bekernel.s

; BefOS Kernel
;
; This work by Chris Pressey of Cat's Eye Technologies
; has been placed into the public domain (see UNLICENSE.)

;--- NOTES ---------------------------------------------------;

; This image can be a maximum of 30464 bytes in size.

;--- BEGIN ---------------------------------------------------;

%include    "../inc/befos.inc"

BITS        16
ORG     BEFOS_OFF

;--- CONSTANTS -----------------------------------------------;

;--- Key Bindings ---------------------------------------------;

%include    "../inc/befkeys.inc"

;--- DATA ----------------------------------------------------;

SEGMENT .data

flags:      db  00h
FLAG_EDIT   EQU 01h ; 1 if we are in Edit Mode
FLAG_STRMODE    EQU 08h ; 1 if we are in String Mode

;--- BSS -----------------------------------------------------;

SEGMENT .bss

temp:       RESW 1
temp2:      RESW 1
templen:    RESW 1
attr:       RESB 1

;--- CODE ----------------------------------------------------;

SEGMENT .text

Start:      mov ax, cs      ; get our code segment
        mov ds, ax      ; set data segment to our cs
        mov ss, ax      ; set stack segment to our cs
        mov sp, 0fffeh  ; set stack ptr -> top of segment

;--- Initialize Video ----------------------------------------;

        call    DiscoverVidBase
        call    TextVid

;--- Initialize Memory ---------------------------------------;

        call    DiscoverRAM

;--- Splash the Screen ---------------------------------------;

        mov cl, 2fh
        call    ClrScreen
        call    RefreshStatus
        call    LoadPage
        call    MoveCursor

;--- Install ISRs --------------------------------------------;

        ;call   PlugBreak
        ;call   PlugPrtSc

;=============================================================;
;=== MAIN LOOP ===============================================;
;=============================================================;

MainLoop:   call    GetKey

        mov ax, [keyhit]
        cmp al, 0
        jne .ASCIIKey
        cmp ah, 3
        je  .ASCIIKey       ; Ctrl-2!
        xor bx, bx
        mov bl, ah
        shl bx, 1
        mov si, bx
        mov ax, [keytab + si]
        call    ax
        jmp MainLoop

.ASCIIKey:  test    [flags], byte FLAG_EDIT
        jz  .NoWrite
        mov cx, [keyhit]
        call    WriteByte
        call    Advance
        jmp MainLoop

.NoWrite:   call    BadLight
        jmp MainLoop

;--- Included Modules ----------------------------------------;

%include "memory.s"
%include "interrupt.s"
%include "video.s"
%include "keyboard.s"
%include "disk.s"

%include "screen.s"
%include "digit.s"
%include "display.s"
%include "statusbar.s"
%include "dataedit.s"

%include "page.s"
%include "pageprop.s"
%include "pageedit.s"
%include "buffedit.s"
%include "copypaste.s"

%include "syscall.s"
%include "interp.s"

;--- END -----------------------------------------------------;