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Implement some syscall handling

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This commit is contained in:
Nero 2020-04-13 13:53:21 +00:00
parent 6ba3e0c071
commit 39ef1f9a3e
1 changed files with 39 additions and 23 deletions
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62
boot/kernel.asm
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@ -1,7 +1,7 @@
cpu 8086
org 0x7C00
stack: equ 0x7C00
stack: equ 0x7C00
framsz: equ 0x300
jmp init
@ -68,23 +68,43 @@ getax: push ds
pop si
ret
sftab: dw 0, 0, 0, 0 ; 00-03
dw 0, 0, 0, 0 ; 04-07
dw 0, 0, 0, 0 ; 08-0b
dw 0, 0, 0, 0 ; 0c-0f
dw 0, 0, 0, 0 ; 10-13
dw 0, 0, 0, 0 ; 14-17
dw 0, 0, 0, 0 ; 18-1b
dw 0, 0, 0, 0 ; 1c-1f
dw 0, 0, 0, 0 ; 20-23
dw 0, dos25, 0, 0 ; 24-27
dw 0, 0, 0, 0 ; 28-2b
dw 0, 0, 0, 0 ; 2c-2f
; No such subfunction - set carry and exit
sferr: stc
ret
; DOSINT 25h: Set interrupt vector
; Subfunction table
align 2
sftab: dw sferr, sferr, sferr, sferr
dw sferr, sferr, sferr, sferr
dw sferr, sferr, sferr, sferr
dw sferr, sferr, sferr, sferr
dw sferr, sferr, sferr, sferr
dw sferr, sferr, sferr, sferr
dw sferr, sferr, sferr, sferr
dw sferr, sferr, sferr, sferr
dw sferr, sferr, sferr, sferr
dw sferr, setint, sferr, sferr
dw sferr, sferr, sferr, sferr
dw sferr, sferr, sferr, sferr
dw sferr, sferr, sferr, sferr
dw sferr, sferr, sferr, sferr
dw sferr, sferr, sferr, sferr
dw sferr, sferr, sferr, sferr
; DOS 25h: Set interrupt vector
; IN al interrupt number
; ds:dx entry point
dos25:
setint: push ax
push bx
xor ah, ah
add al, al
add al, al
mov bx, ax
mov [cs:bx], dx
mov ax, ds
mov [cs:bx+2], ds
pop bx
pop ax
ret
; ===== end of resident, begin of transient startup code
@ -96,16 +116,13 @@ init: xor ax, ax
mov ss, ax
xor sp, sp
mov ax, 0x2521
mov al, 0x21
mov dx, int21h
pushf
push cs
call int21h
call setint
mov ax, 0x2520
mov dx, int20h
pushf
push cs
call int21h
call setint
main: push cs
pop ds
@ -120,5 +137,4 @@ loop: lodsb
end: hlt
jmp end
align 2048
msg: db "rdos kernel stub", 0x0A, 0x0D, 0