%if 0

Usage of the works is permitted provided that this
instrument is retained with the works, so that any entity
that uses the works is notified of this instrument.

DISCLAIMER: THE WORKS ARE WITHOUT WARRANTY.

%endif

	cpu 8086
	org 256
start:
	mov si, 81h
.skip:
    lodsb
    cmp al, 32
    je .skip
    cmp al, 9
    je .skip
	cmp al, '!'
	jne .notex
	not byte [wantfree]
.notex:
	dec si
	call getnumber

init:
	mov ax, 4300h
	int 2Fh
	cmp al, 80h
	je .gotxms
	mov dx, msg.noxms
	jmp errorexit

.gotxms:
	mov ax, 4310h
	int 2Fh
	mov word [handler], bx
	mov word [handler + 2], es
	rol byte [wantfree], 1
	jc free

alloc:
	mov dx, msg.alloc1
	call disp_msg
	mov ax, di
	call disp_ax_dec
	mov dx, msg.alloc2
	call disp_msg

	mov dx, di
	mov ah, 09h
	push cs
	call callhandler
	cmp ax, 1
	jne .error

	push dx
	mov dx, msg.alloc3
	call disp_msg
	pop ax
	call disp_ax_dec
	mov dx, msg.alloc4
	call disp_msg

	mov ax, 4C00h
	int 21h

.error:
	push dx
	mov dx, msg.alloc5
	call disp_msg
	mov al, bl
	call disp_al_hex
	mov dx, msg.alloc6
	call disp_msg
	pop ax
	call disp_ax_dec
	mov dx, msg.alloc7
errorexit:
	call disp_msg

	mov ax, 4C01h
	int 21h

free:
	mov dx, msg.free1
	call disp_msg
	mov ax, di
	call disp_ax_dec
	mov dx, msg.free2
	call disp_msg

	mov dx, di
	mov ah, 0Ah
	push cs
	call callhandler
	cmp ax, 1
	jne .error

	mov dx, msg.free3
	call disp_msg

	mov ax, 4C00h
	int 21h

.error:
	mov dx, msg.free5
	call disp_msg
	mov al, bl
	call disp_al_hex
	mov dx, msg.free6
	jmp errorexit


disp_msg:
	push ax
	mov ah, 09h
	int 21h
	pop ax
	retn


disp_ax_dec:
	push ax
	push cx
	push dx
	mov cx, 10
	mov dx, -1
	push dx
.loop1:
	xor dx, dx
	div cx
	push dx
	test ax, ax
	jnz .loop1

.loop2:
	pop ax
	add al, '0'
	jc .end
	xchg dx, ax
	mov ah, 02h
	int 21h
	jmp .loop2

.end:
	pop dx
	pop cx
	pop ax
	retn


disp_ax_hex:
    xchg al, ah
    call disp_al_hex
    xchg al, ah
disp_al_hex:
    push cx
    mov cl, 4
    rol al, cl
    call disp_al_nybble_hex
    rol al, cl
    pop cx
disp_al_nybble_hex:
    push ax
    push dx
    and al, 15
    add al, '0'
    cmp al, '9'
    jbe .got
    add al, 7
.got:
    xchg dx, ax
    mov ah, 02h
    int 21h
    pop dx
    pop ax
    retn


callhandler:
	jmp 0:0
handler equ $ - 4


		; INP:	si -> text
		; OUT:	si - 1 -> end (nondigit)
		;	di = number
getnumber:
.skip:
    lodsb
    cmp al, 32
    je .skip
    cmp al, 9
    je .skip
    cmp al, '0'
    jb error
    cmp al, '9'
    ja error
    xor di, di
    jmp .digit
.loop:
    lodsb
.digit:
	cmp al, '_'
	je .loop
    sub al, '0'
    jb .end
    cmp al, 10
    jae .end
    cbw
    add di, di  ; times 2
    mov bx, di
    add di, di  ; times 4
    add di, di  ; times 8
    add di, bx  ; times 10
    add di, ax
    jmp .loop

.end:
	retn

error:
	mov dx, msg.error
	jmp errorexit

wantfree:	db 0

msg:
.error:			db "Error!",13,10,36
.noxms:			db "No XMS entry found!",13,10,36
.alloc1:		db "Trying to allocate ",36
.alloc2:		db " KiB, ",36
.alloc3:		db "success, handle=",36
.alloc7:
.alloc4:		db 13,10,36
.free5:
.alloc5:		db "error, code=",36
.alloc6:		db "h, dx=",36
.free1:			db "Trying to free handle=",36
.free2:			db ", ",36
.free6:			db "h",13,10,36
.free3:			db "success",13,10,36