| /* infcodes.c -- process literals and length/distance pairs |
| * Copyright (C) 1995 Mark Adler |
| * For conditions of distribution and use, see copyright notice in zlib.h |
| */ |
| |
| #include "zutil.h" |
| #include "inftrees.h" |
| #include "infutil.h" |
| #include "infcodes.h" |
| |
| /* simplify the use of the inflate_huft type with some defines */ |
| #define base more.Base |
| #define next more.Next |
| #define exop word.what.Exop |
| #define bits word.what.Bits |
| |
| /* inflate codes private state */ |
| struct inflate_codes_state { |
| |
| /* mode */ |
| enum { /* waiting for "i:"=input, "o:"=output, "x:"=nothing */ |
| START, /* x: set up for LEN */ |
| LEN, /* i: get length/literal/eob next */ |
| LENEXT, /* i: getting length extra (have base) */ |
| DIST, /* i: get distance next */ |
| DISTEXT, /* i: getting distance extra */ |
| COPY, /* o: copying bytes in window, waiting for space */ |
| LIT, /* o: got literal, waiting for output space */ |
| WASH, /* o: got eob, possibly still output waiting */ |
| END, /* x: got eob and all data flushed */ |
| BAD} /* x: got error */ |
| mode; /* current inflate_codes mode */ |
| |
| /* mode dependent information */ |
| uInt len; |
| union { |
| struct { |
| inflate_huft *tree; /* pointer into tree */ |
| uInt need; /* bits needed */ |
| } code; /* if LEN or DIST, where in tree */ |
| uInt lit; /* if LIT, literal */ |
| struct { |
| uInt get; /* bits to get for extra */ |
| uInt dist; /* distance back to copy from */ |
| } copy; /* if EXT or COPY, where and how much */ |
| } sub; /* submode */ |
| |
| /* mode independent information */ |
| Byte lbits; /* ltree bits decoded per branch */ |
| Byte dbits; /* dtree bits decoder per branch */ |
| inflate_huft *ltree; /* literal/length/eob tree */ |
| inflate_huft *dtree; /* distance tree */ |
| |
| }; |
| |
| |
| struct inflate_codes_state *inflate_codes_new(bl, bd, tl, td, z) |
| uInt bl, bd; |
| inflate_huft *tl, *td; |
| z_stream *z; |
| { |
| struct inflate_codes_state *c; |
| |
| if ((c = (struct inflate_codes_state *) |
| ZALLOC(z,1,sizeof(struct inflate_codes_state))) != Z_NULL) |
| { |
| c->mode = START; |
| c->lbits = (Byte)bl; |
| c->dbits = (Byte)bd; |
| c->ltree = tl; |
| c->dtree = td; |
| } |
| return c; |
| } |
| |
| |
| int inflate_codes(s, z, r) |
| struct inflate_blocks_state *s; |
| z_stream *z; |
| int r; |
| { |
| uInt j; /* temporary storage */ |
| inflate_huft *t; /* temporary pointer */ |
| int e; /* extra bits or operation */ |
| uLong b; /* bit buffer */ |
| uInt k; /* bits in bit buffer */ |
| Byte *p; /* input data pointer */ |
| uInt n; /* bytes available there */ |
| Byte *q; /* output window write pointer */ |
| uInt m; /* bytes to end of window or read pointer */ |
| Byte *f; /* pointer to copy strings from */ |
| struct inflate_codes_state *c = s->sub.codes; /* codes state */ |
| |
| /* copy input/output information to locals (UPDATE macro restores) */ |
| LOAD |
| |
| /* process input and output based on current state */ |
| while (1) switch (c->mode) |
| { /* waiting for "i:"=input, "o:"=output, "x:"=nothing */ |
| case START: /* x: set up for LEN */ |
| /* %%% check for avail in and out to do fast loop %%% */ |
| c->sub.code.need = c->lbits; |
| c->sub.code.tree = c->ltree; |
| c->mode = LEN; |
| case LEN: /* i: get length/literal/eob next */ |
| j = c->sub.code.need; |
| NEEDBITS(j) |
| t = c->sub.code.tree + ((uInt)b & inflate_mask[j]); |
| DUMPBITS(t->bits) |
| if ((e = (int)(t->exop)) < 0) |
| { |
| if (e == -128) /* invalid code */ |
| { |
| c->mode = BAD; |
| z->msg = "invalid huffman code"; |
| r = Z_DATA_ERROR; |
| LEAVE |
| } |
| e = -e; |
| if (e & 64) /* end of block */ |
| { |
| c->mode = END; |
| break; |
| } |
| c->sub.code.need = e; |
| c->sub.code.tree = t->next; |
| break; |
| } |
| if (e & 16) /* literal */ |
| { |
| c->sub.lit = t->base; |
| c->mode = LIT; |
| break; |
| } |
| c->sub.copy.get = e; |
| c->len = t->base; |
| c->mode = LENEXT; |
| case LENEXT: /* i: getting length extra (have base) */ |
| j = c->sub.copy.get; |
| NEEDBITS(j) |
| c->len += (uInt)b & inflate_mask[j]; |
| DUMPBITS(j) |
| c->sub.code.need = c->dbits; |
| c->sub.code.tree = c->dtree; |
| c->mode = DIST; |
| case DIST: /* i: get distance next */ |
| j = c->sub.code.need; |
| NEEDBITS(j) |
| t = c->sub.code.tree + ((uInt)b & inflate_mask[j]); |
| DUMPBITS(t->bits) |
| if ((e = (int)(t->exop)) < 0) |
| { |
| if (e == -128) |
| { |
| c->mode = BAD; |
| z->msg = "invalid huffman code"; |
| r = Z_DATA_ERROR; |
| LEAVE |
| } |
| c->sub.code.need = -e; |
| c->sub.code.tree = t->next; |
| break; |
| } |
| c->sub.copy.dist = t->base; |
| c->sub.copy.get = e; |
| c->mode = DISTEXT; |
| case DISTEXT: /* i: getting distance extra */ |
| j = c->sub.copy.get; |
| NEEDBITS(j) |
| c->sub.copy.dist += (uInt)b & inflate_mask[j]; |
| DUMPBITS(j) |
| c->mode = COPY; |
| case COPY: /* o: copying bytes in window, waiting for space */ |
| f = q - s->window < c->sub.copy.dist ? |
| s->end - (c->sub.copy.dist - (q - s->window)) : |
| q - c->sub.copy.dist; |
| while (c->len) |
| { |
| NEEDOUT |
| OUTBYTE(*f++) |
| if (f == s->end) |
| f = s->window; |
| c->len--; |
| } |
| c->mode = START; |
| break; |
| case LIT: /* o: got literal, waiting for output space */ |
| NEEDOUT |
| OUTBYTE(c->sub.lit) |
| c->mode = START; |
| break; |
| case WASH: /* o: got eob, possibly more output */ |
| FLUSH |
| if (s->read != s->write) |
| LEAVE |
| c->mode = END; |
| case END: |
| r = Z_STREAM_END; |
| LEAVE |
| case BAD: /* x: got error */ |
| r = Z_DATA_ERROR; |
| LEAVE |
| default: |
| r = Z_STREAM_ERROR; |
| LEAVE |
| } |
| } |
| |
| |
| void inflate_codes_free(c, z) |
| struct inflate_codes_state *c; |
| z_stream *z; |
| { |
| inflate_trees_free(c->dtree, z); |
| inflate_trees_free(c->ltree, z); |
| ZFREE(z, c); |
| } |