sl@0: /* infcodes.c -- process literals and length/distance pairs
sl@0:  * Copyright (C) 1995-2002 Mark Adler
sl@0:  * For conditions of distribution and use, see copyright notice in zlib.h 
sl@0:  */
sl@0: 
sl@0: #include "zutil.h"
sl@0: #include "inftrees.h"
sl@0: #include "infblock.h"
sl@0: #include "infcodes.h"
sl@0: #include "infutil.h"
sl@0: #include "inffast.h"
sl@0: 
sl@0: /* simplify the use of the inflate_huft type with some defines */
sl@0: #define exop word.what.Exop
sl@0: #define bits word.what.Bits
sl@0: 
sl@0: typedef enum {        /* waiting for "i:"=input, "o:"=output, "x:"=nothing */
sl@0:       START,    /* x: set up for LEN */
sl@0:       LEN,      /* i: get length/literal/eob next */
sl@0:       LENEXT,   /* i: getting length extra (have base) */
sl@0:       DIST,     /* i: get distance next */
sl@0:       DISTEXT,  /* i: getting distance extra */
sl@0:       COPY,     /* o: copying bytes in window, waiting for space */
sl@0:       LIT,      /* o: got literal, waiting for output space */
sl@0:       WASH,     /* o: got eob, possibly still output waiting */
sl@0:       END,      /* x: got eob and all data flushed */
sl@0:       BADCODE}  /* x: got error */
sl@0: inflate_codes_mode;
sl@0: 
sl@0: /* inflate codes private state */
sl@0: struct inflate_codes_state {
sl@0: 
sl@0:   /* mode */
sl@0:   inflate_codes_mode mode;      /* current inflate_codes mode */
sl@0: 
sl@0:   /* mode dependent information */
sl@0:   uInt len;
sl@0:   union {
sl@0:     struct {
sl@0:       const inflate_huft *tree;       /* pointer into tree */
sl@0:       uInt need;                /* bits needed */
sl@0:     } code;             /* if LEN or DIST, where in tree */
sl@0:     uInt lit;           /* if LIT, literal */
sl@0:     struct {
sl@0:       uInt get;                 /* bits to get for extra */
sl@0:       uInt dist;                /* distance back to copy from */
sl@0:     } copy;             /* if EXT or COPY, where and how much */
sl@0:   } sub;                /* submode */
sl@0: 
sl@0:   /* mode independent information */
sl@0:   Byte lbits;           /* ltree bits decoded per branch */
sl@0:   Byte dbits;           /* dtree bits decoder per branch */
sl@0:   const inflate_huft *ltree;          /* literal/length/eob tree */
sl@0:   const inflate_huft *dtree;          /* distance tree */
sl@0: 
sl@0: };
sl@0: 
sl@0: 
sl@0: inflate_codes_statef *inflate_codes_new(
sl@0: uInt bl, uInt bd,
sl@0: const inflate_huft *tl,
sl@0: const inflate_huft *td, /* need separate declaration for Borland C++ */
sl@0: z_streamp z)
sl@0: {
sl@0:   inflate_codes_statef *c;
sl@0: 
sl@0:   if ((c = (inflate_codes_statef *)
sl@0:        ZALLOC(z,1,sizeof(struct inflate_codes_state))) != Z_NULL)
sl@0:   {
sl@0:     c->mode = START;
sl@0:     c->lbits = (Byte)bl;
sl@0:     c->dbits = (Byte)bd;
sl@0:     c->ltree = tl;
sl@0:     c->dtree = td;
sl@0:     Tracev((stderr, "inflate:       codes new\n"));
sl@0:   }
sl@0:   return c;
sl@0: }
sl@0: 
sl@0: 
sl@0: int inflate_codes(
sl@0: inflate_blocks_statef *s,
sl@0: z_streamp z,
sl@0: int r)
sl@0: {
sl@0:   uInt j;               /* temporary storage */
sl@0:   const inflate_huft *t;      /* temporary pointer */
sl@0:   uInt e;               /* extra bits or operation */
sl@0:   uLong b;              /* bit buffer */
sl@0:   uInt k;               /* bits in bit buffer */
sl@0:   Bytef *p;             /* input data pointer */
sl@0:   uInt n;               /* bytes available there */
sl@0:   Bytef *q;             /* output window write pointer */
sl@0:   uInt m;               /* bytes to end of window or read pointer */
sl@0:   Bytef *f;             /* pointer to copy strings from */
sl@0:   inflate_codes_statef *c = s->sub.decode.codes;  /* codes state */
sl@0: 
sl@0:   /* copy input/output information to locals (UPDATE macro restores) */
sl@0:   LOAD
sl@0: 
sl@0:   /* process input and output based on current state */
sl@0:   for (;;) switch (c->mode)
sl@0:   {             /* waiting for "i:"=input, "o:"=output, "x:"=nothing */
sl@0:     case START:         /* x: set up for LEN */
sl@0: #ifndef SLOW
sl@0:       if (m >= 258 && n >= 10)
sl@0:       {
sl@0:         UPDATE
sl@0:         r = inflate_fast(c->lbits, c->dbits, c->ltree, c->dtree, s, z);
sl@0:         LOAD
sl@0:         if (r != Z_OK)
sl@0:         {
sl@0:           c->mode = r == Z_STREAM_END ? WASH : BADCODE;
sl@0:           break;
sl@0:         }
sl@0:       }
sl@0: #endif /* !SLOW */
sl@0:       c->sub.code.need = c->lbits;
sl@0:       c->sub.code.tree = c->ltree;
sl@0:       c->mode = LEN;
sl@0:     case LEN:           /* i: get length/literal/eob next */
sl@0:       j = c->sub.code.need;
sl@0:       NEEDBITS(j)
sl@0:       t = c->sub.code.tree + ((uInt)b & inflate_mask[j]);
sl@0:       DUMPBITS(t->bits)
sl@0:       e = (uInt)(t->exop);
sl@0:       if (e == 0)               /* literal */
sl@0:       {
sl@0:         c->sub.lit = t->base;
sl@0:         Tracevv((stderr, t->base >= 0x20 && t->base < 0x7f ?
sl@0:                  "inflate:         literal '%c'\n" :
sl@0:                  "inflate:         literal 0x%02x\n", t->base));
sl@0:         c->mode = LIT;
sl@0:         break;
sl@0:       }
sl@0:       if (e & 16)               /* length */
sl@0:       {
sl@0:         c->sub.copy.get = e & 15;
sl@0:         c->len = t->base;
sl@0:         c->mode = LENEXT;
sl@0:         break;
sl@0:       }
sl@0:       if ((e & 64) == 0)        /* next table */
sl@0:       {
sl@0:         c->sub.code.need = e;
sl@0:         c->sub.code.tree = t + t->base;
sl@0:         break;
sl@0:       }
sl@0:       if (e & 32)               /* end of block */
sl@0:       {
sl@0:         Tracevv((stderr, "inflate:         end of block\n"));
sl@0:         c->mode = WASH;
sl@0:         break;
sl@0:       }
sl@0:       c->mode = BADCODE;        /* invalid code */
sl@0:       z->msg = (char*)"invalid literal/length code";
sl@0:       r = Z_DATA_ERROR;
sl@0:       LEAVE
sl@0:     case LENEXT:        /* i: getting length extra (have base) */
sl@0:       j = c->sub.copy.get;
sl@0:       NEEDBITS(j)
sl@0:       c->len += (uInt)b & inflate_mask[j];
sl@0:       DUMPBITS(j)
sl@0:       c->sub.code.need = c->dbits;
sl@0:       c->sub.code.tree = c->dtree;
sl@0:       Tracevv((stderr, "inflate:         length %u\n", c->len));
sl@0:       c->mode = DIST;
sl@0:     case DIST:          /* i: get distance next */
sl@0:       j = c->sub.code.need;
sl@0:       NEEDBITS(j)
sl@0:       t = c->sub.code.tree + ((uInt)b & inflate_mask[j]);
sl@0:       DUMPBITS(t->bits)
sl@0:       e = (uInt)(t->exop);
sl@0:       if (e & 16)               /* distance */
sl@0:       {
sl@0:         c->sub.copy.get = e & 15;
sl@0:         c->sub.copy.dist = t->base;
sl@0:         c->mode = DISTEXT;
sl@0:         break;
sl@0:       }
sl@0:       if ((e & 64) == 0)        /* next table */
sl@0:       {
sl@0:         c->sub.code.need = e;
sl@0:         c->sub.code.tree = t + t->base;
sl@0:         break;
sl@0:       }
sl@0:       c->mode = BADCODE;        /* invalid code */
sl@0:       z->msg = (char*)"invalid distance code";
sl@0:       r = Z_DATA_ERROR;
sl@0:       LEAVE
sl@0:     case DISTEXT:       /* i: getting distance extra */
sl@0:       j = c->sub.copy.get;
sl@0:       NEEDBITS(j)
sl@0:       c->sub.copy.dist += (uInt)b & inflate_mask[j];
sl@0:       DUMPBITS(j)
sl@0:       Tracevv((stderr, "inflate:         distance %u\n", c->sub.copy.dist));
sl@0:       c->mode = COPY;
sl@0:     case COPY:          /* o: copying bytes in window, waiting for space */
sl@0:       f = q - c->sub.copy.dist;
sl@0:       while (f < s->window)             /* modulo window size-"while" instead */
sl@0:         f += s->end - s->window;        /* of "if" handles invalid distances */
sl@0:       while (c->len)
sl@0:       {
sl@0:         NEEDOUT
sl@0:         OUTBYTE(*f++)
sl@0:         if (f == s->end)
sl@0:           f = s->window;
sl@0:         c->len--;
sl@0:       }
sl@0:       c->mode = START;
sl@0:       break;
sl@0:     case LIT:           /* o: got literal, waiting for output space */
sl@0:       NEEDOUT
sl@0:       OUTBYTE(c->sub.lit)
sl@0:       c->mode = START;
sl@0:       break;
sl@0:     case WASH:          /* o: got eob, possibly more output */
sl@0:       if (k > 7)        /* return unused byte, if any */
sl@0:       {
sl@0:         Assert(k < 16, "inflate_codes grabbed too many bytes")
sl@0:         k -= 8;
sl@0:         n++;
sl@0:         p--;            /* can always return one */
sl@0:       }
sl@0:       FLUSH
sl@0:       if (s->read != s->write)
sl@0:         LEAVE
sl@0:       c->mode = END;
sl@0:     case END:
sl@0:       r = Z_STREAM_END;
sl@0:       LEAVE
sl@0:     case BADCODE:       /* x: got error */
sl@0:       r = Z_DATA_ERROR;
sl@0:       LEAVE
sl@0:     default:
sl@0:       r = Z_STREAM_ERROR;
sl@0:       LEAVE
sl@0:   }
sl@0: #ifdef NEED_DUMMY_RETURN
sl@0:   return Z_STREAM_ERROR;  /* Some dumb compilers complain without this */
sl@0: #endif
sl@0: }
sl@0: 
sl@0: 
sl@0: void inflate_codes_free(
sl@0: inflate_codes_statef *c,
sl@0: z_streamp z)
sl@0: {
sl@0:   ZFREE(z, c);
sl@0:   Tracev((stderr, "inflate:       codes free\n"));
sl@0: }