[pcsx_rearmed.git] / deps / libchdr / deps / zlib-1.3.1 / 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(z_streamp strm, unsigned start) {
    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 const *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	*/
648db22b	50	void ZLIB_INTERNAL inflate_fast(z_streamp strm, unsigned start) {
b24e7fce	51	struct inflate_state FAR *state;
	52	z_const unsigned char FAR in; / local strm->next_in */
	53	z_const unsigned char FAR last; / have enough input while in < last */
	54	unsigned char FAR out; / local strm->next_out */
	55	unsigned char FAR beg; / inflate()'s initial strm->next_out */
	56	unsigned char FAR end; / while out < end, enough space available */
	57	#ifdef INFLATE_STRICT
	58	unsigned dmax; /* maximum distance from zlib header */
	59	#endif
	60	unsigned wsize; /* window size or zero if not using window */
	61	unsigned whave; /* valid bytes in the window */
	62	unsigned wnext; /* window write index */
	63	unsigned char FAR window; / allocated sliding window, if wsize != 0 */
	64	unsigned long hold; /* local strm->hold */
	65	unsigned bits; /* local strm->bits */
	66	code const FAR lcode; / local strm->lencode */
	67	code const FAR dcode; / local strm->distcode */
	68	unsigned lmask; /* mask for first level of length codes */
	69	unsigned dmask; /* mask for first level of distance codes */
9e052883	70	code const here; / retrieved table entry */
b24e7fce	71	unsigned op; /* code bits, operation, extra bits, or */
	72	/* window position, window bytes to copy */
	73	unsigned len; /* match length, unused bytes */
	74	unsigned dist; /* match distance */
	75	unsigned char FAR from; / where to copy match from */
	76
	77	/* copy state to local variables */
	78	state = (struct inflate_state FAR *)strm->state;
	79	in = strm->next_in;
	80	last = in + (strm->avail_in - 5);
	81	out = strm->next_out;
	82	beg = out - (start - strm->avail_out);
	83	end = out + (strm->avail_out - 257);
	84	#ifdef INFLATE_STRICT
	85	dmax = state->dmax;
	86	#endif
	87	wsize = state->wsize;
	88	whave = state->whave;
	89	wnext = state->wnext;
	90	window = state->window;
	91	hold = state->hold;
	92	bits = state->bits;
	93	lcode = state->lencode;
	94	dcode = state->distcode;
	95	lmask = (1U << state->lenbits) - 1;
	96	dmask = (1U << state->distbits) - 1;
	97
	98	/* decode literals and length/distances until end-of-block or not enough
	99	input data or output space */
	100	do {
	101	if (bits < 15) {
	102	hold += (unsigned long)(*in++) << bits;
	103	bits += 8;
	104	hold += (unsigned long)(*in++) << bits;
	105	bits += 8;
	106	}
9e052883	107	here = lcode + (hold & lmask);
b24e7fce	108	dolen:
9e052883	109	op = (unsigned)(here->bits);
b24e7fce	110	hold >>= op;
b24e7fce	111	bits -= op;
9e052883	112	op = (unsigned)(here->op);
b24e7fce	113	if (op == 0) { /* literal */
9e052883	114	Tracevv((stderr, here->val >= 0x20 && here->val < 0x7f ?
b24e7fce	115	"inflate: literal '%c'\n" :
9e052883	116	"inflate: literal 0x%02x\n", here->val));
9e052883	117	*out++ = (unsigned char)(here->val);
b24e7fce	118	}
b24e7fce	119	else if (op & 16) { /* length base */
9e052883	120	len = (unsigned)(here->val);
b24e7fce	121	op &= 15; /* number of extra bits */
	122	if (op) {
	123	if (bits < op) {
	124	hold += (unsigned long)(*in++) << bits;
	125	bits += 8;
	126	}
	127	len += (unsigned)hold & ((1U << op) - 1);
	128	hold >>= op;
	129	bits -= op;
	130	}
	131	Tracevv((stderr, "inflate: length %u\n", len));
	132	if (bits < 15) {
	133	hold += (unsigned long)(*in++) << bits;
	134	bits += 8;
	135	hold += (unsigned long)(*in++) << bits;
	136	bits += 8;
	137	}
9e052883	138	here = dcode + (hold & dmask);
b24e7fce	139	dodist:
9e052883	140	op = (unsigned)(here->bits);
b24e7fce	141	hold >>= op;
b24e7fce	142	bits -= op;
9e052883	143	op = (unsigned)(here->op);
b24e7fce	144	if (op & 16) { /* distance base */
9e052883	145	dist = (unsigned)(here->val);
b24e7fce	146	op &= 15; /* number of extra bits */
	147	if (bits < op) {
	148	hold += (unsigned long)(*in++) << bits;
	149	bits += 8;
	150	if (bits < op) {
	151	hold += (unsigned long)(*in++) << bits;
	152	bits += 8;
	153	}
	154	}
	155	dist += (unsigned)hold & ((1U << op) - 1);
	156	#ifdef INFLATE_STRICT
	157	if (dist > dmax) {
	158	strm->msg = (char *)"invalid distance too far back";
	159	state->mode = BAD;
	160	break;
	161	}
	162	#endif
	163	hold >>= op;
	164	bits -= op;
	165	Tracevv((stderr, "inflate: distance %u\n", dist));
	166	op = (unsigned)(out - beg); /* max distance in output */
	167	if (dist > op) { /* see if copy from window */
	168	op = dist - op; /* distance back in window */
	169	if (op > whave) {
	170	if (state->sane) {
	171	strm->msg =
	172	(char *)"invalid distance too far back";
	173	state->mode = BAD;
	174	break;
	175	}
	176	#ifdef INFLATE_ALLOW_INVALID_DISTANCE_TOOFAR_ARRR
	177	if (len <= op - whave) {
	178	do {
	179	*out++ = 0;
	180	} while (--len);
	181	continue;
	182	}
	183	len -= op - whave;
	184	do {
	185	*out++ = 0;
	186	} while (--op > whave);
	187	if (op == 0) {
	188	from = out - dist;
	189	do {
	190	out++ = from++;
	191	} while (--len);
	192	continue;
	193	}
	194	#endif
	195	}
	196	from = window;
	197	if (wnext == 0) { /* very common case */
	198	from += wsize - op;
	199	if (op < len) { /* some from window */
	200	len -= op;
	201	do {
	202	out++ = from++;
	203	} while (--op);
	204	from = out - dist; /* rest from output */
	205	}
	206	}
	207	else if (wnext < op) { /* wrap around window */
	208	from += wsize + wnext - op;
	209	op -= wnext;
210	if (op < len) { /* some from end of window */
211	len -= op;
212	do {
213	out++ = from++;
214	} while (--op);
215	from = window;
216	if (wnext < len) { /* some from start of window */
217	op = wnext;
218	len -= op;
219	do {
220	out++ = from++;
221	} while (--op);
222	from = out - dist; /* rest from output */
223	}
224	}
225	}
226	else { /* contiguous in window */
227	from += wnext - op;
228	if (op < len) { /* some from window */
229	len -= op;
230	do {
231	out++ = from++;
232	} while (--op);
233	from = out - dist; /* rest from output */
234	}
235	}
236	while (len > 2) {
237	out++ = from++;
238	out++ = from++;
239	out++ = from++;
240	len -= 3;
241	}
242	if (len) {
243	out++ = from++;
244	if (len > 1)
245	out++ = from++;
246	}
247	}
248	else {
249	from = out - dist; /* copy direct from output */
250	do { /* minimum length is three */
251	out++ = from++;
252	out++ = from++;
253	out++ = from++;
254	len -= 3;
255	} while (len > 2);
256	if (len) {
257	out++ = from++;
258	if (len > 1)
259	out++ = from++;
260	}
261	}
262	}
263	else if ((op & 64) == 0) { /* 2nd level distance code */
9e052883	264	here = dcode + here->val + (hold & ((1U << op) - 1));
b24e7fce	265	goto dodist;
	266	}
	267	else {
	268	strm->msg = (char *)"invalid distance code";
	269	state->mode = BAD;
	270	break;
	271	}
	272	}
	273	else if ((op & 64) == 0) { /* 2nd level length code */
9e052883	274	here = lcode + here->val + (hold & ((1U << op) - 1));
b24e7fce	275	goto dolen;
	276	}
	277	else if (op & 32) { /* end-of-block */
	278	Tracevv((stderr, "inflate: end of block\n"));
	279	state->mode = TYPE;
	280	break;
	281	}
	282	else {
	283	strm->msg = (char *)"invalid literal/length code";
	284	state->mode = BAD;
	285	break;
	286	}
	287	} while (in < last && out < end);
	288
	289	/* return unused bytes (on entry, bits < 8, so in won't go too far back) */
	290	len = bits >> 3;
	291	in -= len;
	292	bits -= len << 3;
	293	hold &= (1U << bits) - 1;
	294
	295	/* update state and return */
	296	strm->next_in = in;
	297	strm->next_out = out;
	298	strm->avail_in = (unsigned)(in < last ? 5 + (last - in) : 5 - (in - last));
	299	strm->avail_out = (unsigned)(out < end ?
	300	257 + (end - out) : 257 - (out - end));
	301	state->hold = hold;
	302	state->bits = bits;
	303	return;
	304	}
	305
	306	/*
	307	inflate_fast() speedups that turned out slower (on a PowerPC G3 750CXe):
	308	- Using bit fields for code structure
	309	- Different op definition to avoid & for extra bits (do & for table bits)
	310	- Three separate decoding do-loops for direct, window, and wnext == 0
	311	- Special case for distance > 1 copies to do overlapped load and store copy
	312	- Explicit branch predictions (based on measured branch probabilities)
	313	- Deferring match copy and interspersed it with decoding subsequent codes
	314	- Swapping literal/length else
	315	- Swapping window/direct else
	316	- Larger unrolled copy loops (three is about right)
	317	- Moving len -= 3 statement into middle of loop
	318	*/
	319
	320	#endif /* !ASMINF */