# All files / node_modules/upng-js/node_modules/pako/lib/zlib inffast.js

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    18x
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     'use strict';

    // (C) 1995-2013 Jean-loup Gailly and Mark Adler
    // (C) 2014-2017 Vitaly Puzrin and Andrey Tupitsin
    //
    // This software is provided 'as-is', without any express or implied
    // warranty. In no event will the authors be held liable for any damages
    // arising from the use of this software.
    //
    // Permission is granted to anyone to use this software for any purpose,
    // including commercial applications, and to alter it and redistribute it
    // freely, subject to the following restrictions:
    //
    // 1. The origin of this software must not be misrepresented; you must not
    //   claim that you wrote the original software. If you use this software
    //   in a product, an acknowledgment in the product documentation would be
    //   appreciated but is not required.
    // 2. Altered source versions must be plainly marked as such, and must not be
    //   misrepresented as being the original software.
    // 3. This notice may not be removed or altered from any source distribution.

    // See state defs from inflate.js
    var BAD = 30;       /* got a data error -- remain here until reset */
    var TYPE = 12;      /* i: waiting for type bits, including last-flag bit */

    /*
       Decode literal, length, and distance codes and write out the resulting
       literal and match bytes until either not enough input or output is
       available, an end-of-block is encountered, or a data error is encountered.
       When large enough input and output buffers are supplied to inflate(), for
       example, a 16K input buffer and a 64K output buffer, more than 95% of the
       inflate execution time is spent in this routine.

       Entry assumptions:

            state.mode === LEN
            strm.avail_in >= 6
            strm.avail_out >= 258
            start >= strm.avail_out
            state.bits < 8

       On return, state.mode is one of:

            LEN -- ran out of enough output space or enough available input
            TYPE -- reached end of block code, inflate() to interpret next block
            BAD -- error in block data

       Notes:

        - The maximum input bits used by a length/distance pair is 15 bits for the
          length code, 5 bits for the length extra, 15 bits for the distance code,
          and 13 bits for the distance extra.  This totals 48 bits, or six bytes.
          Therefore if strm.avail_in >= 6, then there is enough input to avoid
          checking for available input while decoding.

        - The maximum bytes that a single length/distance pair can output is 258
          bytes, which is the maximum length that can be coded.  inflate_fast()
          requires strm.avail_out >= 258 for each loop to avoid checking for
          output space.
     */
    module.exports = function inflate_fast(strm, start) {
      var state;
      var _in;                    /* local strm.input */
      var last;                   /* have enough input while in < last */
      var _out;                   /* local strm.output */
      var beg;                    /* inflate()'s initial strm.output */
      var end;                    /* while out < end, enough space available */
    //#ifdef INFLATE_STRICT
      var dmax;                   /* maximum distance from zlib header */
    //#endif
      var wsize;                  /* window size or zero if not using window */
      var whave;                  /* valid bytes in the window */
      var wnext;                  /* window write index */
      // Use `s_window` instead `window`, avoid conflict with instrumentation tools
      var s_window;               /* allocated sliding window, if wsize != 0 */
      var hold;                   /* local strm.hold */
      var bits;                   /* local strm.bits */
      var lcode;                  /* local strm.lencode */
      var dcode;                  /* local strm.distcode */
      var lmask;                  /* mask for first level of length codes */
      var dmask;                  /* mask for first level of distance codes */
      var here;                   /* retrieved table entry */
      var op;                     /* code bits, operation, extra bits, or */
                                  /*  window position, window bytes to copy */
      var len;                    /* match length, unused bytes */
      var dist;                   /* match distance */
      var from;                   /* where to copy match from */
      var from_source;

      var input, output; // JS specific, because we have no pointers

      /* copy state to local variables */
      state = strm.state;
      //here = state.here;
      _in = strm.next_in;
      input = strm.input;
      last = _in + (strm.avail_in - 5);
      _out = strm.next_out;
      output = strm.output;
      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;
      s_window = state.window;
      hold = state.hold;
      bits = state.bits;
      lcode = state.lencode;
      dcode = state.distcode;
      lmask = (1 << state.lenbits) - 1;
      dmask = (1 << state.distbits) - 1;

      /* decode literals and length/distances until end-of-block or not enough
         input data or output space */

      top:
      do {
    I    if (bits < 15) {
          hold += input[_in++] << bits;
          bits += 8;
          hold += input[_in++] << bits;
          bits += 8;
        }

        here = lcode[hold & lmask];

        dolen:
        for (;;) { // Goto emulation
          op = here >>> 24/*here.bits*/;
          hold >>>= op;
          bits -= op;
          op = (here >>> 16) & 0xff/*here.op*/;
          if (op === 0) {                          /* literal */
            //Tracevv((stderr, here.val >= 0x20 && here.val < 0x7f ?
            //        "inflate:         literal '%c'\n" :
            //        "inflate:         literal 0x%02x\n", here.val));
            output[_out++] = here & 0xffff/*here.val*/;
          }
          else if (op & 16) {                     /* length base */
            len = here & 0xffff/*here.val*/;
            op &= 15;                           /* number of extra bits */
    I        if (op) {
    I          if (bits < op) {
                hold += input[_in++] << bits;
                bits += 8;
              }
              len += hold & ((1 << op) - 1);
              hold >>>= op;
              bits -= op;
            }
            //Tracevv((stderr, "inflate:         length %u\n", len));
    I        if (bits < 15) {
              hold += input[_in++] << bits;
              bits += 8;
              hold += input[_in++] << bits;
              bits += 8;
            }
            here = dcode[hold & dmask];

            dodist:
            for (;;) { // goto emulation
              op = here >>> 24/*here.bits*/;
              hold >>>= op;
              bits -= op;
              op = (here >>> 16) & 0xff/*here.op*/;

              if (op & 16) {                      /* distance base */
                dist = here & 0xffff/*here.val*/;
                op &= 15;                       /* number of extra bits */
    I            if (bits < op) {
                  hold += input[_in++] << bits;
                  bits += 8;
    I              if (bits < op) {
                    hold += input[_in++] << bits;
                    bits += 8;
                  }
                }
                dist += hold & ((1 << op) - 1);
    //#ifdef INFLATE_STRICT
    I            if (dist > dmax) {
                  strm.msg = 'invalid distance too far back';
                  state.mode = BAD;
                  break top;
                }
    //#endif
                hold >>>= op;
                bits -= op;
                //Tracevv((stderr, "inflate:         distance %u\n", dist));
                op = _out - beg;                /* max distance in output */
                if (dist > op) {                /* see if copy from window */
                  op = dist - op;               /* distance back in window */
    I              if (op > whave) {
    I                if (state.sane) {
                      strm.msg = 'invalid distance too far back';
                      state.mode = BAD;
                      break top;
                    }

    // (!) This block is disabled in zlib defaults,
    // don't enable it for binary compatibility
    //#ifdef INFLATE_ALLOW_INVALID_DISTANCE_TOOFAR_ARRR
    //                if (len <= op - whave) {
    //                  do {
    //                    output[_out++] = 0;
    //                  } while (--len);
    //                  continue top;
    //                }
    //                len -= op - whave;
    //                do {
    //                  output[_out++] = 0;
    //                } while (--op > whave);
    //                if (op === 0) {
    //                  from = _out - dist;
    //                  do {
    //                    output[_out++] = output[from++];
    //                  } while (--len);
    //                  continue top;
    //                }
    //#endif
                  }
                  from = 0; // window index
                  from_source = s_window;
                  if (wnext === 0) {           /* very common case */
                    from += wsize - op;
    I                if (op < len) {         /* some from window */
                      len -= op;
                      do {
                        output[_out++] = s_window[from++];
                      } while (--op);
                      from = _out - dist;  /* rest from output */
                      from_source = output;
                    }
                  }
                  else if (wnext < op) {      /* wrap around window */
                    from += wsize + wnext - op;
                    op -= wnext;
    I                if (op < len) {         /* some from end of window */
                      len -= op;
                      do {
                        output[_out++] = s_window[from++];
                      } while (--op);
                      from = 0;
    I                  if (wnext < len) {  /* some from start of window */
                        op = wnext;
                        len -= op;
                        do {
                          output[_out++] = s_window[from++];
                        } while (--op);
                        from = _out - dist;      /* rest from output */
                        from_source = output;
                      }
                    }
                  }
                  else {                      /* contiguous in window */
                    from += wnext - op;
    I                if (op < len) {         /* some from window */
                      len -= op;
                      do {
                        output[_out++] = s_window[from++];
                      } while (--op);
                      from = _out - dist;  /* rest from output */
                      from_source = output;
                    }
                  }
                  while (len > 2) {
                    output[_out++] = from_source[from++];
                    output[_out++] = from_source[from++];
                    output[_out++] = from_source[from++];
                    len -= 3;
                  }
    I              if (len) {
                    output[_out++] = from_source[from++];
    I                if (len > 1) {
                      output[_out++] = from_source[from++];
                    }
                  }
                }
                else {
                  from = _out - dist;          /* copy direct from output */
                  do {                        /* minimum length is three */
                    output[_out++] = output[from++];
                    output[_out++] = output[from++];
                    output[_out++] = output[from++];
                    len -= 3;
                  } while (len > 2);
    I              if (len) {
                    output[_out++] = output[from++];
    I                if (len > 1) {
                      output[_out++] = output[from++];
                    }
                  }
                }
              }
              else if ((op & 64) === 0) {          /* 2nd level distance code */
                here = dcode[(here & 0xffff)/*here.val*/ + (hold & ((1 << op) - 1))];
                continue dodist;
              }
              else {
                strm.msg = 'invalid distance code';
                state.mode = BAD;
                break top;
              }

              break; // need to emulate goto via "continue"
            }
          }
          else if ((op & 64) === 0) {              /* 2nd level length code */
            here = lcode[(here & 0xffff)/*here.val*/ + (hold & ((1 << op) - 1))];
            continue dolen;
          }
          else if (op & 32) {                     /* end-of-block */
            //Tracevv((stderr, "inflate:         end of block\n"));
            state.mode = TYPE;
            break top;
          }
          else {
            strm.msg = 'invalid literal/length code';
            state.mode = BAD;
            break top;
          }

          break; // need to emulate goto via "continue"
        }
      } while (_in < last && _out < end);

      /* return unused bytes (on entry, bits < 8, so in won't go too far back) */
      len = bits >> 3;
      _in -= len;
      bits -= len << 3;
      hold &= (1 << bits) - 1;

      /* update state and return */
      strm.next_in = _in;
      strm.next_out = _out;
      strm.avail_in = (_in < last ? 5 + (last - _in) : 5 - (_in - last));
      strm.avail_out = (_out < end ? 257 + (end - _out) : 257 - (_out - end));
      state.hold = hold;
      state.bits = bits;
      return;
    };