+++ /dev/null
-;
-; jmemdosa.asm
-;
-; Copyright (C) 1992, Thomas G. Lane.
-; This file is part of the Independent JPEG Group's software.
-; For conditions of distribution and use, see the accompanying README file.
-;
-; This file contains low-level interface routines to support the MS-DOS
-; backing store manager (jmemdos.c). Routines are provided to access disk
-; files through direct DOS calls, and to access XMS and EMS drivers.
-;
-; This file should assemble with Microsoft's MASM or any compatible
-; assembler (including Borland's Turbo Assembler). If you haven't got
-; a compatible assembler, better fall back to jmemansi.c or jmemname.c.
-;
-; To minimize dependence on the C compiler's register usage conventions,
-; we save and restore all 8086 registers, even though most compilers only
-; require SI,DI,DS to be preserved. Also, we use only 16-bit-wide return
-; values, which everybody returns in AX.
-;
-; Based on code contributed by Ge' Weijers.
-;
-
-JMEMDOSA_TXT segment byte public 'CODE'
-
- assume cs:JMEMDOSA_TXT
-
- public _jdos_open
- public _jdos_close
- public _jdos_seek
- public _jdos_read
- public _jdos_write
- public _jxms_getdriver
- public _jxms_calldriver
- public _jems_available
- public _jems_calldriver
-
-;
-; short far jdos_open (short far * handle, char far * filename)
-;
-; Create and open a temporary file
-;
-_jdos_open proc far
- push bp ; linkage
- mov bp,sp
- push si ; save all registers for safety
- push di
- push bx
- push cx
- push dx
- push es
- push ds
- mov cx,0 ; normal file attributes
- lds dx,dword ptr [bp+10] ; get filename pointer
- mov ah,3ch ; create file
- int 21h
- jc open_err ; if failed, return error code
- lds bx,dword ptr [bp+6] ; get handle pointer
- mov word ptr [bx],ax ; save the handle
- xor ax,ax ; return zero for OK
-open_err: pop ds ; restore registers and exit
- pop es
- pop dx
- pop cx
- pop bx
- pop di
- pop si
- pop bp
- ret
-_jdos_open endp
-
-
-;
-; short far jdos_close (short handle)
-;
-; Close the file handle
-;
-_jdos_close proc far
- push bp ; linkage
- mov bp,sp
- push si ; save all registers for safety
- push di
- push bx
- push cx
- push dx
- push es
- push ds
- mov bx,word ptr [bp+6] ; file handle
- mov ah,3eh ; close file
- int 21h
- jc close_err ; if failed, return error code
- xor ax,ax ; return zero for OK
-close_err: pop ds ; restore registers and exit
- pop es
- pop dx
- pop cx
- pop bx
- pop di
- pop si
- pop bp
- ret
-_jdos_close endp
-
-
-;
-; short far jdos_seek (short handle, long offset)
-;
-; Set file position
-;
-_jdos_seek proc far
- push bp ; linkage
- mov bp,sp
- push si ; save all registers for safety
- push di
- push bx
- push cx
- push dx
- push es
- push ds
- mov bx,word ptr [bp+6] ; file handle
- mov dx,word ptr [bp+8] ; LS offset
- mov cx,word ptr [bp+10] ; MS offset
- mov ax,4200h ; absolute seek
- int 21h
- jc seek_err ; if failed, return error code
- xor ax,ax ; return zero for OK
-seek_err: pop ds ; restore registers and exit
- pop es
- pop dx
- pop cx
- pop bx
- pop di
- pop si
- pop bp
- ret
-_jdos_seek endp
-
-
-;
-; short far jdos_read (short handle, void far * buffer, unsigned short count)
-;
-; Read from file
-;
-_jdos_read proc far
- push bp ; linkage
- mov bp,sp
- push si ; save all registers for safety
- push di
- push bx
- push cx
- push dx
- push es
- push ds
- mov bx,word ptr [bp+6] ; file handle
- lds dx,dword ptr [bp+8] ; buffer address
- mov cx,word ptr [bp+12] ; number of bytes
- mov ah,3fh ; read file
- int 21h
- jc read_err ; if failed, return error code
- cmp ax,word ptr [bp+12] ; make sure all bytes were read
- je read_ok
- mov ax,1 ; else return 1 for not OK
- jmp short read_err
-read_ok: xor ax,ax ; return zero for OK
-read_err: pop ds ; restore registers and exit
- pop es
- pop dx
- pop cx
- pop bx
- pop di
- pop si
- pop bp
- ret
-_jdos_read endp
-
-
-;
-; short far jdos_write (short handle, void far * buffer, unsigned short count)
-;
-; Write to file
-;
-_jdos_write proc far
- push bp ; linkage
- mov bp,sp
- push si ; save all registers for safety
- push di
- push bx
- push cx
- push dx
- push es
- push ds
- mov bx,word ptr [bp+6] ; file handle
- lds dx,dword ptr [bp+8] ; buffer address
- mov cx,word ptr [bp+12] ; number of bytes
- mov ah,40h ; write file
- int 21h
- jc write_err ; if failed, return error code
- cmp ax,word ptr [bp+12] ; make sure all bytes written
- je write_ok
- mov ax,1 ; else return 1 for not OK
- jmp short write_err
-write_ok: xor ax,ax ; return zero for OK
-write_err: pop ds ; restore registers and exit
- pop es
- pop dx
- pop cx
- pop bx
- pop di
- pop si
- pop bp
- ret
-_jdos_write endp
-
-
-;
-; void far jxms_getdriver (XMSDRIVER far *)
-;
-; Get the address of the XMS driver, or NULL if not available
-;
-_jxms_getdriver proc far
- push bp ; linkage
- mov bp,sp
- push si ; save all registers for safety
- push di
- push bx
- push cx
- push dx
- push es
- push ds
- mov ax,4300h ; call multiplex interrupt with
- int 2fh ; a magic cookie, hex 4300
- cmp al,80h ; AL should contain hex 80
- je xmsavail
- xor dx,dx ; no XMS driver available
- xor ax,ax ; return a nil pointer
- jmp short xmsavail_done
-xmsavail: mov ax,4310h ; fetch driver address with
- int 2fh ; another magic cookie
- mov dx,es ; copy address to dx:ax
- mov ax,bx
-xmsavail_done: les bx,dword ptr [bp+6] ; get pointer to return value
- mov word ptr es:[bx],ax
- mov word ptr es:[bx+2],dx
- pop ds ; restore registers and exit
- pop es
- pop dx
- pop cx
- pop bx
- pop di
- pop si
- pop bp
- ret
-_jxms_getdriver endp
-
-
-;
-; void far jxms_calldriver (XMSDRIVER, XMScontext far *)
-;
-; The XMScontext structure contains values for the AX,DX,BX,SI,DS registers.
-; These are loaded, the XMS call is performed, and the new values of the
-; AX,DX,BX registers are written back to the context structure.
-;
-_jxms_calldriver proc far
- push bp ; linkage
- mov bp,sp
- push si ; save all registers for safety
- push di
- push bx
- push cx
- push dx
- push es
- push ds
- les bx,dword ptr [bp+10] ; get XMScontext pointer
- mov ax,word ptr es:[bx] ; load registers
- mov dx,word ptr es:[bx+2]
- mov si,word ptr es:[bx+6]
- mov ds,word ptr es:[bx+8]
- mov bx,word ptr es:[bx+4]
- call dword ptr [bp+6] ; call the driver
- mov cx,bx ; save returned BX for a sec
- les bx,dword ptr [bp+10] ; get XMScontext pointer
- mov word ptr es:[bx],ax ; put back ax,dx,bx
- mov word ptr es:[bx+2],dx
- mov word ptr es:[bx+4],cx
- pop ds ; restore registers and exit
- pop es
- pop dx
- pop cx
- pop bx
- pop di
- pop si
- pop bp
- ret
-_jxms_calldriver endp
-
-
-;
-; short far jems_available (void)
-;
-; Have we got an EMS driver? (this comes straight from the EMS 4.0 specs)
-;
-_jems_available proc far
- push si ; save all registers for safety
- push di
- push bx
- push cx
- push dx
- push es
- push ds
- mov ax,3567h ; get interrupt vector 67h
- int 21h
- push cs
- pop ds
- mov di,000ah ; check offs 10 in returned seg
- lea si,ASCII_device_name ; against literal string
- mov cx,8
- cld
- repe cmpsb
- jne no_ems
- mov ax,1 ; match, it's there
- jmp short avail_done
-no_ems: xor ax,ax ; it's not there
-avail_done: pop ds ; restore registers and exit
- pop es
- pop dx
- pop cx
- pop bx
- pop di
- pop si
- ret
-
-ASCII_device_name db "EMMXXXX0"
-
-_jems_available endp
-
-
-;
-; void far jems_calldriver (EMScontext far *)
-;
-; The EMScontext structure contains values for the AX,DX,BX,SI,DS registers.
-; These are loaded, the EMS trap is performed, and the new values of the
-; AX,DX,BX registers are written back to the context structure.
-;
-_jems_calldriver proc far
- push bp ; linkage
- mov bp,sp
- push si ; save all registers for safety
- push di
- push bx
- push cx
- push dx
- push es
- push ds
- les bx,dword ptr [bp+6] ; get EMScontext pointer
- mov ax,word ptr es:[bx] ; load registers
- mov dx,word ptr es:[bx+2]
- mov si,word ptr es:[bx+6]
- mov ds,word ptr es:[bx+8]
- mov bx,word ptr es:[bx+4]
- int 67h ; call the EMS driver
- mov cx,bx ; save returned BX for a sec
- les bx,dword ptr [bp+6] ; get EMScontext pointer
- mov word ptr es:[bx],ax ; put back ax,dx,bx
- mov word ptr es:[bx+2],dx
- mov word ptr es:[bx+4],cx
- pop ds ; restore registers and exit
- pop es
- pop dx
- pop cx
- pop bx
- pop di
- pop si
- pop bp
- ret
-_jems_calldriver endp
-
-JMEMDOSA_TXT ends
-
- end
projects / synfig.git / blobdiff