/*
	This C language subroutine provides an interface
	to the input flags of the ADSP-21020.

	The Run Time Library for the C Language.

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

	Created on 01/07/91

	The function returns 0 for modes [0,4], and
	the flag value (0 or 1) for any other mode. An
	invalid flag will result in a -1 return value.

	#include <21020.h>			    <Header>
	int poll_flag_in(int flag, int mode);	    <Prototype>

	flag = { 0, 1, 2, 3 }
	mode = { 0 = transition lo to hi
		 1 = transition hi to lo
		 2 = flag hi
		 3 = flag low
		 4 = transition 
	     other = read only flag
		}
*/

#include "lib_glob.h"
#include "020_glob.h"

.SEGMENT/CODE	Code_Space_Name;
.FILE 		RTL_FILENAME;

.GLOBAL	    	_poll_flag_in;

_poll_flag_in:	R4=PASS R4, R0=dm_0;	/*Test for flag 0, return 0*/
		IF EQ JUMP (PC, tst_0) (DB);
		R4=R4-1;
		FETCH_RETURN		/* Fetches Return addr from the start */
		IF EQ JUMP (PC, tst_1);
		R4=R4-1;
		IF EQ JUMP (PC, tst_2);
		R4=R4-1;
		IF EQ JUMP (PC, tst_3);
error_return:	R0=-1;			/*Error return*/
		JUMP (PC, restore_state);

tst_0:		R8=PASS R8;
		IF EQ JUMP (PC, trans_lo_to_hi0);
		R8=R8-1;
		IF EQ JUMP (PC, trans_hi_to_lo0);
		R8=R8-1;
		IF EQ JUMP (PC, lo_to_hi0);
		R8=R8-1;
		IF EQ JUMP (PC, hi_to_lo0);
		R8=R8-1;
		IF EQ JUMP (PC, trans0);	/*If the input is not 0-4, return flag*/
		JUMP (PC, restore_state) (DB);
		IF FLAG0_IN R0=R0+1;
		nop;

trans0:		IF FLAG0_IN JUMP (PC, hi_to_lo0);
		JUMP (PC, lo_to_hi0);

trans_lo_to_hi0:IF NOT FLAG0_IN JUMP (PC, lo_to_hi0); /*These two cycles are needed*/
		IF FLAG0_IN JUMP (PC, trans_lo_to_hi0);   /* would be un-interruptable*/
lo_to_hi0:	IF FLAG0_IN JUMP (PC, restore_state);
		IF NOT FLAG0_IN JUMP (PC, lo_to_hi0);
		JUMP (PC, restore_state);

trans_hi_to_lo0:IF FLAG0_IN JUMP (PC, hi_to_lo0);
		IF NOT FLAG0_IN JUMP (PC, trans_hi_to_lo0);
hi_to_lo0:	IF NOT FLAG0_IN JUMP (PC, restore_state);
		IF FLAG0_IN JUMP (PC, hi_to_lo0);
		JUMP (PC, restore_state);

tst_1:		R8=PASS R8;
		IF EQ JUMP (PC, trans_lo_to_hi1);
		R8=R8-1;
		IF EQ JUMP (PC, trans_hi_to_lo1);
		R8=R8-1;
		IF EQ JUMP (PC, lo_to_hi1);
		R8=R8-1;
		IF EQ JUMP (PC, hi_to_lo1);
		R8=R8-1;
		IF EQ JUMP (PC, trans1);
		JUMP (PC, restore_state) (DB);
		IF FLAG1_IN R0=R0+1;
		NOP;

trans1:		IF FLAG1_IN JUMP (PC, hi_to_lo1);
		JUMP (PC, lo_to_hi1);

trans_lo_to_hi1:IF NOT FLAG1_IN JUMP (PC, lo_to_hi1);	    /*These two cycles are needed*/
		IF FLAG1_IN JUMP (PC, trans_lo_to_hi1);   /* would be un-interruptable*/
lo_to_hi1:	IF FLAG1_IN JUMP (PC, restore_state);
		IF NOT FLAG1_IN JUMP (PC, lo_to_hi1);
		JUMP (PC, restore_state);

trans_hi_to_lo1:IF FLAG1_IN JUMP (PC, hi_to_lo1);
		IF NOT FLAG1_IN JUMP (PC, trans_hi_to_lo1);
hi_to_lo1:	IF NOT FLAG1_IN JUMP (PC, restore_state);
		IF FLAG1_IN JUMP (PC, hi_to_lo1);
		JUMP (PC, restore_state);

tst_2:		R8=PASS R8;
		IF EQ JUMP (PC, trans_lo_to_hi2);
		R8=R8-1;
		IF EQ JUMP (PC, trans_hi_to_lo2);
		R8=R8-1;
		IF EQ JUMP (PC, lo_to_hi2);
		R8=R8-1;
		IF EQ JUMP (PC, hi_to_lo2);
		R8=R8-1;
		IF EQ JUMP (PC, trans2);
		JUMP (PC, restore_state) (DB);
		IF FLAG2_IN R0=R0+1;
		NOP;

trans2:		IF FLAG2_IN JUMP (hi_to_lo2);
		JUMP (PC, lo_to_hi2);

trans_lo_to_hi2:IF NOT FLAG2_IN JUMP (PC, lo_to_hi2);	    /*These two cycles are needed*/
		IF FLAG2_IN JUMP (PC, trans_lo_to_hi2);   /* would be un-interruptable*/
lo_to_hi2:	IF FLAG2_IN JUMP (PC, restore_state);
		IF NOT FLAG2_IN JUMP (PC, lo_to_hi2);
		JUMP (PC, restore_state);

trans_hi_to_lo2:IF FLAG2_IN JUMP (PC, hi_to_lo2);
		IF NOT FLAG2_IN JUMP (PC, trans_hi_to_lo2);
hi_to_lo2:	IF NOT FLAG2_IN JUMP (PC, restore_state);
		IF FLAG2_IN JUMP (PC, hi_to_lo2);
		JUMP (PC, restore_state);

tst_3:		R8=PASS R8;
		IF EQ JUMP (PC, trans_lo_to_hi3);
		R8=R8-1;
		IF EQ JUMP (PC, trans_hi_to_lo3);
		R8=R8-1;
		IF EQ JUMP (PC, lo_to_hi3);
		R8=R8-1;
		IF EQ JUMP (PC, hi_to_lo3);
		R8=R8-1;
		IF EQ JUMP (PC, trans3);
		JUMP (PC, restore_state) (DB);
		IF FLAG3_IN R0=R0+1;
		NOP;

trans3:		IF FLAG3_IN JUMP (PC, hi_to_lo3);
		JUMP (PC, lo_to_hi3);

trans_lo_to_hi3:IF NOT FLAG3_IN JUMP (PC, lo_to_hi3);	    /*These two cycles are needed*/
		IF FLAG3_IN JUMP (PC, trans_lo_to_hi3);   /* would be un-interruptable*/
lo_to_hi3:	IF FLAG3_IN JUMP (PC, restore_state);
		IF NOT FLAG3_IN JUMP (PC, lo_to_hi3);
		JUMP (PC, restore_state);

trans_hi_to_lo3:IF FLAG3_IN JUMP (PC, hi_to_lo3);
		IF NOT FLAG3_IN JUMP (PC, trans_hi_to_lo3);
hi_to_lo3:	IF NOT FLAG3_IN JUMP (PC, restore_state);
		IF FLAG3_IN JUMP (PC, hi_to_lo3);
		JUMP (PC, restore_state);

restore_state:	FETCH_RETURN
		RETURN (DB);
		RESTORE_STACK
		RESTORE_FRAME

.ENDSEG;