/*
	This C language subroutine scales
	a floating point number by an 2^x

	The Run Time Library for the C Language.

	Gordon A. Sterling	(617) 461 - 3076
	DSP Development Tools Engineering

	Created on 04/22/90 
	Updated on 5/94 by AS

	#include <math.h>				<Header>
	double ldexp(double x, int exp);		<Prototype>

*/

#include "lib_glob.h"
#include "mth_glob.h"

.SEGMENT/CODE	Code_Space_Name;
.FILE RTL_FILENAME;

.GLOBAL	    _ldexp;

_ldexp:	    reads(R4,1);
	    reads(R8,2); 
	    reads(R12,3);

	    R1=FEXT R4 BY 20:11; /*Extract biased exponent*/
	    R1=R1+R12, FETCH_RETURN	    /*Add scale factor*/
	    R2=D_MAX_BIASED_EXP;	    /*Check for maximum exp*/
	    COMP(R1,R2), R12=R1;
	    IF GT JUMP (PC, overflow);
	    R2=0x800FFFFF;
	    R0=R4 AND R2, R1=R8;
	    R0=R0 OR LSHIFT R12 BY 20;	/*Place exponent bits*/

restore_state:	RETURN (DB);
		RESTORE_STACK
		RESTORE_FRAME

overflow:	R1=HUGE_VAL_LSW;
		JUMP (PC, restore_state) (DB);
		R2=HUGE_VAL_MSW;
		F0=F2 COPYSIGN F0;

.ENDSEG;