; File:
;                         intr.asm
; Description:
;       Assembly implementation of calling an interrupt
;
;                    Copyright (c) 2000
;                       Steffen Kaiser
;                       All Rights Reserved
;
; This file is part of FreeDOS.
;
; FreeDOS is free software; you can redistribute it and/or
; modify it under the terms of the GNU General Public License
; as published by the Free Software Foundation; either version
; 2, or (at your option) any later version.
;
; DOS-C is distributed in the hope that it will be useful, but
; WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
; the GNU General Public License for more details.
;
; You should have received a copy of the GNU General Public
; License along with DOS-C; see the file COPYING.  If not,
; write to the Free Software Foundation, Inc.,
; 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
;

		%include "segs.inc"

%macro INTR 0
        
                push    bp                      ; Standard C entry
                mov     bp,sp
                push    si
                push    di
                push	ds
                push    es

                mov	ax, [bp+4]		; interrupt number
                mov	[cs:%%intr_1-1], al
                jmp 	short %%intr_2		; flush the instruction cache
%%intr_2	mov	bx, [bp+6]		; regpack structure
		mov	ax, [bx]
		mov	cx, [bx+4]
		mov	dx, [bx+6]
		mov	si, [bx+8]
		mov	di, [bx+10]
		mov	bp, [bx+12]
		push	word [bx+14]		; ds
		mov	es, [bx+16]
		mov	bx, [bx+2]
		pop	ds
		int	0
%%intr_1:

		pushf
		push	ds
		push	bx
		mov	bx, sp
		mov	ds, [ss:bx+8]
		mov	bx, [ss:bx+20]		; address of REGPACK
		mov	[bx], ax
		pop	word [bx+2]
		mov	[bx+4], cx
		mov	[bx+6], dx
		mov	[bx+8], si
		mov	[bx+10], di
		mov	[bx+12], bp
		pop	word [bx+14]
		mov	[bx+16], es
		pop	word [bx+22]

		pop	es
		pop	ds
		pop	di
		pop	si
		pop	bp
		ret
%endmacro

segment	HMA_TEXT

;; COUNT ASMCFUNC res_DosExec(COUNT mode, exec_blk * ep, BYTE * lp)
    global _res_DosExec
_res_DosExec:        
        mov ah, 4bh
        mov bx, sp
        mov al, [bx+2]
        push ds
        pop es
        mov dx, [bx+6]          ; filename
        mov bx, [bx+4]          ; exec block
        int 21h
        jc short no_exec_error
        xor ax, ax
no_exec_error:
        ret

;; UCOUNT ASMCFUNC res_read(int fd, void *buf, UCOUNT count); 
    global _res_read
_res_read: 
        mov bx, sp
        mov cx, [bx+6]
        mov dx, [bx+4]
        mov bx, [bx+2]
        mov ah, 3fh
        int 21h
        jnc no_read_error
        mov ax, -1
no_read_error:
        ret

segment	INIT_TEXT
;
;       void init_call_intr(nr, rp)
;       REG int nr
;       REG struct REGPACK *rp
;
		global	_init_call_intr
_init_call_intr:
		INTR

;
; int init_call_XMScall( (WORD FAR * driverAddress)(), WORD AX, WORD DX)
;
; this calls HIMEM.SYS 
;
                global _init_call_XMScall
_init_call_XMScall:
            push bp
            mov  bp,sp
            
            mov  ax,[bp+8]
            mov  dx,[bp+10]
            call far [bp+4]

            pop  bp
            ret
            
; void FAR *DetectXMSDriver(VOID)
global _DetectXMSDriver
_DetectXMSDriver:
        mov ax, 4300h
        int 2fh                 ; XMS installation check

        cmp al, 80h
        je detected
        xor ax, ax
        xor dx, dx
        ret

detected:
        push es
        push bx
        mov ax, 4310h           ; XMS get driver address
        int 2fh
        
        mov ax, bx
        mov dx, es
        pop bx
        pop es
        ret        

global _keycheck        
_keycheck:      
        mov ah, 1
        int 16h
        ret                

;; int open(const char *pathname, int flags); 
    global _open
_open: 
        ;; first implementation of init calling DOS through ints:
        mov bx, sp
        mov ah, 3dh
        ;; we know that SS=DS during init stage.
        mov al, [bx+4]
        mov dx, [bx+2]
        int 21h
        ;; AX has file handle

common_exit:        
        jnc common_no_error
common_error:
        mov ax, -1
common_no_error:
        ret

;; int close(int fd);
    global _close
_close:         
        mov bx, sp
        mov bx, [bx+2]
        mov ah, 3eh
        int 21h
        jmp short common_exit

;; UCOUNT read(int fd, void *buf, UCOUNT count); 
    global _read
_read: 
        mov bx, sp
        mov cx, [bx+6]
        mov dx, [bx+4]
        mov bx, [bx+2]
        mov ah, 3fh
        int 21h
        jmp short common_exit

;; int dup2(int oldfd, int newfd); 
    global _dup2
_dup2:
        mov bx, sp
        mov cx, [bx+4]
        mov bx, [bx+2]
        mov ah, 46h
        int 21h
        jmp short common_exit
        
;; VOID init_PSPSet(seg psp_seg)
    global _init_PSPSet
_init_PSPSet:
	mov ah, 50h
	mov bx, sp
	mov bx, [bx+2]
	int 21h
	ret

;; COUNT init_DosExec(COUNT mode, exec_blk * ep, BYTE * lp)
    global _init_DosExec
_init_DosExec:        
        mov ah, 4bh
        mov bx, sp
        mov al, [bx+2]
        push ds
        pop es
        mov dx, [bx+6]          ; filename
        mov bx, [bx+4]          ; exec block
        int 21h
        jc short exec_no_error
        xor ax, ax
exec_no_error:
        ret

;; int init_setdrive(int drive)
   global _init_setdrive
_init_setdrive:
	mov ah, 0x0e
common_dl_int21:
	mov bx, sp
	mov dl, [bx+2]
	int 21h
	ret

;; int init_switchar(int char)
   global _init_switchar
_init_switchar:
	mov ax, 0x3701
	jmp short common_dl_int21

;; int allocmem(UWORD size, seg *segp)
    global _allocmem
_allocmem:        
        mov ah, 48h
        mov bx, sp
        mov bx, [bx+2]
        int 21h
        jc short common_error
        mov bx, sp
        mov bx, [bx+4]
        mov [bx], ax
        xor ax, ax
        ret
                        
;; void set_DTA(void far *dta)        
    global _set_DTA
_set_DTA
	mov ah, 1ah
	mov bx, sp
	push ds
	lds dx, [bx+2]
	int 21h
	pop ds
	ret