Richard Purdie | 4f3865f | 2006-06-22 14:47:34 -0700 | [diff] [blame] | 1 | /* inffast.c -- fast decoding |
| 2 | * Copyright (C) 1995-2004 Mark Adler |
| 3 | * For conditions of distribution and use, see copyright notice in zlib.h |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4 | */ |
| 5 | |
| 6 | #include <linux/zutil.h> |
| 7 | #include "inftrees.h" |
Richard Purdie | 4f3865f | 2006-06-22 14:47:34 -0700 | [diff] [blame] | 8 | #include "inflate.h" |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 9 | #include "inffast.h" |
| 10 | |
Benjamin Herrenschmidt | 6846ee5 | 2010-01-13 16:19:34 +1100 | [diff] [blame] | 11 | /* Only do the unaligned "Faster" variant when |
| 12 | * CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS is set |
| 13 | * |
| 14 | * On powerpc, it won't be as we don't include autoconf.h |
| 15 | * automatically for the boot wrapper, which is intended as |
| 16 | * we run in an environment where we may not be able to deal |
| 17 | * with (even rare) alignment faults. In addition, we do not |
| 18 | * define __KERNEL__ for arch/powerpc/boot unlike x86 |
| 19 | */ |
| 20 | |
| 21 | #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS |
| 22 | #include <asm/unaligned.h> |
| 23 | #include <asm/byteorder.h> |
| 24 | #endif |
| 25 | |
Richard Purdie | 4f3865f | 2006-06-22 14:47:34 -0700 | [diff] [blame] | 26 | #ifndef ASMINF |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 27 | |
Richard Purdie | 4f3865f | 2006-06-22 14:47:34 -0700 | [diff] [blame] | 28 | /* Allow machine dependent optimization for post-increment or pre-increment. |
| 29 | Based on testing to date, |
| 30 | Pre-increment preferred for: |
| 31 | - PowerPC G3 (Adler) |
| 32 | - MIPS R5000 (Randers-Pehrson) |
| 33 | Post-increment preferred for: |
| 34 | - none |
| 35 | No measurable difference: |
| 36 | - Pentium III (Anderson) |
| 37 | - M68060 (Nikl) |
| 38 | */ |
| 39 | #ifdef POSTINC |
| 40 | # define OFF 0 |
| 41 | # define PUP(a) *(a)++ |
Joakim Tjernlund | ac4c2a3 | 2010-01-08 14:42:40 -0800 | [diff] [blame] | 42 | # define UP_UNALIGNED(a) get_unaligned((a)++) |
Richard Purdie | 4f3865f | 2006-06-22 14:47:34 -0700 | [diff] [blame] | 43 | #else |
| 44 | # define OFF 1 |
| 45 | # define PUP(a) *++(a) |
Joakim Tjernlund | ac4c2a3 | 2010-01-08 14:42:40 -0800 | [diff] [blame] | 46 | # define UP_UNALIGNED(a) get_unaligned(++(a)) |
Richard Purdie | 4f3865f | 2006-06-22 14:47:34 -0700 | [diff] [blame] | 47 | #endif |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 48 | |
Richard Purdie | 4f3865f | 2006-06-22 14:47:34 -0700 | [diff] [blame] | 49 | /* |
| 50 | Decode literal, length, and distance codes and write out the resulting |
| 51 | literal and match bytes until either not enough input or output is |
| 52 | available, an end-of-block is encountered, or a data error is encountered. |
| 53 | When large enough input and output buffers are supplied to inflate(), for |
| 54 | example, a 16K input buffer and a 64K output buffer, more than 95% of the |
| 55 | inflate execution time is spent in this routine. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 56 | |
Richard Purdie | 4f3865f | 2006-06-22 14:47:34 -0700 | [diff] [blame] | 57 | Entry assumptions: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 58 | |
Richard Purdie | 4f3865f | 2006-06-22 14:47:34 -0700 | [diff] [blame] | 59 | state->mode == LEN |
| 60 | strm->avail_in >= 6 |
| 61 | strm->avail_out >= 258 |
| 62 | start >= strm->avail_out |
| 63 | state->bits < 8 |
| 64 | |
| 65 | On return, state->mode is one of: |
| 66 | |
| 67 | LEN -- ran out of enough output space or enough available input |
| 68 | TYPE -- reached end of block code, inflate() to interpret next block |
| 69 | BAD -- error in block data |
| 70 | |
| 71 | Notes: |
| 72 | |
| 73 | - The maximum input bits used by a length/distance pair is 15 bits for the |
| 74 | length code, 5 bits for the length extra, 15 bits for the distance code, |
| 75 | and 13 bits for the distance extra. This totals 48 bits, or six bytes. |
| 76 | Therefore if strm->avail_in >= 6, then there is enough input to avoid |
| 77 | checking for available input while decoding. |
| 78 | |
| 79 | - The maximum bytes that a single length/distance pair can output is 258 |
| 80 | bytes, which is the maximum length that can be coded. inflate_fast() |
| 81 | requires strm->avail_out >= 258 for each loop to avoid checking for |
| 82 | output space. |
Randy Dunlap | b762450e | 2006-06-27 02:53:26 -0700 | [diff] [blame] | 83 | |
| 84 | - @start: inflate()'s starting value for strm->avail_out |
Richard Purdie | 4f3865f | 2006-06-22 14:47:34 -0700 | [diff] [blame] | 85 | */ |
Randy Dunlap | b762450e | 2006-06-27 02:53:26 -0700 | [diff] [blame] | 86 | void inflate_fast(z_streamp strm, unsigned start) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 87 | { |
Richard Purdie | 4f3865f | 2006-06-22 14:47:34 -0700 | [diff] [blame] | 88 | struct inflate_state *state; |
Denys Vlasenko | 8336793 | 2007-09-30 17:56:49 -0700 | [diff] [blame] | 89 | const unsigned char *in; /* local strm->next_in */ |
| 90 | const unsigned char *last; /* while in < last, enough input available */ |
| 91 | unsigned char *out; /* local strm->next_out */ |
| 92 | unsigned char *beg; /* inflate()'s initial strm->next_out */ |
| 93 | unsigned char *end; /* while out < end, enough space available */ |
Richard Purdie | 4f3865f | 2006-06-22 14:47:34 -0700 | [diff] [blame] | 94 | #ifdef INFLATE_STRICT |
| 95 | unsigned dmax; /* maximum distance from zlib header */ |
| 96 | #endif |
| 97 | unsigned wsize; /* window size or zero if not using window */ |
| 98 | unsigned whave; /* valid bytes in the window */ |
| 99 | unsigned write; /* window write index */ |
Denys Vlasenko | 8336793 | 2007-09-30 17:56:49 -0700 | [diff] [blame] | 100 | unsigned char *window; /* allocated sliding window, if wsize != 0 */ |
Richard Purdie | 4f3865f | 2006-06-22 14:47:34 -0700 | [diff] [blame] | 101 | unsigned long hold; /* local strm->hold */ |
| 102 | unsigned bits; /* local strm->bits */ |
Denys Vlasenko | 8336793 | 2007-09-30 17:56:49 -0700 | [diff] [blame] | 103 | code const *lcode; /* local strm->lencode */ |
| 104 | code const *dcode; /* local strm->distcode */ |
Richard Purdie | 4f3865f | 2006-06-22 14:47:34 -0700 | [diff] [blame] | 105 | unsigned lmask; /* mask for first level of length codes */ |
| 106 | unsigned dmask; /* mask for first level of distance codes */ |
| 107 | code this; /* retrieved table entry */ |
| 108 | unsigned op; /* code bits, operation, extra bits, or */ |
| 109 | /* window position, window bytes to copy */ |
| 110 | unsigned len; /* match length, unused bytes */ |
| 111 | unsigned dist; /* match distance */ |
Denys Vlasenko | 8336793 | 2007-09-30 17:56:49 -0700 | [diff] [blame] | 112 | unsigned char *from; /* where to copy match from */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 113 | |
Richard Purdie | 4f3865f | 2006-06-22 14:47:34 -0700 | [diff] [blame] | 114 | /* copy state to local variables */ |
| 115 | state = (struct inflate_state *)strm->state; |
| 116 | in = strm->next_in - OFF; |
| 117 | last = in + (strm->avail_in - 5); |
| 118 | out = strm->next_out - OFF; |
| 119 | beg = out - (start - strm->avail_out); |
| 120 | end = out + (strm->avail_out - 257); |
| 121 | #ifdef INFLATE_STRICT |
| 122 | dmax = state->dmax; |
| 123 | #endif |
| 124 | wsize = state->wsize; |
| 125 | whave = state->whave; |
| 126 | write = state->write; |
| 127 | window = state->window; |
| 128 | hold = state->hold; |
| 129 | bits = state->bits; |
| 130 | lcode = state->lencode; |
| 131 | dcode = state->distcode; |
| 132 | lmask = (1U << state->lenbits) - 1; |
| 133 | dmask = (1U << state->distbits) - 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 134 | |
Richard Purdie | 4f3865f | 2006-06-22 14:47:34 -0700 | [diff] [blame] | 135 | /* decode literals and length/distances until end-of-block or not enough |
| 136 | input data or output space */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 137 | do { |
Richard Purdie | 4f3865f | 2006-06-22 14:47:34 -0700 | [diff] [blame] | 138 | if (bits < 15) { |
| 139 | hold += (unsigned long)(PUP(in)) << bits; |
| 140 | bits += 8; |
| 141 | hold += (unsigned long)(PUP(in)) << bits; |
| 142 | bits += 8; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 143 | } |
Richard Purdie | 4f3865f | 2006-06-22 14:47:34 -0700 | [diff] [blame] | 144 | this = lcode[hold & lmask]; |
| 145 | dolen: |
| 146 | op = (unsigned)(this.bits); |
| 147 | hold >>= op; |
| 148 | bits -= op; |
| 149 | op = (unsigned)(this.op); |
| 150 | if (op == 0) { /* literal */ |
| 151 | PUP(out) = (unsigned char)(this.val); |
| 152 | } |
| 153 | else if (op & 16) { /* length base */ |
| 154 | len = (unsigned)(this.val); |
| 155 | op &= 15; /* number of extra bits */ |
| 156 | if (op) { |
| 157 | if (bits < op) { |
| 158 | hold += (unsigned long)(PUP(in)) << bits; |
| 159 | bits += 8; |
| 160 | } |
| 161 | len += (unsigned)hold & ((1U << op) - 1); |
| 162 | hold >>= op; |
| 163 | bits -= op; |
| 164 | } |
| 165 | if (bits < 15) { |
| 166 | hold += (unsigned long)(PUP(in)) << bits; |
| 167 | bits += 8; |
| 168 | hold += (unsigned long)(PUP(in)) << bits; |
| 169 | bits += 8; |
| 170 | } |
| 171 | this = dcode[hold & dmask]; |
| 172 | dodist: |
| 173 | op = (unsigned)(this.bits); |
| 174 | hold >>= op; |
| 175 | bits -= op; |
| 176 | op = (unsigned)(this.op); |
| 177 | if (op & 16) { /* distance base */ |
| 178 | dist = (unsigned)(this.val); |
| 179 | op &= 15; /* number of extra bits */ |
| 180 | if (bits < op) { |
| 181 | hold += (unsigned long)(PUP(in)) << bits; |
| 182 | bits += 8; |
| 183 | if (bits < op) { |
| 184 | hold += (unsigned long)(PUP(in)) << bits; |
| 185 | bits += 8; |
| 186 | } |
| 187 | } |
| 188 | dist += (unsigned)hold & ((1U << op) - 1); |
| 189 | #ifdef INFLATE_STRICT |
| 190 | if (dist > dmax) { |
| 191 | strm->msg = (char *)"invalid distance too far back"; |
| 192 | state->mode = BAD; |
| 193 | break; |
| 194 | } |
| 195 | #endif |
| 196 | hold >>= op; |
| 197 | bits -= op; |
| 198 | op = (unsigned)(out - beg); /* max distance in output */ |
| 199 | if (dist > op) { /* see if copy from window */ |
| 200 | op = dist - op; /* distance back in window */ |
| 201 | if (op > whave) { |
| 202 | strm->msg = (char *)"invalid distance too far back"; |
| 203 | state->mode = BAD; |
| 204 | break; |
| 205 | } |
| 206 | from = window - OFF; |
| 207 | if (write == 0) { /* very common case */ |
| 208 | from += wsize - op; |
| 209 | if (op < len) { /* some from window */ |
| 210 | len -= op; |
| 211 | do { |
| 212 | PUP(out) = PUP(from); |
| 213 | } while (--op); |
| 214 | from = out - dist; /* rest from output */ |
| 215 | } |
| 216 | } |
| 217 | else if (write < op) { /* wrap around window */ |
| 218 | from += wsize + write - op; |
| 219 | op -= write; |
| 220 | if (op < len) { /* some from end of window */ |
| 221 | len -= op; |
| 222 | do { |
| 223 | PUP(out) = PUP(from); |
| 224 | } while (--op); |
| 225 | from = window - OFF; |
| 226 | if (write < len) { /* some from start of window */ |
| 227 | op = write; |
| 228 | len -= op; |
| 229 | do { |
| 230 | PUP(out) = PUP(from); |
| 231 | } while (--op); |
| 232 | from = out - dist; /* rest from output */ |
| 233 | } |
| 234 | } |
| 235 | } |
| 236 | else { /* contiguous in window */ |
| 237 | from += write - op; |
| 238 | if (op < len) { /* some from window */ |
| 239 | len -= op; |
| 240 | do { |
| 241 | PUP(out) = PUP(from); |
| 242 | } while (--op); |
| 243 | from = out - dist; /* rest from output */ |
| 244 | } |
| 245 | } |
| 246 | while (len > 2) { |
| 247 | PUP(out) = PUP(from); |
| 248 | PUP(out) = PUP(from); |
| 249 | PUP(out) = PUP(from); |
| 250 | len -= 3; |
| 251 | } |
| 252 | if (len) { |
| 253 | PUP(out) = PUP(from); |
| 254 | if (len > 1) |
| 255 | PUP(out) = PUP(from); |
| 256 | } |
| 257 | } |
| 258 | else { |
Benjamin Herrenschmidt | 6846ee5 | 2010-01-13 16:19:34 +1100 | [diff] [blame] | 259 | #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS |
Joakim Tjernlund | ac4c2a3 | 2010-01-08 14:42:40 -0800 | [diff] [blame] | 260 | unsigned short *sout; |
| 261 | unsigned long loops; |
| 262 | |
Richard Purdie | 4f3865f | 2006-06-22 14:47:34 -0700 | [diff] [blame] | 263 | from = out - dist; /* copy direct from output */ |
Joakim Tjernlund | ac4c2a3 | 2010-01-08 14:42:40 -0800 | [diff] [blame] | 264 | /* minimum length is three */ |
| 265 | /* Align out addr */ |
| 266 | if (!((long)(out - 1 + OFF) & 1)) { |
| 267 | PUP(out) = PUP(from); |
| 268 | len--; |
| 269 | } |
| 270 | sout = (unsigned short *)(out - OFF); |
| 271 | if (dist > 2) { |
| 272 | unsigned short *sfrom; |
| 273 | |
| 274 | sfrom = (unsigned short *)(from - OFF); |
| 275 | loops = len >> 1; |
| 276 | do |
| 277 | PUP(sout) = UP_UNALIGNED(sfrom); |
| 278 | while (--loops); |
| 279 | out = (unsigned char *)sout + OFF; |
| 280 | from = (unsigned char *)sfrom + OFF; |
| 281 | } else { /* dist == 1 or dist == 2 */ |
| 282 | unsigned short pat16; |
| 283 | |
| 284 | pat16 = *(sout-2+2*OFF); |
| 285 | if (dist == 1) |
| 286 | #if defined(__BIG_ENDIAN) |
| 287 | pat16 = (pat16 & 0xff) | ((pat16 & 0xff) << 8); |
| 288 | #elif defined(__LITTLE_ENDIAN) |
| 289 | pat16 = (pat16 & 0xff00) | ((pat16 & 0xff00) >> 8); |
| 290 | #else |
| 291 | #error __BIG_ENDIAN nor __LITTLE_ENDIAN is defined |
| 292 | #endif |
| 293 | loops = len >> 1; |
| 294 | do |
| 295 | PUP(sout) = pat16; |
| 296 | while (--loops); |
| 297 | out = (unsigned char *)sout + OFF; |
| 298 | } |
| 299 | if (len & 1) |
| 300 | PUP(out) = PUP(from); |
Benjamin Herrenschmidt | 6846ee5 | 2010-01-13 16:19:34 +1100 | [diff] [blame] | 301 | #else /* CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS */ |
| 302 | from = out - dist; /* copy direct from output */ |
| 303 | do { /* minimum length is three */ |
| 304 | PUP(out) = PUP(from); |
| 305 | PUP(out) = PUP(from); |
| 306 | PUP(out) = PUP(from); |
| 307 | len -= 3; |
| 308 | } while (len > 2); |
| 309 | if (len) { |
| 310 | PUP(out) = PUP(from); |
| 311 | if (len > 1) |
| 312 | PUP(out) = PUP(from); |
| 313 | } |
| 314 | #endif /* !CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS */ |
Richard Purdie | 4f3865f | 2006-06-22 14:47:34 -0700 | [diff] [blame] | 315 | } |
| 316 | } |
| 317 | else if ((op & 64) == 0) { /* 2nd level distance code */ |
| 318 | this = dcode[this.val + (hold & ((1U << op) - 1))]; |
| 319 | goto dodist; |
| 320 | } |
| 321 | else { |
| 322 | strm->msg = (char *)"invalid distance code"; |
| 323 | state->mode = BAD; |
| 324 | break; |
| 325 | } |
| 326 | } |
| 327 | else if ((op & 64) == 0) { /* 2nd level length code */ |
| 328 | this = lcode[this.val + (hold & ((1U << op) - 1))]; |
| 329 | goto dolen; |
| 330 | } |
| 331 | else if (op & 32) { /* end-of-block */ |
| 332 | state->mode = TYPE; |
| 333 | break; |
| 334 | } |
| 335 | else { |
| 336 | strm->msg = (char *)"invalid literal/length code"; |
| 337 | state->mode = BAD; |
| 338 | break; |
| 339 | } |
| 340 | } while (in < last && out < end); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 341 | |
Richard Purdie | 4f3865f | 2006-06-22 14:47:34 -0700 | [diff] [blame] | 342 | /* return unused bytes (on entry, bits < 8, so in won't go too far back) */ |
| 343 | len = bits >> 3; |
| 344 | in -= len; |
| 345 | bits -= len << 3; |
| 346 | hold &= (1U << bits) - 1; |
| 347 | |
| 348 | /* update state and return */ |
| 349 | strm->next_in = in + OFF; |
| 350 | strm->next_out = out + OFF; |
| 351 | strm->avail_in = (unsigned)(in < last ? 5 + (last - in) : 5 - (in - last)); |
| 352 | strm->avail_out = (unsigned)(out < end ? |
| 353 | 257 + (end - out) : 257 - (out - end)); |
| 354 | state->hold = hold; |
| 355 | state->bits = bits; |
| 356 | return; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 357 | } |
Richard Purdie | 4f3865f | 2006-06-22 14:47:34 -0700 | [diff] [blame] | 358 | |
| 359 | /* |
| 360 | inflate_fast() speedups that turned out slower (on a PowerPC G3 750CXe): |
| 361 | - Using bit fields for code structure |
| 362 | - Different op definition to avoid & for extra bits (do & for table bits) |
| 363 | - Three separate decoding do-loops for direct, window, and write == 0 |
| 364 | - Special case for distance > 1 copies to do overlapped load and store copy |
| 365 | - Explicit branch predictions (based on measured branch probabilities) |
| 366 | - Deferring match copy and interspersed it with decoding subsequent codes |
| 367 | - Swapping literal/length else |
| 368 | - Swapping window/direct else |
| 369 | - Larger unrolled copy loops (three is about right) |
| 370 | - Moving len -= 3 statement into middle of loop |
| 371 | */ |
| 372 | |
| 373 | #endif /* !ASMINF */ |