-/* inffast.c -- fast decoding
- * Copyright (C) 1995-2004 Mark Adler
- * For conditions of distribution and use, see copyright notice in zlib.h
+/* 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 <linux/zutil.h>
#include "inftrees.h"
-#include "inflate.h"
+#include "infblock.h"
+#include "infcodes.h"
+#include "infutil.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.
-
- - @start: inflate()'s starting value for strm->avail_out
- */
-void inflate_fast(z_streamp strm, unsigned start)
+struct inflate_codes_state;
+
+/* 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 zlib_inflate_fast(
+ uInt bl,
+ uInt bd,
+ inflate_huft *tl,
+ inflate_huft *td, /* need separate declaration for Borland C++ */
+ inflate_blocks_statef *s,
+ z_streamp z
+)
{
- struct inflate_state *state;
- unsigned char *in; /* local strm->next_in */
- unsigned char *last; /* while in < last, enough input available */
- unsigned char *out; /* local strm->next_out */
- unsigned char *beg; /* inflate()'s initial strm->next_out */
- unsigned char *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 *window; /* allocated sliding window, if wsize != 0 */
- unsigned long hold; /* local strm->hold */
- unsigned bits; /* local strm->bits */
- code const *lcode; /* local strm->lencode */
- code const *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 *from; /* where to copy match from */
-
- /* copy state to local variables */
- state = (struct inflate_state *)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 */
+ inflate_huft *t; /* temporary pointer */
+ uInt e; /* extra bits or operation */
+ uLong b; /* bit buffer */
+ uInt k; /* bits in bit buffer */
+ Byte *p; /* input data pointer */
+ uInt n; /* bytes available there */
+ Byte *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 */
+ Byte *r; /* copy source pointer */
+
+ /* load input, output, bit values */
+ LOAD
+
+ /* initialize masks */
+ ml = zlib_inflate_mask[bl];
+ md = zlib_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)
+ *q++ = (Byte)t->base;
+ m--;
+ continue;
+ }
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 */
- 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;
- }
- 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;
- 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);
- }
- }
+ DUMPBITS(t->bits)
+ if (e & 16)
+ {
+ /* get extra bits for length */
+ e &= 15;
+ c = t->base + ((uInt)b & zlib_inflate_mask[e]);
+ DUMPBITS(e)
+
+ /* 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 & zlib_inflate_mask[e]);
+ DUMPBITS(e)
+
+ /* do the copy */
+ m -= c;
+ r = q - d;
+ if (r < s->window) /* wrap if needed */
+ {
+ do {
+ r += s->end - s->window; /* force pointer in window */
+ } while (r < s->window); /* covers invalid distances */
+ e = s->end - r;
+ if (c > e)
+ {
+ c -= e; /* wrapped copy */
+ do {
+ *q++ = *r++;
+ } while (--e);
+ r = s->window;
+ do {
+ *q++ = *r++;
+ } while (--c);
+ }
+ else /* normal copy */
+ {
+ *q++ = *r++; c--;
+ *q++ = *r++; c--;
+ do {
+ *q++ = *r++;
+ } while (--c);
+ }
}
- else if ((op & 64) == 0) { /* 2nd level distance code */
- this = dcode[this.val + (hold & ((1U << op) - 1))];
- goto dodist;
+ else /* normal copy */
+ {
+ *q++ = *r++; c--;
+ *q++ = *r++; c--;
+ do {
+ *q++ = *r++;
+ } while (--c);
}
- 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 */
- state->mode = TYPE;
break;
+ }
+ else if ((e & 64) == 0)
+ {
+ t += t->base;
+ e = (t += ((uInt)b & zlib_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 & zlib_inflate_mask[e]))->exop) == 0)
+ {
+ DUMPBITS(t->bits)
+ *q++ = (Byte)t->base;
+ m--;
+ 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;
+ }
+ else if (e & 32)
+ {
+ 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;
}
-
-/*
- 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 */
git://git.onelab.eu / linux-2.6.git / blobdiff