WebSVN - AndroidProjects - Blame - Rev 244 - /tools/osframework/source/ImageLib/jpeg/jmemdosa.asm

Rev	Author	Line No.	Line
244	chris	1	;
		2	; jmemdosa.asm
		3	;
		4	; Copyright (C) 1992, Thomas G. Lane.
		5	; This file is part of the Independent JPEG Group's software.
		6	; For conditions of distribution and use, see the accompanying README file.
		7	;
		8	; This file contains low-level interface routines to support the MS-DOS
		9	; backing store manager (jmemdos.c). Routines are provided to access disk
		10	; files through direct DOS calls, and to access XMS and EMS drivers.
		11	;
		12	; This file should assemble with Microsoft's MASM or any compatible
		13	; assembler (including Borland's Turbo Assembler). If you haven't got
		14	; a compatible assembler, better fall back to jmemansi.c or jmemname.c.
		15	;
		16	; To minimize dependence on the C compiler's register usage conventions,
		17	; we save and restore all 8086 registers, even though most compilers only
		18	; require SI,DI,DS to be preserved. Also, we use only 16-bit-wide return
		19	; values, which everybody returns in AX.
		20	;
		21	; Based on code contributed by Ge' Weijers.
		22	;
		23
		24	JMEMDOSA_TXT segment byte public 'CODE'
		25
		26	assume cs:JMEMDOSA_TXT
		27
		28	public _jdos_open
		29	public _jdos_close
		30	public _jdos_seek
		31	public _jdos_read
		32	public _jdos_write
		33	public _jxms_getdriver
		34	public _jxms_calldriver
		35	public _jems_available
		36	public _jems_calldriver
		37
		38	;
		39	; short far jdos_open (short far * handle, char far * filename)
		40	;
		41	; Create and open a temporary file
		42	;
		43	_jdos_open proc far
		44	push bp ; linkage
		45	mov bp,sp
		46	push si ; save all registers for safety
		47	push di
		48	push bx
		49	push cx
		50	push dx
		51	push es
		52	push ds
		53	mov cx,0 ; normal file attributes
		54	lds dx,dword ptr [bp+10] ; get filename pointer
		55	mov ah,3ch ; create file
		56	int 21h
		57	jc open_err ; if failed, return error code
		58	lds bx,dword ptr [bp+6] ; get handle pointer
		59	mov word ptr [bx],ax ; save the handle
		60	xor ax,ax ; return zero for OK
		61	open_err: pop ds ; restore registers and exit
		62	pop es
		63	pop dx
		64	pop cx
		65	pop bx
		66	pop di
		67	pop si
		68	pop bp
		69	ret
		70	_jdos_open endp
		71
		72
		73	;
		74	; short far jdos_close (short handle)
		75	;
		76	; Close the file handle
		77	;
		78	_jdos_close proc far
		79	push bp ; linkage
		80	mov bp,sp
		81	push si ; save all registers for safety
		82	push di
		83	push bx
		84	push cx
		85	push dx
		86	push es
		87	push ds
		88	mov bx,word ptr [bp+6] ; file handle
		89	mov ah,3eh ; close file
		90	int 21h
		91	jc close_err ; if failed, return error code
		92	xor ax,ax ; return zero for OK
		93	close_err: pop ds ; restore registers and exit
		94	pop es
		95	pop dx
		96	pop cx
		97	pop bx
		98	pop di
		99	pop si
		100	pop bp
		101	ret
		102	_jdos_close endp
		103
		104
		105	;
		106	; short far jdos_seek (short handle, long offset)
		107	;
		108	; Set file position
		109	;
		110	_jdos_seek proc far
		111	push bp ; linkage
		112	mov bp,sp
		113	push si ; save all registers for safety
		114	push di
		115	push bx
		116	push cx
		117	push dx
		118	push es
		119	push ds
		120	mov bx,word ptr [bp+6] ; file handle
		121	mov dx,word ptr [bp+8] ; LS offset
		122	mov cx,word ptr [bp+10] ; MS offset
		123	mov ax,4200h ; absolute seek
		124	int 21h
		125	jc seek_err ; if failed, return error code
		126	xor ax,ax ; return zero for OK
		127	seek_err: pop ds ; restore registers and exit
		128	pop es
		129	pop dx
		130	pop cx
		131	pop bx
		132	pop di
		133	pop si
		134	pop bp
		135	ret
		136	_jdos_seek endp
		137
		138
		139	;
		140	; short far jdos_read (short handle, void far * buffer, unsigned short count)
		141	;
		142	; Read from file
		143	;
		144	_jdos_read proc far
		145	push bp ; linkage
		146	mov bp,sp
		147	push si ; save all registers for safety
		148	push di
		149	push bx
		150	push cx
		151	push dx
		152	push es
		153	push ds
		154	mov bx,word ptr [bp+6] ; file handle
		155	lds dx,dword ptr [bp+8] ; buffer address
		156	mov cx,word ptr [bp+12] ; number of bytes
		157	mov ah,3fh ; read file
		158	int 21h
		159	jc read_err ; if failed, return error code
		160	cmp ax,word ptr [bp+12] ; make sure all bytes were read
		161	je read_ok
		162	mov ax,1 ; else return 1 for not OK
		163	jmp short read_err
		164	read_ok: xor ax,ax ; return zero for OK
		165	read_err: pop ds ; restore registers and exit
		166	pop es
		167	pop dx
		168	pop cx
		169	pop bx
		170	pop di
		171	pop si
		172	pop bp
		173	ret
		174	_jdos_read endp
		175
		176
		177	;
		178	; short far jdos_write (short handle, void far * buffer, unsigned short count)
		179	;
		180	; Write to file
		181	;
		182	_jdos_write proc far
		183	push bp ; linkage
		184	mov bp,sp
		185	push si ; save all registers for safety
		186	push di
		187	push bx
		188	push cx
		189	push dx
		190	push es
		191	push ds
		192	mov bx,word ptr [bp+6] ; file handle
		193	lds dx,dword ptr [bp+8] ; buffer address
		194	mov cx,word ptr [bp+12] ; number of bytes
		195	mov ah,40h ; write file
		196	int 21h
		197	jc write_err ; if failed, return error code
		198	cmp ax,word ptr [bp+12] ; make sure all bytes written
		199	je write_ok
		200	mov ax,1 ; else return 1 for not OK
		201	jmp short write_err
		202	write_ok: xor ax,ax ; return zero for OK
		203	write_err: pop ds ; restore registers and exit
		204	pop es
		205	pop dx
		206	pop cx
		207	pop bx
		208	pop di
		209	pop si
		210	pop bp
		211	ret
		212	_jdos_write endp
		213
		214
		215	;
		216	; void far jxms_getdriver (XMSDRIVER far *)
		217	;
		218	; Get the address of the XMS driver, or NULL if not available
		219	;
		220	_jxms_getdriver proc far
		221	push bp ; linkage
		222	mov bp,sp
		223	push si ; save all registers for safety
		224	push di
		225	push bx
		226	push cx
		227	push dx
		228	push es
		229	push ds
		230	mov ax,4300h ; call multiplex interrupt with
		231	int 2fh ; a magic cookie, hex 4300
		232	cmp al,80h ; AL should contain hex 80
		233	je xmsavail
		234	xor dx,dx ; no XMS driver available
		235	xor ax,ax ; return a nil pointer
		236	jmp short xmsavail_done
		237	xmsavail: mov ax,4310h ; fetch driver address with
		238	int 2fh ; another magic cookie
		239	mov dx,es ; copy address to dx:ax
		240	mov ax,bx
		241	xmsavail_done: les bx,dword ptr [bp+6] ; get pointer to return value
		242	mov word ptr es:[bx],ax
		243	mov word ptr es:[bx+2],dx
		244	pop ds ; restore registers and exit
		245	pop es
		246	pop dx
		247	pop cx
		248	pop bx
		249	pop di
		250	pop si
		251	pop bp
		252	ret
		253	_jxms_getdriver endp
		254
		255
		256	;
		257	; void far jxms_calldriver (XMSDRIVER, XMScontext far *)
		258	;
		259	; The XMScontext structure contains values for the AX,DX,BX,SI,DS registers.
		260	; These are loaded, the XMS call is performed, and the new values of the
		261	; AX,DX,BX registers are written back to the context structure.
		262	;
		263	_jxms_calldriver proc far
		264	push bp ; linkage
		265	mov bp,sp
		266	push si ; save all registers for safety
		267	push di
		268	push bx
		269	push cx
		270	push dx
		271	push es
		272	push ds
		273	les bx,dword ptr [bp+10] ; get XMScontext pointer
		274	mov ax,word ptr es:[bx] ; load registers
		275	mov dx,word ptr es:[bx+2]
		276	mov si,word ptr es:[bx+6]
		277	mov ds,word ptr es:[bx+8]
		278	mov bx,word ptr es:[bx+4]
		279	call dword ptr [bp+6] ; call the driver
		280	mov cx,bx ; save returned BX for a sec
		281	les bx,dword ptr [bp+10] ; get XMScontext pointer
		282	mov word ptr es:[bx],ax ; put back ax,dx,bx
		283	mov word ptr es:[bx+2],dx
		284	mov word ptr es:[bx+4],cx
		285	pop ds ; restore registers and exit
		286	pop es
		287	pop dx
		288	pop cx
		289	pop bx
		290	pop di
		291	pop si
		292	pop bp
		293	ret
		294	_jxms_calldriver endp
		295
		296
		297	;
		298	; short far jems_available (void)
		299	;
		300	; Have we got an EMS driver? (this comes straight from the EMS 4.0 specs)
		301	;
		302	_jems_available proc far
		303	push si ; save all registers for safety
		304	push di
		305	push bx
		306	push cx
		307	push dx
		308	push es
		309	push ds
		310	mov ax,3567h ; get interrupt vector 67h
		311	int 21h
		312	push cs
		313	pop ds
		314	mov di,000ah ; check offs 10 in returned seg
		315	lea si,ASCII_device_name ; against literal string
		316	mov cx,8
		317	cld
		318	repe cmpsb
		319	jne no_ems
		320	mov ax,1 ; match, it's there
		321	jmp short avail_done
		322	no_ems: xor ax,ax ; it's not there
		323	avail_done: pop ds ; restore registers and exit
		324	pop es
		325	pop dx
		326	pop cx
		327	pop bx
		328	pop di
		329	pop si
		330	ret
		331
		332	ASCII_device_name db "EMMXXXX0"
		333
		334	_jems_available endp
		335
		336
		337	;
		338	; void far jems_calldriver (EMScontext far *)
		339	;
		340	; The EMScontext structure contains values for the AX,DX,BX,SI,DS registers.
		341	; These are loaded, the EMS trap is performed, and the new values of the
		342	; AX,DX,BX registers are written back to the context structure.
		343	;
		344	_jems_calldriver proc far
		345	push bp ; linkage
		346	mov bp,sp
		347	push si ; save all registers for safety
		348	push di
		349	push bx
		350	push cx
		351	push dx
		352	push es
		353	push ds
		354	les bx,dword ptr [bp+6] ; get EMScontext pointer
		355	mov ax,word ptr es:[bx] ; load registers
		356	mov dx,word ptr es:[bx+2]
		357	mov si,word ptr es:[bx+6]
		358	mov ds,word ptr es:[bx+8]
		359	mov bx,word ptr es:[bx+4]
		360	int 67h ; call the EMS driver
		361	mov cx,bx ; save returned BX for a sec
		362	les bx,dword ptr [bp+6] ; get EMScontext pointer
		363	mov word ptr es:[bx],ax ; put back ax,dx,bx
		364	mov word ptr es:[bx+2],dx
		365	mov word ptr es:[bx+4],cx
		366	pop ds ; restore registers and exit
		367	pop es
		368	pop dx
		369	pop cx
		370	pop bx
		371	pop di
		372	pop si
		373	pop bp
		374	ret
		375	_jems_calldriver endp
		376
		377	JMEMDOSA_TXT ends
		378
		379	end

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