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authordimitri <dimitri@afe2bf4a-e733-0410-8a33-86f594647bc7>2002-02-24 18:57:25 (GMT)
committerdimitri <dimitri@afe2bf4a-e733-0410-8a33-86f594647bc7>2002-02-24 18:57:25 (GMT)
commitc7bc295f92f56d1dea369663e058933f550a0187 (patch)
tree81d72027898b1a75221b9ca82b04075277821a9f /libpng/inffast.c
parent9793ce49f1d7641854ef0608b34c1dd2d4891a20 (diff)
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Release-1.2.14-20020224
Diffstat (limited to 'libpng/inffast.c')
-rw-r--r--libpng/inffast.c170
1 files changed, 170 insertions, 0 deletions
diff --git a/libpng/inffast.c b/libpng/inffast.c
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--- /dev/null
+++ b/libpng/inffast.c
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+/* 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;
+}