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/* inffast.c -- process literals and length/distance pairs fast
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* Copyright (C) 1995-2002 Mark Adler
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* For conditions of distribution and use, see copyright notice in zlib.h
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struct inflate_codes_state {int dummy;}; /* for buggy compilers */
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/* simplify the use of the inflate_huft type with some defines */
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#define exop word.what.Exop
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#define bits word.what.Bits
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/* macros for bit input with no checking and for returning unused bytes */
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#define GRABBITS(j) {while(k<(j)){b|=((uLong)NEXTBYTE)<<k;k+=8;}}
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#define UNGRAB {c=z->avail_in-n;c=(k>>3)<c?k>>3:c;n+=c;p-=c;k-=c<<3;}
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/* Called with number of bytes left to write in window at least 258
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(the maximum string length) and number of input bytes available
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at least ten. The ten bytes are six bytes for the longest length/
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distance pair plus four bytes for overloading the bit buffer. */
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int inflate_fast(bl, bd, tl, td, s, z)
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inflate_huft *td; /* need separate declaration for Borland C++ */
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inflate_blocks_statef *s;
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inflate_huft *t; /* temporary pointer */
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uInt e; /* extra bits or operation */
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uLong b; /* bit buffer */
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uInt k; /* bits in bit buffer */
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Bytef *p; /* input data pointer */
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uInt n; /* bytes available there */
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Bytef *q; /* output window write pointer */
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uInt m; /* bytes to end of window or read pointer */
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uInt ml; /* mask for literal/length tree */
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uInt md; /* mask for distance tree */
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uInt c; /* bytes to copy */
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uInt d; /* distance back to copy from */
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Bytef *r; /* copy source pointer */
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/* load input, output, bit values */
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/* initialize masks */
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ml = inflate_mask[bl];
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md = inflate_mask[bd];
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/* do until not enough input or output space for fast loop */
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do { /* assume called with m >= 258 && n >= 10 */
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/* get literal/length code */
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GRABBITS(20) /* max bits for literal/length code */
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if ((e = (t = tl + ((uInt)b & ml))->exop) == 0)
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Tracevv((stderr, t->base >= 0x20 && t->base < 0x7f ?
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"inflate: * literal '%c'\n" :
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"inflate: * literal 0x%02x\n", t->base));
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/* get extra bits for length */
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c = t->base + ((uInt)b & inflate_mask[e]);
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Tracevv((stderr, "inflate: * length %u\n", c));
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/* decode distance base of block to copy */
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GRABBITS(15); /* max bits for distance code */
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e = (t = td + ((uInt)b & md))->exop;
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/* get extra bits to add to distance base */
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GRABBITS(e) /* get extra bits (up to 13) */
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d = t->base + ((uInt)b & inflate_mask[e]);
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Tracevv((stderr, "inflate: * distance %u\n", d));
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if (r < s->window) /* wrap if needed */
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r += s->end - s->window; /* force pointer in window */
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} while (r < s->window); /* covers invalid distances */
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c -= e; /* wrapped copy */
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else /* normal copy */
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else /* normal copy */
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else if ((e & 64) == 0)
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e = (t += ((uInt)b & inflate_mask[e]))->exop;
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z->msg = (char*)"invalid distance code";
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if ((e = (t += ((uInt)b & inflate_mask[e]))->exop) == 0)
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Tracevv((stderr, t->base >= 0x20 && t->base < 0x7f ?
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"inflate: * literal '%c'\n" :
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"inflate: * literal 0x%02x\n", t->base));
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*q++ = (Byte)t->base;
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Tracevv((stderr, "inflate: * end of block\n"));
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z->msg = (char*)"invalid literal/length code";
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} while (m >= 258 && n >= 10);
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/* not enough input or output--restore pointers and return */
added
removed
zlib/inffast.c
