FreeBSD/Linux Kernel Cross Reference
sys/lib/libz/infcodes.c

     /* $NetBSD: infcodes.c,v 1.5 2003/03/18 20:00:47 mycroft Exp $ */
     
     /* infcodes.c -- process literals and length/distance pairs
      * Copyright (C) 1995-2002 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 {
          const 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 */
      const inflate_huft *ltree;    /* literal/length/eob tree */
      const inflate_huft *dtree;    /* distance tree */
    
    };
    
    
    inflate_codes_statef *inflate_codes_new(bl, bd, tl, td, z)
    uInt bl, bd;
    const inflate_huft *tl;
    const 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 */
      const 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 */
         f = q - c->sub.copy.dist;
         while (f < s->window)             /* modulo window size-"while" instead */
           f += s->end - s->window;        /* of "if" handles invalid distances */
         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"));
   }

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