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