Category : C++ Source Code
Archive   : VMVCPP.ZIP
Filename : XMS.ASM

.model large,pascal

include xms.inc

.data?

pfnXms dd 1 dup (?)


.code XMS_TEXT


public __ErrXmsCall
__ErrXmsCall proc near

assume ds:nothing

call [pfnXms] ;AX = 0 and BL < 0 if error
or ax,ax
jnz Exit ;Brif no error
or bl,bl
jns Exit ;Brif no error

mov al,bl ;AL = Error code
cbw ;AH = 00 or FF
add ax,errXmsBase-0FF80h ;Map to ERR value

;This add instruction also sets the carray flag

Exit:
ret

__ErrXmsCall endp


;BOOL PUBLIC __FXmsCheckInstalled(void);

public __FXmsCheckInstalled
__FXmsCheckInstalled proc

assume ds:@data

mov ax,4300h
int 2fh
cmp al,80h ;Is driver installed?
jne NoXms ;Brif not

mov ax,4310h
int 2fh ;ES:BX = XMS control function
mov word ptr [pfnXms],bx
mov word ptr [pfnXms+2],es

xor ax,ax ;AH = 00h (Get XMS Version Number)
call [pfnXms] ;AX = XMS Version
cmp ax,0200h ;Is this version 2.00 or better
jae Exit ;Brif so, AX != 0. Returning TRUE

NoXms:
xor ax,ax ;Return FALSE

Exit:
ret

__FXmsCheckInstalled endp

end