#ifndef __MY1KPAD_H__
#define __MY1KPAD_H__

/* 4x4 keypad interface {R0,R1,R2,R3,C0,C1,C2,C3} */
/* 4x3 keypad interface {C1,R0,C0,R3,C2,R2,R1} */

/** DefaultPins: C0-C3 => P1.4-P1.7, R0-R3 => P1.0-P1.3 */
#ifndef KEY_DATA
#define KEY_DATA P1
#endif
#ifndef _ROWS_AT_UPPER_
#define ROWS_FLAG 0x01
#define COLS_FLAG 0x10
#else
#define ROWS_FLAG 0x10
#define COLS_FLAG 0x01
#endif

/** no-key indicator for keypad */
#define KEY_NOT_CODE 0x10

unsigned char key_scan(void) {
	/** scan for key press */
	unsigned char irow, icol, mask, test;
	mask = ROWS_FLAG;
	for (irow=0;irow<4;irow++) {
		KEY_DATA = ~mask; test = COLS_FLAG;
		for (icol=0;icol<4;icol++) {
			if ((KEY_DATA&test)==0) {
				while ((KEY_DATA&test)==0);
				if (icol==3) return irow+0x0A;
				if (irow==0) return icol+1;
				if (irow==1) return icol+4;
				if (irow==2) return icol+7;
				if (icol==1) return 0;
				return (icol>>1)+0x0e;
			}
			test <<= 1;
		}
		mask <<= 1;
	}
	return KEY_NOT_CODE;
}

unsigned char key_wait(void) {
	/** wait for key press */
	unsigned char scan;
	while ((scan=key_scan())==KEY_NOT_CODE);
	return scan;
}