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/* ybmtopbm.c - read a file from Bennet Yee's 'xbm' program and write a pbm.
**
** Written by Jamie Zawinski based on code (C) 1988 by Jef Poskanzer.
**
** Permission to use, copy, modify, and distribute this software and its
** documentation for any purpose and without fee is hereby granted, provided
** that the above copyright notice appear in all copies and that both that
** copyright notice and this permission notice appear in supporting
** documentation. This software is provided "as is" without express or
** implied warranty.
*/
#include "pm.h"
#include "pbm.h"
static short const ybmMagic = ( ( '!' << 8 ) | '!' );
static int item;
static int bitsInBuffer, bitshift;
static void
getinit(FILE * const ifP,
short * const colsP,
short * const rowsP,
short * const depthP,
short * const padrightP) {
short magic;
int rc;
rc = pm_readbigshort(ifP, &magic);
if (rc == -1)
pm_error("EOF / read error");
if (magic != ybmMagic)
pm_error("bad magic number in YBM file");
rc = pm_readbigshort(ifP, colsP);
if (rc == -1 )
pm_error("EOF / read error");
rc = pm_readbigshort(ifP, rowsP);
if (rc == -1)
pm_error("EOF / read error");
*depthP = 1;
*padrightP = ((*colsP + 15) / 16) * 16 - *colsP;
}
static bit
getbit(FILE * const ifP) {
bit b;
if (bitsInBuffer == 0) {
item = (getc(ifP) << 8) | (getc(ifP) << 0);
if (item == EOF)
pm_error("EOF / read error");
bitsInBuffer = 16;
bitshift = 0;
}
b = ((item >> bitshift) & 1 ) ? PBM_BLACK : PBM_WHITE;
--bitsInBuffer;
++bitshift;
return b;
}
int
main(int argc, const char * argv[]) {
FILE * ifP;
bit * bitrow;
short rows, cols, padright;
unsigned int row;
short depth;
const char * inputFile;
pm_proginit(&argc, argv);
if (argc-1 < 1)
inputFile = "-";
else {
inputFile = argv[1];
if (argc-1 > 2)
pm_error("Too many arguments. The only argument is the optional "
"input file name");
}
ifP = pm_openr(inputFile);
bitsInBuffer = 0;
getinit(ifP, &cols, &rows, &depth, &padright);
if (depth != 1)
pm_error("YBM file has depth of %u, must be 1", (unsigned)depth);
pbm_writepbminit(stdout, cols, rows, 0);
bitrow = pbm_allocrow(cols);
for (row = 0; row < rows; ++row) {
/* Get raster. */
unsigned int col;
for (col = 0; col < cols; ++col)
bitrow[col] = getbit(ifP);
/* Discard line padding */
for (col = 0; col < padright; ++col)
getbit(ifP);
pbm_writepbmrow(stdout, bitrow, cols, 0);
}
pm_close(ifP);
pm_close(stdout);
return 0;
}
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