CppUtils/Utils/zlib/inffast.c



#include "zutil.h"
#include "inftrees.h"
#include "inflate.h"
#include "inffast.h"

#ifdef ASMINF
#  pragma message("Assembler code may have bugs -- use at your own risk")
#else


void ZLIB_INTERNAL inflate_fast(strm, start)
z_streamp strm;
unsigned start;         
{
    struct inflate_state FAR *state;
    z_const unsigned char FAR *in;      
    z_const unsigned char FAR *last;    
    unsigned char FAR *out;     
    unsigned char FAR *beg;     
    unsigned char FAR *end;     
#ifdef INFLATE_STRICT
    unsigned dmax;              
#endif
    unsigned wsize;             
    unsigned whave;             
    unsigned wnext;             
    unsigned char FAR *window;  
    unsigned long hold;         
    unsigned bits;              
    code const FAR *lcode;      
    code const FAR *dcode;      
    unsigned lmask;             
    unsigned dmask;             
    code here;                  
    unsigned op;                
                                
    unsigned len;               
    unsigned dist;              
    unsigned char FAR *from;    

    
    state = (struct inflate_state FAR *)strm->state;
    in = strm->next_in;
    last = in + (strm->avail_in - 5);
    out = strm->next_out;
    beg = out - (start - strm->avail_out);
    end = out + (strm->avail_out - 257);
#ifdef INFLATE_STRICT
    dmax = state->dmax;
#endif
    wsize = state->wsize;
    whave = state->whave;
    wnext = state->wnext;
    window = state->window;
    hold = state->hold;
    bits = state->bits;
    lcode = state->lencode;
    dcode = state->distcode;
    lmask = (1U << state->lenbits) - 1;
    dmask = (1U << state->distbits) - 1;

    
    do {
        if (bits < 15) {
            hold += (unsigned long)(*in++) << bits;
            bits += 8;
            hold += (unsigned long)(*in++) << bits;
            bits += 8;
        }
        here = lcode[hold & lmask];
      dolen:
        op = (unsigned)(here.bits);
        hold >>= op;
        bits -= op;
        op = (unsigned)(here.op);
        if (op == 0) {                          
            Tracevv((stderr, here.val >= 0x20 && here.val < 0x7f ?
                    "inflate:         literal '%c'\n" :
                    "inflate:         literal 0x%02x\n", here.val));
            *out++ = (unsigned char)(here.val);
        }
        else if (op & 16) {                     
            len = (unsigned)(here.val);
            op &= 15;                           
            if (op) {
                if (bits < op) {
                    hold += (unsigned long)(*in++) << bits;
                    bits += 8;
                }
                len += (unsigned)hold & ((1U << op) - 1);
                hold >>= op;
                bits -= op;
            }
            Tracevv((stderr, "inflate:         length %u\n", len));
            if (bits < 15) {
                hold += (unsigned long)(*in++) << bits;
                bits += 8;
                hold += (unsigned long)(*in++) << bits;
                bits += 8;
            }
            here = dcode[hold & dmask];
          dodist:
            op = (unsigned)(here.bits);
            hold >>= op;
            bits -= op;
            op = (unsigned)(here.op);
            if (op & 16) {                      
                dist = (unsigned)(here.val);
                op &= 15;                       
                if (bits < op) {
                    hold += (unsigned long)(*in++) << bits;
                    bits += 8;
                    if (bits < op) {
                        hold += (unsigned long)(*in++) << bits;
                        bits += 8;
                    }
                }
                dist += (unsigned)hold & ((1U << op) - 1);
#ifdef INFLATE_STRICT
                if (dist > dmax) {
                    strm->msg = (char *)"invalid distance too far back";
                    state->mode = BAD;
                    break;
                }
#endif
                hold >>= op;
                bits -= op;
                Tracevv((stderr, "inflate:         distance %u\n", dist));
                op = (unsigned)(out - beg);     
                if (dist > op) {                
                    op = dist - op;             
                    if (op > whave) {
                        if (state->sane) {
                            strm->msg =
                                (char *)"invalid distance too far back";
                            state->mode = BAD;
                            break;
                        }
#ifdef INFLATE_ALLOW_INVALID_DISTANCE_TOOFAR_ARRR
                        if (len <= op - whave) {
                            do {
                                *out++ = 0;
                            } while (--len);
                            continue;
                        }
                        len -= op - whave;
                        do {
                            *out++ = 0;
                        } while (--op > whave);
                        if (op == 0) {
                            from = out - dist;
                            do {
                                *out++ = *from++;
                            } while (--len);
                            continue;
                        }
#endif
                    }
                    from = window;
                    if (wnext == 0) {           
                        from += wsize - op;
                        if (op < len) {         
                            len -= op;
                            do {
                                *out++ = *from++;
                            } while (--op);
                            from = out - dist;  
                        }
                    }
                    else if (wnext < op) {      
                        from += wsize + wnext - op;
                        op -= wnext;
                        if (op < len) {         
                            len -= op;
                            do {
                                *out++ = *from++;
                            } while (--op);
                            from = window;
                            if (wnext < len) {  
                                op = wnext;
                                len -= op;
                                do {
                                    *out++ = *from++;
                                } while (--op);
                                from = out - dist;      
                            }
                        }
                    }
                    else {                      
                        from += wnext - op;
                        if (op < len) {         
                            len -= op;
                            do {
                                *out++ = *from++;
                            } while (--op);
                            from = out - dist;  
                        }
                    }
                    while (len > 2) {
                        *out++ = *from++;
                        *out++ = *from++;
                        *out++ = *from++;
                        len -= 3;
                    }
                    if (len) {
                        *out++ = *from++;
                        if (len > 1)
                            *out++ = *from++;
                    }
                }
                else {
                    from = out - dist;          
                    do {                        
                        *out++ = *from++;
                        *out++ = *from++;
                        *out++ = *from++;
                        len -= 3;
                    } while (len > 2);
                    if (len) {
                        *out++ = *from++;
                        if (len > 1)
                            *out++ = *from++;
                    }
                }
            }
            else if ((op & 64) == 0) {          
                here = dcode[here.val + (hold & ((1U << op) - 1))];
                goto dodist;
            }
            else {
                strm->msg = (char *)"invalid distance code";
                state->mode = BAD;
                break;
            }
        }
        else if ((op & 64) == 0) {              
            here = lcode[here.val + (hold & ((1U << op) - 1))];
            goto dolen;
        }
        else if (op & 32) {                     
            Tracevv((stderr, "inflate:         end of block\n"));
            state->mode = TYPE;
            break;
        }
        else {
            strm->msg = (char *)"invalid literal/length code";
            state->mode = BAD;
            break;
        }
    } while (in < last && out < end);

    
    len = bits >> 3;
    in -= len;
    bits -= len << 3;
    hold &= (1U << bits) - 1;

    
    strm->next_in = in;
    strm->next_out = out;
    strm->avail_in = (unsigned)(in < last ? 5 + (last - in) : 5 - (in - last));
    strm->avail_out = (unsigned)(out < end ?
                                 257 + (end - out) : 257 - (out - end));
    state->hold = hold;
    state->bits = bits;
    return;
}



#endif