//**************************************
//     
// Name: Matrices with PIC Microcontroll
//     er
// Description:How to do matrices with t
//     he PIC microcontroller
// By: Rockwell
//
//This code is copyrighted and has// limited warranties.Please see http://
//     www.Planet-Source-Code.com/vb/scripts/Sh
//     owCode.asp?txtCodeId=7424&lngWId;=3//for details.//**************************************
//     

		list p=18f452
		include <p18f452.inc>
cntr	equ 0x00;		locations 0x00 to 0x05 in data memory	assigned to the following
cntc	equ		0x01;	
row		equ		0x02;
col		equ		0x03;
temp	equ		0x04;
ans		equ		0x05;
mat		db		0x00,0x01,0x02,0x03;	the table of values for the matrix
		db		0x10,0x11,0x12,0x13;
		db		0x20,0x21,0x22,0x23;
		db		0x30,0x31,0x32,0x33;
		org 0x040
		goto	start;
rows	movff	cntr,temp;
		movff	cntr,row;
		movf	cntr,w;
		addwf	temp,f;
		movf	temp,w;
		addwf	temp,w;
		addwf	TBLPTRL,f;
		return;
start	movlw	0x02;initialize counter for rows
		movwf	cntr;
		movlw	0x02;initialize counter for columns
		movwf	cntc;
		movlw	high mat;	read higher byte of the matrix to w reg
		movwf	TBLPTRH;	initialize to table pointer high
		movlw	low mat;	read lower byte of the matrix to w reg
		movwf	TBLPTRL;	initialize to table pointer low
		call	rows		;call routine for shifting rows horizontally
		movf cntc,w;		load wreg with no of the column
		movff cntc,col;
		addwfc TBLPTRL,f;	add wreg with tblptrl to point to the corresponding column.
		tblrd*;	read the contents pointed by table pointer 
		movf	TABLAT,w;and store in wreg
		movwf	ans;move result to ans reg
		clrf	TBLPTRL;clear tblptr for next iteration.
stop	goto	stop;end of the program
		end
;rows	movf	cntr,w;
;		addwf	cntr,f;
;		movf	cntr,w;
;		addwf	cntr,w;
;		addwf	TBLPTRL,f;
;		return;