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CALL ABSOLUTE Statement Programming Example
 
The following example uses CALL ABSOLUTE to execute a machine-language
program stored in an array:
 
CONST nASMBYTES=14
' This program prints a message indicating whether or not
' a math coprocessor is installed.
' It uses a machine-language program stored in an array
' to get the information from the operating system.
'AsmBytes is a label; nASMBYTES is a symbolic constant.
DEFINT A-Z
DIM AsmProg(1 TO (nASMBYTES/2))
 
' The machine-language program stored as data to read into
' the array.
AsmBytes:
DATA &H55              :'PUSH BP        Save base pointer.
DATA &H8B, &HEC        :'MOV  BP,SP     Get our own.
DATA &HCD, &H11        :'INT  11H       Make the ROM-BIOS call.
DATA &H8B, &H5E, &H06  :'MOV  BX,[BP+6] Get argument address.
DATA &H89, &H07        :'MOV  [BX],AX   Save list in argument.
DATA &H5D              :'POP  BP        Restore base pointer.
DATA &HCA, &H02, &H00  :'RET  2         Pop argument off stack
                        '               and make far return.
' Get the starting offset of the array.
P=VARPTR(AsmProg(1))
' Poke the machine-language program into the array.
DEF SEG=VARSEG(AsmProg(1)) ' Change the segment.
Restore AsmBytes
FOR I=0 TO nASMBYTES-1
   READ J
   POKE(P+I),J
NEXT I
 
' Execute the program. The program expects a single integer argument.
CALL ABSOLUTE(X%,VARPTR(AsmProg(1)))
DEF SEG   ' Restore the segment.
' X% now contains bit-encoded equipment list returned by DOS.
' Mask off all but the coprocessor bit (bit 2).
CoProcessor=X% AND &H2
' Print the appropriate message.
IF CoProcessor=2 THEN
  PRINT "Math coprocessor present."
ELSE
  PRINT "No math coprocessor."
END IF
END