CppUtils/Utils/zlib/inftrees.c



#include "zutil.h"
#include "inftrees.h"

#define MAXBITS 15

const char inflate_copyright[] =
   " inflate 1.2.11 Copyright 1995-2017 Mark Adler ";



int ZLIB_INTERNAL 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;
{
    unsigned len;               
    unsigned sym;               
    unsigned min, max;          
    unsigned root;              
    unsigned curr;              
    unsigned drop;              
    int left;                   
    unsigned used;              
    unsigned huff;              
    unsigned incr;              
    unsigned fill;              
    unsigned low;               
    unsigned mask;              
    code here;                  
    code FAR *next;             
    const unsigned short FAR *base;     
    const unsigned short FAR *extra;    
    unsigned match;             
    unsigned short count[MAXBITS+1];    
    unsigned short offs[MAXBITS+1];     
    static const unsigned short lbase[31] = { 
        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] = { 
        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, 77, 202};
    static const unsigned short dbase[32] = { 
        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] = { 
        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};

    

    
    for (len = 0; len <= MAXBITS; len++)
        count[len] = 0;
    for (sym = 0; sym < codes; sym++)
        count[lens[sym]]++;

    
    root = *bits;
    for (max = MAXBITS; max >= 1; max--)
        if (count[max] != 0) break;
    if (root > max) root = max;
    if (max == 0) {                     
        here.op = (unsigned char)64;    
        here.bits = (unsigned char)1;
        here.val = (unsigned short)0;
        *(*table)++ = here;             
        *(*table)++ = here;
        *bits = 1;
        return 0;     
    }
    for (min = 1; min < max; min++)
        if (count[min] != 0) break;
    if (root < min) root = min;

    
    left = 1;
    for (len = 1; len <= MAXBITS; len++) {
        left <<= 1;
        left -= count[len];
        if (left < 0) return -1;        
    }
    if (left > 0 && (type == CODES || max != 1))
        return -1;                      

    
    offs[1] = 0;
    for (len = 1; len < MAXBITS; len++)
        offs[len + 1] = offs[len] + count[len];

    
    for (sym = 0; sym < codes; sym++)
        if (lens[sym] != 0) work[offs[lens[sym]]++] = (unsigned short)sym;

    

    
    switch (type) {
    case CODES:
        base = extra = work;    
        match = 20;
        break;
    case LENS:
        base = lbase;
        extra = lext;
        match = 257;
        break;
    default:    
        base = dbase;
        extra = dext;
        match = 0;
    }

    
    huff = 0;                   
    sym = 0;                    
    len = min;                  
    next = *table;              
    curr = root;                
    drop = 0;                   
    low = (unsigned)(-1);       
    used = 1U << root;          
    mask = used - 1;            

    
    if ((type == LENS && used > ENOUGH_LENS) ||
        (type == DISTS && used > ENOUGH_DISTS))
        return 1;

    
    for (;;) {
        
        here.bits = (unsigned char)(len - drop);
        if (work[sym] + 1U < match) {
            here.op = (unsigned char)0;
            here.val = work[sym];
        }
        else if (work[sym] >= match) {
            here.op = (unsigned char)(extra[work[sym] - match]);
            here.val = base[work[sym] - match];
        }
        else {
            here.op = (unsigned char)(32 + 64);         
            here.val = 0;
        }

        
        incr = 1U << (len - drop);
        fill = 1U << curr;
        min = fill;                 
        do {
            fill -= incr;
            next[(huff >> drop) + fill] = here;
        } while (fill != 0);

        
        incr = 1U << (len - 1);
        while (huff & incr)
            incr >>= 1;
        if (incr != 0) {
            huff &= incr - 1;
            huff += incr;
        }
        else
            huff = 0;

        
        sym++;
        if (--(count[len]) == 0) {
            if (len == max) break;
            len = lens[work[sym]];
        }

        
        if (len > root && (huff & mask) != low) {
            
            if (drop == 0)
                drop = root;

            
            next += min;            

            
            curr = len - drop;
            left = (int)(1 << curr);
            while (curr + drop < max) {
                left -= count[curr + drop];
                if (left <= 0) break;
                curr++;
                left <<= 1;
            }

            
            used += 1U << curr;
            if ((type == LENS && used > ENOUGH_LENS) ||
                (type == DISTS && used > ENOUGH_DISTS))
                return 1;

            
            low = huff & mask;
            (*table)[low].op = (unsigned char)curr;
            (*table)[low].bits = (unsigned char)root;
            (*table)[low].val = (unsigned short)(next - *table);
        }
    }

    
    if (huff != 0) {
        here.op = (unsigned char)64;            
        here.bits = (unsigned char)(len - drop);
        here.val = (unsigned short)0;
        next[huff] = here;
    }

    
    *table += used;
    *bits = root;
    return 0;
}