/* 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 OF((
	uInt bl, uInt bd,
	inflate_huft *tl, inflate_huft *td,
	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(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(inflate_codes_statef *c,z_streamp z)
{
  ZFREE(z, c);
  Tracev((stderr, "inflate:	   codes free\n"));
}
