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/* pbm.c
* code for reading the header of an ASCII PBM file
* Copyright (c) 1998 Tim Norman. See LICENSE for details
* 2-25-98
*
* Mar 18, 1998 Jim Peterson <jspeter@birch.ee.vt.edu>
*
* Restructured to encapsulate more of the PBM handling.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#include "pm.h"
#include "nstring.h"
#include "ppapbm.h"
int
make_pbm_stat(pbm_stat * const pbmStatP,
FILE * const ifP) {
char line[1024];
char * rc;
int retval;
pbmStatP->fptr = ifP;
pbmStatP->version = none;
pbmStatP->current_line = 0;
pbmStatP->unread = 0;
rc = fgets(line, 1024, ifP);
if (rc == NULL)
retval = 0;
else {
line[strlen(line)-1] = 0;
if (streq(line,"P1"))
pbmStatP->version=P1;
if (streq(line,"P4"))
pbmStatP->version=P4;
if (pbmStatP->version == none) {
pm_message("unknown PBM magic '%s'", line);
retval = 0;
} else {
do {
char * rc;
rc = fgets(line, 1024, ifP);
if (rc == NULL)
return 0;
} while (line[0] == '#');
{
int rc;
rc = sscanf(line, "%d %d",
&pbmStatP->width, &pbmStatP->height);
if (rc != 2)
retval = 0;
else {
if (pbmStatP->width < 0) {
pm_message("Image has negative width");
retval = 0;
} else if (pbmStatP->width > INT_MAX/2) {
pm_message("Uncomputeably large width: %d",
pbmStatP->width);
retval = 0;
} else if (pbmStatP->height < 0) {
pm_message("Image has negative height");
retval = 0;
} else if (pbmStatP->height > INT_MAX/2) {
pm_message("Uncomputeably large height: %d",
pbmStatP->height);
retval = 0;
} else
retval = 1;
}
}
}
}
return retval;
}
static int
getbytes(FILE * const ifP,
unsigned int const width,
unsigned char * const data) {
unsigned char mask;
unsigned char acc;
unsigned char * place;
unsigned int num;
int retval;
if (width == 0)
retval = 0;
else {
for (mask = 0x80, acc = 0, num = 0, place = data; num < width; ) {
switch (getc(ifP)) {
case EOF:
return 0;
case '1':
acc |= mask;
/* fall through */
case '0':
mask >>= 1;
++num;
if (mask == 0x00) { /* if (num % 8 == 0) */
*place++ = acc;
acc = 0;
mask = 0x80;
}
}
}
if (width % 8 != 0)
*place = acc;
retval = 1;
}
return retval;
}
int
pbm_readline(pbm_stat * const pbmStatP,
unsigned char * const data) {
/*----------------------------------------------------------------------------
Read a single line into data which must be at least (pbmStatP->width+7)/8
bytes of storage.
-----------------------------------------------------------------------------*/
int retval;
if (pbmStatP->current_line >= pbmStatP->height)
retval = 0;
else {
if (pbmStatP->unread) {
memcpy(data, pbmStatP->revdata, (pbmStatP->width+7)/8);
++pbmStatP->current_line;
pbmStatP->unread = 0;
free(pbmStatP->revdata);
pbmStatP->revdata = NULL;
retval = 1;
} else {
switch (pbmStatP->version) {
case P1:
if (getbytes(pbmStatP->fptr, pbmStatP->width, data)) {
pbmStatP->current_line++;
retval = 1;
} else
retval = 0;
break;
case P4: {
int tmp, tmp2;
tmp = (pbmStatP->width+7)/8;
tmp2 = fread(data,1,tmp,pbmStatP->fptr);
if (tmp2 == tmp) {
++pbmStatP->current_line;
retval = 1;
} else {
pm_message("error reading line data (%d)", tmp2);
retval = 0;
}
} break;
default:
pm_message("unknown PBM version");
retval = 0;
}
}
}
return retval;
}
void
pbm_unreadline(pbm_stat * const pbmStatP,
void * const data) {
/*----------------------------------------------------------------------------
Push a line back into the buffer; we read too much!
-----------------------------------------------------------------------------*/
/* can store only one line in the unread buffer */
if (!pbmStatP->unread) {
pbmStatP->unread = 1;
pbmStatP->revdata = malloc ((pbmStatP->width+7)/8);
memcpy(pbmStatP->revdata, data, (pbmStatP->width+7)/8);
--pbmStatP->current_line;
}
}
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