/*
	This C language subroutine computes the
	crosscoherence sequence of its floating
	point inputs.

	The Run Time Library for the C Language.

	Gordon A. Sterling	(617) 461 - 3076
	DSP Development Tools Engineering
    
	Created on 5/27/90
	Updated on 5/94 by AS

	#include <stats.h>					<Header>
	float crosscoh(float out[], float x[], \		<Prototype>
		       float y[], int samples, int lags);	<Prototype>

*/

#include "lib_glob.h"
#include "sts_glob.h"

.SEGMENT/CODE	Code_Space_Name;
.FILE 		RTL_FILENAME;

.GLOBAL	    	_crosscoh;

_crosscoh:	put(R5);
		put(R6);
		put(R7);
		put(R9);
		put(R11);

		R2=dma_i;
		put(R2);
		R2=dmb_i;
		put(R2);

		R5=PASS R4, readparam4(R9);
	    	readparam5(R6);

		F12=FLOAT R9, dm_lnt=dm_0;
		CALL (PC, ___float_divide) (DB);
		F11=2.0;
		F7=1.0;

		R4=R4-R4, dm_ptr=R8;		/*Clear sum, Pt to input*/

		R1=R9-1, F0=DM(dm_ptr,dm_1);
		IF LE JUMP (PC, error_return);	/*Must have > 1 point*/
		LCNTR=R1, DO sum UNTIL LCE;
sum:		    F4=F4+F0, F0=DM(dm_ptr,dm_1);

		F4=F4+F0, dm_ptr=R12;
		F5=F4*F7, R2=R5;

		R4=R4-R4, F0=DM(dm_ptr,dm_1);	/*Clear sum*/

		LCNTR=R1, DO sum2 UNTIL LCE;
sum2:		    F4=F4+F0, F0=DM(dm_ptr,dm_1);
		F4=F4+F0;
		F4=F4*F7;
		F5=F4*F5, R11=R12;		/*Mean*Mean*/

		R1=PASS R8, dm_ptr=R2;
		LCNTR=R6, DO lag_loop UNTIL LCE;
		    R9=R9-1, dma_i=R11;
		    R0=R0-R0, dmb_i=R1;
		    F4=DM(dmb_i,1);
		    F8=DM(dma_i,1);
	    	    LCNTR=R9, DO element_loop UNTIL LCE;
			F8=F8*F4, F4=DM(dmb_i,1);
element_loop:  		F0=F0+F8, F8=DM(dma_i,1);
		    F8=F8*F4;
		    F0=F0+F8;
		    F0=F0*F7;
		    F0=F0-F5;
lag_loop:	    R11=R11+1, DM(dm_ptr,dm_1)=F0;

		R0=PASS R2, FETCH_RETURN

restore_state:	get(dmb_i,1);
		get(dma_i,2);
		get(R11,3);
		get(R9,4);
		get(R7,5);
		get(R6,6);
		get(R5,7);
		RETURN (DB);
		RESTORE_STACK
		RESTORE_FRAME

error_return:	JUMP (PC, restore_state) (DB);
		R0=0;
		FETCH_RETURN

.ENDSEG;