LXR linux/lib/lz4/lz4

   1/*
   2 * LZ4 - Fast LZ compression algorithm
   3 * Copyright (C) 2011-2012, Yann Collet.
   4 * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
   5
   6 * Redistribution and use in source and binary forms, with or without
   7 * modification, are permitted provided that the following conditions are
   8 * met:
   9 *
  10 *     * Redistributions of source code must retain the above copyright
  11 * notice, this list of conditions and the following disclaimer.
  12 *     * Redistributions in binary form must reproduce the above
  13 * copyright notice, this list of conditions and the following disclaimer
  14 * in the documentation and/or other materials provided with the
  15 * distribution.
  16 *
  17 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  18 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  19 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  20 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  21 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  22 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  23 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  27 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  28 *
  29 * You can contact the author at :
  30 * - LZ4 homepage : http://fastcompression.blogspot.com/p/lz4.html
  31 * - LZ4 source repository : http://code.google.com/p/lz4/
  32 *
  33 *  Changed for kernel use by:
  34 *  Chanho Min <chanho.min@lge.com>
  35 */
  36
  37#include <linux/module.h>
  38#include <linux/kernel.h>
  39#include <linux/lz4.h>
  40#include <asm/unaligned.h>
  41#include "lz4defs.h"
  42
  43/*
  44 * LZ4_compressCtx :
  45 * -----------------
  46 * Compress 'isize' bytes from 'source' into an output buffer 'dest' of
  47 * maximum size 'maxOutputSize'.  * If it cannot achieve it, compression
  48 * will stop, and result of the function will be zero.
  49 * return : the number of bytes written in buffer 'dest', or 0 if the
  50 * compression fails
  51 */
  52static inline int lz4_compressctx(void *ctx,
  53                const char *source,
  54                char *dest,
  55                int isize,
  56                int maxoutputsize)
  57{
  58        HTYPE *hashtable = (HTYPE *)ctx;
  59        const u8 *ip = (u8 *)source;
  60#if LZ4_ARCH64
  61        const BYTE * const base = ip;
  62#else
  63        const int base = 0;
  64#endif
  65        const u8 *anchor = ip;
  66        const u8 *const iend = ip + isize;
  67        const u8 *const mflimit = iend - MFLIMIT;
  68        #define MATCHLIMIT (iend - LASTLITERALS)
  69
  70        u8 *op = (u8 *) dest;
  71        u8 *const oend = op + maxoutputsize;
  72        int length;
  73        const int skipstrength = SKIPSTRENGTH;
  74        u32 forwardh;
  75        int lastrun;
  76
  77        /* Init */
  78        if (isize < MINLENGTH)
  79                goto _last_literals;
  80
  81        memset((void *)hashtable, 0, LZ4_MEM_COMPRESS);
  82
  83        /* First Byte */
  84        hashtable[LZ4_HASH_VALUE(ip)] = ip - base;
  85        ip++;
  86        forwardh = LZ4_HASH_VALUE(ip);
  87
  88        /* Main Loop */
  89        for (;;) {
  90                int findmatchattempts = (1U << skipstrength) + 3;
  91                const u8 *forwardip = ip;
  92                const u8 *ref;
  93                u8 *token;
  94
  95                /* Find a match */
  96                do {
  97                        u32 h = forwardh;
  98                        int step = findmatchattempts++ >> skipstrength;
  99                        ip = forwardip;
 100                        forwardip = ip + step;
 101
 102                        if (unlikely(forwardip > mflimit))
 103                                goto _last_literals;
 104
 105                        forwardh = LZ4_HASH_VALUE(forwardip);
 106                        ref = base + hashtable[h];
 107                        hashtable[h] = ip - base;
 108                } while ((ref < ip - MAX_DISTANCE) || (A32(ref) != A32(ip)));
 109
 110                /* Catch up */
 111                while ((ip > anchor) && (ref > (u8 *)source) &&
 112                        unlikely(ip[-1] == ref[-1])) {
 113                        ip--;
 114                        ref--;
 115                }
 116
 117                /* Encode Literal length */
 118                length = (int)(ip - anchor);
 119                token = op++;
 120                /* check output limit */
 121                if (unlikely(op + length + (2 + 1 + LASTLITERALS) +
 122                        (length >> 8) > oend))
 123                        return 0;
 124
 125                if (length >= (int)RUN_MASK) {
 126                        int len;
 127                        *token = (RUN_MASK << ML_BITS);
 128                        len = length - RUN_MASK;
 129                        for (; len > 254 ; len -= 255)
 130                                *op++ = 255;
 131                        *op++ = (u8)len;
 132                } else
 133                        *token = (length << ML_BITS);
 134
 135                /* Copy Literals */
 136                LZ4_BLINDCOPY(anchor, op, length);
 137_next_match:
 138                /* Encode Offset */
 139                LZ4_WRITE_LITTLEENDIAN_16(op, (u16)(ip - ref));
 140
 141                /* Start Counting */
 142                ip += MINMATCH;
 143                /* MinMatch verified */
 144                ref += MINMATCH;
 145                anchor = ip;
 146                while (likely(ip < MATCHLIMIT - (STEPSIZE - 1))) {
 147                        #if LZ4_ARCH64
 148                        u64 diff = A64(ref) ^ A64(ip);
 149                        #else
 150                        u32 diff = A32(ref) ^ A32(ip);
 151                        #endif
 152                        if (!diff) {
 153                                ip += STEPSIZE;
 154                                ref += STEPSIZE;
 155                                continue;
 156                        }
 157                        ip += LZ4_NBCOMMONBYTES(diff);
 158                        goto _endcount;
 159                }
 160                #if LZ4_ARCH64
 161                if ((ip < (MATCHLIMIT - 3)) && (A32(ref) == A32(ip))) {
 162                        ip += 4;
 163                        ref += 4;
 164                }
 165                #endif
 166                if ((ip < (MATCHLIMIT - 1)) && (A16(ref) == A16(ip))) {
 167                        ip += 2;
 168                        ref += 2;
 169                }
 170                if ((ip < MATCHLIMIT) && (*ref == *ip))
 171                        ip++;
 172_endcount:
 173                /* Encode MatchLength */
 174                length = (int)(ip - anchor);
 175                /* Check output limit */
 176                if (unlikely(op + (1 + LASTLITERALS) + (length >> 8) > oend))
 177                        return 0;
 178                if (length >= (int)ML_MASK) {
 179                        *token += ML_MASK;
 180                        length -= ML_MASK;
 181                        for (; length > 509 ; length -= 510) {
 182                                *op++ = 255;
 183                                *op++ = 255;
 184                        }
 185                        if (length > 254) {
 186                                length -= 255;
 187                                *op++ = 255;
 188                        }
 189                        *op++ = (u8)length;
 190                } else
 191                        *token += length;
 192
 193                /* Test end of chunk */
 194                if (ip > mflimit) {
 195                        anchor = ip;
 196                        break;
 197                }
 198
 199                /* Fill table */
 200                hashtable[LZ4_HASH_VALUE(ip-2)] = ip - 2 - base;
 201
 202                /* Test next position */
 203                ref = base + hashtable[LZ4_HASH_VALUE(ip)];
 204                hashtable[LZ4_HASH_VALUE(ip)] = ip - base;
 205                if ((ref > ip - (MAX_DISTANCE + 1)) && (A32(ref) == A32(ip))) {
 206                        token = op++;
 207                        *token = 0;
 208                        goto _next_match;
 209                }
 210
 211                /* Prepare next loop */
 212                anchor = ip++;
 213                forwardh = LZ4_HASH_VALUE(ip);
 214        }
 215
 216_last_literals:
 217        /* Encode Last Literals */
 218        lastrun = (int)(iend - anchor);
 219        if (((char *)op - dest) + lastrun + 1
 220                + ((lastrun + 255 - RUN_MASK) / 255) > (u32)maxoutputsize)
 221                return 0;
 222
 223        if (lastrun >= (int)RUN_MASK) {
 224                *op++ = (RUN_MASK << ML_BITS);
 225                lastrun -= RUN_MASK;
 226                for (; lastrun > 254 ; lastrun -= 255)
 227                        *op++ = 255;
 228                *op++ = (u8)lastrun;
 229        } else
 230                *op++ = (lastrun << ML_BITS);
 231        memcpy(op, anchor, iend - anchor);
 232        op += iend - anchor;
 233
 234        /* End */
 235        return (int)(((char *)op) - dest);
 236}
 237
 238static inline int lz4_compress64kctx(void *ctx,
 239                const char *source,
 240                char *dest,
 241                int isize,
 242                int maxoutputsize)
 243{
 244        u16 *hashtable = (u16 *)ctx;
 245        const u8 *ip = (u8 *) source;
 246        const u8 *anchor = ip;
 247        const u8 *const base = ip;
 248        const u8 *const iend = ip + isize;
 249        const u8 *const mflimit = iend - MFLIMIT;
 250        #define MATCHLIMIT (iend - LASTLITERALS)
 251
 252        u8 *op = (u8 *) dest;
 253        u8 *const oend = op + maxoutputsize;
 254        int len, length;
 255        const int skipstrength = SKIPSTRENGTH;
 256        u32 forwardh;
 257        int lastrun;
 258
 259        /* Init */
 260        if (isize < MINLENGTH)
 261                goto _last_literals;
 262
 263        memset((void *)hashtable, 0, LZ4_MEM_COMPRESS);
 264
 265        /* First Byte */
 266        ip++;
 267        forwardh = LZ4_HASH64K_VALUE(ip);
 268
 269        /* Main Loop */
 270        for (;;) {
 271                int findmatchattempts = (1U << skipstrength) + 3;
 272                const u8 *forwardip = ip;
 273                const u8 *ref;
 274                u8 *token;
 275
 276                /* Find a match */
 277                do {
 278                        u32 h = forwardh;
 279                        int step = findmatchattempts++ >> skipstrength;
 280                        ip = forwardip;
 281                        forwardip = ip + step;
 282
 283                        if (forwardip > mflimit)
 284                                goto _last_literals;
 285
 286                        forwardh = LZ4_HASH64K_VALUE(forwardip);
 287                        ref = base + hashtable[h];
 288                        hashtable[h] = (u16)(ip - base);
 289                } while (A32(ref) != A32(ip));
 290
 291                /* Catch up */
 292                while ((ip > anchor) && (ref > (u8 *)source)
 293                        && (ip[-1] == ref[-1])) {
 294                        ip--;
 295                        ref--;
 296                }
 297
 298                /* Encode Literal length */
 299                length = (int)(ip - anchor);
 300                token = op++;
 301                /* Check output limit */
 302                if (unlikely(op + length + (2 + 1 + LASTLITERALS)
 303                        + (length >> 8) > oend))
 304                        return 0;
 305                if (length >= (int)RUN_MASK) {
 306                        *token = (RUN_MASK << ML_BITS);
 307                        len = length - RUN_MASK;
 308                        for (; len > 254 ; len -= 255)
 309                                *op++ = 255;
 310                        *op++ = (u8)len;
 311                } else
 312                        *token = (length << ML_BITS);
 313
 314                /* Copy Literals */
 315                LZ4_BLINDCOPY(anchor, op, length);
 316
 317_next_match:
 318                /* Encode Offset */
 319                LZ4_WRITE_LITTLEENDIAN_16(op, (u16)(ip - ref));
 320
 321                /* Start Counting */
 322                ip += MINMATCH;
 323                /* MinMatch verified */
 324                ref += MINMATCH;
 325                anchor = ip;
 326
 327                while (ip < MATCHLIMIT - (STEPSIZE - 1)) {
 328                        #if LZ4_ARCH64
 329                        u64 diff = A64(ref) ^ A64(ip);
 330                        #else
 331                        u32 diff = A32(ref) ^ A32(ip);
 332                        #endif
 333
 334                        if (!diff) {
 335                                ip += STEPSIZE;
 336                                ref += STEPSIZE;
 337                                continue;
 338                        }
 339                        ip += LZ4_NBCOMMONBYTES(diff);
 340                        goto _endcount;
 341                }
 342                #if LZ4_ARCH64
 343                if ((ip < (MATCHLIMIT - 3)) && (A32(ref) == A32(ip))) {
 344                        ip += 4;
 345                        ref += 4;
 346                }
 347                #endif
 348                if ((ip < (MATCHLIMIT - 1)) && (A16(ref) == A16(ip))) {
 349                        ip += 2;
 350                        ref += 2;
 351                }
 352                if ((ip < MATCHLIMIT) && (*ref == *ip))
 353                        ip++;
 354_endcount:
 355
 356                /* Encode MatchLength */
 357                len = (int)(ip - anchor);
 358                /* Check output limit */
 359                if (unlikely(op + (1 + LASTLITERALS) + (len >> 8) > oend))
 360                        return 0;
 361                if (len >= (int)ML_MASK) {
 362                        *token += ML_MASK;
 363                        len -= ML_MASK;
 364                        for (; len > 509 ; len -= 510) {
 365                                *op++ = 255;
 366                                *op++ = 255;
 367                        }
 368                        if (len > 254) {
 369                                len -= 255;
 370                                *op++ = 255;
 371                        }
 372                        *op++ = (u8)len;
 373                } else
 374                        *token += len;
 375
 376                /* Test end of chunk */
 377                if (ip > mflimit) {
 378                        anchor = ip;
 379                        break;
 380                }
 381
 382                /* Fill table */
 383                hashtable[LZ4_HASH64K_VALUE(ip-2)] = (u16)(ip - 2 - base);
 384
 385                /* Test next position */
 386                ref = base + hashtable[LZ4_HASH64K_VALUE(ip)];
 387                hashtable[LZ4_HASH64K_VALUE(ip)] = (u16)(ip - base);
 388                if (A32(ref) == A32(ip)) {
 389                        token = op++;
 390                        *token = 0;
 391                        goto _next_match;
 392                }
 393
 394                /* Prepare next loop */
 395                anchor = ip++;
 396                forwardh = LZ4_HASH64K_VALUE(ip);
 397        }
 398
 399_last_literals:
 400        /* Encode Last Literals */
 401        lastrun = (int)(iend - anchor);
 402        if (op + lastrun + 1 + (lastrun - RUN_MASK + 255) / 255 > oend)
 403                return 0;
 404        if (lastrun >= (int)RUN_MASK) {
 405                *op++ = (RUN_MASK << ML_BITS);
 406                lastrun -= RUN_MASK;
 407                for (; lastrun > 254 ; lastrun -= 255)
 408                        *op++ = 255;
 409                *op++ = (u8)lastrun;
 410        } else
 411                *op++ = (lastrun << ML_BITS);
 412        memcpy(op, anchor, iend - anchor);
 413        op += iend - anchor;
 414        /* End */
 415        return (int)(((char *)op) - dest);
 416}
 417
 418int lz4_compress(const unsigned char *src, size_t src_len,
 419                        unsigned char *dst, size_t *dst_len, void *wrkmem)
 420{
 421        int ret = -1;
 422        int out_len = 0;
 423
 424        if (src_len < LZ4_64KLIMIT)
 425                out_len = lz4_compress64kctx(wrkmem, src, dst, src_len,
 426                                lz4_compressbound(src_len));
 427        else
 428                out_len = lz4_compressctx(wrkmem, src, dst, src_len,
 429                                lz4_compressbound(src_len));
 430
 431        if (out_len < 0)
 432                goto exit;
 433
 434        *dst_len = out_len;
 435
 436        return 0;
 437exit:
 438        return ret;
 439}
 440EXPORT_SYMBOL(lz4_compress);
 441
 442MODULE_LICENSE("Dual BSD/GPL");
 443MODULE_DESCRIPTION("LZ4 compressor");
 444