stdlibs/libz/zlib/inftrees.cpp
changeset 65 c4aad78f92f5
parent 50 79045913e4e9
child 66 38bdaa106551
--- a/stdlibs/libz/zlib/inftrees.cpp	Thu Aug 05 23:23:13 2010 +0530
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,349 +0,0 @@
-/* inftrees.cpp -- generate Huffman trees for efficient decoding
- * Copyright (C) 1995-2005 Mark Adler
- * For conditions of distribution and use, see copyright notice in zlib.h
- */
-
-#include "zutil.h"
-#include "inftrees.h"
-
-#define MAXBITS 15
-
-
-const char inflate_copyright[] =
-   " inflate 1.2.3 Copyright 1995-2005 Mark Adler ";
-/*
-  If you use the zlib library in a product, an acknowledgment is welcome
-  in the documentation of your product. If for some reason you cannot
-  include such an acknowledgment, I would appreciate that you keep this
-  copyright string in the executable of your product.
- */
-
-/*
-   Build a set of tables to decode the provided canonical Huffman code.
-   The code lengths are lens[0..codes-1].  The result starts at *table,
-   whose indices are 0..2^bits-1.  work is a writable array of at least
-   lens shorts, which is used as a work area.  type is the type of code
-   to be generated, CODES, LENS, or DISTS.  On return, zero is success,
-   -1 is an invalid code, and +1 means that ENOUGH isn't enough.  table
-   on return points to the next available entry's address.  bits is the
-   requested root table index bits, and on return it is the actual root
-   table index bits.  It will differ if the request is greater than the
-   longest code or if it is less than the shortest code.
- */
-#ifdef __SYMBIAN32__
-int inflate_table(codetype type,unsigned short FAR * lens,unsigned codes, code FAR * FAR * table,unsigned FAR * bits,unsigned short FAR * work)
-#else
-int inflate_table(type, lens, codes, table, bits, work)
-codetype type;
-unsigned short FAR *lens;
-unsigned codes;
-code FAR * FAR *table;
-unsigned FAR *bits;
-unsigned short FAR *work;
-#endif //__SYMBIAN32__
-{
-	// Line to stop compiler warning about unused mandatory global variable 'inflate_copyright'
-	char dontCare = inflate_copyright[0]; dontCare = dontCare;
-	
-    unsigned len;               /* a code's length in bits */
-    unsigned sym;               /* index of code symbols */
-    unsigned min, max;          /* minimum and maximum code lengths */
-    unsigned root;              /* number of index bits for root table */
-    unsigned curr;              /* number of index bits for current table */
-    unsigned drop;              /* code bits to drop for sub-table */
-    int left;                   /* number of prefix codes available */
-    unsigned used;              /* code entries in table used */
-    unsigned huff;              /* Huffman code */
-    unsigned incr;              /* for incrementing code, index */
-    unsigned fill;              /* index for replicating entries */
-    unsigned low;               /* low bits for current root entry */
-    unsigned mask;              /* mask for low root bits */
-    
-/*  Need to replace "this" variable with "current" as "this" is a reserved 
- *  keyword in C++ which is prefectly fine for a c code. As this file
- *  has been changed to C++ "this" needs to be changed.
- */ 
-#   define this current   
-    code this;                  /* table entry for duplication */
-    code FAR *next;             /* next available space in table */
-    const unsigned short FAR *base;     /* base value table to use */
-    const unsigned short FAR *extra;    /* extra bits table to use */
-    int end;                    /* use base and extra for symbol > end */
-    unsigned short count[MAXBITS+1];    /* number of codes of each length */
-    unsigned short offs[MAXBITS+1];     /* offsets in table for each length */
-    static const unsigned short lbase[31] = { /* Length codes 257..285 base */
-        3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31,
-        35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0};
-    static const unsigned short lext[31] = { /* Length codes 257..285 extra */
-        16, 16, 16, 16, 16, 16, 16, 16, 17, 17, 17, 17, 18, 18, 18, 18,
-        19, 19, 19, 19, 20, 20, 20, 20, 21, 21, 21, 21, 16, 201, 196};
-    static const unsigned short dbase[32] = { /* Distance codes 0..29 base */
-        1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193,
-        257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145,
-        8193, 12289, 16385, 24577, 0, 0};
-    static const unsigned short dext[32] = { /* Distance codes 0..29 extra */
-        16, 16, 16, 16, 17, 17, 18, 18, 19, 19, 20, 20, 21, 21, 22, 22,
-        23, 23, 24, 24, 25, 25, 26, 26, 27, 27,
-        28, 28, 29, 29, 64, 64};
-
-    /*
-       Process a set of code lengths to create a canonical Huffman code.  The
-       code lengths are lens[0..codes-1].  Each length corresponds to the
-       symbols 0..codes-1.  The Huffman code is generated by first sorting the
-       symbols by length from short to long, and retaining the symbol order
-       for codes with equal lengths.  Then the code starts with all zero bits
-       for the first code of the shortest length, and the codes are integer
-       increments for the same length, and zeros are appended as the length
-       increases.  For the deflate format, these bits are stored backwards
-       from their more natural integer increment ordering, and so when the
-       decoding tables are built in the large loop below, the integer codes
-       are incremented backwards.
-
-       This routine assumes, but does not check, that all of the entries in
-       lens[] are in the range 0..MAXBITS.  The caller must assure this.
-       1..MAXBITS is interpreted as that code length.  zero means that that
-       symbol does not occur in this code.
-
-       The codes are sorted by computing a count of codes for each length,
-       creating from that a table of starting indices for each length in the
-       sorted table, and then entering the symbols in order in the sorted
-       table.  The sorted table is work[], with that space being provided by
-       the caller.
-
-       The length counts are used for other purposes as well, i.e. finding
-       the minimum and maximum length codes, determining if there are any
-       codes at all, checking for a valid set of lengths, and looking ahead
-       at length counts to determine sub-table sizes when building the
-       decoding tables.
-     */
-
-    /* accumulate lengths for codes (assumes lens[] all in 0..MAXBITS) */
-    for (len = 0; len <= MAXBITS; len++)
-        count[len] = 0;
-    for (sym = 0; sym < codes; sym++)
-        count[lens[sym]]++;
-
-    /* bound code lengths, force root to be within code lengths */
-    root = *bits;
-    for (max = MAXBITS; max >= 1; max--)
-        if (count[max] != 0) break;
-    if (root > max) root = max;
-    if (max == 0) {                     /* no symbols to code at all */
-        this.op = (unsigned char)64;    /* invalid code marker */
-        this.bits = (unsigned char)1;
-        this.val = (unsigned short)0;
-        *(*table)++ = this;             /* make a table to force an error */
-        *(*table)++ = this;
-        *bits = 1;
-        return 0;     /* no symbols, but wait for decoding to report error */
-    }
-    for (min = 1; min <= MAXBITS; min++)
-        if (count[min] != 0) break;
-    if (root < min) root = min;
-
-    /* check for an over-subscribed or incomplete set of lengths */
-    left = 1;
-    for (len = 1; len <= MAXBITS; len++) {
-        left <<= 1;
-        left -= count[len];
-        if (left < 0) return -1;        /* over-subscribed */
-    }
-    if (left > 0 && (type == CODES || max != 1))
-        return -1;                      /* incomplete set */
-
-    /* generate offsets into symbol table for each length for sorting */
-    offs[1] = 0;
-    for (len = 1; len < MAXBITS; len++)
-        offs[len + 1] = offs[len] + count[len];
-
-    /* sort symbols by length, by symbol order within each length */
-    for (sym = 0; sym < codes; sym++)
-        if (lens[sym] != 0) work[offs[lens[sym]]++] = (unsigned short)sym;
-
-    /*
-       Create and fill in decoding tables.  In this loop, the table being
-       filled is at next and has curr index bits.  The code being used is huff
-       with length len.  That code is converted to an index by dropping drop
-       bits off of the bottom.  For codes where len is less than drop + curr,
-       those top drop + curr - len bits are incremented through all values to
-       fill the table with replicated entries.
-
-       root is the number of index bits for the root table.  When len exceeds
-       root, sub-tables are created pointed to by the root entry with an index
-       of the low root bits of huff.  This is saved in low to check for when a
-       new sub-table should be started.  drop is zero when the root table is
-       being filled, and drop is root when sub-tables are being filled.
-
-       When a new sub-table is needed, it is necessary to look ahead in the
-       code lengths to determine what size sub-table is needed.  The length
-       counts are used for this, and so count[] is decremented as codes are
-       entered in the tables.
-
-       used keeps track of how many table entries have been allocated from the
-       provided *table space.  It is checked when a LENS table is being made
-       against the space in *table, ENOUGH, minus the maximum space needed by
-       the worst case distance code, MAXD.  This should never happen, but the
-       sufficiency of ENOUGH has not been proven exhaustively, hence the check.
-       This assumes that when type == LENS, bits == 9.
-
-       sym increments through all symbols, and the loop terminates when
-       all codes of length max, i.e. all codes, have been processed.  This
-       routine permits incomplete codes, so another loop after this one fills
-       in the rest of the decoding tables with invalid code markers.
-     */
-
-    /* set up for code type */
-    switch (type) {
-    case CODES:
-        base = extra = work;    /* dummy value--not used */
-        end = 19;
-        break;
-    case LENS:
-        base = lbase;
-        base -= 257;
-        extra = lext;
-        extra -= 257;
-        end = 256;
-        break;
-    default:            /* DISTS */
-        base = dbase;
-        extra = dext;
-        end = -1;
-    }
-
-    /* initialize state for loop */
-    huff = 0;                   /* starting code */
-    sym = 0;                    /* starting code symbol */
-    len = min;                  /* starting code length */
-    next = *table;              /* current table to fill in */
-    curr = root;                /* current table index bits */
-    drop = 0;                   /* current bits to drop from code for index */
-    low = (unsigned)(-1);       /* trigger new sub-table when len > root */
-    used = 1U << root;          /* use root table entries */
-    mask = used - 1;            /* mask for comparing low */
-
-    /* check available table space */
-    if (type == LENS && used >= ENOUGH - MAXD)
-        return 1;
-
-    /* process all codes and make table entries */
-    for (;;) {
-        /* create table entry */
-        this.bits = (unsigned char)(len - drop);
-        if ((int)(work[sym]) < end) {
-            this.op = (unsigned char)0;
-            this.val = work[sym];
-        }
-        else if ((int)(work[sym]) > end) {
-            this.op = (unsigned char)(extra[work[sym]]);
-            this.val = base[work[sym]];
-        }
-        else {
-            this.op = (unsigned char)(32 + 64);         /* end of block */
-            this.val = 0;
-        }
-
-        /* replicate for those indices with low len bits equal to huff */
-        incr = 1U << (len - drop);
-        fill = 1U << curr;
-        min = fill;                 /* save offset to next table */
-        do {
-            fill -= incr;
-            next[(huff >> drop) + fill] = this;
-        } while (fill != 0);
-
-        /* backwards increment the len-bit code huff */
-        incr = 1U << (len - 1);
-        while (huff & incr)
-            incr >>= 1;
-        if (incr != 0) {
-            huff &= incr - 1;
-            huff += incr;
-        }
-        else
-            huff = 0;
-
-        /* go to next symbol, update count, len */
-        sym++;
-        if (--(count[len]) == 0) {
-            if (len == max) break;
-            len = lens[work[sym]];
-        }
-
-        /* create new sub-table if needed */
-        if (len > root && (huff & mask) != low) {
-            /* if first time, transition to sub-tables */
-            if (drop == 0)
-                drop = root;
-
-            /* increment past last table */
-            next += min;            /* here min is 1 << curr */
-
-            /* determine length of next table */
-            curr = len - drop;
-            left = (int)(1 << curr);
-            while (curr + drop < max) {
-                left -= count[curr + drop];
-                if (left <= 0) break;
-                curr++;
-                left <<= 1;
-            }
-
-            /* check for enough space */
-            used += 1U << curr;
-            if (type == LENS && used >= ENOUGH - MAXD)
-                return 1;
-
-            /* point entry in root table to sub-table */
-            low = huff & mask;
-            (*table)[low].op = (unsigned char)curr;
-            (*table)[low].bits = (unsigned char)root;
-            (*table)[low].val = (unsigned short)(next - *table);
-        }
-    }
-
-    /*
-       Fill in rest of table for incomplete codes.  This loop is similar to the
-       loop above in incrementing huff for table indices.  It is assumed that
-       len is equal to curr + drop, so there is no loop needed to increment
-       through high index bits.  When the current sub-table is filled, the loop
-       drops back to the root table to fill in any remaining entries there.
-     */
-    this.op = (unsigned char)64;                /* invalid code marker */
-    this.bits = (unsigned char)(len - drop);
-    this.val = (unsigned short)0;
-    while (huff != 0) {
-        /* when done with sub-table, drop back to root table */
-        if (drop != 0 && (huff & mask) != low) {
-            drop = 0;
-            len = root;
-            next = *table;
-            this.bits = (unsigned char)len;
-        }
-
-        /* put invalid code marker in table */
-        next[huff >> drop] = this;
-
-        /* backwards increment the len-bit code huff */
-        incr = 1U << (len - 1);
-        while (huff & incr)
-            incr >>= 1;
-        if (incr != 0) {
-            huff &= incr - 1;
-            huff += incr;
-        }
-        else
-            huff = 0;
-    }
-
-    /* set return parameters */
-    *table += used;
-    *bits = root;
-    return 0;
-}
-
-
-
-
-
-