lib.asm

;lib.asm
;Michael Black, 2007

;lib.asm contains assembly functions that you can use in the shell

	.global _interrupt
	.global _enableInterrupts

;int interrupt (int number, int AX, int BX, int CX, int DX)
_interrupt:
	push bp
	mov bp,sp
	mov ax,[bp+4]	;get the interrupt number in AL
	push ds		;use self-modifying code to call the right interrupt
	mov bx,cs
	mov ds,bx
	mov si,#intr
	mov [si+1],al	;change the 00 below to the contents of AL
	pop ds
	mov ax,[bp+6]	;get the other parameters AX, BX, CX, and DX
	mov bx,[bp+8]
	mov cx,[bp+10]
	mov dx,[bp+12]

intr:	int #0x00	;call the interrupt (00 will be changed above)

	;GWB - Allow all of AX to be returned so that we can return 
	;      negative numbers on errors.
	;mov ah,#0	;we only want AL returned
	pop bp
	ret

;void enableInterrupts()
;call at the beginning of programs.  allows timer preemption
_enableInterrupts:
	sti
	ret