Borland Programmer's Resource/Borland_Programmers_Resource_CD_1995.iso/code/bcpp/file1/ems.asm

Assembly Source File | 1995-05-19 | 15.7 KB | 548 lines

COMMENT ~
/*-------------------------------------------------------------------------+
| Module: EMS.ASM                                                          |
| Project: TOOLS                                                           |
| Author: Paul A. Penrose                                                  |
|         (c) 1992, 4D Interactive Systems, Inc.  All rights reserved.     |
| Start Date: 01 Nov 92                                                    |
| Last Revised: 29 Nov 92                                                  |
| Purpose:                                                                 |
|   This module contains the EMS support code.  The functions provided are |
|   C callable and provide complete linkage to the EMS services supported. |
+-------------------------------------------------------------------------*/ ~

IDEAL

MODEL HUGE,C

P286N

DATASEG
;
; Define the equates here
;

;
; Define structures here
;
STRUC physical_map
  segment_sel   DW ?
  page_num      DW ?
ENDS

STRUC handle_size_map
  handle        DW ?
  num_pages     DW ?
ENDS

STRUC handle_name_map
  handle        DW ?
  handle_name   DB 8 DUP(?)
ENDS

STRUC handle_directory
  handle        DW ?
  num_pages     DW ?
  handle_name   DB 9 DUP(?)
ENDS

;
; Declare module level data here
;
ALIGN 2
ems_pageframe           DW  0
ems_errnum              DB  0
ems_function            DB  0
ems_version             DB  0
ASCII_device_name       DB  'EMMXXXX0', 0
map_buffer              DB  2550 DUP(0)
name_buffer             DB  8 DUP(0)
temp                    DW  ?
copyright               DB  'EMS functions (c) 1992, 4D Interactive Systems, Inc. '
                        DB  'All rights reserved'

PUBLIC  ems_errnum, ems_function, ems_version, ems_pageframe

CODESEG

;
; This function initializes the EMS package.  TRUE is returned if the
; initialization is sucessfull, otherwise FALSE is returned.
;
PROC    ems_init
;
; First check to see if there is an EMS driver loaded
;
        push ds                 ;Perform entry setup
        mov  ax,seg ems_function
        mov  ds,ax
        mov  [ems_function],0
        mov  ax,3D00H           ;Open file, read only
        mov  dx,offset ASCII_device_name
        int  21H
        jc   ei_no_driver       ;If not found, report no driver
        mov  bx,ax
        push bx
        mov  [ems_function],1
        mov  ax,4400H           ;Get device info
        int  21H
        pop  bx
        jc   ei_no_driver2
        test dx,0080H           ;Is it a device?
        jz   ei_no_driver2
        push bx
        mov  ax,4407H           ;Is the device ready?
        int  21H
        pop  bx
        or   al,al
        jz   ei_no_driver2
        mov  ax,3E00H           ;Close the driver
        int  21H
;
; Get the EMS version and store it for later reference
;
        mov  ah,46H
        mov  [ems_function],ah
        int  67H
        mov  [ems_errnum],ah
        mov  [ems_version],al
        or   ah,ah
        jnz  ei_error
;
; Next get the pageframe and store it for later reference
;
        mov  ah,41H
        mov  [ems_function],ah
        int  67H
        mov  [ems_errnum],ah
        mov  [ems_pageframe],bx
        or   ah,ah
        jnz  ei_error
        mov  ax,1               ;Return TRUE
        jmp  ei_exit
ei_no_driver2:
        mov  ax,3E00H           ;Close the driver
        int  21H
ei_no_driver:
ei_error:
        xor  ax,ax              ;Return FALSE
ei_exit:
        pop  ds
        ret
ENDP
PUBLIC  ems_init

;
; This function returns the number of free (available) EMS pages
;
PROC    ems_num_free_pages
        ARG  true_size:WORD

        push ds                 ;Perform entry setup
        mov  ax,seg ems_function
        mov  ds,ax
        test [true_size],0FFFFH         ;Report true size?
        jz   nfp_001
        mov  bx,4444H                   ;Put signature "DDDD" in BX:DX
        mov  dx,4444H
nfp_001:
        mov  ah,42H
        mov  [ems_function],ah
        int  67H
        mov  [ems_errnum],ah
        mov  ax,bx
        pop  ds
        ret
ENDP
PUBLIC  ems_num_free_pages

;
; This function is used to allocate a number of EMS pages.  It returns a
; handle that is used to identify these pages to other EMS functions.  If
; a handle of -1 is returned, an error occured.  An optional name of up to
; 8 characters can be passed that is used to name the handle.  This name is
; ignored for EMS driver versions less than 4.0.
;
PROC    ems_alloc
        ARG num_pages:WORD
        ARG handle_name:DWORD

        push ds                 ;Perform entry setup
        mov  ax,seg ems_function
        mov  ds,ax
        push si
        push di
        mov  ah,43H
        mov  [ems_function],ah
        mov  bx,[num_pages]
        int  67H
        mov  [ems_errnum],ah
        or   ah,ah
        jz   ea_good
        mov  dx,0FFFFH                  ;Return -1 if error
ea_good:
        push dx
        cmp  [ems_version],40H          ;Check if we can name it
        jb   ea_exit                    ;  exit if version < 4.0
        les  si,[handle_name]           ;Check the name ptr (NULL = none)
        mov  ax,es
        or   ax,si
        jz   ea_exit
        mov  ax,es                      ;Zero out name_buffer
        push ds                         ;  first swap DS and ES
        pop  es
        mov  ds,ax
        xor  ax,ax                      ;  now set up the loop
        mov  cx,4
        mov  di,offset name_buffer      ;  and zero out the buffer
ea_loop1:
        stosw
        loop ea_loop1
        mov  di,offset name_buffer      ;Copy the name into the buffer
        mov  cx,8                       ;  but only the first 8 chars
ea_loop2:
        lodsb
        or   al,al
        jz   ea_endcopy                 ;Exit if end of string
        stosb
        loop ea_loop2
ea_endcopy:
        push es                         ;Restore DS
        pop  ds
        mov  ax,5301H                   ;Set name
        pop  dx                         ;Get handle
        push dx                         ;  and save it again
        mov  si,offset name_buffer
        mov  [ems_function],ah
        int  67H
        mov  [ems_errnum],ah
ea_exit:
        pop  ax                         ;Recover handle
        pop  di
        pop  si
        pop  ds
        ret
ENDP
PUBLIC  ems_alloc

;
; This function is used to free up EMS pages previously allocated using the
; ems_alloc function.
;
PROC    ems_free
        ARG handle:WORD

        push ds                 ;Perform entry setup
        mov  ax,seg ems_function
        mov  ds,ax
        mov  ah,45H
        mov  [ems_function],ah
        mov  dx,[handle]
        int  67H
        mov  [ems_errnum],ah
        mov  al,ah
        mov  al,0
        pop  ds
        ret
ENDP
PUBLIC  ems_free

;
; This function is used to map a logical page that was previously allocated
; using the ems_alloc function to a physical page.  A non-zero return value
; indicates an error occured.
;
PROC    ems_map_page
        ARG handle:WORD
        ARG logical_page:WORD
        ARG physical_page:WORD

        push ds                 ;Perform entry setup
        mov  ax,seg ems_function
        mov  ds,ax
        mov  bx,[logical_page]
        mov  ax,[physical_page]
        mov  dx,[handle]
        mov  ah,44H
        mov  [ems_function],ah
        int  67H
        mov  [ems_errnum],ah
        mov  al,ah
        xor  ah,ah
        pop  ds
        ret
ENDP
PUBLIC  ems_map_page

;
; This function is used to unmap logical page that is currently mapped to
; a physical page.  A non-zero return value indicates an error occured.
;
PROC    ems_unmap_page
        ARG handle:WORD
        ARG physical_page:WORD

        push ds                 ;Perform entry setup
        mov  ax,seg ems_function
        mov  ds,ax
        mov  ax,[physical_page]
        mov  dx,[handle]
        mov  bx,0FFFFH
        mov  ah,44H
        mov  [ems_function],ah
        int  67H
        mov  [ems_errnum],ah
        mov  al,ah
        xor  ah,ah
        pop  ds
        ret
ENDP
PUBLIC  ems_unmap_page

;
; This function returns the number of physical pages available in the EMS
; page frame.
;
PROC    ems_num_physical_pages
        push ds                 ;Perform entry setup
        mov  ax,seg ems_function
        mov  ds,ax
        cmp  [ems_version],40H          ;Is it ver 4.0 or greater?
        jae  enpp_001
        mov  ax,4                       ;Return 4 pages if ver < 4.0
        pop  ds
        ret
enpp_001:
        push si
        push di
        mov  ax,seg map_buffer          ;Get a map of all mappable physical
        mov  es,ax                      ;  pages in the system
        mov  di,offset map_buffer
        mov  ax,5800H
        mov  [ems_function],ah
        int  67H
        or   ah,ah
        jz   enpp_002
        mov  [ems_errnum],ah            ;Return error
        xor  ax,ax
        pop  ds
        ret
enpp_002:
        mov  si,offset map_buffer       ;Search through the map
        mov  dx,0                       ;highest page found
enpp_003:
        mov  ax,[(physical_map PTR si).page_num]
        cmp  ax,3                       ;Skip this one if it's > 3
        ja   enpp_004
        cmp  ax,dx                      ;Skip if < highest
        jb   enpp_004
        mov  dx,ax                      ;This is the highest < 4
enpp_004:
        add  si,4
        loop enpp_003
        mov  ax,dx                      ;Get the highest page < 4
        inc  ax                         ;Return number of pages
        pop  di
        pop  si
        pop  ds
        ret
ENDP
PUBLIC  ems_num_physical_pages

;
; This function returns the number of open EMS handles
;
PROC    ems_num_open_handles
        push ds                 ;Perform entry setup
        mov  ax,seg ems_function
        mov  ds,ax
        mov  ah,4BH
        mov  [ems_function],ah
        int  67H
        mov  [ems_errnum],ah            ;Return error
        mov  ax,bx
        pop  ds
        ret
ENDP
PUBLIC  ems_num_open_handles

;
; This function will fill in an EMS directory map structure with the current
; status of all open EMS handles.  Returns 0 if no error, else error code.
;
PROC    ems_get_handle_directory
        ARG  handle_dir:DWORD

        push ds                 ;Perform entry setup
        mov  ax,seg ems_function
        mov  ds,ax
        push si
        push di
        push ds                         ;Get map showing number of pages for
        pop  es                         ;  each handle
        mov  di,offset map_buffer
        mov  ah,4DH
        mov  [ems_function],ah
        int  67H
        mov  [ems_errnum],ah            ;Return error
        or   ah,ah
        jnz  eghd_exit
        mov  cx,bx
        mov  si,offset map_buffer       ;Search through the returned data and
        les  di,[handle_dir]            ;  post it to the hande dir
eghd_loop1:
        mov  ax,[(handle_size_map PTR si).handle]
        mov  [es:(handle_directory PTR di).handle],ax
        mov  ax,[(handle_size_map PTR si).num_pages]
        mov  [es:(handle_directory PTR di).num_pages],ax
        mov  [es:(handle_directory PTR di).handle_name],0
        add  di,13
        add  si,4
        loop eghd_loop1

        cmp  [ems_version],40H          ;Exit if ems_version < 4.0
        jb   eghd_exit
        push ds                         ;Get map of name for each handle
        pop  es
        mov  di,offset map_buffer
        mov  ax,5400H
        mov  [ems_function],ah
        int  67H
        mov  [ems_errnum],ah            ;Return error
        or   ah,ah
        jnz  eghd_exit
        mov  cx,ax
        mov  [temp],cx
        mov  si,offset map_buffer       ;Search through the returned data and
        les  di,[handle_dir]            ;  post it to the handle dir
eghd_loop2:
        mov  ax,[(handle_name_map PTR si).handle]
        push di                         ;Find the same handle in the dir
        push cx                         ;  (don't assume that the handles are
        mov  cx,[temp]                  ;   in the same order as the previous
eghd_loop3:                             ;   call)
        cmp  ax,[es:(handle_directory PTR di).handle]
        je   eghd_handle_found
        add  di,13
        loop eghd_loop3
        jmp  eghd_next_handle
eghd_handle_found:
        push si                         ;Copy the name into the directory
        add  si,2                       ;Point to name field
        add  di,4                       ;ditto
        mov  cx,4
        rep movsw                       ;copy the name
        xor  al,al
        stosb                           ;make sure string is terminated
        pop  si
eghd_next_handle:
        pop  cx                         ;Process the next entry
        pop  di
        add  si,10
        loop eghd_loop2
        xor  ah,ah
eghd_exit:
        xor  al,al
        pop  di
        pop  si
        pop  ds
        ret
ENDP
PUBLIC  ems_get_handle_directory

;
; This function will find the handle for any named EMS memory block and return
; it to the caller.  If the name can't be found, 0xFFFF is returned.
;
PROC    ems_find_handle
        ARG  handle_name:DWORD

        push ds                 ;Perform entry setup
        mov  ax,seg ems_function
        mov  ds,ax
        push si
        push di
        les  si,[handle_name]           ;Check the name ptr (NULL = none)
        mov  ax,es
        or   ax,si
        jz   efh_exit
        mov  ax,es                      ;Zero out name_buffer
        push ds                         ;  first swap DS and ES
        pop  es
        mov  ds,ax
        xor  ax,ax                      ;  now set up the loop
        mov  cx,4
        mov  di,offset name_buffer      ;  and zero out the buffer
efh_loop1:
        stosw
        loop efh_loop1
        mov  di,offset name_buffer      ;Copy the name into the buffer
        mov  cx,8                       ;  but only the first 8 chars
efh_loop2:
        lodsb
        or   al,al
        jz   efh_endcopy                 ;Exit if end of string
        stosb
        loop efh_loop2
efh_endcopy:
        push es                         ;Restore DS
        pop  ds
        mov  ax,5401H                   ;Find Name
        mov  si,offset name_buffer
        mov  [ems_function],ah
        int  67H
        mov  [ems_errnum],ah
        or   ah,ah
        jz   efh_exit
        mov  dx,0FFFFH
efh_exit:
        mov  ax,dx                      ;Return handle
        pop  di
        pop  si
        pop  ds
        ret
ENDP
PUBLIC  ems_find_handle

;
; This function will save the current EMS Page Frame mapping context.
;
PROC    ems_save_mapping_context
        ARG  handle:WORD

        push ds                 ;Perform entry setup
        mov  ax,seg ems_function
        mov  ds,ax
        mov  ah,47H
        mov  [ems_function],ah
        mov  dx,[handle]
        int  67H
        mov  [ems_errnum],ah            ;Return error
        xor  al,al
        pop  ds
        ret
ENDP
PUBLIC  ems_save_mapping_context

;
; This function will restore the current EMS Page Frame mapping context.
;
PROC    ems_restore_mapping_context
        ARG  handle:WORD

        push ds                 ;Perform entry setup
        mov  ax,seg ems_function
        mov  ds,ax
        mov  ah,48H
        mov  [ems_function],ah
        mov  dx,[handle]
        int  67H
        mov  [ems_errnum],ah            ;Return error
        xor  al,al
        pop  ds
        ret
ENDP
PUBLIC  ems_restore_mapping_context

END