| .CALL ABSOLUTE Statement Programming Example. |
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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 |
| |
