Src/zlib-1.1.3/inffast.c

/* inffast.c -- process literals and length/distance pairs fast
 * 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"

struct inflate_codes_state {int dummy;}; /* for buggy compilers */

/* simplify the use of the inflate_huft type with some defines */
#define exop word.what.Exop
#define bits word.what.Bits

/* macros for bit input with no checking and for returning unused bytes */
#define GRABBITS(j) {while(k<(j)){b|=((uLong)NEXTBYTE)<<k;k+=8;}}
#define UNGRAB {c=z->avail_in-n;c=(k>>3)<c?k>>3:c;n+=c;p-=c;k-=c<<3;}

/* Called with number of bytes left to write in window at least 258
   (the maximum string length) and number of input bytes available
   at least ten.  The ten bytes are six bytes for the longest length/
   distance pair plus four bytes for overloading the bit buffer. */

int inflate_fast(bl, bd, tl, td, s, z)
uInt bl, bd;
inflate_huft *tl;
inflate_huft *td; /* need separate declaration for Borland C++ */
inflate_blocks_statef *s;
z_streamp z;
{
  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 */
  uInt ml;              /* mask for literal/length tree */
  uInt md;              /* mask for distance tree */
  uInt c;               /* bytes to copy */
  uInt d;               /* distance back to copy from */
  Bytef *r;             /* copy source pointer */

  /* load input, output, bit values */
  LOAD

  /* initialize masks */
  ml = inflate_mask[bl];
  md = inflate_mask[bd];

  /* do until not enough input or output space for fast loop */
  do {                          /* assume called with m >= 258 && n >= 10 */
    /* get literal/length code */
    GRABBITS(20)                /* max bits for literal/length code */
    if ((e = (t = tl + ((uInt)b & ml))->exop) == 0)
    {
      DUMPBITS(t->bits)
      Tracevv((stderr, t->base >= 0x20 && t->base < 0x7f ?
                "inflate:         * literal '%c'\n" :
                "inflate:         * literal 0x%02x\n", t->base));
      *q++ = (Byte)t->base;
      m--;
      continue;
    }
    do {
      DUMPBITS(t->bits)
      if (e & 16)
      {
        /* get extra bits for length */
        e &= 15;
        c = t->base + ((uInt)b & inflate_mask[e]);
        DUMPBITS(e)
        Tracevv((stderr, "inflate:         * length %u\n", c));

        /* decode distance base of block to copy */
        GRABBITS(15);           /* max bits for distance code */
        e = (t = td + ((uInt)b & md))->exop;
        do {
          DUMPBITS(t->bits)
          if (e & 16)
          {
            /* get extra bits to add to distance base */
            e &= 15;
            GRABBITS(e)         /* get extra bits (up to 13) */
            d = t->base + ((uInt)b & inflate_mask[e]);
            DUMPBITS(e)
            Tracevv((stderr, "inflate:         * distance %u\n", d));

            /* do the copy */
            m -= c;
            if ((uInt)(q - s->window) >= d)     /* offset before dest */
            {                                   /*  just copy */
              r = q - d;
              *q++ = *r++;  c--;        /* minimum count is three, */
              *q++ = *r++;  c--;        /*  so unroll loop a little */
            }
            else                        /* else offset after destination */
            {
              e = d - (uInt)(q - s->window); /* bytes from offset to end */
              r = s->end - e;           /* pointer to offset */
              if (c > e)                /* if source crosses, */
              {
                c -= e;                 /* copy to end of window */
                do {
                  *q++ = *r++;
                } while (--e);
                r = s->window;          /* copy rest from start of window */
              }
            }
            do {                        /* copy all or what's left */
              *q++ = *r++;
            } while (--c);
            break;
          }
          else if ((e & 64) == 0)
          {
            t += t->base;
            e = (t += ((uInt)b & inflate_mask[e]))->exop;
          }
          else
          {
            z->msg = (char*)"invalid distance code";
            UNGRAB
            UPDATE
            return Z_DATA_ERROR;
          }
        } while (1);
        break;
      }
      if ((e & 64) == 0)
      {
        t += t->base;
        if ((e = (t += ((uInt)b & inflate_mask[e]))->exop) == 0)
        {
          DUMPBITS(t->bits)
          Tracevv((stderr, t->base >= 0x20 && t->base < 0x7f ?
                    "inflate:         * literal '%c'\n" :
                    "inflate:         * literal 0x%02x\n", t->base));
          *q++ = (Byte)t->base;
          m--;
          break;
        }
      }
      else if (e & 32)
      {
        Tracevv((stderr, "inflate:         * end of block\n"));
        UNGRAB
        UPDATE
        return Z_STREAM_END;
      }
      else
      {
        z->msg = (char*)"invalid literal/length code";
        UNGRAB
        UPDATE
        return Z_DATA_ERROR;
      }
    } while (1);
  } while (m >= 258 && n >= 10);

  /* not enough input or output--restore pointers and return */
  UNGRAB
  UPDATE
  return Z_OK;
}
1	/* inffast.c -- process literals and length/distance pairs fast
2	* Copyright (C) 1995-1998 Mark Adler
3	* For conditions of distribution and use, see copyright notice in zlib.h
4	*/
5
6	#include "zutil.h"
7	#include "inftrees.h"
8	#include "infblock.h"
9	#include "infcodes.h"
10	#include "infutil.h"
11	#include "inffast.h"
12
13	struct inflate_codes_state {int dummy;}; /* for buggy compilers */
14
15	/* simplify the use of the inflate_huft type with some defines */
16	#define exop word.what.Exop
17	#define bits word.what.Bits
18
19	/* macros for bit input with no checking and for returning unused bytes */
20	#define GRABBITS(j) {while(k<(j)){b\|=((uLong)NEXTBYTE)<<k;k+=8;}}
21	#define UNGRAB {c=z->avail_in-n;c=(k>>3)<c?k>>3:c;n+=c;p-=c;k-=c<<3;}
22
23	/* Called with number of bytes left to write in window at least 258
24	(the maximum string length) and number of input bytes available
25	at least ten. The ten bytes are six bytes for the longest length/
26	distance pair plus four bytes for overloading the bit buffer. */
27
28	int inflate_fast(bl, bd, tl, td, s, z)
29	uInt bl, bd;
30	inflate_huft *tl;
31	inflate_huft td; / need separate declaration for Borland C++ */
32	inflate_blocks_statef *s;
33	z_streamp z;
34	{
35	inflate_huft t; / temporary pointer */
36	uInt e; /* extra bits or operation */
37	uLong b; /* bit buffer */
38	uInt k; /* bits in bit buffer */
39	Bytef p; / input data pointer */
40	uInt n; /* bytes available there */
41	Bytef q; / output window write pointer */
42	uInt m; /* bytes to end of window or read pointer */
43	uInt ml; /* mask for literal/length tree */
44	uInt md; /* mask for distance tree */
45	uInt c; /* bytes to copy */
46	uInt d; /* distance back to copy from */
47	Bytef r; / copy source pointer */
48
49	/* load input, output, bit values */
50	LOAD
51
52	/* initialize masks */
53	ml = inflate_mask[bl];
54	md = inflate_mask[bd];
55
56	/* do until not enough input or output space for fast loop */
57	do { /* assume called with m >= 258 && n >= 10 */
58	/* get literal/length code */
59	GRABBITS(20) /* max bits for literal/length code */
60	if ((e = (t = tl + ((uInt)b & ml))->exop) == 0)
61	{
62	DUMPBITS(t->bits)
63	Tracevv((stderr, t->base >= 0x20 && t->base < 0x7f ?
64	"inflate: * literal '%c'\n" :
65	"inflate: * literal 0x%02x\n", t->base));
66	*q++ = (Byte)t->base;
67	m--;
68	continue;
69	}
70	do {
71	DUMPBITS(t->bits)
72	if (e & 16)
73	{
74	/* get extra bits for length */
75	e &= 15;
76	c = t->base + ((uInt)b & inflate_mask[e]);
77	DUMPBITS(e)
78	Tracevv((stderr, "inflate: * length %u\n", c));
79
80	/* decode distance base of block to copy */
81	GRABBITS(15); /* max bits for distance code */
82	e = (t = td + ((uInt)b & md))->exop;
83	do {
84	DUMPBITS(t->bits)
85	if (e & 16)
86	{
87	/* get extra bits to add to distance base */
88	e &= 15;
89	GRABBITS(e) /* get extra bits (up to 13) */
90	d = t->base + ((uInt)b & inflate_mask[e]);
91	DUMPBITS(e)
92	Tracevv((stderr, "inflate: * distance %u\n", d));
93
94	/* do the copy */
95	m -= c;
96	if ((uInt)(q - s->window) >= d) /* offset before dest */
97	{ /* just copy */
98	r = q - d;
99	q++ = r++; c--; /* minimum count is three, */
100	q++ = r++; c--; /* so unroll loop a little */
101	}
102	else /* else offset after destination */
103	{
104	e = d - (uInt)(q - s->window); /* bytes from offset to end */
105	r = s->end - e; /* pointer to offset */
106	if (c > e) /* if source crosses, */
107	{
108	c -= e; /* copy to end of window */
109	do {
110	q++ = r++;
111	} while (--e);
112	r = s->window; /* copy rest from start of window */
113	}
114	}
115	do { /* copy all or what's left */
116	q++ = r++;
117	} while (--c);
118	break;
119	}
120	else if ((e & 64) == 0)
121	{
122	t += t->base;
123	e = (t += ((uInt)b & inflate_mask[e]))->exop;
124	}
125	else
126	{
127	z->msg = (char*)"invalid distance code";
128	UNGRAB
129	UPDATE
130	return Z_DATA_ERROR;
131	}
132	} while (1);
133	break;
134	}
135	if ((e & 64) == 0)
136	{
137	t += t->base;
138	if ((e = (t += ((uInt)b & inflate_mask[e]))->exop) == 0)
139	{
140	DUMPBITS(t->bits)
141	Tracevv((stderr, t->base >= 0x20 && t->base < 0x7f ?
142	"inflate: * literal '%c'\n" :
143	"inflate: * literal 0x%02x\n", t->base));
144	*q++ = (Byte)t->base;
145	m--;
146	break;
147	}
148	}
149	else if (e & 32)
150	{
151	Tracevv((stderr, "inflate: * end of block\n"));
152	UNGRAB
153	UPDATE
154	return Z_STREAM_END;
155	}
156	else
157	{
158	z->msg = (char*)"invalid literal/length code";
159	UNGRAB
160	UPDATE
161	return Z_DATA_ERROR;
162	}
163	} while (1);
164	} while (m >= 258 && n >= 10);
165
166	/* not enough input or output--restore pointers and return */
167	UNGRAB
168	UPDATE
169	return Z_OK;
170	}