getkeyh.asm masm

; Assemble and link with Turbo Assembler to getkeyh.com file with:
; tasm getkeyh.asm
; tlink /t getkeyh
;
; You can use JWASM a MASM clone available on MacOS/Linux/Windows to
; build getkeyh.com . You can use:
; jwasm -bin -Fo=getkeyh.com -0 getkeyh.asm
;
; -0 generates code that can run on 8088/8086 processors
; -1 for 186+ processors
; -2 for 286+ processors
;
; MASM 6.0+ and Segmented Linker LINK.EXE (5.60) can generate getkeyh.com:
; masm getkeyh.asm;
; link /t getkeyh,getkeyh.com;
;
; MASM5.x doesn't support ".model tiny" you have to use ".model small"
; and use LINK.EXE 5.60:
; masm getkeyh.asm;
; link /t getkeyh,getkeyh.com;

.model tiny                    ; We will generate a COM file

.code
org 100h                       ; COM Programs have an ORG 100h

GetKeyH PROC
    push bp
    mov  bp, sp
    les  bx, [bp+6]            ; ES:BX = address of variable to return value in
                               ; [bp+0] is where BP was pushed
                               ; [bp+2] is where the 32-bit far return address is
                               ; [bp+6] is where last parameter is
                               ; Parameters are pushed on stack left to right
                               ; like pascal calling convention.

    in   al,60h                ; Get scancode from keyboard
    xchg dx,ax
    xor  ax,ax                 ; assume no key (AX=0)
    test dl,10000000b          ; is it key up event?
    jnz  short getkeyhD        ;     if it is return 0 (in AX)
    mov  al, dl                ; Otherwise keydown, AX = scan code
getkeyhD:
    mov  es:[bx], ax           ; Update var with scancode so Turbo Basic can read it
    pop bp                     ; Do not use `RET`, Turbo Basic will return for us
GetKeyH ENDP

END GetKeyH                    ; Entrypoint is GetKeyH