/* * Copyright (c) 2000-2012 Marc Alexander Lehmann * * Redistribution and use in source and binary forms, with or without modifica- * tion, are permitted provided that the following conditions are met: * * 1. Redistributions of source code must retain the above copyright notice, * this list of conditions and the following disclaimer. * * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER- * CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE- * CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH- * ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED * OF THE POSSIBILITY OF SUCH DAMAGE. * * Alternatively, the contents of this file may be used under the terms of * the GNU General Public License ("GPL") version 2 or any later version, * in which case the provisions of the GPL are applicable instead of * the above. If you wish to allow the use of your version of this file * only under the terms of the GPL and not to allow others to use your * version of this file under the BSD license, indicate your decision * by deleting the provisions above and replace them with the notice * and other provisions required by the GPL. If you do not delete the * provisions above, a recipient may use your version of this file under * either the BSD or the GPL. */ #include "lzfP.h" #define HASH(p) (p[0] << 6) ^ (p[1] << 3) ^ p[2] #define MAX_LIT (1 << 5) #define MAX_OFF (1 << 13) #define MAX_REF ((1 << 8) + (1 << 3)) #if __GNUC__ >= 3 # define expect(expr,value) __builtin_expect ((expr),(value)) # define inline inline #else # define expect(expr,value) (expr) # define inline static #endif #define expect_false(expr) expect ((expr) != 0, 0) #define expect_true(expr) expect ((expr) != 0, 1) /* * compressed format * * 000LLLLL ; literal, L+1=1..33 octets * LLLooooo oooooooo ; backref L+1=1..7 octets, o+1=1..4096 offset * 111ooooo LLLLLLLL oooooooo ; backref L+8 octets, o+1=1..4096 offset * */ unsigned int lzf_compress_best (const void *const in_data, unsigned int in_len, void *out_data, unsigned int out_len) { const u8 *ip = (const u8 *)in_data; u8 *op = (u8 *)out_data; const u8 *in_end = ip + in_len; u8 *out_end = op + out_len; const u8 *first [1 << (6+8)]; /* most recent occurance of a match */ u16 prev [MAX_OFF]; /* how many bytes to go backwards for te next match */ int lit; if (!in_len || !out_len) return 0; lit = 0; op++; /* start run */ lit++; *op++ = *ip++; while (ip < in_end - 2) { int best_l = 0; const u8 *best_p; int e = (in_end - ip < MAX_REF ? in_end - ip : MAX_REF) - 1; unsigned int res = ((unsigned int)ip) & (MAX_OFF - 1); u16 hash = HASH (ip); u16 diff; const u8 *b = ip < (u8 *)in_data + MAX_OFF ? in_data : ip - MAX_OFF; const u8 *p = first [hash]; prev [res] = ip - p; /* update ptr to previous hash match */ first [hash] = ip; /* first hash match is here */ if (p < ip) while (p >= b) { if (p[2] == ip[2]) /* first two bytes almost always match */ if (p[best_l] == ip[best_l]) /* new match must be longer than the old one to qualify */ if (p[1] == ip[1] && p[0] == ip[0]) /* just to be sure */ { int l = 3; while (p[l] == ip[l] && l < e) ++l; if (l >= best_l) { best_p = p; best_l = l; } } diff = prev [((unsigned int)p) & (MAX_OFF - 1)]; p = diff ? p - diff : (u8 *)diff; } if (best_l) { int len = best_l; int off = ip - best_p - 1; if (expect_false (op + 3 + 1 >= out_end)) /* first a faster conservative test */ if (op - !lit + 3 + 1 >= out_end) /* second the exact but rare test */ return 0; op [- lit - 1] = lit - 1; /* stop run */ op -= !lit; /* undo run if length is zero */ len -= 2; /* len is now #octets - 1 */ ip++; if (len < 7) { *op++ = (off >> 8) + (len << 5); } else { *op++ = (off >> 8) + ( 7 << 5); *op++ = len - 7; } *op++ = off; lit = 0; op++; /* start run */ ip += len + 1; if (expect_false (ip >= in_end - 2)) break; ip -= len + 1; //printf (" fill %p for %d\n", ip, len);//D do { u16 hash = HASH (ip); res = ((unsigned int)ip) & (MAX_OFF - 1); p = first [hash]; prev [res] = ip - p; /* update ptr to previous hash match */ first [hash] = ip; /* first hash match is here */ ip++; } while (len--); } else { /* one more literal byte we must copy */ if (expect_false (op >= out_end)) return 0; lit++; *op++ = *ip++; if (expect_false (lit == MAX_LIT)) { op [- lit - 1] = lit - 1; /* stop run */ lit = 0; op++; /* start run */ } } } if (op + 3 > out_end) /* at most 3 bytes can be missing here */ return 0; while (ip < in_end) { lit++; *op++ = *ip++; if (expect_false (lit == MAX_LIT)) { op [- lit - 1] = lit - 1; /* stop run */ lit = 0; op++; /* start run */ } } op [- lit - 1] = lit - 1; /* end run */ op -= !lit; /* undo run if length is zero */ return op - (u8 *)out_data; }