552 lines
14 KiB
C
552 lines
14 KiB
C
/*
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* Copyright (c) 1985, 1986 The Regents of the University of California.
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* All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* James A. Woods, derived from original work by Spencer Thomas
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* and Joseph Orost.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include "cmcompress.h"
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#include <errno.h>
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#include <string.h>
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static const char_type magic_header[] = { "\037\235" }; /* 1F 9D */
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/* Defines for third byte of header */
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#define BIT_MASK 0x1f
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#define BLOCK_MASK 0x80
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#define CHECK_GAP 10000 /* ratio check interval */
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/* Masks 0x40 and 0x20 are free. I think 0x20 should mean that there is
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a fourth header byte (for expansion).
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*/
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#define INIT_BITS 9 /* initial number of bits/code */
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#ifdef COMPATIBLE /* But wrong! */
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# define MAXCODE(n_bits) (1 << (n_bits) - 1)
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#else
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# define MAXCODE(n_bits) ((1 << (n_bits)) - 1)
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#endif /* COMPATIBLE */
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#define htabof(i) cdata->htab[i]
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#define codetabof(i) cdata->codetab[i]
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/*
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* the next two codes should not be changed lightly, as they must not
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* lie within the contiguous general code space.
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*/
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#define FIRST 257 /* first free entry */
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#define CLEAR 256 /* table clear output code */
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#ifdef DEBUG
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static void prratio( FILE *stream, long int num, long int den);
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#endif
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int cmcompress_compress_initialize(struct cmcompress_stream* cdata)
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{
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cdata->maxbits = BITS; /* user settable max # bits/code */
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cdata->maxmaxcode = 1 << BITS; /* should NEVER generate this code */
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cdata->hsize = HSIZE; /* for dynamic table sizing */
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cdata->free_ent = 0; /* first unused entry */
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cdata->nomagic = 0; /* Use a 3-byte magic number header, unless old file */
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cdata->block_compress = BLOCK_MASK;
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cdata->clear_flg = 0;
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cdata->ratio = 0;
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cdata->checkpoint = CHECK_GAP;
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cdata->input_stream = 0;
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cdata->output_stream = 0;
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cdata->client_data = 0;
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return 1;
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}
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static void cl_hash(struct cmcompress_stream* cdata, count_int hsize) /* reset code table */
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{
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register count_int *htab_p = cdata->htab+hsize;
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register long i;
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register long m1 = -1;
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i = hsize - 16;
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do
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{ /* might use Sys V memset(3) here */
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*(htab_p-16) = m1;
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*(htab_p-15) = m1;
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*(htab_p-14) = m1;
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*(htab_p-13) = m1;
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*(htab_p-12) = m1;
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*(htab_p-11) = m1;
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*(htab_p-10) = m1;
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*(htab_p-9) = m1;
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*(htab_p-8) = m1;
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*(htab_p-7) = m1;
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*(htab_p-6) = m1;
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*(htab_p-5) = m1;
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*(htab_p-4) = m1;
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*(htab_p-3) = m1;
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*(htab_p-2) = m1;
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*(htab_p-1) = m1;
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htab_p -= 16;
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}
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while ((i -= 16) >= 0);
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for ( i += 16; i > 0; i-- )
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{
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*--htab_p = m1;
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}
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}
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/*-
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* Output the given code.
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* Inputs:
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* code: A n_bits-bit integer. If == -1, then EOF. This assumes
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* that n_bits =< (long)wordsize - 1.
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* Outputs:
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* Outputs code to the file.
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* Assumptions:
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* Chars are 8 bits long.
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* Algorithm:
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* Maintain a BITS character long buffer (so that 8 codes will
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* fit in it exactly). Use the VAX insv instruction to insert each
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* code in turn. When the buffer fills up empty it and start over.
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*/
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static char buf[BITS];
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#ifndef vax
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char_type lmask[9] = {0xff, 0xfe, 0xfc, 0xf8, 0xf0, 0xe0, 0xc0, 0x80, 0x00};
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char_type rmask[9] = {0x00, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f, 0xff};
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#endif /* vax */
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static int output(struct cmcompress_stream* cdata, code_int code)
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{
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#ifdef DEBUG
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static int col = 0;
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#endif /* DEBUG */
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/*
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* On the VAX, it is important to have the register declarations
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* in exactly the order given, or the asm will break.
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*/
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register int r_off = cdata->offset, bits= cdata->n_bits;
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register char * bp = buf;
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#ifdef DEBUG
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if ( verbose )
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{
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fprintf( stderr, "%5d%c", code,
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(col+=6) >= 74 ? (col = 0, '\n') : ' ' );
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}
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#endif /* DEBUG */
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if ( code >= 0 )
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{
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#if defined(vax) && !defined(__GNUC__)
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/*
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* VAX and PCC DEPENDENT!! Implementation on other machines is
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* below.
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*
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* Translation: Insert BITS bits from the argument starting at
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* cdata->offset bits from the beginning of buf.
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*/
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0; /* Work around for pcc -O bug with asm and if stmt */
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asm( "insv 4(ap),r11,r10,(r9)" );
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#else
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/*
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* byte/bit numbering on the VAX is simulated by the following code
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*/
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/*
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* Get to the first byte.
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*/
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bp += (r_off >> 3);
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r_off &= 7;
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/*
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* Since code is always >= 8 bits, only need to mask the first
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* hunk on the left.
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*/
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*bp = (char)((*bp & rmask[r_off]) | ((code << r_off) & lmask[r_off]));
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bp++;
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bits -= (8 - r_off);
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code >>= 8 - r_off;
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/* Get any 8 bit parts in the middle (<=1 for up to 16 bits). */
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if ( bits >= 8 )
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{
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*bp++ = (char)(code);
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code >>= 8;
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bits -= 8;
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}
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/* Last bits. */
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if(bits)
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{
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*bp = (char)(code);
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}
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#endif /* vax */
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cdata->offset += cdata->n_bits;
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if ( cdata->offset == (cdata->n_bits << 3) )
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{
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bp = buf;
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bits = cdata->n_bits;
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cdata->bytes_out += bits;
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do
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{
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if ( cdata->output_stream(cdata, bp, 1) != 1 )
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{
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return 0;
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}
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bp++;
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}
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while(--bits);
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cdata->offset = 0;
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}
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/*
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* If the next entry is going to be too big for the code size,
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* then increase it, if possible.
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*/
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if ( cdata->free_ent > cdata->maxcode || (cdata->clear_flg > 0))
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{
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/*
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* Write the whole buffer, because the input side won't
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* discover the size increase until after it has read it.
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*/
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if ( cdata->offset > 0 )
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{
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if ( cdata->output_stream(cdata, buf, cdata->n_bits) != cdata->n_bits )
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{
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return 0;
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}
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cdata->bytes_out += cdata->n_bits;
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}
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cdata->offset = 0;
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if ( cdata->clear_flg )
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{
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cdata->maxcode = MAXCODE (cdata->n_bits = INIT_BITS);
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cdata->clear_flg = 0;
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}
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else
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{
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cdata->n_bits++;
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if ( cdata->n_bits == cdata->maxbits )
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{
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cdata->maxcode = cdata->maxmaxcode;
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}
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else
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{
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cdata->maxcode = MAXCODE(cdata->n_bits);
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}
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}
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#ifdef DEBUG
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if ( debug )
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{
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fprintf( stderr, "\nChange to %d bits\n", cdata->n_bits );
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col = 0;
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}
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#endif /* DEBUG */
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}
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}
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else
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{
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/*
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* At EOF, write the rest of the buffer.
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*/
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if ( cdata->offset > 0 )
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{
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cdata->offset = (cdata->offset + 7) / 8;
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if ( cdata->output_stream(cdata, buf, cdata->offset ) != cdata->offset )
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{
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return 0;
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}
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cdata->bytes_out += cdata->offset;
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}
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cdata->offset = 0;
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(void)fflush( stdout );
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if( ferror( stdout ) )
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{
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return 0;
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}
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#ifdef DEBUG
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if ( verbose )
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{
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fprintf( stderr, "\n" );
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}
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#endif
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}
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return 1;
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}
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/*
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* compress stdin to stdout
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*
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* Algorithm: use open addressing double hashing (no chaining) on the
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* prefix code / next character combination. We do a variant of Knuth's
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* algorithm D (vol. 3, sec. 6.4) along with G. Knott's relatively-prime
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* secondary probe. Here, the modular division first probe is gives way
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* to a faster exclusive-or manipulation. Also do block compression with
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* an adaptive reset, whereby the code table is cleared when the compression
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* ratio decreases, but after the table fills. The variable-length output
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* codes are re-sized at this point, and a special CLEAR code is generated
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* for the decompressor. Late addition: construct the table according to
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* file size for noticeable speed improvement on small files. Please direct
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* questions about this implementation to ames!jaw.
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*/
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int cmcompress_compress_start(struct cmcompress_stream* cdata)
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{
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#ifndef COMPATIBLE
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if (cdata->nomagic == 0)
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{
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char headLast = (char)(cdata->maxbits | cdata->block_compress);
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cdata->output_stream(cdata, (const char*)magic_header, 2);
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cdata->output_stream(cdata, &headLast, 1);
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if(ferror(stdout))
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{
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printf("Error...\n");
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}
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}
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#endif /* COMPATIBLE */
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cdata->offset = 0;
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cdata->bytes_out = 3; /* includes 3-byte header mojo */
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cdata->out_count = 0;
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cdata->clear_flg = 0;
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cdata->ratio = 0;
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cdata->in_count = 1;
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cdata->checkpoint = CHECK_GAP;
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cdata->maxcode = MAXCODE(cdata->n_bits = INIT_BITS);
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cdata->free_ent = ((cdata->block_compress) ? FIRST : 256 );
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cdata->first_pass = 1;
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cdata->hshift = 0;
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for ( cdata->fcode = (long) cdata->hsize; cdata->fcode < 65536L; cdata->fcode *= 2L )
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{
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cdata->hshift++;
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}
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cdata->hshift = 8 - cdata->hshift; /* set hash code range bound */
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cdata->hsize_reg = cdata->hsize;
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cl_hash(cdata, (count_int) cdata->hsize_reg); /* clear hash table */
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return 1;
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}
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static int cl_block (struct cmcompress_stream* cdata) /* table clear for block compress */
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{
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register long int rat;
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cdata->checkpoint = cdata->in_count + CHECK_GAP;
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#ifdef DEBUG
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if ( cdata->debug )
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{
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fprintf ( stderr, "count: %ld, ratio: ", cdata->in_count );
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prratio ( stderr, cdata->in_count, cdata->bytes_out );
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fprintf ( stderr, "\n");
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}
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#endif /* DEBUG */
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if(cdata->in_count > 0x007fffff)
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{ /* shift will overflow */
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rat = cdata->bytes_out >> 8;
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if(rat == 0)
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{ /* Don't divide by zero */
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rat = 0x7fffffff;
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}
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else
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{
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rat = cdata->in_count / rat;
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}
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}
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else
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{
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rat = (cdata->in_count << 8) / cdata->bytes_out; /* 8 fractional bits */
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}
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if ( rat > cdata->ratio )
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{
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cdata->ratio = rat;
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}
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else
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{
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cdata->ratio = 0;
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#ifdef DEBUG
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if(cdata->verbose)
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{
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dump_tab(); /* dump string table */
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}
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#endif
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cl_hash (cdata, (count_int) cdata->hsize );
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cdata->free_ent = FIRST;
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cdata->clear_flg = 1;
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if ( !output (cdata, (code_int) CLEAR ) )
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{
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return 0;
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}
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#ifdef DEBUG
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if(cdata->debug)
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{
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fprintf ( stderr, "clear\n" );
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}
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#endif /* DEBUG */
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}
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return 1;
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}
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int cmcompress_compress(struct cmcompress_stream* cdata, void* buff, size_t n)
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{
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register code_int i;
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register int c;
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register int disp;
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unsigned char* input_buffer = (unsigned char*)buff;
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size_t cc;
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/*printf("cmcompress_compress(%p, %p, %d)\n", cdata, buff, n);*/
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if ( cdata->first_pass )
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{
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cdata->ent = input_buffer[0];
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++ input_buffer;
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-- n;
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cdata->first_pass = 0;
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}
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for ( cc = 0; cc < n; ++ cc )
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{
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c = input_buffer[cc];
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cdata->in_count++;
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cdata->fcode = (long) (((long) c << cdata->maxbits) + cdata->ent);
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i = ((c << cdata->hshift) ^ cdata->ent); /* xor hashing */
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if ( htabof (i) == cdata->fcode )
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{
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cdata->ent = codetabof (i);
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continue;
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}
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else if ( (long)htabof (i) < 0 ) /* empty slot */
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{
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goto nomatch;
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}
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disp = (int)(cdata->hsize_reg - i); /* secondary hash (after G. Knott) */
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if ( i == 0 )
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{
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disp = 1;
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}
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probe:
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if ( (i -= disp) < 0 )
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{
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i += cdata->hsize_reg;
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}
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if ( htabof (i) == cdata->fcode )
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{
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cdata->ent = codetabof (i);
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continue;
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}
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if ( (long)htabof (i) > 0 )
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{
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goto probe;
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}
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nomatch:
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if ( !output(cdata, (code_int) cdata->ent ) )
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{
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return 0;
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}
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cdata->out_count++;
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cdata->ent = c;
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if (
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#ifdef SIGNED_COMPARE_SLOW
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(unsigned) cdata->free_ent < (unsigned) cdata->maxmaxcode
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#else
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cdata->free_ent < cdata->maxmaxcode
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#endif
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)
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{
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codetabof (i) = (unsigned short)(cdata->free_ent++); /* code -> hashtable */
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htabof (i) = cdata->fcode;
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}
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else if ( (count_int)cdata->in_count >= cdata->checkpoint && cdata->block_compress )
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{
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if ( !cl_block (cdata) )
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{
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return 0;
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}
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}
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}
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return 1;
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}
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int cmcompress_compress_finalize(struct cmcompress_stream* cdata)
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{
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/*
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* Put out the final code.
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*/
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if ( !output(cdata, (code_int)cdata->ent ) )
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{
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return 0;
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}
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cdata->out_count++;
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if ( !output(cdata, (code_int)-1 ) )
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{
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return 0;
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}
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if(cdata->bytes_out > cdata->in_count) /* exit(2) if no savings */
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{
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return 0;
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}
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return 1;
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}
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#if defined(DEBUG)
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static void prratio(FILE *stream, long int num, long int den)
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{
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register int q; /* Doesn't need to be long */
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if(num > 214748L)
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{ /* 2147483647/10000 */
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|
q = num / (den / 10000L);
|
|
}
|
|
else
|
|
{
|
|
q = 10000L * num / den; /* Long calculations, though */
|
|
}
|
|
if (q < 0)
|
|
{
|
|
putc('-', stream);
|
|
q = -q;
|
|
}
|
|
fprintf(stream, "%d.%02d%%", q / 100, q % 100);
|
|
}
|
|
#endif
|
|
|