.TITLE	Sys_Btest

	.PSECT _Sys_Btest, EXE, NOWRT, RD
	.ENTRY Sys_Btest, ^M<>

;++
;
; Author:	Jonathan Welch
;
; Functional description:
;
;	The bit specified by the position and base operands is tested and
;	its state is returned.
;
; Calling sequence:
;
;	State = Sys_Btest(Bitposition, Base)
;
; Formal arguments:
;
;	Bitposition
;	  VMS Usage  : longword_unsigned
;	  type       : longword (unsigned)
;	  access     : read only
;	  mechanism  : by value
;
;	An offset from the base operand specifying which bit to test.
;
;	Base
;	  VMS Usage  : address
;	  type       : longword (unsigned)
;	  access     : read only
;	  mechanism  : by reference
;
;	Base address to offset "Bitposition" bits from.
;
; Implicit Inputs:
;
;	none
;
; Implicit Outputs:
;
;	none
;
; Routine value:
;
;	0 if the specified bit is off.
;	1 if the specified bit is on.
;
;--

Bitpos = 4
Base = 8

	MOVL	#0, R0				; assume bit is off.
	BBC	Bitpos(AP), @Base(AP), Exit	; it is, exit.
	MOVL	#1, R0				; it's set, return 1.
Exit:	RET

	.END