ASSEMBLY LANGUAGE DRIVERS FOR SEALEVEL SYSTEM PIO48 BOARD

			    C INTERFACE


(c)Copyright Sealevel Systems Incorporated, 1993 - 1995

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	>>>>>>>>>>>>>>>> File: PIO48_C.OBJ <<<<<<<<<<<<<<<<<<<<
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	SETBIT - Sets a bit (0-7) on a specified PIO48 port.
	
	Syntax: SETBIT(PORT,BIT,ONOFF)
	 Where: PORT = desired port
		BIT = bit to set or reset (0-7)
		ONOFF = 1 to turn bit on
			0 to turn bit off
       Returns: ERROR CODE = 1 - bit out of range
			     0 - no error

	The following C example would set bit 2 on port 300 Hex:

	extern int setbit(int,int,int);
	main()
	{
	int port,bit,onoff,error;
	port=0x300;
	bit=2;
	onoff=1;
	error=setbit(port,bit,onoff);
	}
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	TESTBIT - Reads the status of a bit (0-7) on a specified PIO48 port.

	Syntax: TESTBIT(PORT,BIT)
	 Where: PORT = desired port
		BIT = bit to test (0-7)
       Returns: STATUS = 0 - bit low
			 1 - bit high
			 3 - bit out of range

	The following C example would check bit 0 on port 300 Hex
        and loop until the bit was high:

	extern int testbit(int,int);
	main()
	{
	int port,bit,status;
	port=0x300;
	bit=0;
   test:status=testbit(port,bit);
	if (status != 1)
	    goto test;
	}
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	RDBYTE - Reads a byte value from a specified PIO48 port.

	Syntax: RDBYTE(PORT)
	 Where: PORT = desired port
       Returns: PORT STATUS

	The following C example prints the status of port 300 Hex:

	extern int rdbyte(int);
	main()
	{
	int port;
	port=0x300;
	printf("The status of 300 Hex = %d",rdbyte(port));
	}
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	SETBYTE - Sets a byte on a specified PIO48 port.

	Syntax: SETBYTE(PORT,BV)
	 Where: PORT = desired port
		BV = byte value
       Returns: Nothing

	The following C example writes a 55 Hex (1010101) to port 300 Hex:

	extern int setbyte(int,int);
	main()
	{
	int port,bv;
	port=0x300;
	bv=0x55;
	setbyte(port,byte);
	}
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	CLBYTE - Clears a byte on a specified PIO48 port.

	Syntax: CLBYTE(PORT)
	 Where: PORT = desired port
       Returns: Nothing

	The following C example clears port 300 Hex:

	extern int clbyte(int);
	main()
	{
	int port;
	port=0x300;
	clbyte(port,byte);
	}
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