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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 107 | pj | 1 | /* inffast.c -- process literals and length/distance pairs fast |
| 2 | * Copyright (C) 1995-2002 Mark Adler |
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| 3 | * For conditions of distribution and use, see copyright notice in zlib.h |
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| 4 | */ |
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| 5 | |||
| 6 | #include "zutil.h" |
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| 7 | #include "inftrees.h" |
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| 8 | #include "infblock.h" |
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| 9 | #include "infcodes.h" |
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| 10 | #include "infutil.h" |
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| 11 | #include "inffast.h" |
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| 12 | |||
| 13 | struct inflate_codes_state {int dummy;}; /* for buggy compilers */ |
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| 14 | |||
| 15 | /* simplify the use of the inflate_huft type with some defines */ |
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| 16 | #define exop word.what.Exop |
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| 17 | #define bits word.what.Bits |
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| 18 | |||
| 19 | /* macros for bit input with no checking and for returning unused bytes */ |
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| 20 | #define GRABBITS(j) {while(k<(j)){b|=((uLong)NEXTBYTE)<<k;k+=8;}} |
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| 21 | #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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| 22 | |||
| 23 | /* Called with number of bytes left to write in window at least 258 |
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| 24 | (the maximum string length) and number of input bytes available |
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| 25 | at least ten. The ten bytes are six bytes for the longest length/ |
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| 26 | distance pair plus four bytes for overloading the bit buffer. */ |
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| 27 | |||
| 28 | int inflate_fast(bl, bd, tl, td, s, z) |
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| 29 | uInt bl, bd; |
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| 30 | inflate_huft *tl; |
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| 31 | inflate_huft *td; /* need separate declaration for Borland C++ */ |
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| 32 | inflate_blocks_statef *s; |
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| 33 | z_streamp z; |
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| 34 | { |
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| 35 | inflate_huft *t; /* temporary pointer */ |
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| 36 | uInt e; /* extra bits or operation */ |
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| 37 | uLong b; /* bit buffer */ |
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| 38 | uInt k; /* bits in bit buffer */ |
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| 39 | Bytef *p; /* input data pointer */ |
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| 40 | uInt n; /* bytes available there */ |
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| 41 | Bytef *q; /* output window write pointer */ |
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| 42 | uInt m; /* bytes to end of window or read pointer */ |
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| 43 | uInt ml; /* mask for literal/length tree */ |
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| 44 | uInt md; /* mask for distance tree */ |
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| 45 | uInt c; /* bytes to copy */ |
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| 46 | uInt d; /* distance back to copy from */ |
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| 47 | Bytef *r; /* copy source pointer */ |
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| 48 | |||
| 49 | /* load input, output, bit values */ |
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| 50 | LOAD |
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| 51 | |||
| 52 | /* initialize masks */ |
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| 53 | ml = inflate_mask[bl]; |
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| 54 | md = inflate_mask[bd]; |
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| 55 | |||
| 56 | /* do until not enough input or output space for fast loop */ |
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| 57 | do { /* assume called with m >= 258 && n >= 10 */ |
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| 58 | /* get literal/length code */ |
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| 59 | GRABBITS(20) /* max bits for literal/length code */ |
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| 60 | if ((e = (t = tl + ((uInt)b & ml))->exop) == 0) |
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| 61 | { |
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| 62 | DUMPBITS(t->bits) |
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| 63 | Tracevv((stderr, t->base >= 0x20 && t->base < 0x7f ? |
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| 64 | "inflate: * literal '%c'\n" : |
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| 65 | "inflate: * literal 0x%02x\n", t->base)); |
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| 66 | *q++ = (Byte)t->base; |
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| 67 | m--; |
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| 68 | continue; |
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| 69 | } |
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| 70 | do { |
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| 71 | DUMPBITS(t->bits) |
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| 72 | if (e & 16) |
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| 73 | { |
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| 74 | /* get extra bits for length */ |
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| 75 | e &= 15; |
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| 76 | c = t->base + ((uInt)b & inflate_mask[e]); |
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| 77 | DUMPBITS(e) |
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| 78 | Tracevv((stderr, "inflate: * length %u\n", c)); |
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| 79 | |||
| 80 | /* decode distance base of block to copy */ |
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| 81 | GRABBITS(15); /* max bits for distance code */ |
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| 82 | e = (t = td + ((uInt)b & md))->exop; |
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| 83 | do { |
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| 84 | DUMPBITS(t->bits) |
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| 85 | if (e & 16) |
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| 86 | { |
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| 87 | /* get extra bits to add to distance base */ |
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| 88 | e &= 15; |
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| 89 | GRABBITS(e) /* get extra bits (up to 13) */ |
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| 90 | d = t->base + ((uInt)b & inflate_mask[e]); |
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| 91 | DUMPBITS(e) |
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| 92 | Tracevv((stderr, "inflate: * distance %u\n", d)); |
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| 93 | |||
| 94 | /* do the copy */ |
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| 95 | m -= c; |
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| 96 | r = q - d; |
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| 97 | if (r < s->window) /* wrap if needed */ |
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| 98 | { |
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| 99 | do { |
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| 100 | r += s->end - s->window; /* force pointer in window */ |
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| 101 | } while (r < s->window); /* covers invalid distances */ |
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| 102 | e = s->end - r; |
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| 103 | if (c > e) |
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| 104 | { |
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| 105 | c -= e; /* wrapped copy */ |
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| 106 | do { |
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| 107 | *q++ = *r++; |
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| 108 | } while (--e); |
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| 109 | r = s->window; |
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| 110 | do { |
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| 111 | *q++ = *r++; |
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| 112 | } while (--c); |
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| 113 | } |
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| 114 | else /* normal copy */ |
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| 115 | { |
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| 116 | *q++ = *r++; c--; |
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| 117 | *q++ = *r++; c--; |
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| 118 | do { |
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| 119 | *q++ = *r++; |
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| 120 | } while (--c); |
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| 121 | } |
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| 122 | } |
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| 123 | else /* normal copy */ |
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| 124 | { |
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| 125 | *q++ = *r++; c--; |
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| 126 | *q++ = *r++; c--; |
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| 127 | do { |
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| 128 | *q++ = *r++; |
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| 129 | } while (--c); |
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| 130 | } |
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| 131 | break; |
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| 132 | } |
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| 133 | else if ((e & 64) == 0) |
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| 134 | { |
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| 135 | t += t->base; |
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| 136 | e = (t += ((uInt)b & inflate_mask[e]))->exop; |
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| 137 | } |
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| 138 | else |
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| 139 | { |
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| 140 | z->msg = (char*)"invalid distance code"; |
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| 141 | UNGRAB |
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| 142 | UPDATE |
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| 143 | return Z_DATA_ERROR; |
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| 144 | } |
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| 145 | } while (1); |
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| 146 | break; |
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| 147 | } |
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| 148 | if ((e & 64) == 0) |
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| 149 | { |
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| 150 | t += t->base; |
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| 151 | if ((e = (t += ((uInt)b & inflate_mask[e]))->exop) == 0) |
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| 152 | { |
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| 153 | DUMPBITS(t->bits) |
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| 154 | Tracevv((stderr, t->base >= 0x20 && t->base < 0x7f ? |
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| 155 | "inflate: * literal '%c'\n" : |
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| 156 | "inflate: * literal 0x%02x\n", t->base)); |
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| 157 | *q++ = (Byte)t->base; |
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| 158 | m--; |
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| 159 | break; |
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| 160 | } |
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| 161 | } |
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| 162 | else if (e & 32) |
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| 163 | { |
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| 164 | Tracevv((stderr, "inflate: * end of block\n")); |
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| 165 | UNGRAB |
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| 166 | UPDATE |
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| 167 | return Z_STREAM_END; |
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| 168 | } |
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| 169 | else |
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| 170 | { |
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| 171 | z->msg = (char*)"invalid literal/length code"; |
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| 172 | UNGRAB |
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| 173 | UPDATE |
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| 174 | return Z_DATA_ERROR; |
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| 175 | } |
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| 176 | } while (1); |
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| 177 | } while (m >= 258 && n >= 10); |
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| 178 | |||
| 179 | /* not enough input or output--restore pointers and return */ |
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| 180 | UNGRAB |
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| 181 | UPDATE |
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| 182 | return Z_OK; |
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| 183 | } |