/*
 *	iopen -
 *
 *				Paul Haeberli - 1984
 *
 */
#include	<stdio.h>
#include	<stdlib.h>
#include	"image.h"

IMAGE *imgopen();

IMAGE *iopen(file, mode, type, dim, xsize, ysize, zsize)
char *file;
register char *mode;
unsigned int type, dim, xsize, ysize, zsize;
{
    return(imgopen(0, file, mode, type, dim, xsize, ysize, zsize));
}

IMAGE *fiopen(f, mode, type, dim, xsize, ysize, zsize)
int f;
register char *mode;
unsigned int type, dim, xsize, ysize, zsize;
{
    return(imgopen(f, 0, mode, type, dim, xsize, ysize, zsize));
}

IMAGE *imgopen(f, file, mode, type, dim, xsize, ysize, zsize)
char *file;
int f;
register char *mode;
unsigned int type, dim, xsize, ysize, zsize;
{
	register IMAGE 	*image;
	register rw;
	int tablesize;
	register int i, max;

	image = (IMAGE*)calloc(1,sizeof(IMAGE));
	rw = mode[1] == '+';
	if(rw) {
	    i_errhdlr("iopen: read/write mode not supported\n");
		return NULL;
	}
	if (*mode=='w') {
		if (file) {
		    f = creat(file, 0666);
		    if (rw && f>=0) {
			    close(f);
			    f = open(file, 2);
		    }
		}
		if (f < 0) {
		    i_errhdlr("iopen: can't open output file %s\n",file);
		    return NULL;
		}
		image->imagic = IMAGIC;
		image->type = type;
		image->xsize = xsize;
		image->ysize = 1;
		image->zsize = 1;
		if (dim>1)
		    image->ysize = ysize;
		if (dim>2)
		    image->zsize = zsize;
		if(image->zsize == 1) {
		    image->dim = 2;
		    if(image->ysize == 1)
			image->dim = 1;
		} else {
		    image->dim = 3;
		}
		image->min = 10000000;
		image->max = 0;
		isetname(image,"no name"); 
		image->wastebytes = 0;
		image->dorev = 0;
		if (write(f,image,sizeof(IMAGE)) != sizeof(IMAGE)) {
		    i_errhdlr("iopen: error on write of image header\n");
		    return NULL;
		}
	} else {
		if (file)
		    f = open(file, rw? 2: 0);
		if (f < 0)
		    return(NULL);
		if (read(f,image,sizeof(IMAGE)) != sizeof(IMAGE)) {
		    i_errhdlr("iopen: error on read of image header\n");
		    return NULL;
		}
		if( ((image->imagic>>8) | ((image->imagic&0xff)<<8)) 
							     == IMAGIC ) {
		    image->dorev = 1;
		    cvtimage(image);
		} else
		    image->dorev = 0;
		if (image->imagic != IMAGIC) {
			i_errhdlr("iopen: bad magic in image file %x\n",image->imagic);
		    return NULL;
		}
	}
	if (rw)
	    image->flags = _IORW;
	else if (*mode != 'r')
	    image->flags = _IOWRT;
	else
	    image->flags = _IOREAD;
	if(ISRLE(image->type)) {
	    tablesize = image->ysize*image->zsize*sizeof(long);
	    image->rowstart = (unsigned long *)malloc(tablesize);
	    image->rowsize = (long *)malloc(tablesize);
	    if( image->rowstart == 0 || image->rowsize == 0 ) {
		i_errhdlr("iopen: error on table alloc\n");
		return NULL;
	    }
	    image->rleend = 512L+2*tablesize;
	    if (*mode=='w') {
		max = image->ysize*image->zsize;
		for(i=0; i<max; i++) {
		    image->rowstart[i] = 0;
		    image->rowsize[i] = -1;
		}
	    } else {
		tablesize = image->ysize*image->zsize*sizeof(long);
		lseek(f, 512L, 0);
		if (read(f,image->rowstart,tablesize) != tablesize) {
		    i_errhdlr("iopen: error on read of rowstart\n");
		    return NULL;
		}
		if(image->dorev)
		    cvtlongs(image->rowstart,tablesize);
		if (read(f,image->rowsize,tablesize) != tablesize) {
		    i_errhdlr("iopen: error on read of rowsize\n");
		    return NULL;
		}
		if(image->dorev)
		    cvtlongs(image->rowsize,tablesize);
	    }
	}
	image->cnt = 0;
	image->ptr = 0;
	image->base = 0;
	if( (image->tmpbuf = ibufalloc(image)) == 0 ) {	
	    i_errhdlr("iopen: error on tmpbuf alloc %d\n",image->xsize);
	    return NULL;
	}
	image->x = image->y = image->z = 0;
	image->file = f;
	image->offset = 512L;			/* set up for img_optseek */
	lseek(image->file, 512L, 0);
	return(image);
}

unsigned short *ibufalloc(image)
register IMAGE *image;
{
    return (unsigned short *)malloc(IBUFSIZE(image->xsize));
}

reverse(lwrd) 
register unsigned long lwrd;
{
    return ((lwrd>>24) 		| 
	   (lwrd>>8 & 0xff00) 	| 
	   (lwrd<<8 & 0xff0000) | 
	   (lwrd<<24) 		);
}

cvtshorts( buffer, n)
register unsigned short buffer[];
register long n;
{
    register short i;
    register long nshorts = n>>1;
    register unsigned short swrd;

    for(i=0; i<nshorts; i++) {
	swrd = *buffer;
	*buffer++ = (swrd>>8) | (swrd<<8);
    }
}

cvtlongs( buffer, n)
register long buffer[];
register long n;
{
    register short i;
    register long nlongs = n>>2;
    register unsigned long lwrd;

    for(i=0; i<nlongs; i++) {
	lwrd = buffer[i];
	buffer[i] =     ((lwrd>>24) 		| 
	   		(lwrd>>8 & 0xff00) 	| 
	   		(lwrd<<8 & 0xff0000) 	| 
	   		(lwrd<<24) 		);
    }
}

cvtimage( buffer )
register long buffer[];
{
    cvtshorts(buffer,12);
    cvtlongs(buffer+3,12);
    cvtlongs(buffer+26,4);
}

static void (*i_errfunc)();

/*	error handler for the image library.  If the iseterror() routine
	has been called, sprintf's the args into a string and calls the
	error function.  Otherwise calls fprintf with the args and then
	exit.  This allows 'old' programs to assume that no errors
	ever need be worried about, while programs that know how and
	want to can handle the errors themselves.  Olson, 11/88
*/
i_errhdlr(fmt, a1, a2, a3, a4)	/* most args currently used is 2 */
char *fmt;
{
	if(i_errfunc) {
		char ebuf[2048];	/* be generous; if an error includes a
			pathname, the maxlen is 1024, so we shouldn't ever 
			overflow this! */
		sprintf(ebuf, fmt, a1, a2, a3, a4);
		(*i_errfunc)(ebuf);
		return;
	}
	fprintf(stderr, fmt, a1, a2, a3, a4);
	exit(1);
}

/* this function sets the error handler for i_errhdlr */
i_seterror(func)
void (*func)();
{
	i_errfunc = func;
}