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+/* lzo1.c -- implementation of the LZO1 algorithm
+
+ This file is part of the LZO real-time data compression library.
+
+ Copyright (C) 2008 Markus Franz Xaver Johannes Oberhumer
+ Copyright (C) 2007 Markus Franz Xaver Johannes Oberhumer
+ Copyright (C) 2006 Markus Franz Xaver Johannes Oberhumer
+ Copyright (C) 2005 Markus Franz Xaver Johannes Oberhumer
+ Copyright (C) 2004 Markus Franz Xaver Johannes Oberhumer
+ Copyright (C) 2003 Markus Franz Xaver Johannes Oberhumer
+ Copyright (C) 2002 Markus Franz Xaver Johannes Oberhumer
+ Copyright (C) 2001 Markus Franz Xaver Johannes Oberhumer
+ Copyright (C) 2000 Markus Franz Xaver Johannes Oberhumer
+ Copyright (C) 1999 Markus Franz Xaver Johannes Oberhumer
+ Copyright (C) 1998 Markus Franz Xaver Johannes Oberhumer
+ Copyright (C) 1997 Markus Franz Xaver Johannes Oberhumer
+ Copyright (C) 1996 Markus Franz Xaver Johannes Oberhumer
+ All Rights Reserved.
+
+ The LZO library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU General Public License as
+ published by the Free Software Foundation; either version 2 of
+ the License, or (at your option) any later version.
+
+ The LZO library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with the LZO library; see the file COPYING.
+ If not, write to the Free Software Foundation, Inc.,
+ 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+
+ Markus F.X.J. Oberhumer
+ <markus@oberhumer.com>
+ http://www.oberhumer.com/opensource/lzo/
+ */
+
+
+#include "lzo_conf.h"
+#include "lzo/lzo1.h"
+
+
+/***********************************************************************
+// The next two defines can be changed to customize LZO1.
+// The default version is LZO1-5/1.
+************************************************************************/
+
+/* run bits (3 - 5) - the compressor and the decompressor
+ * must use the same value. */
+#if !defined(RBITS)
+# define RBITS 5
+#endif
+
+/* compression level (1 - 9) - this only affects the compressor.
+ * 1 is fastest, 9 is best compression ratio */
+#if !defined(CLEVEL)
+# define CLEVEL 1 /* fastest by default */
+#endif
+
+
+/* check configuration */
+#if (RBITS < 3 || RBITS > 5)
+# error "invalid RBITS"
+#endif
+#if (CLEVEL < 1 || CLEVEL > 9)
+# error "invalid CLEVEL"
+#endif
+
+
+/***********************************************************************
+// You should not have to change anything below this line.
+************************************************************************/
+
+/*
+ Format of the marker byte
+
+
+ 76543210
+ --------
+ 00000000 a long run (a 'R0' run) - there are short and long R0 runs
+ 000rrrrr a short run with len r
+ mmmooooo a short match (len = 2+m, o = offset low bits)
+ 111ooooo a long match (o = offset low bits)
+*/
+
+
+#define RSIZE (1 << RBITS)
+#define RMASK (RSIZE - 1)
+
+#define OBITS RBITS /* offset and run-length use same bits */
+#define OSIZE (1 << OBITS)
+#define OMASK (OSIZE - 1)
+
+#define MBITS (8 - OBITS)
+#define MSIZE (1 << MBITS)
+#define MMASK (MSIZE - 1)
+
+
+/* sanity checks */
+#if (OBITS < 3 || OBITS > 5)
+# error "invalid OBITS"
+#endif
+#if (MBITS < 3 || MBITS > 5)
+# error "invalid MBITS"
+#endif
+
+
+/***********************************************************************
+// some macros to improve readability
+************************************************************************/
+
+/* Minimum len of a match */
+#define MIN_MATCH 3
+#define THRESHOLD (MIN_MATCH - 1)
+
+/* Minimum len of match coded in 2 bytes */
+#define MIN_MATCH_SHORT MIN_MATCH
+
+/* Maximum len of match coded in 2 bytes */
+#define MAX_MATCH_SHORT (THRESHOLD + (MSIZE - 2))
+/* MSIZE - 2: 0 is used to indicate runs,
+ * MSIZE-1 is used to indicate a long match */
+
+/* Minimum len of match coded in 3 bytes */
+#define MIN_MATCH_LONG (MAX_MATCH_SHORT + 1)
+
+/* Maximum len of match coded in 3 bytes */
+#define MAX_MATCH_LONG (MIN_MATCH_LONG + 255)
+
+/* Maximum offset of a match */
+#define MAX_OFFSET (1 << (8 + OBITS))
+
+
+/*
+
+RBITS | MBITS MIN THR. MSIZE MAXS MINL MAXL MAXO R0MAX R0FAST
+======+===============================================================
+ 3 | 5 3 2 32 32 33 288 2048 263 256
+ 4 | 4 3 2 16 16 17 272 4096 271 264
+ 5 | 3 3 2 8 8 9 264 8192 287 280
+
+ */
+
+
+/***********************************************************************
+// internal configuration
+// all of these affect compression only
+************************************************************************/
+
+/* choose the hashing strategy */
+#ifndef LZO_HASH
+#define LZO_HASH LZO_HASH_LZO_INCREMENTAL_A
+#endif
+#define D_INDEX1(d,p) d = DM(DMUL(0x21,DX2(p,5,5)) >> 5)
+#define D_INDEX2(d,p) d = d ^ D_MASK
+
+#define DBITS (8 + RBITS)
+#include "lzo_dict.h"
+#define DVAL_LEN DVAL_LOOKAHEAD
+
+
+/***********************************************************************
+// get algorithm info, return memory required for compression
+************************************************************************/
+
+LZO_EXTERN(lzo_uint) lzo1_info ( int *rbits, int *clevel );
+
+LZO_PUBLIC(lzo_uint)
+lzo1_info ( int *rbits, int *clevel )
+{
+ if (rbits)
+ *rbits = RBITS;
+ if (clevel)
+ *clevel = CLEVEL;
+ return D_SIZE * lzo_sizeof(lzo_bytep);
+}
+
+
+/***********************************************************************
+// decode a R0 literal run (a long run)
+************************************************************************/
+
+#define R0MIN (RSIZE) /* Minimum len of R0 run of literals */
+#define R0MAX (R0MIN + 255) /* Maximum len of R0 run of literals */
+#define R0FAST (R0MAX & ~7u) /* R0MAX aligned to 8 byte boundary */
+
+#if (R0MAX - R0FAST != 7) || ((R0FAST & 7) != 0)
+# error "something went wrong"
+#endif
+
+/* 7 special codes from R0FAST+1 .. R0MAX
+ * these codes mean long R0 runs with lengths
+ * 512, 1024, 2048, 4096, 8192, 16384, 32768 */
+
+
+/***********************************************************************
+// LZO1 decompress a block of data.
+//
+// Could be easily translated into assembly code.
+************************************************************************/
+
+LZO_PUBLIC(int)
+lzo1_decompress ( const lzo_bytep in , lzo_uint in_len,
+ lzo_bytep out, lzo_uintp out_len,
+ lzo_voidp wrkmem )
+{
+ lzo_bytep op;
+ const lzo_bytep ip;
+ const lzo_bytep const ip_end = in + in_len;
+ lzo_uint t;
+
+ LZO_UNUSED(wrkmem);
+
+ op = out;
+ ip = in;
+ while (ip < ip_end)
+ {
+ t = *ip++; /* get marker */
+
+ if (t < R0MIN) /* a literal run */
+ {
+ if (t == 0) /* a R0 literal run */
+ {
+ t = *ip++;
+ if (t >= R0FAST - R0MIN) /* a long R0 run */
+ {
+ t -= R0FAST - R0MIN;
+ if (t == 0)
+ t = R0FAST;
+ else
+ {
+#if 0
+ t = 256u << ((unsigned) t);
+#else
+ /* help the optimizer */
+ lzo_uint tt = 256;
+ do tt <<= 1; while (--t > 0);
+ t = tt;
+#endif
+ }
+ MEMCPY8_DS(op,ip,t);
+ continue;
+ }
+ t += R0MIN;
+ }
+ MEMCPY_DS(op,ip,t);
+ }
+ else /* a match */
+ {
+ lzo_uint tt;
+ /* get match offset */
+ const lzo_bytep m_pos = op - 1;
+ m_pos -= (lzo_uint)(t & OMASK) | (((lzo_uint) *ip++) << OBITS);
+
+ /* get match len */
+ if (t >= ((MSIZE - 1) << OBITS)) /* all m-bits set */
+ tt = (MIN_MATCH_LONG - THRESHOLD) + *ip++; /* a long match */
+ else
+ tt = t >> OBITS; /* a short match */
+
+ assert(m_pos >= out);
+ assert(m_pos < op);
+ /* a half unrolled loop */
+ *op++ = *m_pos++;
+ *op++ = *m_pos++;
+ MEMCPY_DS(op,m_pos,tt);
+ }
+ }
+
+ *out_len = pd(op, out);
+
+ /* the next line is the only check in the decompressor ! */
+ return (ip == ip_end ? LZO_E_OK :
+ (ip < ip_end ? LZO_E_INPUT_NOT_CONSUMED : LZO_E_INPUT_OVERRUN));
+}
+
+
+/***********************************************************************
+// code a literal run
+************************************************************************/
+
+static
+#if LZO_ARCH_AVR
+__lzo_noinline
+#endif
+lzo_bytep
+store_run(lzo_bytep op, const lzo_bytep ii, lzo_uint r_len)
+{
+ assert(r_len > 0);
+
+ /* code a long R0 run */
+ if (r_len >= 512)
+ {
+ unsigned r_bits = 7; /* 256 << 7 == 32768 */
+ do {
+ while (r_len >= (256u << r_bits))
+ {
+ r_len -= (256u << r_bits);
+ *op++ = 0; *op++ = LZO_BYTE((R0FAST - R0MIN) + r_bits);
+ MEMCPY8_DS(op, ii, (256u << r_bits));
+ }
+ } while (--r_bits > 0);
+ }
+ while (r_len >= R0FAST)
+ {
+ r_len -= R0FAST;
+ *op++ = 0; *op++ = R0FAST - R0MIN;
+ MEMCPY8_DS(op, ii, R0FAST);
+ }
+
+ if (r_len >= R0MIN)
+ {
+ /* code a short R0 run */
+ *op++ = 0; *op++ = LZO_BYTE(r_len - R0MIN);
+ MEMCPY_DS(op, ii, r_len);
+ }
+ else if (r_len > 0)
+ {
+ /* code a 'normal' run */
+ *op++ = LZO_BYTE(r_len);
+ MEMCPY_DS(op, ii, r_len);
+ }
+
+ assert(r_len == 0);
+ return op;
+}
+
+
+
+/***********************************************************************
+// LZO1 compress a block of data.
+//
+// Could be translated into assembly code without too much effort.
+//
+// I apologize for the spaghetti code, but it really helps the optimizer.
+************************************************************************/
+
+static int
+do_compress ( const lzo_bytep in , lzo_uint in_len,
+ lzo_bytep out, lzo_uintp out_len,
+ lzo_voidp wrkmem )
+{
+ const lzo_bytep ip;
+#if defined(__LZO_HASH_INCREMENTAL)
+ lzo_xint dv;
+#endif
+ lzo_bytep op;
+ const lzo_bytep m_pos;
+ const lzo_bytep const ip_end = in+in_len - DVAL_LEN - MIN_MATCH_LONG;
+ const lzo_bytep const in_end = in+in_len - DVAL_LEN;
+ const lzo_bytep ii;
+ lzo_dict_p const dict = (lzo_dict_p) wrkmem;
+
+#if !defined(NDEBUG)
+ const lzo_bytep m_pos_sav;
+#endif
+
+ op = out;
+ ip = in;
+ ii = ip; /* point to start of literal run */
+ if (in_len <= MIN_MATCH_LONG + DVAL_LEN + 1)
+ goto the_end;
+
+ /* init dictionary */
+#if defined(LZO_DETERMINISTIC)
+ BZERO8_PTR(wrkmem,sizeof(lzo_dict_t),D_SIZE);
+#endif
+
+ DVAL_FIRST(dv,ip);
+ UPDATE_D(dict,0,dv,ip,in);
+ ip++;
+ DVAL_NEXT(dv,ip);
+
+ do {
+ lzo_uint m_off;
+ lzo_uint dindex;
+
+ DINDEX1(dindex,ip);
+ GINDEX(m_pos,m_off,dict,dindex,in);
+ if (LZO_CHECK_MPOS(m_pos,m_off,in,ip,MAX_OFFSET))
+ goto literal;
+ if (m_pos[0] == ip[0] && m_pos[1] == ip[1] && m_pos[2] == ip[2])
+ goto match;
+ DINDEX2(dindex,ip);
+ GINDEX(m_pos,m_off,dict,dindex,in);
+ if (LZO_CHECK_MPOS(m_pos,m_off,in,ip,MAX_OFFSET))
+ goto literal;
+ if (m_pos[0] == ip[0] && m_pos[1] == ip[1] && m_pos[2] == ip[2])
+ goto match;
+ goto literal;
+
+
+literal:
+ UPDATE_I(dict,0,dindex,ip,in);
+ if (++ip >= ip_end)
+ break;
+ continue;
+
+match:
+ UPDATE_I(dict,0,dindex,ip,in);
+#if !defined(NDEBUG) && defined(LZO_DICT_USE_PTR)
+ m_pos_sav = m_pos;
+#endif
+ m_pos += 3;
+ {
+ /* we have found a match (of at least length 3) */
+#if !defined(NDEBUG) && !defined(LZO_DICT_USE_PTR)
+ assert((m_pos_sav = ip - m_off) == (m_pos - 3));
+#endif
+ /* 1) store the current literal run */
+ if (pd(ip,ii) > 0)
+ {
+ lzo_uint t = pd(ip,ii);
+#if 1
+ /* OPTIMIZED: inline the copying of a short run */
+ if (t < R0MIN)
+ {
+ *op++ = LZO_BYTE(t);
+ MEMCPY_DS(op, ii, t);
+ }
+ else
+#endif
+ op = store_run(op,ii,t);
+ }
+
+ /* 2a) compute match len */
+ ii = ip; /* point to start of current match */
+
+ /* we already matched MIN_MATCH bytes,
+ * m_pos also already advanced MIN_MATCH bytes */
+ ip += MIN_MATCH;
+ assert(m_pos < ip);
+
+ /* try to match another MIN_MATCH_LONG - MIN_MATCH bytes
+ * to see if we get a long match */
+
+#define PS *m_pos++ != *ip++
+
+#if (MIN_MATCH_LONG - MIN_MATCH == 2) /* MBITS == 2 */
+ if (PS || PS)
+#elif (MIN_MATCH_LONG - MIN_MATCH == 6) /* MBITS == 3 */
+ if (PS || PS || PS || PS || PS || PS)
+#elif (MIN_MATCH_LONG - MIN_MATCH == 14) /* MBITS == 4 */
+ if (PS || PS || PS || PS || PS || PS || PS ||
+ PS || PS || PS || PS || PS || PS || PS)
+#elif (MIN_MATCH_LONG - MIN_MATCH == 30) /* MBITS == 5 */
+ if (PS || PS || PS || PS || PS || PS || PS || PS ||
+ PS || PS || PS || PS || PS || PS || PS || PS ||
+ PS || PS || PS || PS || PS || PS || PS || PS ||
+ PS || PS || PS || PS || PS || PS)
+#else
+# error "MBITS not yet implemented"
+#endif
+ {
+ lzo_uint m_len;
+
+ /* 2b) code a short match */
+ assert(pd(ip,m_pos) == m_off);
+ --ip; /* ran one too far, point back to non-match */
+ m_len = pd(ip, ii);
+ assert(m_len >= MIN_MATCH_SHORT);
+ assert(m_len <= MAX_MATCH_SHORT);
+ assert(m_off > 0);
+ assert(m_off <= MAX_OFFSET);
+ assert(ii-m_off == m_pos_sav);
+ assert(lzo_memcmp(m_pos_sav,ii,m_len) == 0);
+ --m_off;
+ /* code short match len + low offset bits */
+ *op++ = LZO_BYTE(((m_len - THRESHOLD) << OBITS) |
+ (m_off & OMASK));
+ /* code high offset bits */
+ *op++ = LZO_BYTE(m_off >> OBITS);
+
+
+ /* 2c) Insert phrases (beginning with ii+1) into the dictionary. */
+
+#define SI /* nothing */
+#define DI ++ii; DVAL_NEXT(dv,ii); UPDATE_D(dict,0,dv,ii,in);
+#define XI assert(ii < ip); ii = ip; DVAL_FIRST(dv,(ip));
+
+#if (CLEVEL == 9) || (CLEVEL >= 7 && MBITS <= 4) || (CLEVEL >= 5 && MBITS <= 3)
+ /* Insert the whole match (ii+1)..(ip-1) into dictionary. */
+ ++ii;
+ do {
+ DVAL_NEXT(dv,ii);
+ UPDATE_D(dict,0,dv,ii,in);
+ } while (++ii < ip);
+ DVAL_NEXT(dv,ii);
+ assert(ii == ip);
+ DVAL_ASSERT(dv,ip);
+#elif (CLEVEL >= 3)
+ SI DI DI XI
+#elif (CLEVEL >= 2)
+ SI DI XI
+#else
+ XI
+#endif
+
+ }
+ else
+ {
+ /* we've found a long match - see how far we can still go */
+ const lzo_bytep end;
+ lzo_uint m_len;
+
+ assert(ip <= in_end);
+ assert(ii == ip - MIN_MATCH_LONG);
+
+ if (pd(in_end,ip) <= (MAX_MATCH_LONG - MIN_MATCH_LONG))
+ end = in_end;
+ else
+ {
+ end = ip + (MAX_MATCH_LONG - MIN_MATCH_LONG);
+ assert(end < in_end);
+ }
+
+ while (ip < end && *m_pos == *ip)
+ m_pos++, ip++;
+ assert(ip <= in_end);
+
+ /* 2b) code the long match */
+ m_len = pd(ip, ii);
+ assert(m_len >= MIN_MATCH_LONG);
+ assert(m_len <= MAX_MATCH_LONG);
+ assert(m_off > 0);
+ assert(m_off <= MAX_OFFSET);
+ assert(ii-m_off == m_pos_sav);
+ assert(lzo_memcmp(m_pos_sav,ii,m_len) == 0);
+ assert(pd(ip,m_pos) == m_off);
+ --m_off;
+ /* code long match flag + low offset bits */
+ *op++ = LZO_BYTE(((MSIZE - 1) << OBITS) | (m_off & OMASK));
+ /* code high offset bits */
+ *op++ = LZO_BYTE(m_off >> OBITS);
+ /* code match len */
+ *op++ = LZO_BYTE(m_len - MIN_MATCH_LONG);
+
+
+ /* 2c) Insert phrases (beginning with ii+1) into the dictionary. */
+#if (CLEVEL == 9)
+ /* Insert the whole match (ii+1)..(ip-1) into dictionary. */
+ /* This is not recommended because it is slow. */
+ ++ii;
+ do {
+ DVAL_NEXT(dv,ii);
+ UPDATE_D(dict,0,dv,ii,in);
+ } while (++ii < ip);
+ DVAL_NEXT(dv,ii);
+ assert(ii == ip);
+ DVAL_ASSERT(dv,ip);
+#elif (CLEVEL >= 8)
+ SI DI DI DI DI DI DI DI DI XI
+#elif (CLEVEL >= 7)
+ SI DI DI DI DI DI DI DI XI
+#elif (CLEVEL >= 6)
+ SI DI DI DI DI DI DI XI
+#elif (CLEVEL >= 5)
+ SI DI DI DI DI XI
+#elif (CLEVEL >= 4)
+ SI DI DI DI XI
+#elif (CLEVEL >= 3)
+ SI DI DI XI
+#elif (CLEVEL >= 2)
+ SI DI XI
+#else
+ XI
+#endif
+ }
+
+ /* ii now points to the start of next literal run */
+ assert(ii == ip);
+ }
+ } while (ip < ip_end);
+
+
+
+the_end:
+ assert(ip <= in_end);
+
+
+#if defined(LZO_RETURN_IF_NOT_COMPRESSIBLE)
+ /* return -1 if op == out to indicate that we
+ * couldn't compress and didn't copy anything.
+ */
+ if (op == out)
+ {
+ *out_len = 0;
+ return LZO_E_NOT_COMPRESSIBLE;
+ }
+#endif
+
+
+ /* store the final literal run */
+ if (pd(in_end+DVAL_LEN,ii) > 0)
+ op = store_run(op,ii,pd(in_end+DVAL_LEN,ii));
+
+ *out_len = pd(op, out);
+ return 0; /* compression went ok */
+}
+
+
+/***********************************************************************
+// compress public entry point.
+************************************************************************/
+
+LZO_PUBLIC(int)
+lzo1_compress ( const lzo_bytep in , lzo_uint in_len,
+ lzo_bytep out, lzo_uintp out_len,
+ lzo_voidp wrkmem )
+{
+ int r = LZO_E_OK;
+
+ /* don't try to compress a block that's too short */
+ if (in_len <= 0)
+ *out_len = 0;
+ else if (in_len <= MIN_MATCH_LONG + DVAL_LEN + 1)
+ {
+#if defined(LZO_RETURN_IF_NOT_COMPRESSIBLE)
+ r = LZO_E_NOT_COMPRESSIBLE;
+#else
+ *out_len = pd(store_run(out,in,in_len), out);
+#endif
+ }
+ else
+ r = do_compress(in,in_len,out,out_len,wrkmem);
+
+ return r;
+}
+
+
+/*
+vi:ts=4:et
+*/
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