[apple/xnu.git] / libkern / zlib / inffast.c

/*
 * Copyright (c) 2008-2016 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 *
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 *
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
/* inffast.c -- fast decoding
 * Copyright (C) 1995-2004 Mark Adler
 * For conditions of distribution and use, see copyright notice in zlib.h
 */


#include "zutil.h"
#include "inftrees.h"
#include "inflate.h"
#include "inffast.h"

#ifndef ASMINF

/* Allow machine dependent optimization for post-increment or pre-increment.
   Based on testing to date,
   Pre-increment preferred for:
   - PowerPC G3 (Adler)
   - MIPS R5000 (Randers-Pehrson)
   Post-increment preferred for:
   - none
   No measurable difference:
   - Pentium III (Anderson)
   - M68060 (Nikl)
 */
#ifdef POSTINC
#  define OFF 0
#  define PUP(a) *(a)++
#else
#  define OFF 1
#  define PUP(a) *++(a)
#endif

/*
   Decode literal, length, and distance codes and write out the resulting
   literal and match bytes until either not enough input or output is
   available, an end-of-block is encountered, or a data error is encountered.
   When large enough input and output buffers are supplied to inflate(), for
   example, a 16K input buffer and a 64K output buffer, more than 95% of the
   inflate execution time is spent in this routine.

   Entry assumptions:

        state->mode == LEN
        strm->avail_in >= 6
        strm->avail_out >= 258
        start >= strm->avail_out
        state->bits < 8

   On return, state->mode is one of:

        LEN -- ran out of enough output space or enough available input
        TYPE -- reached end of block code, inflate() to interpret next block
        BAD -- error in block data

   Notes:

    - The maximum input bits used by a length/distance pair is 15 bits for the
      length code, 5 bits for the length extra, 15 bits for the distance code,
      and 13 bits for the distance extra.  This totals 48 bits, or six bytes.
      Therefore if strm->avail_in >= 6, then there is enough input to avoid
      checking for available input while decoding.

    - The maximum bytes that a single length/distance pair can output is 258
      bytes, which is the maximum length that can be coded.  inflate_fast()
      requires strm->avail_out >= 258 for each loop to avoid checking for
      output space.

      @param start inflate()'s starting value for strm->avail_out
 */
void
inflate_fast(z_streamp strm, unsigned start)
{
    struct inflate_state FAR *state;
    unsigned char FAR *in;      /* local strm->next_in */
    unsigned char FAR *last;    /* while in < last, enough input available */
    unsigned char FAR *out;     /* local strm->next_out */
    unsigned char FAR *beg;     /* inflate()'s initial strm->next_out */
    unsigned char FAR *end;     /* while out < end, enough space available */
#ifdef INFLATE_STRICT
    unsigned dmax;              /* maximum distance from zlib header */
#endif
    unsigned wsize;             /* window size or zero if not using window */
    unsigned whave;             /* valid bytes in the window */
    unsigned write;             /* window write index */
    unsigned char FAR *window;  /* allocated sliding window, if wsize != 0 */
    unsigned long hold;         /* local strm->hold */
    unsigned bits;              /* local strm->bits */
    code const FAR *lcode;      /* local strm->lencode */
    code const FAR *dcode;      /* local strm->distcode */
    unsigned lmask;             /* mask for first level of length codes */
    unsigned dmask;             /* mask for first level of distance codes */
    code this;                  /* retrieved table entry */
    unsigned op;                /* code bits, operation, extra bits, or */
                                /*  window position, window bytes to copy */
    unsigned len;               /* match length, unused bytes */
    unsigned dist;              /* match distance */
    unsigned char FAR *from;    /* where to copy match from */

    /* copy state to local variables */
    state = (struct inflate_state FAR *)strm->state;
    in = strm->next_in - OFF;
    last = in + (strm->avail_in - 5);
    out = strm->next_out - OFF;
    beg = out - (start - strm->avail_out);
    end = out + (strm->avail_out - 257);
#ifdef INFLATE_STRICT
    dmax = state->dmax;
#endif
    wsize = state->wsize;
    whave = state->whave;
    write = state->write;
    window = state->window;
    hold = state->hold;
    bits = state->bits;
    lcode = state->lencode;
    dcode = state->distcode;
    lmask = (1U << state->lenbits) - 1;
    dmask = (1U << state->distbits) - 1;

    /* decode literals and length/distances until end-of-block or not enough
       input data or output space */
    do {
        if (bits < 15) {
            hold += (unsigned long)(PUP(in)) << bits;
            bits += 8;
            hold += (unsigned long)(PUP(in)) << bits;
            bits += 8;
        }
        this = lcode[hold & lmask];
      dolen:
        op = (unsigned)(this.bits);
        hold >>= op;
        bits -= op;
        op = (unsigned)(this.op);
        if (op == 0) {                          /* literal */
            Tracevv((stderr, this.val >= 0x20 && this.val < 0x7f ?
                    "inflate:         literal '%c'\n" :
                    "inflate:         literal 0x%02x\n", this.val));
            PUP(out) = (unsigned char)(this.val);
        }
        else if (op & 16) {                     /* length base */
            len = (unsigned)(this.val);
            op &= 15;                           /* number of extra bits */
            if (op) {
                if (bits < op) {
                    hold += (unsigned long)(PUP(in)) << bits;
                    bits += 8;
                }
                len += (unsigned)hold & ((1U << op) - 1);
                hold >>= op;
                bits -= op;
            }
            Tracevv((stderr, "inflate:         length %u\n", len));
            if (bits < 15) {
                hold += (unsigned long)(PUP(in)) << bits;
                bits += 8;
                hold += (unsigned long)(PUP(in)) << bits;
                bits += 8;
            }
            this = dcode[hold & dmask];
          dodist:
            op = (unsigned)(this.bits);
            hold >>= op;
            bits -= op;
            op = (unsigned)(this.op);
            if (op & 16) {                      /* distance base */
                dist = (unsigned)(this.val);
                op &= 15;                       /* number of extra bits */
                if (bits < op) {
                    hold += (unsigned long)(PUP(in)) << bits;
                    bits += 8;
                    if (bits < op) {
                        hold += (unsigned long)(PUP(in)) << bits;
                        bits += 8;
                    }
                }
                dist += (unsigned)hold & ((1U << op) - 1);
#ifdef INFLATE_STRICT
                if (dist > dmax) {
                    strm->msg = (char *)"invalid distance too far back";
                    state->mode = BAD;
                    break;
                }
#endif
                hold >>= op;
                bits -= op;
                Tracevv((stderr, "inflate:         distance %u\n", dist));
                op = (unsigned)(out - beg);     /* max distance in output */
                if (dist > op) {                /* see if copy from window */
                    op = dist - op;             /* distance back in window */
                    if (op > whave) {
                        strm->msg = (char *)"invalid distance too far back";
                        state->mode = BAD;
                        break;
                    }
                    from = window - OFF;
                    if (write == 0) {           /* very common case */
                        from += wsize - op;
                        if (op < len) {         /* some from window */
                            len -= op;
                            do {
                                PUP(out) = PUP(from);
                            } while (--op);
                            from = out - dist;  /* rest from output */
                        }
                    }
                    else if (write < op) {      /* wrap around window */
                        from += wsize + write - op;
                        op -= write;
                        if (op < len) {         /* some from end of window */
                            len -= op;
                            do {
                                PUP(out) = PUP(from);
                            } while (--op);
                            from = window - OFF;
                            if (write < len) {  /* some from start of window */
                                op = write;
                                len -= op;
                                do {
                                    PUP(out) = PUP(from);
                                } while (--op);
                                from = out - dist;      /* rest from output */
                            }
                        }
                    }
                    else {                      /* contiguous in window */
                        from += write - op;
                        if (op < len) {         /* some from window */
                            len -= op;
                            do {
                                PUP(out) = PUP(from);
                            } while (--op);
                            from = out - dist;  /* rest from output */
                        }
                    }
                    while (len > 2) {
                        PUP(out) = PUP(from);
                        PUP(out) = PUP(from);
                        PUP(out) = PUP(from);
                        len -= 3;
                    }
                    if (len) {
                        PUP(out) = PUP(from);
                        if (len > 1)
                            PUP(out) = PUP(from);
                    }
                }
                else {
                    from = out - dist;          /* copy direct from output */
                    do {                        /* minimum length is three */
                        PUP(out) = PUP(from);
                        PUP(out) = PUP(from);
                        PUP(out) = PUP(from);
                        len -= 3;
                    } while (len > 2);
                    if (len) {
                        PUP(out) = PUP(from);
                        if (len > 1)
                            PUP(out) = PUP(from);
                    }
                }
            }
            else if ((op & 64) == 0) {          /* 2nd level distance code */
                this = dcode[this.val + (hold & ((1U << op) - 1))];
                goto dodist;
            }
            else {
                strm->msg = (char *)"invalid distance code";
                state->mode = BAD;
                break;
            }
        }
        else if ((op & 64) == 0) {              /* 2nd level length code */
            this = lcode[this.val + (hold & ((1U << op) - 1))];
            goto dolen;
        }
        else if (op & 32) {                     /* end-of-block */
            Tracevv((stderr, "inflate:         end of block\n"));
            state->mode = TYPE;
            break;
        }
        else {
            strm->msg = (char *)"invalid literal/length code";
            state->mode = BAD;
            break;
        }
    } while (in < last && out < end);

    /* return unused bytes (on entry, bits < 8, so in won't go too far back) */
    len = bits >> 3;
    in -= len;
    bits -= len << 3;
    hold &= (1U << bits) - 1;

    /* update state and return */
    strm->next_in = in + OFF;
    strm->next_out = out + OFF;
    strm->avail_in = (unsigned)(in < last ? 5 + (last - in) : 5 - (in - last));
    strm->avail_out = (unsigned)(out < end ?
                                 257 + (end - out) : 257 - (out - end));
    state->hold = hold;
    state->bits = bits;
    return;
}

/*
   inflate_fast() speedups that turned out slower (on a PowerPC G3 750CXe):
   - Using bit fields for code structure
   - Different op definition to avoid & for extra bits (do & for table bits)
   - Three separate decoding do-loops for direct, window, and write == 0
   - Special case for distance > 1 copies to do overlapped load and store copy
   - Explicit branch predictions (based on measured branch probabilities)
   - Deferring match copy and interspersed it with decoding subsequent codes
   - Swapping literal/length else
   - Swapping window/direct else
   - Larger unrolled copy loops (three is about right)
   - Moving len -= 3 statement into middle of loop
 */

#endif /* !ASMINF */
Commit	Line	Data
b0d623f7	1	/*
39037602	2	* Copyright (c) 2008-2016 Apple Inc. All rights reserved.
b0d623f7 A	3	*
b0d623f7 A	4	* @APPLE_OSREFERENCE_LICENSE_HEADER_START@
39037602	5	*
b0d623f7 A	6	* This file contains Original Code and/or Modifications of Original Code
	7	* as defined in and that are subject to the Apple Public Source License
	8	* Version 2.0 (the 'License'). You may not use this file except in
	9	* compliance with the License. The rights granted to you under the License
	10	* may not be used to create, or enable the creation or redistribution of,
	11	* unlawful or unlicensed copies of an Apple operating system, or to
	12	* circumvent, violate, or enable the circumvention or violation of, any
	13	* terms of an Apple operating system software license agreement.
39037602	14	*
b0d623f7 A	15	* Please obtain a copy of the License at
b0d623f7 A	16	* http://www.opensource.apple.com/apsl/ and read it before using this file.
39037602	17	*
b0d623f7 A	18	* The Original Code and all software distributed under the License are
	19	* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
	20	* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
	21	* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
	22	* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
	23	* Please see the License for the specific language governing rights and
	24	* limitations under the License.
39037602	25	*
b0d623f7 A	26	* @APPLE_OSREFERENCE_LICENSE_HEADER_END@
	27	*/
	28	/* inffast.c -- fast decoding
	29	* Copyright (C) 1995-2004 Mark Adler
	30	* For conditions of distribution and use, see copyright notice in zlib.h
	31	*/
	32
b7266188	33
b0d623f7 A	34	#include "zutil.h"
	35	#include "inftrees.h"
	36	#include "inflate.h"
	37	#include "inffast.h"
	38
	39	#ifndef ASMINF
	40
	41	/* Allow machine dependent optimization for post-increment or pre-increment.
	42	Based on testing to date,
	43	Pre-increment preferred for:
	44	- PowerPC G3 (Adler)
	45	- MIPS R5000 (Randers-Pehrson)
	46	Post-increment preferred for:
	47	- none
	48	No measurable difference:
	49	- Pentium III (Anderson)
	50	- M68060 (Nikl)
	51	*/
	52	#ifdef POSTINC
	53	# define OFF 0
	54	# define PUP(a) *(a)++
	55	#else
	56	# define OFF 1
	57	# define PUP(a) *++(a)
	58	#endif
	59
	60	/*
	61	Decode literal, length, and distance codes and write out the resulting
	62	literal and match bytes until either not enough input or output is
	63	available, an end-of-block is encountered, or a data error is encountered.
	64	When large enough input and output buffers are supplied to inflate(), for
	65	example, a 16K input buffer and a 64K output buffer, more than 95% of the
	66	inflate execution time is spent in this routine.
	67
	68	Entry assumptions:
	69
	70	state->mode == LEN
	71	strm->avail_in >= 6
	72	strm->avail_out >= 258
	73	start >= strm->avail_out
	74	state->bits < 8
	75
	76	On return, state->mode is one of:
	77
	78	LEN -- ran out of enough output space or enough available input
	79	TYPE -- reached end of block code, inflate() to interpret next block
	80	BAD -- error in block data
	81
	82	Notes:
	83
	84	- The maximum input bits used by a length/distance pair is 15 bits for the
	85	length code, 5 bits for the length extra, 15 bits for the distance code,
	86	and 13 bits for the distance extra. This totals 48 bits, or six bytes.
	87	Therefore if strm->avail_in >= 6, then there is enough input to avoid
	88	checking for available input while decoding.
	89
	90	- The maximum bytes that a single length/distance pair can output is 258
	91	bytes, which is the maximum length that can be coded. inflate_fast()
	92	requires strm->avail_out >= 258 for each loop to avoid checking for
	93	output space.
39037602 A	94
39037602 A	95	@param start inflate()'s starting value for strm->avail_out
b0d623f7	96	*/
39037602 A	97	void
39037602 A	98	inflate_fast(z_streamp strm, unsigned start)
b0d623f7 A	99	{
	100	struct inflate_state FAR *state;
	101	unsigned char FAR in; / local strm->next_in */
	102	unsigned char FAR last; / while in < last, enough input available */
	103	unsigned char FAR out; / local strm->next_out */
	104	unsigned char FAR beg; / inflate()'s initial strm->next_out */
	105	unsigned char FAR end; / while out < end, enough space available */
	106	#ifdef INFLATE_STRICT
	107	unsigned dmax; /* maximum distance from zlib header */
	108	#endif
	109	unsigned wsize; /* window size or zero if not using window */
	110	unsigned whave; /* valid bytes in the window */
	111	unsigned write; /* window write index */
	112	unsigned char FAR window; / allocated sliding window, if wsize != 0 */
	113	unsigned long hold; /* local strm->hold */
	114	unsigned bits; /* local strm->bits */
	115	code const FAR lcode; / local strm->lencode */
	116	code const FAR dcode; / local strm->distcode */
	117	unsigned lmask; /* mask for first level of length codes */
	118	unsigned dmask; /* mask for first level of distance codes */
	119	code this; /* retrieved table entry */
	120	unsigned op; /* code bits, operation, extra bits, or */
	121	/* window position, window bytes to copy */
	122	unsigned len; /* match length, unused bytes */
	123	unsigned dist; /* match distance */
	124	unsigned char FAR from; / where to copy match from */
	125
	126	/* copy state to local variables */
	127	state = (struct inflate_state FAR *)strm->state;
	128	in = strm->next_in - OFF;
	129	last = in + (strm->avail_in - 5);
	130	out = strm->next_out - OFF;
	131	beg = out - (start - strm->avail_out);
	132	end = out + (strm->avail_out - 257);
	133	#ifdef INFLATE_STRICT
	134	dmax = state->dmax;
	135	#endif
	136	wsize = state->wsize;
	137	whave = state->whave;
	138	write = state->write;
	139	window = state->window;
	140	hold = state->hold;
	141	bits = state->bits;
	142	lcode = state->lencode;
	143	dcode = state->distcode;
	144	lmask = (1U << state->lenbits) - 1;
	145	dmask = (1U << state->distbits) - 1;
	146
	147	/* decode literals and length/distances until end-of-block or not enough
	148	input data or output space */
	149	do {
	150	if (bits < 15) {
	151	hold += (unsigned long)(PUP(in)) << bits;
	152	bits += 8;
	153	hold += (unsigned long)(PUP(in)) << bits;
	154	bits += 8;
	155	}
	156	this = lcode[hold & lmask];
	157	dolen:
	158	op = (unsigned)(this.bits);
	159	hold >>= op;
	160	bits -= op;
	161	op = (unsigned)(this.op);
	162	if (op == 0) { /* literal */
163	Tracevv((stderr, this.val >= 0x20 && this.val < 0x7f ?
164	"inflate: literal '%c'\n" :
165	"inflate: literal 0x%02x\n", this.val));
166	PUP(out) = (unsigned char)(this.val);
167	}
168	else if (op & 16) { /* length base */
169	len = (unsigned)(this.val);
170	op &= 15; /* number of extra bits */
171	if (op) {
172	if (bits < op) {
173	hold += (unsigned long)(PUP(in)) << bits;
174	bits += 8;
175	}
176	len += (unsigned)hold & ((1U << op) - 1);
177	hold >>= op;
178	bits -= op;
179	}
180	Tracevv((stderr, "inflate: length %u\n", len));
181	if (bits < 15) {
182	hold += (unsigned long)(PUP(in)) << bits;
183	bits += 8;
184	hold += (unsigned long)(PUP(in)) << bits;
185	bits += 8;
186	}
187	this = dcode[hold & dmask];
188	dodist:
189	op = (unsigned)(this.bits);
190	hold >>= op;
191	bits -= op;
192	op = (unsigned)(this.op);
193	if (op & 16) { /* distance base */
194	dist = (unsigned)(this.val);
195	op &= 15; /* number of extra bits */
196	if (bits < op) {
197	hold += (unsigned long)(PUP(in)) << bits;
198	bits += 8;
199	if (bits < op) {
200	hold += (unsigned long)(PUP(in)) << bits;
201	bits += 8;
202	}
203	}
204	dist += (unsigned)hold & ((1U << op) - 1);
205	#ifdef INFLATE_STRICT
206	if (dist > dmax) {
207	strm->msg = (char *)"invalid distance too far back";
208	state->mode = BAD;
209	break;
210	}
211	#endif
212	hold >>= op;
213	bits -= op;
214	Tracevv((stderr, "inflate: distance %u\n", dist));
215	op = (unsigned)(out - beg); /* max distance in output */
216	if (dist > op) { /* see if copy from window */
217	op = dist - op; /* distance back in window */
218	if (op > whave) {
219	strm->msg = (char *)"invalid distance too far back";
220	state->mode = BAD;
221	break;
222	}
223	from = window - OFF;
224	if (write == 0) { /* very common case */
225	from += wsize - op;
226	if (op < len) { /* some from window */
227	len -= op;
228	do {
229	PUP(out) = PUP(from);
230	} while (--op);
231	from = out - dist; /* rest from output */
232	}
233	}
234	else if (write < op) { /* wrap around window */
235	from += wsize + write - op;
236	op -= write;
237	if (op < len) { /* some from end of window */
238	len -= op;
239	do {
240	PUP(out) = PUP(from);
241	} while (--op);
242	from = window - OFF;
243	if (write < len) { /* some from start of window */
244	op = write;
245	len -= op;
246	do {
247	PUP(out) = PUP(from);
248	} while (--op);
249	from = out - dist; /* rest from output */
250	}
251	}
252	}
253	else { /* contiguous in window */
254	from += write - op;
255	if (op < len) { /* some from window */
256	len -= op;
257	do {
258	PUP(out) = PUP(from);
259	} while (--op);
260	from = out - dist; /* rest from output */
261	}
262	}
263	while (len > 2) {
264	PUP(out) = PUP(from);
265	PUP(out) = PUP(from);
266	PUP(out) = PUP(from);
267	len -= 3;
268	}
269	if (len) {
270	PUP(out) = PUP(from);
271	if (len > 1)
272	PUP(out) = PUP(from);
273	}
274	}
275	else {
276	from = out - dist; /* copy direct from output */
277	do { /* minimum length is three */
278	PUP(out) = PUP(from);
279	PUP(out) = PUP(from);
280	PUP(out) = PUP(from);
281	len -= 3;
282	} while (len > 2);
283	if (len) {
284	PUP(out) = PUP(from);
285	if (len > 1)
286	PUP(out) = PUP(from);
287	}
288	}
289	}
290	else if ((op & 64) == 0) { /* 2nd level distance code */
291	this = dcode[this.val + (hold & ((1U << op) - 1))];
292	goto dodist;
293	}
294	else {
295	strm->msg = (char *)"invalid distance code";
296	state->mode = BAD;
297	break;
298	}
299	}
300	else if ((op & 64) == 0) { /* 2nd level length code */
301	this = lcode[this.val + (hold & ((1U << op) - 1))];
302	goto dolen;
303	}
304	else if (op & 32) { /* end-of-block */
305	Tracevv((stderr, "inflate: end of block\n"));
306	state->mode = TYPE;
307	break;
308	}
309	else {
310	strm->msg = (char *)"invalid literal/length code";
311	state->mode = BAD;
312	break;
313	}
314	} while (in < last && out < end);
315
316	/* return unused bytes (on entry, bits < 8, so in won't go too far back) */
317	len = bits >> 3;
318	in -= len;
319	bits -= len << 3;
320	hold &= (1U << bits) - 1;
321
322	/* update state and return */
323	strm->next_in = in + OFF;
324	strm->next_out = out + OFF;
325	strm->avail_in = (unsigned)(in < last ? 5 + (last - in) : 5 - (in - last));
326	strm->avail_out = (unsigned)(out < end ?
327	257 + (end - out) : 257 - (out - end));
328	state->hold = hold;
329	state->bits = bits;
330	return;
331	}
332
333	/*
334	inflate_fast() speedups that turned out slower (on a PowerPC G3 750CXe):
335	- Using bit fields for code structure
336	- Different op definition to avoid & for extra bits (do & for table bits)
337	- Three separate decoding do-loops for direct, window, and write == 0
338	- Special case for distance > 1 copies to do overlapped load and store copy
339	- Explicit branch predictions (based on measured branch probabilities)
340	- Deferring match copy and interspersed it with decoding subsequent codes
341	- Swapping literal/length else
342	- Swapping window/direct else
343	- Larger unrolled copy loops (three is about right)
344	- Moving len -= 3 statement into middle of loop
345	*/
346
347	#endif /* !ASMINF */