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adcroft |
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/* |
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** Copyright (C) 1995, 1996, 1997, 1998 Hewlett-Packard Company |
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** Originally by Kevin Hughes, kev@kevcom.com, 3/11/94 |
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** |
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** This program and library is free software; you can redistribute it and/or |
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** modify it under the terms of the GNU (Library) General Public License |
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** as published by the Free Software Foundation; either version 2 |
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** of the License, or any later version. |
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** |
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** This program is distributed in the hope that it will be useful, |
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** but WITHOUT ANY WARRANTY; without even the implied warranty of |
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** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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** GNU (Library) General Public License for more details. |
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** |
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** You should have received a copy of the GNU (Library) General Public License |
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** along with this program; if not, write to the Free Software |
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** Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
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*/ |
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void compress1(int num, FILE *fp, int (*f_putc)(int , FILE *)); |
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/* unsigned char *compress2(int num, unsigned char *buffer);*/ |
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unsigned char *compress3(int num, unsigned char *buffer); |
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int uncompress1(FILE *fp, int (*f_getc)(FILE *fp)); |
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int uncompress2(unsigned char **buffer); |
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unsigned long PACKLONG(unsigned long num); |
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void PACKLONG2(unsigned long num, unsigned char *buffer); |
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unsigned long UNPACKLONG(unsigned long num); |
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unsigned long UNPACKLONG2(unsigned char *buffer); |
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unsigned char *compress_location(SWISH *,IndexFILE *, LOCATION *); |
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void compress_location_values(unsigned char **buf,unsigned char **flagp,int filenum,int frequency, int *position); |
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void compress_location_positions(unsigned char **buf,unsigned char *flag,int frequency, int *position); |
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LOCATION *uncompress_location(SWISH *,IndexFILE *,unsigned char *); |
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void uncompress_location_values(unsigned char **buf,unsigned char *flag, int *filenum,int *frequency); |
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void uncompress_location_positions(unsigned char **buf, unsigned char flag, int frequency, int *position); |
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void CompressCurrentLocEntry(SWISH *,IndexFILE *,ENTRY *); |
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void SwapLocData(SWISH *,ENTRY *,unsigned char *,int); |
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void unSwapLocData(SWISH *,int, ENTRY *); |
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void sortSwapLocData(SWISH * , ENTRY *); |
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void unSwapLocDataEntry_old(SWISH *,ENTRY *); |
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/* Here is the worst case size for a compressed number |
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** MAXINTCOMPSIZE stands for MAXimum INTeger COMPressed SIZE |
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** |
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** There are many places in the code in which we allocate |
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** space for a compressed number. In the worst case this size is 5 |
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** for 32 bit number, 10 for a 64 bit number. |
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** |
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** The way this compression works is reserving the first bit |
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** in each byte to store a flag. The flag is set in all bytes |
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** except for the last one. |
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** This only gives 7 bits per byte to store the number. |
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** |
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** For example, to store 1000 (binary 1111101000) we will get: |
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** |
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** 1st byte 2th byte |
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** 10000111 01101000 |
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** ^ ^ |
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** | | |
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** | Flag to indicate that this is tha last byte |
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** | |
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** Flag set to indicate that more bytes follow this one |
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** |
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** So, to compress a 32 bit number we need 5 bytes and for |
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** a 64 bit number we will use 10 bytes for the worst case |
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*/ |
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#define MAXINTCOMPSIZE (((sizeof(int) * 8) / 7) + (((sizeof(int) * 8) % 7) ? 1 : 0)) |
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