/* Tbmptopnm.c - read a pilot Tbmp file and write a Portable aNyMap
 *
 * Program by Ian Goldberg <iang@cs.berkeley.edu>
 */

#include "pnm.h"

int
main( int argc, char **argv )
{
    FILE* ifp;
    unsigned short rows, cols, color, cpr, flags;
    unsigned long pad;
    int i,j;
    unsigned char *inbyte;
    unsigned char inbit;
    int twobit = 0;
    int format;
    xel *xelrow;
    unsigned char *Tbmprow;

    /* Parse default params */
    pnm_init( &argc, argv );

    if (argc > 1 && !strcmp(argv[1], "-2bit")) {
	twobit = 1;
	--argc; ++argv;
    }
    if ( argc > 2 || (argc == 2 && argv[1][0] == '-')) {
	pm_usage( "[-2bit] [Tbmpfile]" );
    }

    if ( argc == 2 )
	ifp = pm_openr( argv[1] );
    else
	ifp = stdin;

    /* Read the bitmap header */
    pm_readbigshort( ifp, &cols );
    pm_readbigshort( ifp, &rows );
    pm_readbigshort( ifp, &cpr );
    pm_readbigshort( ifp, &flags );
    pm_readbiglong( ifp, &pad );
    pm_readbiglong( ifp, &pad );

    /* Sanity check */
    if (twobit && (cols & 1)) {
	pm_error("Odd number of columns in 2-bit mode");
    }
    if (twobit) cols >>= 1;
    if ((twobit && cpr != ((cols+7)/8)*2) ||
	(!twobit && cpr != ((cols+15)/16)*2)) {
	pm_error("Wrong number of chars per row");
    }
    if (flags) {
	pm_error("Unknown flags field in bitmap");
    }

    /* Write the pnm header */
    format = twobit ? PGM_TYPE : PBM_TYPE;
    pnm_writepnminit(stdout, cols, rows, 255, format, 0);
    xelrow = pnm_allocrow(cols);

    /* Read the picture data, one row at a time */
    Tbmprow = (unsigned char *)malloc(cpr);
    if (!Tbmprow) {
	pm_error("Unable to allocate %d bytes", cpr);
    }
    for (i=0;i<rows;++i) {
	if (fread( Tbmprow, 1, cpr, ifp ) != cpr) {
	    pm_error("Error reading Tbmp file");
	}
	inbit = twobit ? 6 : 7;
	inbyte = Tbmprow;
	for (j=0; j<cols; ++j) {
	    if (twobit) {
		color = ((*inbyte) & (3 << inbit)) >> inbit;
		switch (color) {
		    case 0: PNM_ASSIGN1(xelrow[j], 255); break;
		    case 1: PNM_ASSIGN1(xelrow[j], 170); break;
		    case 2: PNM_ASSIGN1(xelrow[j], 85); break;
		    default: PNM_ASSIGN1(xelrow[j], 0); break;
		}
	    } else {
		if ((*inbyte) & (1 << inbit)) {
		    PNM_ASSIGN1(xelrow[j], 0);
		} else {
		    PNM_ASSIGN1(xelrow[j], 255);
		}
	    }
	    if (!inbit) {
		++inbyte;
		inbit = twobit ? 6 : 7;
	    } else {
		inbit -= (twobit ? 2 : 1);
	    }
	}
	pnm_writepnmrow(stdout, xelrow, cols, 255, format, 0);
    }

    pm_close( ifp );

    exit( 0 );
}