[pcsx_rearmed.git] / deps / libchdr / deps / zlib-1.2.11 / inffast.c

/* inffast.c -- fast decoding
 * Copyright (C) 1995-2017 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"

#ifdef ASMINF
#  pragma message("Assembler code may have bugs -- use at your own risk")
#else

/*
   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.
 */
void ZLIB_INTERNAL inflate_fast(strm, start)
z_streamp strm;
unsigned start;         /* inflate()'s starting value for strm->avail_out */
{
    struct inflate_state FAR *state;
    z_const unsigned char FAR *in;      /* local strm->next_in */
    z_const unsigned char FAR *last;    /* have enough input while in < last */
    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 wnext;             /* 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 here;                  /* 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;
    last = in + (strm->avail_in - 5);
    out = strm->next_out;
    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;
    wnext = state->wnext;
    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)(*in++) << bits;
            bits += 8;
            hold += (unsigned long)(*in++) << bits;
            bits += 8;
        }
        here = lcode[hold & lmask];
      dolen:
        op = (unsigned)(here.bits);
        hold >>= op;
        bits -= op;
        op = (unsigned)(here.op);
        if (op == 0) {                          /* literal */
            Tracevv((stderr, here.val >= 0x20 && here.val < 0x7f ?
                    "inflate:         literal '%c'\n" :
                    "inflate:         literal 0x%02x\n", here.val));
            *out++ = (unsigned char)(here.val);
        }
        else if (op & 16) {                     /* length base */
            len = (unsigned)(here.val);
            op &= 15;                           /* number of extra bits */
            if (op) {
                if (bits < op) {
                    hold += (unsigned long)(*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)(*in++) << bits;
                bits += 8;
                hold += (unsigned long)(*in++) << bits;
                bits += 8;
            }
            here = dcode[hold & dmask];
          dodist:
            op = (unsigned)(here.bits);
            hold >>= op;
            bits -= op;
            op = (unsigned)(here.op);
            if (op & 16) {                      /* distance base */
                dist = (unsigned)(here.val);
                op &= 15;                       /* number of extra bits */
                if (bits < op) {
                    hold += (unsigned long)(*in++) << bits;
                    bits += 8;
                    if (bits < op) {
                        hold += (unsigned long)(*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) {
                        if (state->sane) {
                            strm->msg =
                                (char *)"invalid distance too far back";
                            state->mode = BAD;
                            break;
                        }
#ifdef INFLATE_ALLOW_INVALID_DISTANCE_TOOFAR_ARRR
                        if (len <= op - whave) {
                            do {
                                *out++ = 0;
                            } while (--len);
                            continue;
                        }
                        len -= op - whave;
                        do {
                            *out++ = 0;
                        } while (--op > whave);
                        if (op == 0) {
                            from = out - dist;
                            do {
                                *out++ = *from++;
                            } while (--len);
                            continue;
                        }
#endif
                    }
                    from = window;
                    if (wnext == 0) {           /* very common case */
                        from += wsize - op;
                        if (op < len) {         /* some from window */
                            len -= op;
                            do {
                                *out++ = *from++;
                            } while (--op);
                            from = out - dist;  /* rest from output */
                        }
                    }
                    else if (wnext < op) {      /* wrap around window */
                        from += wsize + wnext - op;
                        op -= wnext;
                        if (op < len) {         /* some from end of window */
                            len -= op;
                            do {
                                *out++ = *from++;
                            } while (--op);
                            from = window;
                            if (wnext < len) {  /* some from start of window */
                                op = wnext;
                                len -= op;
                                do {
                                    *out++ = *from++;
                                } while (--op);
                                from = out - dist;      /* rest from output */
                            }
                        }
                    }
                    else {                      /* contiguous in window */
                        from += wnext - op;
                        if (op < len) {         /* some from window */
                            len -= op;
                            do {
                                *out++ = *from++;
                            } while (--op);
                            from = out - dist;  /* rest from output */
                        }
                    }
                    while (len > 2) {
                        *out++ = *from++;
                        *out++ = *from++;
                        *out++ = *from++;
                        len -= 3;
                    }
                    if (len) {
                        *out++ = *from++;
                        if (len > 1)
                            *out++ = *from++;
                    }
                }
                else {
                    from = out - dist;          /* copy direct from output */
                    do {                        /* minimum length is three */
                        *out++ = *from++;
                        *out++ = *from++;
                        *out++ = *from++;
                        len -= 3;
                    } while (len > 2);
                    if (len) {
                        *out++ = *from++;
                        if (len > 1)
                            *out++ = *from++;
                    }
                }
            }
            else if ((op & 64) == 0) {          /* 2nd level distance code */
                here = dcode[here.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 */
            here = lcode[here.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;
    strm->next_out = out;
    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 wnext == 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
b24e7fce	1	/* inffast.c -- fast decoding
	2	* Copyright (C) 1995-2017 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 "inflate.h"
	9	#include "inffast.h"
	10
	11	#ifdef ASMINF
	12	# pragma message("Assembler code may have bugs -- use at your own risk")
	13	#else
	14
	15	/*
	16	Decode literal, length, and distance codes and write out the resulting
	17	literal and match bytes until either not enough input or output is
	18	available, an end-of-block is encountered, or a data error is encountered.
	19	When large enough input and output buffers are supplied to inflate(), for
	20	example, a 16K input buffer and a 64K output buffer, more than 95% of the
	21	inflate execution time is spent in this routine.
	22
	23	Entry assumptions:
	24
	25	state->mode == LEN
	26	strm->avail_in >= 6
	27	strm->avail_out >= 258
	28	start >= strm->avail_out
	29	state->bits < 8
	30
	31	On return, state->mode is one of:
	32
	33	LEN -- ran out of enough output space or enough available input
	34	TYPE -- reached end of block code, inflate() to interpret next block
	35	BAD -- error in block data
	36
	37	Notes:
	38
	39	- The maximum input bits used by a length/distance pair is 15 bits for the
	40	length code, 5 bits for the length extra, 15 bits for the distance code,
	41	and 13 bits for the distance extra. This totals 48 bits, or six bytes.
	42	Therefore if strm->avail_in >= 6, then there is enough input to avoid
	43	checking for available input while decoding.
	44
	45	- The maximum bytes that a single length/distance pair can output is 258
	46	bytes, which is the maximum length that can be coded. inflate_fast()
	47	requires strm->avail_out >= 258 for each loop to avoid checking for
	48	output space.
	49	*/
	50	void ZLIB_INTERNAL inflate_fast(strm, start)
	51	z_streamp strm;
	52	unsigned start; /* inflate()'s starting value for strm->avail_out */
	53	{
	54	struct inflate_state FAR *state;
	55	z_const unsigned char FAR in; / local strm->next_in */
	56	z_const unsigned char FAR last; / have enough input while in < last */
	57	unsigned char FAR out; / local strm->next_out */
	58	unsigned char FAR beg; / inflate()'s initial strm->next_out */
	59	unsigned char FAR end; / while out < end, enough space available */
	60	#ifdef INFLATE_STRICT
	61	unsigned dmax; /* maximum distance from zlib header */
	62	#endif
	63	unsigned wsize; /* window size or zero if not using window */
	64	unsigned whave; /* valid bytes in the window */
65	unsigned wnext; /* window write index */
66	unsigned char FAR window; / allocated sliding window, if wsize != 0 */
67	unsigned long hold; /* local strm->hold */
68	unsigned bits; /* local strm->bits */
69	code const FAR lcode; / local strm->lencode */
70	code const FAR dcode; / local strm->distcode */
71	unsigned lmask; /* mask for first level of length codes */
72	unsigned dmask; /* mask for first level of distance codes */
73	code here; /* retrieved table entry */
74	unsigned op; /* code bits, operation, extra bits, or */
75	/* window position, window bytes to copy */
76	unsigned len; /* match length, unused bytes */
77	unsigned dist; /* match distance */
78	unsigned char FAR from; / where to copy match from */
79
80	/* copy state to local variables */
81	state = (struct inflate_state FAR *)strm->state;
82	in = strm->next_in;
83	last = in + (strm->avail_in - 5);
84	out = strm->next_out;
85	beg = out - (start - strm->avail_out);
86	end = out + (strm->avail_out - 257);
87	#ifdef INFLATE_STRICT
88	dmax = state->dmax;
89	#endif
90	wsize = state->wsize;
91	whave = state->whave;
92	wnext = state->wnext;
93	window = state->window;
94	hold = state->hold;
95	bits = state->bits;
96	lcode = state->lencode;
97	dcode = state->distcode;
98	lmask = (1U << state->lenbits) - 1;
99	dmask = (1U << state->distbits) - 1;
100
101	/* decode literals and length/distances until end-of-block or not enough
102	input data or output space */
103	do {
104	if (bits < 15) {
105	hold += (unsigned long)(*in++) << bits;
106	bits += 8;
107	hold += (unsigned long)(*in++) << bits;
108	bits += 8;
109	}
110	here = lcode[hold & lmask];
111	dolen:
112	op = (unsigned)(here.bits);
113	hold >>= op;
114	bits -= op;
115	op = (unsigned)(here.op);
116	if (op == 0) { /* literal */
117	Tracevv((stderr, here.val >= 0x20 && here.val < 0x7f ?
118	"inflate: literal '%c'\n" :
119	"inflate: literal 0x%02x\n", here.val));
120	*out++ = (unsigned char)(here.val);
121	}
122	else if (op & 16) { /* length base */
123	len = (unsigned)(here.val);
124	op &= 15; /* number of extra bits */
125	if (op) {
126	if (bits < op) {
127	hold += (unsigned long)(*in++) << bits;
128	bits += 8;
129	}
130	len += (unsigned)hold & ((1U << op) - 1);
131	hold >>= op;
132	bits -= op;
133	}
134	Tracevv((stderr, "inflate: length %u\n", len));
135	if (bits < 15) {
136	hold += (unsigned long)(*in++) << bits;
137	bits += 8;
138	hold += (unsigned long)(*in++) << bits;
139	bits += 8;
140	}
141	here = dcode[hold & dmask];
142	dodist:
143	op = (unsigned)(here.bits);
144	hold >>= op;
145	bits -= op;
146	op = (unsigned)(here.op);
147	if (op & 16) { /* distance base */
148	dist = (unsigned)(here.val);
149	op &= 15; /* number of extra bits */
150	if (bits < op) {
151	hold += (unsigned long)(*in++) << bits;
152	bits += 8;
153	if (bits < op) {
154	hold += (unsigned long)(*in++) << bits;
155	bits += 8;
156	}
157	}
158	dist += (unsigned)hold & ((1U << op) - 1);
159	#ifdef INFLATE_STRICT
160	if (dist > dmax) {
161	strm->msg = (char *)"invalid distance too far back";
162	state->mode = BAD;
163	break;
164	}
165	#endif
166	hold >>= op;
167	bits -= op;
168	Tracevv((stderr, "inflate: distance %u\n", dist));
169	op = (unsigned)(out - beg); /* max distance in output */
170	if (dist > op) { /* see if copy from window */
171	op = dist - op; /* distance back in window */
172	if (op > whave) {
173	if (state->sane) {
174	strm->msg =
175	(char *)"invalid distance too far back";
176	state->mode = BAD;
177	break;
178	}
179	#ifdef INFLATE_ALLOW_INVALID_DISTANCE_TOOFAR_ARRR
180	if (len <= op - whave) {
181	do {
182	*out++ = 0;
183	} while (--len);
184	continue;
185	}
186	len -= op - whave;
187	do {
188	*out++ = 0;
189	} while (--op > whave);
190	if (op == 0) {
191	from = out - dist;
192	do {
193	out++ = from++;
194	} while (--len);
195	continue;
196	}
197	#endif
198	}
199	from = window;
200	if (wnext == 0) { /* very common case */
201	from += wsize - op;
202	if (op < len) { /* some from window */
203	len -= op;
204	do {
205	out++ = from++;
206	} while (--op);
207	from = out - dist; /* rest from output */
208	}
209	}
210	else if (wnext < op) { /* wrap around window */
211	from += wsize + wnext - op;
212	op -= wnext;
213	if (op < len) { /* some from end of window */
214	len -= op;
215	do {
216	out++ = from++;
217	} while (--op);
218	from = window;
219	if (wnext < len) { /* some from start of window */
220	op = wnext;
221	len -= op;
222	do {
223	out++ = from++;
224	} while (--op);
225	from = out - dist; /* rest from output */
226	}
227	}
228	}
229	else { /* contiguous in window */
230	from += wnext - op;
231	if (op < len) { /* some from window */
232	len -= op;
233	do {
234	out++ = from++;
235	} while (--op);
236	from = out - dist; /* rest from output */
237	}
238	}
239	while (len > 2) {
240	out++ = from++;
241	out++ = from++;
242	out++ = from++;
243	len -= 3;
244	}
245	if (len) {
246	out++ = from++;
247	if (len > 1)
248	out++ = from++;
249	}
250	}
251	else {
252	from = out - dist; /* copy direct from output */
253	do { /* minimum length is three */
254	out++ = from++;
255	out++ = from++;
256	out++ = from++;
257	len -= 3;
258	} while (len > 2);
259	if (len) {
260	out++ = from++;
261	if (len > 1)
262	out++ = from++;
263	}
264	}
265	}
266	else if ((op & 64) == 0) { /* 2nd level distance code */
267	here = dcode[here.val + (hold & ((1U << op) - 1))];
268	goto dodist;
269	}
270	else {
271	strm->msg = (char *)"invalid distance code";
272	state->mode = BAD;
273	break;
274	}
275	}
276	else if ((op & 64) == 0) { /* 2nd level length code */
277	here = lcode[here.val + (hold & ((1U << op) - 1))];
278	goto dolen;
279	}
280	else if (op & 32) { /* end-of-block */
281	Tracevv((stderr, "inflate: end of block\n"));
282	state->mode = TYPE;
283	break;
284	}
285	else {
286	strm->msg = (char *)"invalid literal/length code";
287	state->mode = BAD;
288	break;
289	}
290	} while (in < last && out < end);
291
292	/* return unused bytes (on entry, bits < 8, so in won't go too far back) */
293	len = bits >> 3;
294	in -= len;
295	bits -= len << 3;
296	hold &= (1U << bits) - 1;
297
298	/* update state and return */
299	strm->next_in = in;
300	strm->next_out = out;
301	strm->avail_in = (unsigned)(in < last ? 5 + (last - in) : 5 - (in - last));
302	strm->avail_out = (unsigned)(out < end ?
303	257 + (end - out) : 257 - (out - end));
304	state->hold = hold;
305	state->bits = bits;
306	return;
307	}
308
309	/*
310	inflate_fast() speedups that turned out slower (on a PowerPC G3 750CXe):
311	- Using bit fields for code structure
312	- Different op definition to avoid & for extra bits (do & for table bits)
313	- Three separate decoding do-loops for direct, window, and wnext == 0
314	- Special case for distance > 1 copies to do overlapped load and store copy
315	- Explicit branch predictions (based on measured branch probabilities)
316	- Deferring match copy and interspersed it with decoding subsequent codes
317	- Swapping literal/length else
318	- Swapping window/direct else
319	- Larger unrolled copy loops (three is about right)
320	- Moving len -= 3 statement into middle of loop
321	*/
322
323	#endif /* !ASMINF */