example2.bas

DOS保护模式下汇编程序设计.zip

'The following Microsoft BASIC 7.0 program should be linked with the above
'library.  The BASIC program first initializes XLIB.  Next, it creates a
'single precision array.  A control block for SUMARRAY is then constructed
'and the call to SUMARRAY is executed.  Finally, the condition code in the
'control block is inspected and results are printed.

DEFINT A-Z

'Declare XLIB procedures
DECLARE FUNCTION XLIBMEMREQ& ()
DECLARE FUNCTION INITXLIB& ()
DECLARE FUNCTION XLIBCONFIG% ()

'Declare procedures in the library linked with XLIB
DECLARE FUNCTION LINADR& (SEG VARIABLE AS ANY)
DECLARE SUB SUMARRAY (SEG VARIABLE AS ANY)

'Structure for the control block
TYPE ARRAYDATA
  CONDCODE AS LONG      'Location to receive any error codes
  N AS LONG             'Number of elements to be summed
  ADDRESS AS LONG       'Linear address of the array
  SUM AS SINGLE         'Location for array sum
END TYPE

'Check XLIBCONFIG to see if XLIB has already been initialized.  If not then
'call XLIBMEMREQ to find amount of conventional memory needed by XLIB and
'release at least this amount with the BASIC SETMEM function.  XLIBMEMREQ
'returns with sign bit of DX set if an error occurred.  The error is then
'identified by AX.  XLIB will not be terminated upon completion of this
'program in the Microsoft QBX environment; therefore, initialization is
'required only once within the environment.
IF XLIBCONFIG = 0 THEN
  TEMP& = XLIBMEMREQ
  IF TEMP& >= 0& THEN
    IF TEMP& > 0 THEN TEMP& = SETMEM(-TEMP& - 16&)
    TEMP& = INITXLIB                 'INITXLIB error code returned in TEMP&
  ELSE
    TEMP& = TEMP& AND &H7FFFFFFF     'Mask sign bit to leave error code only
  END IF
  IF TEMP& THEN
    PRINT "Library initialization error:  "; HEX$(TEMP&)
    END
  END IF
END IF

DIM A(100) AS SINGLE
DIM AD AS ARRAYDATA

FOR I = 0 TO 100            'Assign numbers to array
  A(I) = I
NEXT I

AD.CONDCODE = 0&            'Clear the error code
AD.N = 50&                  'Sum first 50 elements
AD.ADDRESS = LINADR(A(0))   'Calculate and record linear address of A(0)

CALL SUMARRAY(AD)

IF AD.CONDCODE THEN
  PRINT "Error: "; HEX$(AD.CONDCODE)
ELSE
  PRINT "Sum: "; AD.SUM     'Should equal 1225
END IF

END