/*
	This C language subroutine clears a specified 
	interrupt in the IRPTL register.

	The Run Time Library for the C Language.

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

	Created on 1/2/93
	Updated by AS in 8/94 to save/restore mode1

	#include <signal.h>					<Header>
	int clear_interrupt(int sig);				<Prototype>
*/

#include "lib_glob.h"
#include "sig_glob.h"

.SEGMENT/CODE	Code_Space_Name;
.FILE 		RTL_FILENAME;

.GLOBAL		___clear_interrupt020;

___clear_interrupt020:	R0=___SIG_FIRST_INTERRUPT; /* Lowest supported interrupt*/
		COMP(R4,R0), R2=MODE1;		/*Hold initial state		*/
		IF LT JUMP (PC, error_return);	/* Bad interrupt number!	*/

		R0=___SIG_LAST_HARDWARE_INT-1;	/* Total number of hard ints	*/
		COMP(R4,R0);
		IF GT JUMP (PC, error_return);	/* Bad interrupt number!	*/

		R12=1;
		R12=LSHIFT R12 BY R4;		/* Place '1' at int number	*/

		JUMP (PC, stop_ints_real) (DB);
		BIT CLR MODE1 0x1000;		/* Disable all interrupts	*/
		R4=NOT R12;			/* Determine mask for IRPTL	*/
		
stop_ints_real:	R8=IRPTL;			/* Get latch register		*/
		R0=R8 AND R12;			/* Set return value		*/
		R8=R8 AND R4, FETCH_RETURN	/* Clear interrupt		*/
		JUMP (PC, restore_state) (DB);
		IRPTL=R8;			/* Restore IRPTL		*/
		MODE1=R2;

restore_state:	RETURN (DB);
		RESTORE_STACK
		RESTORE_FRAME

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

.ENDSEG;