Category : Assembly Language Source Code
Archive   : ASMLIB35.ZIP
Filename : EMSXMS.DOC

 
Output of file : EMSXMS.DOC contained in archive : ASMLIB35.ZIP

******************** EXPANDED AND EXTENDED MEMORY **************************

ASMLIB's EMS subroutines detect and manipulate Expanded Memory hardware
and software. Expanded memory, when installed in any PC, can help solve
many memory limitation problems. Call IsEMS before using any other
ASMLIB EMS subroutines.

EMS memory is allocated in blocks of 16k increments

Error codes returned by EMS functions are:

AH = 0 no error
AH = 80h error in memory manager software
AH = 81h error in expanded memory hardware
AH = 84h bad function code passed to memory manager
AH = 85h no EMM handles available
AH = 89h you tried to allocate zero pages


ASMLIB also supports XMS-compatible extended memory. You must call IsXMS
to determine if XMS memory is available before using any ASMLIB XMS
subroutines.

XMS memory is available on many 286 or better computers with a suitable
driver. On 286 computers, XMS memory will be much slower than EMS memory.
XMS memory is not available on XT (or compatible) computers.

XMS memory is allocated in 1k increments

XMS error codes include:

AH = 0 no error
AH = 0A0h all extended memory is allocated
AH = 0A1h no handles available
AH = 0A2h, 0A3h, 0A5h handle is invalid
AH = 0A4h, 0A6h offset is invalid
AH = 0A7h length is invalid


ASMLIB's EMS and XMS subroutines were written with identical calling
parameters and identical returned information for comparble EMS and XMS
subroutines. For example, AllocEMS and AllocXMS are both called with
DX:AX = the number of bytes requested.


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ALLOCEMS: allocates EMS memory
Source: ems.asm

Call with: DX:AX = number of bytes of memory to allocate

EMS memory is allocated in 16k blocks. AllocEMS will allocate
multiple blocks if nessesary.
NOTE: You must first use IsEMS to determine if Expanded
memory is installed.

Returns: if CF = 0, BX = EMS handle
if CF = 1, AH = EMS error code
Uses: AX, BX, flags
Example: see example code at the end of this file



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ALLOCXMS: allocates XMS memory
Source: xms.asm

Call with: DX:AX = number of bytes of memory to allocate

XMS memory is allocated in 1k blocks. AllocXMS will allocate
multiple blocks if nessesary.
NOTE: You must first use IsXMS to determine if XMS Extended
memory is available.

Returns: if CF = 0, BX = XMS handle
if CF = 1, AH = XMS error code
Uses: AX, BX, flags
Example: see example code at the end of this file



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EMGET: copy data from EMS memory to system RAM
Source: emputget.asm ($emspage.asm)

Call with: BX = EMS handle
ES:[DI] pointing to destination buffer
DS:[SI] pointing to 4-byte offset in EMS block
DX:AX = number of bytes to copy
Returns: if CF = 0, no error
if CF = 1, AH = EMS error code
Uses: AX, flags
Example: see example code at the end of this file



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EMMVER: determines Expanded Memory Manager version
Source: emmver.asm

Call with: no parameters
Returns: if CF = 1, AH = EMS error code
if CF = 0, AH = major version number
AL = minor version number
Uses: AX, flags
Example:

include asm.inc

extrn isems:proc, emmver:proc

.code
.
.
.
call isems
jc no_ems
call emmver ; get emm version
jc ems_error
cmp ah,4 ; version 4.x?
jb version3x ; nope, an older EMM version




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EMPUT: copy data to EMS memory from system RAM
Source: emputget.asm ($emspage.asm)

Call with: BX = EMS handle
ES:[DI] pointing to data to copy
DS:[SI] pointing to 4-byte offset in EMS block
DX:AX = number of bytes to copy
Returns: if CF = 0, no error
if CF = 1, AH = EMS error code
Uses: AX, flags
Example: see example code at the end of this file



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EMSFREE: determine free EMS memory
Source: emsfree.asm

Call with: no parameters

EMSFree does not verify that EMS memory is installed; you should
call IsEMS to determine if EMS memory is installed before using
this subroutine. Do not confuse this subroutine with FreeEMS,
which releases a previously allocated EMS block and handle.

Returns: DX:AX = bytes of EMS memory available
Uses: AX, DX, flags
Example:

include asm.inc

public myprog
extrn isems:proc, emsfree:proc

.code
myprog proc
call isems ; see if EMS memory is installed
jc nope
call emsfree ; is enough available?
.
.
.


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EMSTOTAL: determine total EMS memory installed
Source: emsfree.asm

Call with: no parameters
EMSTotal does not verify that EMS memory is installed; you should
call IsEMS to determine if EMS memory is installed before using
this subroutine.
Returns: DX:AX = bytes of EMS memory installed
Uses: AX, DX, flags
Example:

include asm.inc

public myprog
extrn isems:proc, emstotal:proc

.code
myprog proc
call isems ; see if EMS memory is installed
jc nope
call emstotal ; how much?
.
.
.


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FREEEMS: releases an EMS memory block and handle
Source: ems.asm

Call with: BX = EMS handle

NOTE: DOS does not release EMS memory when your program
returns to DOS. Your program must close any open EMS handles
before quitting, or the EMS memory associated with the handles
will be unavailable to other programs. Do not confuse this
subroutine with EMSFree, whick determines the EMS memory
available.

Returns: if CF = 0, no error
if CF = 1, AH = EMS error code
Uses: AX, flags
Example: see example code at the end of this file



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FREEXMS: releases an XMS memory block and handle
Source: xms.asm

Call with: BX = XMS handle

NOTE: DOS does not release XMS memory when your program
returns to DOS. Your program must close any open XMS handles
before quitting, or the XMS memory associated with the handles
will be unavailable to other programs. Do not confuse this
subroutine with XMSFree, whick determines the XMS memory
available.

Returns: if CF = 0, no error
if CF = 1, AH = XMS error code
Uses: AX, flags
Example: see example code at the end of this file



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ISEMS: detects EMS driver
Source: isems.asm

Call with: no parameters
Returns: if CF = 1, no Expanded Memory manager installed
if CF = 0, EMS memory is installed
Uses: CF
Example: see example code at the end of this file



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ISXMS: detects XMS driver
Source: isxms.asm
Call with: no parameters
Returns: if CF = 1, no XMS driver is installed
if CF = 0, XMS memory is available
Uses: CF
Example: see example code at the end of this file



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XMGET: copy data from XMS memory to system RAM
Source: xmputget.asm (xms.asm)

Call with: BX = XMS handle
ES:[DI] pointing to destination buffer
DS:[SI] pointing to 4-byte offset in XMS block
DX:AX = number of bytes to copy
Returns: if CF = 0, no error
if CF = 1, AH = XMS error code
Uses: AX, flags
Example: see example code at the end of this file



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XMPUT: copy data to XMS memory from system RAM
Source: xmputget.asm (xms.asm)

Call with: BX = XMS handle
ES:[DI] pointing to data to copy
DS:[SI] pointing to 4-byte offset in XMS block
DX:AX = number of bytes to copy
Returns: if CF = 0, no error
if CF = 1, AH = XMS error code
Uses: AX, flags
Example: see example code at the end of this file





; EXPANDED AND EXTENDED MEMORY EXAMPLE CODE

; This example determines if EMS or XMS memory is installed, allocates
; 32k of EMS or XMS memory, copies a Herules graph to the allocated memory
; and later, copies the data back to the video buffer and releases
; the memory block

include asm.inc

public herc2x

extrn isems:proc, isxms:proc
extrn allocems:proc, allocxms:proc
extrn emput:proc, xmput:proc
extrn emget:proc, xmget:proc
extrn freeems:proc, freexms:proc

.data
IF @codesize
xalloc dd 0
xput dd 0
xget dd 0
xfree dd 0
ELSE
xalloc dw 0
xput dw 0
xget dw 0
xfree dw 0
ENDIF
xoffset dw 0,0
xhandle dw 0
xerror dw 0

.code
herc2x proc
; program fragment assumes DS:@data
; set up default conditions: use EMS
mov xerror,offset ems_error
mov word ptr xalloc,offset allocems
mov word ptr xput,offset emput
mov word ptr xget,offset emget
mov word ptr xfree,offset freeems
IF @codesize
mov ax,seg allocems
mov word ptr xalloc+2,ax ; all ASMLIB code in same segment
mov word ptr xput+2,ax
mov word ptr xget+2,ax
mov word ptr xfree+2,ax
ENDIF
; see if EMS is installed
call isems
jnc allocate_memory

; EMS not installed - see if XMS memory is avaialble
; set up for XMS subroutines
mov xerror,offset xms_error
mov word ptr xalloc,offset allocxms
mov word ptr xput,offset xmput
mov word ptr xget,offset xmget
mov word ptr xfree,offset freexms
IF @codesize
mov ax,seg allocxms
mov word ptr xalloc+2,ax ; all ASMLIB code in same segment
mov word ptr xput+2,ax
mov word ptr xget+2,ax
mov word ptr xfree+2,ax
ENDIF
call isxms
jc foiled_again ; don't use EMS or XMS

; allocate 32k
allocate_memory:
mov ax,32768
xor dx,dx ; DX:AX = 32768
call xalloc ; allocate EMS or XMS memory block
jc xerror
mov xhandle,bx ; save the handle

; copy the graph to EMS
mov di,0B000h ; Hercules buffer
mov es,di
xor di,di ; ES:[BX] -> video buffer
mov ax,32768 ; copy entire graph
lea si,xoffset ; start at offset 0 in memory block
call xput ; copy the graph to memory
jc xerror

; later ...
; copy the graph back to the video buffer
mov bx,xhandle
mov dx,0B000h
mov es,dx
xor di,di ; ES:[DI] points to destination
mov ax,32768 ; copy all 32k
xor dx,dx ; DX:AX = 32768
lea si,xoffset ; start at offset 0 in memory block
call xget ; copy the graph back to video buffer
jc xerror

; all done with graph copy; release the memory block
call xfree
jc xerror


  3 Responses to “Category : Assembly Language Source Code
Archive   : ASMLIB35.ZIP
Filename : EMSXMS.DOC

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