;===========================================================================
; File Name:	mod6_cnt.asm
;
; Module Name: 	MOD6_CNT				      
;
; Initialization Routine: MOD6_CNT_INIT
;
; Originator:	Digital Control Systems Group
;			Texas Instruments
;
; Description:	This module implements a modulo 6 counter. It counts from 
;		state 0 through 5, then resets to 0 and repeats the process.  
;		The state of the output variable m6_cntr changes to the next 
;		state every time it receives a trigger input through the input 
;		variable m6_trig_in. 
;
;			|~~~~~~~~~~~~~~~|
;			| 		|
;    m6_trig_in	o------>|   MOD6_CNT	|----->o  m6_cntr
;			|		|
;			|_______________|
;
;
;
;=====================================================================================
; History:
;-------------------------------------------------------------------------------------
; 9-15-2000	Release	Rev 1.0
;===========================================================================
;(To use this Module, copy this section to main system file)
;		.ref	MOD6_CNT, MOD6_CNT_INIT			;function call
;		.ref	m6_trig_in, m6_cntr			;Inputs
;===========================================================================
;Module definitions for external reference.
		.def	MOD6_CNT, MOD6_CNT_INIT			;function call
		.def	m6_trig_in, m6_cntr			;Inputs
;===========================================================================
		.include	x24x_app.h

;===========================================================================
;Variable Definitions for mod6_cnt module
;---------------------------------------------------------------------------
;m6_cntr		.usect	"mod6_cnt",1	;Mod 6 counter output
;m6_trig_in	.usect	"mod6_cnt",1	;Mod 6 counter trigger input

m6_cntr_vars	.usect	"mod6_cnt",2,1	
m6_cntr			.set	m6_cntr_vars+0		;Mod 6 counter output
m6_trig_in		.set	m6_cntr_vars+1		;Mod 6 counter trigger input
		
		
;======================================================================
MOD6_CNT_INIT:
;======================================================================
		LDP	#m6_cntr
		SPLK	#0h, m6_cntr
		SPLK	#0h, m6_trig_in
		RET

;======================================================================
MOD6_CNT:
;======================================================================
		LDP	#m6_cntr
		LACC	m6_trig_in
		BCND	M6C_END, EQ		;If no trigger exit

CHK_STATE:	LACC	m6_cntr
		SUB	#05h			;Check if at last state
		BCND	M6_RST_ST0,EQ	;If yes, re-init ptr to 1st state
		LACC	m6_cntr		;If not, select next State (Sn->Sn+1)
		ADD	#01h
		SACL	m6_cntr		;i.e. inc commutation_ptr
		B	M6C_END
M6_RST_ST0:
		SPLK	#0h, m6_cntr	;Reset state pointer to 0
M6C_END:
		RET