbol for run-length encoding. |
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// |
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(*iM)++; |
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frq[*iM] = 1; |
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fHeap[nf] = &frq[*iM]; |
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nf++; |
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// |
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// Build an array, scode, such that scode[i] contains the number |
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// of bits assigned to symbol i. Conceptually this is done by |
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// constructing a tree whose leaves are the symbols with non-zero |
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// frequency: |
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// |
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// Make a heap that contains all symbols with a non-zero frequency, |
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// with the least frequent symbol on top. |
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// |
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// Repeat until only one symbol is left on the heap: |
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// |
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// Take the two least frequent symbols off the top of the heap. |
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// Create a new node that has first two nodes as children, and |
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// whose frequency is the sum of the frequencies of the first |
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// two nodes. Put the new node back into the heap. |
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// |
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// The last node left on the heap is the root of the tree. For each |
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// leaf node, the distance between the root and the leaf is the length |
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// of the code for the corresponding symbol. |
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// |
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// The loop below doesn't actually build the tree; instead we compute |
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// the distances of the leaves from the root on the fly. When a new |
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// node is added to the heap, then that node's descendants are linked |
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// into a single linear list that starts at the new node, and the code |
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// lengths of the descendants (that is, their distance from the root |
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// of the tree) are incremented by one. |
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// |
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make_heap (&fHeap[0], &fHeap[nf], FHeapCompare()); |
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AutoArray <Int64, HUF_ENCSIZE> scode; |
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memset (scode, 0, sizeof (Int64) * HUF_ENCSIZE); |
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while (nf > 1) |
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{ |
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// |
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// Find the indices, mm and m, of the two smallest non-zero frq |
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// values in fHeap, add the smallest frq to the second-smallest |
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// frq, and remove the smallest frq value from fHeap. |
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// |
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int mm = fHeap[0] - frq; |
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pop_heap (&fHeap[0], &fHeap[nf], FHeapCompare()); |
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--nf; |
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int m = fHeap[0] - frq; |
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pop_heap (&fHeap[0], &fHeap[nf], FHeapCompare()); |
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frq[m ] += frq[mm]; |
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push_heap (&fHeap[0], &fHeap[nf], FHeapCompare()); |
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// |
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// The entries in scode are linked into lists with the |
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// entries in hlink serving as "next" pointers and with |
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// the end of a list marked by hlink[j] == j. |
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// |
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// Traverse the lists that start at scode[m] and scode[mm]. |
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// For each element visited, increment the length of the |
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// corresponding code by one bit. (If we visit scode[j] |
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// during the traversal, then the code for symbol j becomes |
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// one bit longer.) |
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// |
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// Merge the lists that start at scode[m] and scode[mm] |
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// into a single list that starts at scode[m]. |
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// |
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// |
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// Add a bit to all codes in the first list. |
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// |
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for (int j = m; true; j = hlink[j]) |
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{ |
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scode[j]++; |
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assert (scode[j] <= 58); |
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if (hlink[j] == j) |
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{ |
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// |
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// Merge the two lists. |
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// |
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hlink[j] = mm; |
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break; |
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} |
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} |
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// |
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// Add a bit to all codes in the second list |
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// |
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for (int j = mm; true; j = hlink[j]) |
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{ |
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scode[j]++; |
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assert (scode[j] <= 58); |
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if (hlink[j] == j) |
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break; |
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} |
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} |
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// |
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// Build a canonical Huffman code table, replacing the code |
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// lengths in scode with (code, code length) pairs. Copy the |
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// code table from scode into frq. |
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// |
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hufCanonicalCodeTable (scode); |
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memcpy (frq, scode, sizeof (Int64) * HUF_ENCSIZE); |
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} |
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// |
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// Pack an encoding table: |
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// - only code lengths, not actual codes, are stored |
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// - runs of zeroes are compressed as follows: |
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// |
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// unpacked packed |
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// -------------------------------- |
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// 1 zero 0 (6 bits) |
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// 2 zeroes 59 |
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// 3 zeroes 60 |
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// 4 zeroes 61 |
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// 5 zeroes 62 |
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// n zeroes (6 or more) 63 n-6 (6 + 8 bits) |
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// |
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const int SHORT_ZEROCODE_RUN = 59; |
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const int LONG_ZEROCODE_RUN = 63; |
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const int SHORTEST_LONG_RUN = 2 + LONG_ZEROCODE_RUN - SHORT_ZEROCODE_RUN; |
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const int LONGEST_LONG_RUN = 255 + SHORTEST_LONG_RUN; |
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void |
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hufPackEncTable |
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(const Int64* hcode, // i : encoding table [HUF_ENCSIZE] |
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int im, // i : min hcode index |
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int iM, // i : max hcode index |
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char** pcode) // o: ptr to packed table (updated) |
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{ |
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char *p = *pcode; |
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Int64 c = 0; |
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int lc = 0; |
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for (; im <= iM; im++) |
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{ |
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int l = hufLength (hcode[im]); |
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if (l == 0) |
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{ |
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int zerun = 1; |
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while ((im < iM) && (zerun < LONGEST_LONG_RUN)) |
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{ |
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if (hufLength (hcode[im+1]) > 0 ) |
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break; |
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im++; |
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zerun++; |
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} |
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if (zerun >= 2) |
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{ |
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if (zerun >= SHORTEST_LONG_RUN) |
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{ |
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outputBits (6, LONG_ZEROCODE_RUN, c, lc, p); |
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outputBits (8, zerun - SHORTEST_LONG_RUN, c, lc, p); |
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} |
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else |
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{ |
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outputBits (6, SHORT_ZEROCODE_RUN + zerun - 2, c, lc, p); |
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} |
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continue; |
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} |
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} |
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outputBits (6, l, c, lc, p); |
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} |
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if (lc > 0) |
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*p++ = (unsigned char) (c << (8 - lc)); |
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*pcode = p; |
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} |
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// |
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// Unpack an encoding table packed by hufPackEncTable(): |
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// |
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void |
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hufUnpackEncTable |
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(const char** pcode, // io: ptr to packed table (updated) |
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int ni, // i : input size (in bytes) |
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int im, // i : min hcode index |
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int iM, // i : max hcode index |
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Int64* hcode) // o: encoding table [HUF_ENCSIZE] |
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{ |
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memset (hcode, 0, sizeof (Int64) * HUF_ENCSIZE); |
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const char *p = *pcode; |
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Int64 c = 0; |
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int lc = 0; |
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for (; im <= iM; im++) |
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{ |
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if (p - *pcode > ni) |
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unexpectedEndOfTable(); |
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Int64 l = hcode[im] = getBits (6, c, lc, p); // code length |
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if (l == (Int64) LONG_ZEROCODE_RUN) |
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{ |
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if (p - *pcode > ni) |
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unexpectedEndOfTable(); |
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int zerun = getBits (8, c, lc, p) + SHORTEST_LONG_RUN; |
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if (im + zerun > iM + 1) |
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tableTooLong(); |
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while (zerun--) |
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hcode[im++] = 0; |
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im--; |
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} |
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else if (l >= (Int64) SHORT_ZEROCODE_RUN) |
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{ |
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int zerun = l - SHORT_ZEROCODE_RUN + 2; |
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if (im + zerun > iM + 1) |
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tableTooLong(); |
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while (zerun--) |
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hcode[im++] = 0; |
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im--; |
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} |
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} |
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*pcode = (char *) p; |
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hufCanonicalCodeTable (hcode); |
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} |
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// |
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// DECODING TABLE BUILDING |
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// |
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// |
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// Clear a newly allocated decoding table so that it contains only zeroes. |
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// |
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void |
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hufClearDecTable |
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(HufDec * hdecod) // io: (allocated by caller) |
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// decoding table [HUF_DECSIZE] |
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{ |
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memset (hdecod, 0, sizeof (HufDec) * HUF_DECSIZE); |
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} |
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// |
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// Build a decoding hash table based on the encoding table hcode: |
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// - short codes (<= HUF_DECBITS) are resolved with a single table access; |
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// - long code entry allocations are not optimized, because long codes are |
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// unfrequent; |
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// - decoding tables are used by hufDecode(); |
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// |
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|
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void |
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hufBuildDecTable |
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(const Int64* hcode, // i : encoding table |
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int im, // i : min index in hcode |
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int iM, // i : max index in hcode |
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HufDec * hdecod) // o: (allocated by caller) |
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// decoding table [HUF_DECSIZE] |
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{ |
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// |
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// Init hashtable & loop on all codes. |
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// Assumes that hufClearDecTable(hdecod) has already been called. |
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// |
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for (; im <= iM; im++) |
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{ |
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Int64 c = hufCode (hcode[im]); |
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int l = hufLength (hcode[im]); |
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|
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if (c >> l) |
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{ |
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// |
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// Error: c is supposed to be an l-bit code, |
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// but c contains a value that is greater |
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// than the largest l-bit number. |
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// |
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|
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invalidTableEntry(); |
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} |
|
|
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if (l > HUF_DECBITS) |
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{ |
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// |
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// Long code: add a secondary entry |
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// |
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|
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HufDec *pl = hdecod + (c >> (l - HUF_DECBITS)); |
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|
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if (pl->len) |
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{ |
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// |
|
// Error: a short code has already |
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// been stored in table entry *pl. |
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// |
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|
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invalidTableEntry(); |
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} |
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|
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pl->lit++; |
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|
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if (pl->p) |
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{ |
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int *p = pl->p; |
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pl->p = new int [pl->lit]; |
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|
|
for (int i = 0; i < pl->lit - 1; ++i) |
|
pl->p[i] = p[i]; |
|
|
|
delete [] p; |
|
} |
|
else |
|
{ |
|
pl->p = new int [1]; |
|
} |
|
|
|
pl->p[pl->lit - 1]= im; |
|
} |
|
else if (l) |
|
{ |
|
// |
|
// Short code: init all primary entries |
|
// |
|
|
|
HufDec *pl = hdecod + (c << (HUF_DECBITS - l)); |
|
|
|
for (Int64 i = 1 << (HUF_DECBITS - l); i > 0; i--, pl++) |
|
{ |
|
if (pl->len || pl->p) |
|
{ |
|
// |
|
// Error: a short code or a long code has |
|
// already been stored in table entry *pl. |
|
// |
|
|
|
invalidTableEntry(); |
|
} |
|
|
|
pl->len = l; |
|
pl->lit = im; |
|
} |
|
} |
|
} |
|
} |
|
|
|
|
|
// |
|
// Free the long code entries of a decoding table built by hufBuildDecTable() |
|
// |
|
|
|
void |
|
hufFreeDecTable (HufDec *hdecod) // io: Decoding table |
|
{ |
|
for (int i = 0; i < HUF_DECSIZE; i++) |
|
{ |
|
if (hdecod[i].p) |
|
{ |
|
delete [] hdecod[i].p; |
|
hdecod[i].p = 0; |
|
} |
|
} |
|
} |
|
|
|
|
|
// |
|
// ENCODING |
|
// |
|
|
|
inline void |
|
outputCode (Int64 code, Int64 &c, int &lc, char *&out) |
|
{ |
|
outputBits (hufLength (code), hufCode (code), c, lc, out); |
|
} |
|
|
|
|
|
inline void |
|
sendCode (Int64 sCode, int runCount, Int64 runCode, |
|
Int64 &c, int &lc, char *&out) |
|
{ |
|
static const int RLMIN = 32; // min count to activate run-length coding |
|
|
|
if (runCount > RLMIN) |
|
{ |
|
outputCode (sCode, c, lc, out); |
|
outputCode (runCode, c, lc, out); |
|
outputBits (8, runCount, c, lc, out); |
|
} |
|
else |
|
{ |
|
while (runCount-- >= 0) |
|
outputCode (sCode, c, lc, out); |
|
} |
|
} |
|
|
|
|
|
// |
|
// Encode (compress) ni values based on the Huffman encoding table hcode: |
|
// |
|
|
|
int |
|
hufEncode // return: output size (in bits) |
|
(const Int64* hcode, // i : encoding table |
|
const unsigned short* in, // i : uncompressed input buffer |
|
const int ni, // i : input buffer size (in bytes) |
|
int rlc, // i : rl code |
|
char* out) // o: compressed output buffer |
|
{ |
|
char *outStart = out; |
|
Int64 c = 0; // bits not yet written to out |
|
int lc = 0; // number of valid bits in c (LSB) |
|
int s = in[0]; |
|
int cs = 0; |
|
|
|
// |
|
// Loop on input values |
|
// |
|
|
|
for (int i = 1; i < ni; i++) |
|
{ |
|
// |
|
// Count same values or send code |
|
// |
|
|
|
if (s == in[i] && cs < 255) |
|
{ |
|
cs++; |
|
} |
|
else |
|
{ |
|
sendCode (hcode[s], cs, hcode[rlc], c, lc, out); |
|
cs=0; |
|
} |
|
|
|
s = in[i]; |
|
} |
|
|
|
// |
|
// Send remaining code |
|
// |
|
|
|
sendCode (hcode[s], cs, hcode[rlc], c, lc, out); |
|
|
|
if (lc) |
|
*out = (c << (8 - lc)) & 0xff; |
|
|
|
return (out - outStart) * 8 + lc; |
|
} |
|
|
|
|
|
// |
|
// DECODING |
|
// |
|
|
|
// |
|
// In order to force the compiler to inline them, |
|
// getChar() and getCode() are implemented as macros |
|
// instead of "inline" functions. |
|
// |
|
|
|
#define getChar(c, lc, in) \ |
|
{ \ |
|
c = (c << 8) | *(unsigned char *)(in++); \ |
|
lc += 8; \ |
|
} |
|
|
|
|
|
#define getCode(po, rlc, c, lc, in, out, oe) \ |
|
{ \ |
|
if (po == rlc) \ |
|
{ \ |
|
if (lc < 8) \ |
|
getChar(c, lc, in); \ |
|
\ |
|
lc -= 8; \ |
|
\ |
|
unsigned char cs = (c >> lc); \ |
|
\ |
|
if (out + cs > oe) \ |
|
tooMuchData(); \ |
|
\ |
|
unsigned short s = out[-1]; \ |
|
\ |
|
while (cs-- > 0) \ |
|
*out++ = s; \ |
|
} \ |
|
else if (out < oe) \ |
|
{ \ |
|
*out++ = po; \ |
|
} \ |
|
else \ |
|
{ \ |
|
tooMuchData(); \ |
|
} \ |
|
} |
|
|
|
|
|
// |
|
// Decode (uncompress) ni bits based on encoding & decoding tables: |
|
// |
|
|
|
void |
|
hufDecode |
|
(const Int64 * hcode, // i : encoding table |
|
const HufDec * hdecod, // i : decoding table |
|
const char* in, // i : compressed input buffer |
|
int ni, // i : input size (in bits) |
|
int rlc, // i : run-length code |
|
int no, // i : expected output size (in bytes) |
|
unsigned short* out) // o: uncompressed output buffer |
|
{ |
|
Int64 c = 0; |
|
int lc = 0; |
|
unsigned short * outb = out; |
|
unsigned short * oe = out + no; |
|
const char * ie = in + (ni + 7) / 8; // input byte size |
|
|
|
// |
|
// Loop on input bytes |
|
// |
|
|
|
while (in < ie) |
|
{ |
|
getChar (c, lc, in); |
|
|
|
// |
|
// Access decoding table |
|
// |
|
|
|
while (lc >= HUF_DECBITS) |
|
{ |
|
const HufDec pl = hdecod[(c >> (lc-HUF_DECBITS)) & HUF_DECMASK]; |
|
|
|
if (pl.len) |
|
{ |
|
// |
|
// Get short code |
|
// |
|
|
|
lc -= pl.len; |
|
getCode (pl.lit, rlc, c, lc, in, out, oe); |
|
} |
|
else |
|
{ |
|
if (!pl.p) |
|
invalidCode(); // wrong code |
|
|
|
// |
|
// Search long code |
|
// |
|
|
|
int j; |
|
|
|
for (j = 0; j < pl.lit; j++) |
|
{ |
|
int l = hufLength (hcode[pl.p[j]]); |
|
|
|
while (lc < l && in < ie) // get more bits |
|
getChar (c, lc, in); |
|
|
|
if (lc >= l) |
|
{ |
|
if (hufCode (hcode[pl.p[j]]) == |
|
((c >> (lc - l)) & ((Int64(1) << l) - 1))) |
|
{ |
|
// |
|
// Found : get long code |
|
// |
|
|
|
lc -= l; |
|
getCode (pl.p[j], rlc, c, lc, in, out, oe); |
|
break; |
|
} |
|
} |
|
} |
|
|
|
if (j == pl.lit) |
|
invalidCode(); // Not found |
|
} |
|
} |
|
} |
|
|
|
// |
|
// Get remaining (short) codes |
|
// |
|
|
|
int i = (8 - ni) & 7; |
|
c >>= i; |
|
lc -= i; |
|
|
|
while (lc > 0) |
|
{ |
|
const HufDec pl = hdecod[(c << (HUF_DECBITS - lc)) & HUF_DECMASK]; |
|
|
|
if (pl.len) |
|
{ |
|
lc -= pl.len; |
|
getCode (pl.lit, rlc, c, lc, in, out, oe); |
|
} |
|
else |
|
{ |
|
invalidCode(); // wrong (long) code |
|
} |
|
} |
|
|
|
if (out - outb != no) |
|
notEnoughData (); |
|
} |
|
|
|
|
|
void |
|
countFrequencies (Int64 freq[HUF_ENCSIZE], |
|
const unsigned short data[/*n*/], |
|
int n) |
|
{ |
|
for (int i = 0; i < HUF_ENCSIZE; ++i) |
|
freq[i] = 0; |
|
|
|
for (int i = 0; i < n; ++i) |
|
++freq[data[i]]; |
|
} |
|
|
|
|
|
void |
|
writeUInt (char buf[4], unsigned int i) |
|
{ |
|
unsigned char *b = (unsigned char *) buf; |
|
|
|
b[0] = i; |
|
b[1] = i >> 8; |
|
b[2] = i >> 16; |
|
b[3] = i >> 24; |
|
} |
|
|
|
|
|
unsigned int |
|
readUInt (const char buf[4]) |
|
{ |
|
const unsigned char *b = (const unsigned char *) buf; |
|
|
|
return ( b[0] & 0x000000ff) | |
|
((b[1] << 8) & 0x0000ff00) | |
|
((b[2] << 16) & 0x00ff0000) | |
|
((b[3] << 24) & 0xff000000); |
|
} |
|
|
|
} // namespace |
|
|
|
|
|
// |
|
// EXTERNAL INTERFACE |
|
// |
|
|
|
|
|
int |
|
hufCompress (const unsigned short raw[], |
|
int nRaw, |
|
char compressed[]) |
|
{ |
|
if (nRaw == 0) |
|
return 0; |
|
|
|
AutoArray <Int64, HUF_ENCSIZE> freq; |
|
|
|
countFrequencies (freq, raw, nRaw); |
|
|
|
int im, iM; |
|
hufBuildEncTable (freq, &im, &iM); |
|
|
|
char *tableStart = compressed + 20; |
|
char *tableEnd = tableStart; |
|
hufPackEncTable (freq, im, iM, &tableEnd); |
|
int tableLength = tableEnd - tableStart; |
|
|
|
char *dataStart = tableEnd; |
|
int nBits = hufEncode (freq, raw, nRaw, iM, dataStart); |
|
int dataLength = (nBits + 7) / 8; |
|
|
|
writeUInt (compressed, im); |
|
writeUInt (compressed + 4, iM); |
|
writeUInt (compressed + 8, tableLength); |
|
writeUInt (compressed + 12, nBits); |
|
writeUInt (compressed + 16, 0); // room for future extensions |
|
|
|
return dataStart + dataLength - compressed; |
|
} |
|
|
|
|
|
void |
|
hufUncompress (const char compressed[], |
|
int nCompressed, |
|
unsigned short raw[], |
|
int nRaw) |
|
{ |
|
if (nCompressed == 0) |
|
{ |
|
if (nRaw != 0) |
|
notEnoughData(); |
|
|
|
return; |
|
} |
|
|
|
int im = readUInt (compressed); |
|
int iM = readUInt (compressed + 4); |
|
// int tableLength = readUInt (compressed + 8); |
|
int nBits = readUInt (compressed + 12); |
|
|
|
if (im < 0 || im >= HUF_ENCSIZE || iM < 0 || iM >= HUF_ENCSIZE) |
|
invalidTableSize(); |
|
|
|
const char *ptr = compressed + 20; |
|
|
|
AutoArray <Int64, HUF_ENCSIZE> freq; |
|
AutoArray <HufDec, HUF_DECSIZE> hdec; |
|
|
|
hufClearDecTable (hdec); |
|
|
|
hufUnpackEncTable (&ptr, nCompressed - (ptr - compressed), im, iM, freq); |
|
|
|
try |
|
{ |
|
if (nBits > 8 * (nCompressed - (ptr - compressed))) |
|
invalidNBits(); |
|
|
|
hufBuildDecTable (freq, im, iM, hdec); |
|
hufDecode (freq, hdec, ptr, nBits, iM, nRaw, raw); |
|
} |
|
catch (...) |
|
{ |
|
hufFreeDecTable (hdec); |
|
throw; |
|
} |
|
|
|
hufFreeDecTable (hdec); |
|
} |
|
|
|
|
|
} // namespace Imf
|
|
|