***************************************
****File name:park.asm
; Module Name	: 	PARK
; 
; Description:	This transformation converts vectors in balanced 2-phase 
;					orthogonal stationary system into orthogonal rotating 
;					reference frame.
;	id = ialfa * sin_theta - ibeta * cos_theta
;	iq = ialfa * cos_theta + ibeta * sin_theta
;
;					|~~~~~~~~~~~~~~~|
;park_alfa  o---->	|		     	|----->o  park_d
;park_beta	o----	|      PARK	    |
;sin_theta	o---->	|		      	|----->o  park_q
;cos_theta			|______________	|

;==================================================
;Module definitions for external reference.
		.def	PARK            			;function call
		.def	park_alfa,park_beta,sin,cos	;Inputs
		.def	park_d,park_q				;Outputs
***************************************
park_alfa  .usect "park",1
park_beta  .usect "park",1
sin        .usect "park",1
cos	       .usect "park",1
park_d     .usect "park",1
park_q     .usect "park",1    
;-----------------------------------
;Calculate the Park transform

;-----------------------------------
PARK:
    NOP
    ;SPM   1					; SPM set for Q15 multiplication        
    ;id = ialfa * sin_theta - ibeta * cos_theta
	LT	  park_alfa     	; TREG = ialfa
	MPY	  sin       		; PREG = ialfa * sin_theta
	LTP	  park_beta     	; ACC = ialfa * sin_theta and TREG = ibeta 
	MPY	  cos     			; PREG = ialfa * cos_teta
	;iq = ialfa * cos_theta + ibeta * sin_theta
	MPYS  sin       	    ; ACC = ialfa * sin_theta - ibeta * cos_theta and PREG=ibeta*sin_theta
	SACH  park_d			; id = ialfa * sin_theta - ibeta * cos_theta        
	LTP	  park_alfa     	; ACC = ibeta*sin_theta and TREG = ialfa
	MPY   cos   			; PREG = ialfa*cos_theta
	APAC              		; ACC = ialfa * cos_theta + ibeta * sin_theta
	SACH  park_q      		; iq = ialfa * cos_theta + ibeta * sin_theta
    RET