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/* libpbm2.c - pbm utility library part 2
**
** Copyright (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 "pbm.h"
#include "libpbm.h"
#include "fileio.h"
static bit
getbit (FILE * const file) {
char ch;
do {
ch = pm_getc( file );
} while ( ch == ' ' || ch == '\t' || ch == '\n' || ch == '\r' );
if ( ch != '0' && ch != '1' )
pm_error( "junk in file where bits should be" );
return ( ch == '1' ) ? 1 : 0;
}
void
pbm_readpbminitrest( file, colsP, rowsP )
FILE* file;
int* colsP;
int* rowsP;
{
/* Read size. */
*colsP = (int)pm_getuint( file );
*rowsP = (int)pm_getuint( file );
/* *colsP and *rowsP really should be unsigned int, but they come
from the time before unsigned ints (or at least from a person
trained in that tradition), so they are int. We could simply
consider negative numbers to mean values > INT_MAX/2 and much
code would just automatically work. But some code would fail
miserably. So we consider values that won't fit in an int to
be unprocessable.
*/
if (*colsP < 0)
pm_error("Number of columns in header is too large.");
if (*rowsP < 0)
pm_error("Number of columns in header is too large.");
}
void
pbm_readpbminit( file, colsP, rowsP, formatP )
FILE* file;
int* colsP;
int* rowsP;
int* formatP;
{
/* Check magic number. */
*formatP = pm_readmagicnumber( file );
switch ( PBM_FORMAT_TYPE(*formatP) )
{
case PBM_TYPE:
pbm_readpbminitrest( file, colsP, rowsP );
break;
default:
pm_error( "bad magic number - not a pbm file" );
}
}
void
pbm_readpbmrow( file, bitrow, cols, format )
FILE* file;
bit* bitrow;
int cols, format;
{
register int col, bitshift;
register bit* bP;
switch ( format )
{
case PBM_FORMAT:
for ( col = 0, bP = bitrow; col < cols; ++col, ++bP )
*bP = getbit( file );
break;
case RPBM_FORMAT: {
register unsigned char item;
bitshift = -1; item = 0; /* item's value is meaningless here */
for ( col = 0, bP = bitrow; col < cols; ++col, ++bP )
{
if ( bitshift == -1 )
{
item = pm_getrawbyte( file );
bitshift = 7;
}
*bP = ( item >> bitshift ) & 1;
--bitshift;
}
}
break;
default:
pm_error( "can't happen" );
}
}
void
pbm_readpbmrow_packed(FILE * const file,
unsigned char * const packed_bits,
int const cols,
int const format) {
switch(format) {
case PBM_FORMAT: {
unsigned int col;
unsigned int byteIndex;
/* We first clear the return buffer, then set ones where needed */
for (byteIndex = 0; byteIndex < pbm_packed_bytes(cols); ++byteIndex)
packed_bits[byteIndex] = 0x00;
for (col = 0; col < cols; ++col) {
unsigned char mask;
mask = getbit(file) << (7 - col % 8);
packed_bits[col / 8] |= mask;
}
}
break;
case RPBM_FORMAT: {
int bytes_read;
bytes_read = fread(packed_bits, 1, pbm_packed_bytes(cols), file);
if (bytes_read < pbm_packed_bytes(cols)) {
if (feof(file))
if (bytes_read == 0)
pm_error("Attempt to read a raw PBM image row, but "
"no more rows left in file.");
else
pm_error("EOF in the middle of a raw PBM row.");
else
pm_error("I/O error reading raw PBM row");
}
}
break;
default:
pm_error( "Internal error in pbm_readpbmrow_packed." );
}
}
bit**
pbm_readpbm( file, colsP, rowsP )
FILE* file;
int* colsP;
int* rowsP;
{
register bit** bits;
int format, row;
pbm_readpbminit( file, colsP, rowsP, &format );
bits = pbm_allocarray( *colsP, *rowsP );
for ( row = 0; row < *rowsP; ++row )
pbm_readpbmrow( file, bits[row], *colsP, format );
return bits;
}
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