/* infcodes.c -- process literals and length/distance pairs * Copyright (C) 1995-1998 Mark Adler * For conditions of distribution and use, see copyright notice in zlib.h */ #include "zutil.h" #include "inftrees.h" #include "infblock.h" #include "infcodes.h" #include "infutil.h" #include "inffast.h" /* simplify the use of the inflate_huft type with some defines */ #define exop word.what.Exop #define bits word.what.Bits typedef 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 */ BADCODE} /* x: got error */ inflate_codes_mode; /* inflate codes private state */ struct inflate_codes_state { /* mode */ inflate_codes_mode 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 */ }; inflate_codes_statef *inflate_codes_new(bl, bd, tl, td, z) uInt bl, bd; inflate_huft *tl; inflate_huft *td; /* need separate declaration for Borland C++ */ z_streamp z; { inflate_codes_statef *c; if ((c = (inflate_codes_statef *) 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; Tracev((stderr, "inflate: codes new\n")); } return c; } int inflate_codes(s, z, r) inflate_blocks_statef *s; z_streamp z; int r; { uInt j; /* temporary storage */ inflate_huft *t; /* temporary pointer */ uInt e; /* extra bits or operation */ uLong b; /* bit buffer */ uInt k; /* bits in bit buffer */ Bytef *p; /* input data pointer */ uInt n; /* bytes available there */ Bytef *q; /* output window write pointer */ uInt m; /* bytes to end of window or read pointer */ Bytef *f; /* pointer to copy strings from */ inflate_codes_statef *c = s->sub.decode.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 */ #ifndef SLOW if (m >= 258 && n >= 10) { UPDATE r = inflate_fast(c->lbits, c->dbits, c->ltree, c->dtree, s, z); LOAD if (r != Z_OK) { c->mode = r == Z_STREAM_END ? WASH : BADCODE; break; } } #endif /* !SLOW */ 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) e = (uInt)(t->exop); if (e == 0) /* literal */ { c->sub.lit = t->base; Tracevv((stderr, t->base >= 0x20 && t->base < 0x7f ? "inflate: literal '%c'\n" : "inflate: literal 0x%02x\n", t->base)); c->mode = LIT; break; } if (e & 16) /* length */ { c->sub.copy.get = e & 15; c->len = t->base; c->mode = LENEXT; break; } if ((e & 64) == 0) /* next table */ { c->sub.code.need = e; c->sub.code.tree = t + t->base; break; } if (e & 32) /* end of block */ { Tracevv((stderr, "inflate: end of block\n")); c->mode = WASH; break; } c->mode = BADCODE; /* invalid code */ z->msg = (char*)"invalid literal/length code"; r = Z_DATA_ERROR; LEAVE 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; Tracevv((stderr, "inflate: length %u\n", c->len)); 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) e = (uInt)(t->exop); if (e & 16) /* distance */ { c->sub.copy.get = e & 15; c->sub.copy.dist = t->base; c->mode = DISTEXT; break; } if ((e & 64) == 0) /* next table */ { c->sub.code.need = e; c->sub.code.tree = t + t->base; break; } c->mode = BADCODE; /* invalid code */ z->msg = (char*)"invalid distance code"; r = Z_DATA_ERROR; LEAVE case DISTEXT: /* i: getting distance extra */ j = c->sub.copy.get; NEEDBITS(j) c->sub.copy.dist += (uInt)b & inflate_mask[j]; DUMPBITS(j) Tracevv((stderr, "inflate: distance %u\n", c->sub.copy.dist)); c->mode = COPY; case COPY: /* o: copying bytes in window, waiting for space */ #ifndef __TURBOC__ /* Turbo C bug for following expression */ f = (uInt)(q - s->window) < c->sub.copy.dist ? s->end - (c->sub.copy.dist - (q - s->window)) : q - c->sub.copy.dist; #else f = q - c->sub.copy.dist; if ((uInt)(q - s->window) < c->sub.copy.dist) f = s->end - (c->sub.copy.dist - (uInt)(q - s->window)); #endif 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 */ if (k > 7) /* return unused byte, if any */ { Assert(k < 16, "inflate_codes grabbed too many bytes") k -= 8; n++; p--; /* can always return one */ } FLUSH if (s->read != s->write) LEAVE c->mode = END; case END: r = Z_STREAM_END; LEAVE case BADCODE: /* x: got error */ r = Z_DATA_ERROR; LEAVE default: r = Z_STREAM_ERROR; LEAVE } #ifdef NEED_DUMMY_RETURN return Z_STREAM_ERROR; /* Some dumb compilers complain without this */ #endif } void inflate_codes_free(c, z) inflate_codes_statef *c; z_streamp z; { ZFREE(z, c); Tracev((stderr, "inflate: codes free\n")); }
