summaryrefslogtreecommitdiff
path: root/lib/zlib_inflate/inffast.c
diff options
context:
space:
mode:
Diffstat (limited to 'lib/zlib_inflate/inffast.c')
-rw-r--r--lib/zlib_inflate/inffast.c176
1 files changed, 176 insertions, 0 deletions
diff --git a/lib/zlib_inflate/inffast.c b/lib/zlib_inflate/inffast.c
new file mode 100644
index 000000000000..0bd7623fc85a
--- /dev/null
+++ b/lib/zlib_inflate/inffast.c
@@ -0,0 +1,176 @@
+/* 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 "infblock.h"
+#include "infcodes.h"
+#include "infutil.h"
+#include "inffast.h"
+
+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
+)
+{
+ 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 {
+ 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 /* normal copy */
+ {
+ *q++ = *r++; c--;
+ *q++ = *r++; c--;
+ do {
+ *q++ = *r++;
+ } while (--c);
+ }
+ 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 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;
+}