359 lines
8.4 KiB
NASM
359 lines
8.4 KiB
NASM
; File:
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; intr.asm
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; Description:
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; Assembly implementation of calling an interrupt
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;
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; Copyright (c) 2000
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; Steffen Kaiser
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; All Rights Reserved
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;
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; This file is part of FreeDOS.
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;
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; FreeDOS is free software; you can redistribute it and/or
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; modify it under the terms of the GNU General Public License
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; as published by the Free Software Foundation; either version
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; 2, or (at your option) any later version.
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;
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; DOS-C is distributed in the hope that it will be useful, but
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; WITHOUT ANY WARRANTY; without even the implied warranty of
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; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
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; the GNU General Public License for more details.
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;
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; You should have received a copy of the GNU General Public
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; License along with DOS-C; see the file COPYING. If not,
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; write to the Free Software Foundation, Inc.,
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; 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
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;
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%include "segs.inc"
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%include "stacks.inc"
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%macro INTR 1
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push bp ; Standard C entry
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mov bp,sp
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push si
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push di
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%ifdef WATCOM
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push bx
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push cx
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push dx
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push es
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%endif
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push ds
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pushf
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; Flags are preserved across the entire
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; function call, particularly IF.
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arg nr, {rp,%1}
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mov ax, [.nr] ; interrupt number
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mov [cs:%%intr_1-1], al
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jmp short %%intr_2 ; flush the instruction cache
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%%intr_2:
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%if %1 == 4
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lds bx, [.rp] ; regpack structure FAR
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%else
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mov bx, [.rp] ; regpack structure
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%endif
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mov dx, [bx+6]
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mov si, [bx+8]
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mov di, [bx+10]
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mov bp, [bx+12]
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push word [bx+14] ; ds
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mov es, [bx+16]
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pushf
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pop cx
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and cx, 0F02Ah
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; Get the current reserved bits from the FL
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; register. Hardens against possible weirdness
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; around eg the NEC V20/V30 MD flag.
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mov ax, [bx + 22] ; flags
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and ax, ~ 0F72Ah
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; Clear most of the top bits of the FL input.
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; Particularly, clear DF, IF, and TF. Callers
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; often do not initialise all of the iregs
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; structure passed to us. Avoid weirdness
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; when DF would be set (DN) or when TF would
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; enable tracing randomly.
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or ax, cx
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; Set reserved bits to same as current FL.
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push ax
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mov ax, [bx]
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mov cx, [bx+4]
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mov bx, [bx+2]
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popf ; set live FL
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pop ds
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sti
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int 0
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%%intr_1:
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pushf
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push ds
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push bx
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mov bx, sp
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%if %1 == 4
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%ifdef WATCOM
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lds bx, [ss:bx+(14+8)+4] ; FAR address of REGPACK, pascal convention
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%else
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lds bx, [ss:bx+14+.rp-bp] ; FAR address of REGPACK, SP=BX + skip saved registers (14) +
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%endif
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%else
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mov ds, [ss:bx+8]
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%ifdef WATCOM
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mov bx, [ss:bx+26] ; NEAR address of REGPACK, pascal convention
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%else
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mov bx, [ss:bx+14+.rp-bp] ; NEAR address of REGPACK
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%endif
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%endif
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mov [bx], ax
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pop word [bx+2] ; bx
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mov [bx+4], cx
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mov [bx+6], dx
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mov [bx+8], si
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mov [bx+10], di
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mov [bx+12], bp
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pop word [bx+14] ; ds
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mov [bx+16], es
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pop word [bx+22] ; flags
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; restore all registers to values from INTR entry
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popf
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pop ds
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%ifdef WATCOM
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pop es
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pop dx
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pop cx
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pop bx
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%endif
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pop di
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pop si
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pop bp
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%endmacro
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segment HMA_TEXT
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;
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; void ASMPASCAL call_intr(WORD nr, struct REGPACK FAR *rp)
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;
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global CALL_INTR
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CALL_INTR:
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INTR 4 ; rp is far, DWORD argument
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ret 6
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;; COUNT ASMPASCAL res_DosExec(COUNT mode, exec_blk * ep, BYTE * lp)
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global RES_DOSEXEC
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RES_DOSEXEC:
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pop es ; ret address
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popargs ax,bx,dx ; mode, exec block, filename
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push es ; ret address
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mov ah, 4bh
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push ds
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pop es ; es = ds
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int 21h
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jc short no_exec_error
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xor ax, ax
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no_exec_error:
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ret
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;; UCOUNT ASMPASCAL res_read(int fd, void *buf, UCOUNT count);
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global RES_READ
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RES_READ:
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pop ax ; ret address
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popargs bx,dx,cx ; fd, buf, count
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push ax ; ret address
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mov ah, 3fh
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int 21h
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jnc no_read_error
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mov ax, -1
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no_read_error:
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ret
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segment INIT_TEXT
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;
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; void init_call_intr(nr, rp)
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; REG int nr
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; REG struct REGPACK *rp
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;
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global INIT_CALL_INTR
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INIT_CALL_INTR:
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INTR 2 ; rp is near, WORD argument
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ret 4
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;
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; int init_call_XMScall( (WORD FAR * driverAddress)(), WORD AX, WORD DX)
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;
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; this calls HIMEM.SYS
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;
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global INIT_CALL_XMSCALL
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INIT_CALL_XMSCALL:
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pop bx ; ret address
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popargs {es,cx},ax,dx
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push cs ; ret address
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push bx
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push es ; driver address ("jmp es:cx")
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push cx
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retf
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; void FAR *DetectXMSDriver(VOID)
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global DETECTXMSDRIVER
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DETECTXMSDRIVER:
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mov ax, 4300h
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int 2fh ; XMS installation check
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cmp al, 80h
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je detected
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xor ax, ax
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xor dx, dx
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ret
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detected:
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push es
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push bx
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mov ax, 4310h ; XMS get driver address
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int 2fh
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mov ax, bx
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mov dx, es
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pop bx
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pop es
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ret
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global KEYCHECK
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KEYCHECK:
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mov ah, 1
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int 16h
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ret
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;; int open(const char *pathname, int flags);
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global INIT_DOSOPEN
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INIT_DOSOPEN:
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;; init calling DOS through ints:
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pop bx ; ret address
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popargs dx,ax ; pathname, flags
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push bx ; ret address
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mov ah, 3dh
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;; AX will have the file handle
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common_int21:
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int 21h
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jnc common_no_error
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mov ax, -1
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common_no_error:
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ret
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;; int close(int fd);
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global CLOSE
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CLOSE:
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pop ax ; ret address
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pop bx ; fd
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push ax ; ret address
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mov ah, 3eh
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jmp short common_int21
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;; UCOUNT read(int fd, void *buf, UCOUNT count);
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global READ
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READ:
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pop ax ; ret address
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popargs bx,dx,cx ; fd,buf,count
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push ax ; ret address
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mov ah, 3fh
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jmp short common_int21
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;; int dup2(int oldfd, int newfd);
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global DUP2
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DUP2:
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pop ax ; ret address
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popargs bx,cx ; oldfd,newfd
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push ax ; ret address
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mov ah, 46h
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jmp short common_int21
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;
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; ULONG ASMPASCAL lseek(int fd, long position);
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;
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global LSEEK
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LSEEK:
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pop ax ; ret address
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popargs bx,{cx,dx} ; fd, position high:low
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push ax ; ret address
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mov ax,4200h ; origin: start of file
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int 21h
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jnc seek_ret ; CF=1?
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sbb ax,ax ; then dx:ax = -1, else unchanged
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sbb dx,dx
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seek_ret:
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ret
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;; VOID init_PSPSet(seg psp_seg)
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global INIT_PSPSET
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INIT_PSPSET:
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pop ax ; ret address
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pop bx ; psp_seg
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push ax ; ret_address
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mov ah, 50h
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int 21h
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ret
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;; COUNT init_DosExec(COUNT mode, exec_blk * ep, BYTE * lp)
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global INIT_DOSEXEC
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INIT_DOSEXEC:
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pop es ; ret address
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popargs ax,bx,dx ; mode, exec block, filename
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push es ; ret address
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mov ah, 4bh
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push ds
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pop es ; es = ds
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int 21h
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jc short exec_no_error
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xor ax, ax
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exec_no_error:
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ret
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;; int init_setdrive(int drive)
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global INIT_SETDRIVE
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INIT_SETDRIVE:
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mov ah, 0x0e
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common_dl_int21:
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pop bx ; ret address
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pop dx ; drive/char
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push bx
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int 21h
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ret
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;; int init_switchar(int char)
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global INIT_SWITCHAR
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INIT_SWITCHAR:
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mov ax, 0x3701
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jmp short common_dl_int21
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;
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; seg ASMPASCAL allocmem(UWORD size);
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;
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global ALLOCMEM
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ALLOCMEM:
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pop ax ; ret address
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pop bx ; size
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push ax ; ret address
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mov ah, 48h
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int 21h
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sbb bx, bx ; carry=1 -> ax=-1
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or ax, bx ; segment
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ret
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;; void set_DTA(void far *dta)
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global SET_DTA
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SET_DTA:
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pop ax ; ret address
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popargs {bx,dx} ; seg:off(dta)
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push ax ; ret address
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mov ah, 1ah
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push ds
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mov ds, bx
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int 21h
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pop ds
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ret
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