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/*
Convert a PBM image into the DjVu Bitonal RLE format
described in the csepdjvu(1) documentation
Copyright (c) 2004 Scott Pakin <scott+pbm@pakin.org>
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, 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.
3. The name of the author may not be used to endorse or promote products
derived from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE AUTHOR "AS IS" AND ANY EXPRESS OR
IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
INCIDENTAL, SPECIAL, 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 OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include "pbm.h"
/* Write a byte to a file and check for errors. */
static void
writebyte(FILE * const ofP,
unsigned char const c) {
if (fputc (c, ofP) == EOF)
pm_error ("failed to write to the RLE file. Errno=%d (%s)",
errno, strerror(errno));
}
/* Write a run length to the RLE file. */
static void
write_rle(FILE * const rlefile,
uint32_t const tallyArg) {
uint32_t remainingTally;
remainingTally = tallyArg; /* initial value */
do {
/* Output a single run. */
if (remainingTally < 192) {
/* Single-byte runs */
writebyte (rlefile, remainingTally);
remainingTally >>= 8;
}
else {
/* Two-byte runs */
writebyte (rlefile, ((remainingTally>>8) & 0x3F) + 0xC0);
writebyte (rlefile, remainingTally & 0xFF);
remainingTally >>= 14;
}
/* Very large runs need to be split into smaller runs. We
therefore need to toggle back to the same color we had for the
previous smaller run.
*/
if (remainingTally > 0)
writebyte (rlefile, 0);
}
while (remainingTally > 0);
}
int
main (int argc, const char * argv[]) {
FILE * const rlefile = stdout; /* Generated Bitonal RLE file */
FILE * pbmfile; /* PBM file to convert */
int numcols, numrows; /* Width and height in pixels of the PBM file */
int format; /* Original image type before conversion to PBM */
bit * pbmrow; /* One row of the PBM file */
unsigned int row;
const char * pbmfilename; /* Name of input file */
pm_proginit(&argc, argv);
if (argc-1 < 1)
pbmfilename = "-";
else if (argc-1 == 1)
pbmfilename = argv[1];
else
pm_error("Program takes at most 1 argument -- the input file name. "
"You specified %d", argc-1);
pbmfile = pm_openr(pbmfilename);
/* Write an RLE header. */
pbm_readpbminit(pbmfile, &numcols, &numrows, &format);
fprintf(rlefile, "R4\n");
fprintf(rlefile, "%d %d\n", numcols, numrows);
/* Write the RLE data. */
pbmrow = pbm_allocrow(numcols);
for (row = 0; row < numrows; ++row) {
unsigned int col;
uint32_t pixeltally; /* Run length of the current color */
bit prevpixel; /* Previous pixel seen */
pbm_readpbmrow(pbmfile, pbmrow, numcols, format);
prevpixel = PBM_WHITE; /* Bitonal RLE rows always start with white */
pixeltally = 0;
for (col = 0; col < numcols; ++col) {
bit newpixel = pbmrow[col]; /* Current pixel color */
if (newpixel == prevpixel)
++pixeltally;
else {
write_rle(rlefile, pixeltally);
pixeltally = 1;
prevpixel = newpixel;
}
}
write_rle(rlefile, pixeltally);
}
pbm_freerow(pbmrow);
if (rlefile != stdout)
pm_close(rlefile);
if (pbmfile != stdin)
pm_close(pbmfile);
return 0;
}
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