; xgfx.asm
bits 16
%include "xgfx.h"
global heap1
global heapsz
global exit
global xputchar
global xvideomode
global xgetchar
global xdrawpointT
global xdrawpoint
global xopen
global xclose
global xmove
global xread
global xsetpalette

heap1   dd _heap
_heap:
        times 0x1000 db 0x00
        times 0x1000 db 0x00
        times 0x1000 db 0x00
        times 0x1000 db 0x00
        times 0x1000 db 0x00
        times 0x1000 db 0x00
        times 0x1000 db 0x00
        times 0x1000 db 0x00
heapsz  dw ($-_heap)

xsetpalette:
        push bp
        mov bp,sp

        mov ax,0x1010
        arg bx,0
        xor cx,cx
        xor dx,dx
        arg ch,2
        arg cl,3
        arg dh,1
        int 0x10

        mov sp,bp
        pop bp
        ret

xopen:
        push bp
        mov bp,sp

        mov ax,0x3d00
        arg dx,0
        clc
        int 0x21

        jc .error
        jmp .end

    .error:
        ; xor ax,ax
        neg ax
     .end:
        mov sp,bp
        pop bp
        ret

xmove:
        push bp
        mov bp,sp

        mov ax,0x4200
        arg bx,0
        xor cx,cx
        arg dx,1

        clc
        int 0x21

        jc .error
        mov ax,0x01
        jmp .end
    .error:
        xor ax,ax
    .end:
        mov sp,bp
        pop bp
        ret

xclose:
        push bp
        mov bp,sp

        mov ax,0x3e00
        arg bx,0
        clc
        int 0x21

        jc .error
        mov ax,0x01
        jmp .end
    .error:
        xor ax,ax
    .end:
        mov sp,bp
        pop bp
        ret

readbuf db 0x00

xread:
        push bp
        mov bp,sp

        mov ax,0x3f00
        arg bx,0
        mov cx,0x01
        mov dx,readbuf

        clc
        int 0x21
        jc .error

        mov bx,readbuf
        xor ax,ax
        mov byte al,[bx]
        jmp .end

    .error:
        mov ah,0xff
    .end:
        mov sp,bp
        pop bp
        ret


xdrawpoint:
        push bp
        mov bp,sp

        arg cx,0
        arg dx,1
        arg ax,2

        xor bx,bx
        mov ah,0x0c
        int 0x10

        mov sp,bp
        pop bp
        ret

xdrawpointT:
        push bp
        mov bp,sp

        arg ax,0
        arg dx,1

        and dx,0xf
        and ax,0xf
        mov dh,al

        xor ax,ax
        mov ah,0x02
        xor bx,bx
        int 0x10

        mov ah,0x0a
        mov al,'+'
        xor bx,bx
        mov cx,0x01
        int 0x10

        mov ax,0x01
        mov sp,bp
        pop bp
        ret

xgetchar:
        push bp
        mov bp,sp

        xor ax,ax
        int 0x16

        mov sp,bp
        pop bp
        ret

xvideomode:
        push bp
        mov bp,sp

        arg ax,0
        xor ah,ah
        int 0x10

        mov sp,bp
        pop bp
        ret

exit:
        push bp
        mov bp,sp

        xor ax,ax
        int 0x21

    .halt:
        cli
        hlt
        jmp .halt
    
        mov sp,bp
        pop bp
        ret

xputchar:
        push bp
        mov bp,sp

        arg ax,0
        mov ah,0x0e
        xor bx,bx
        int 0x10

        mov sp,bp
        pop bp
        ret