NEC CP/M-86 - Page 177

CGroup
Driver_Code
Group Driver_Code
CSeg
Public Driver
Driver: Mov Ax, Sp
Mov Bx,
Ss
; Save caller's stack pointers
; Note
that Mov Ss, xxx Mov Sp, xxx is not interruptable on 8086.
Mov Ss, Stack Base ; Switch to driver's stack
Mov Sp,
Offset Top_Stack
Push Bx
; Push caller's stack pointer
Push Ax
Push Bp
; Save caller's frame
Push Ds
; Save
parameter pointer
Push Dx
Pushf ; Save caller's direction flag
; Invoke the driver. Ds:Dx points to the parameter block. It returns with
; a Retf.
CalIf
Popf
Pop
Pop
Pop
Pop
Pop
Mov
Mov
Retf
DcLDriver
Dx
Ds
Bp
Ax
Bx
Ss, Bx
Sp, Ax
Stack Base
Dw Seg Top _ Stack
DcLDriver_Code CSeg
; Invoke the driver with Ds:Dx
; Restore caller's direction flag
; Restore caller's Ds:Dx
; Restore caller's stack frame
; Restore caller's Ss:Sp
; via
;
Bx
; and Ax
Extrn DcLDriver
:Far
Stack SSeg
Rs
16
; This module pushes 8 words
; Top_Stack is defined in the last module linked in.
Extrn Top_Stack :Byte
End
GSX-86: Graphics for the APe
9-45