/* hr_clear.c - Clear high resolution display page from start of page
 * to end of page by filling with the bit pattern for the specified
 * color c.  Two bytes, one word, are filled on each access since
 * adjacent bytes of the same color have the low 7 bits inverted.
 * Integers must be unsigned.  Returns void.
 *
 * Environment:	Apple II, Aztec c65 V1.05B
 * Programmer:	Don Strayer
 * Date:		15-Jun-88
 */

#include <hr_apple2.h,d2>

hr_clear( sop , eop , c )
	int sop;						/* start of page */
	int eop;						/* end of page */
	int c;							/* color */

{	int *wa;						/* pointer to word address */
	int pat;						/* bit pattern for that word */

	switch ( c )					/* set pattern for specified color */

	{	case HR_BLACK:
		{	pat = 0;				/* black - binary zeroes */
			break;
		}
		case HR_PURPLE:				/* odd columns on, high order off */
		{	pat = 21802;			/* binary 0101010100101010 */
			break;
		}
		case HR_BLUE:				/* even columns on, high order off */
		{	pat = 10837;			/* binary 0010101001010101 */
			break;
		}
		case HR_GREEN:				/* odd columns on, high order on */
		{	pat = 54698;			/* binary 1101010110101010 */
			break;
		}
		case HR_ORANGE:				/* even columns on, high order on */
		{	pat = 43733;			/* binary 1010101011010101 */
			break;
		}
		case HR_WHITE:
		{	pat = 65535;			/* white - binary ones */
			break;
		}
		default:
		{	pat = 0;				/* default black - binary zeroes */
			break;
		}
	}

	for ( wa = sop; wa < eop; ++wa )	/* fill the page from sop to eop */
			*wa = pat;

	return();
}