v4.0/src/MEMM/MEMM/EXTPOOL.ASM

   1
   2
   3         page 58,132
   4 ;******************************************************************************
   5         TITLE   EXTPOOL -  MODULE to manage a pool of extended memory
   6 ;******************************************************************************
   7 ;
   8 ;   (C) Copyright MICROSOFT Corp. 1986
   9 ;
  10 ;   Title:      MEMM.EXE - MICROSOFT Expanded Memory Manager 386 Driver
  11 ;
  12 ;   Module:     EXTPOOL - Manage a pool of extended memory.
  13 ;
  14 ;   Version:    0.01
  15 ;
  16 ;   Date:       Sep 1, 1988
  17 ;
  18 ;   Author:     ISP (ISP)
  19 ;
  20 ;******************************************************************************
  21 ;
  22 ;       Change Log:
  23 ;
  24 ;       DATE     REVISION       Description
  25 ;       -------- --------       --------------------------------------------
  26 ;******************************************************************************
  27 ;   Functional Description:
  28 ;
  29 ;   "Fixit Orders"  Crisis mode file.  We need to ship data structures up hi.
  30 ;    So at init time we get a pool of extended memory and manage it for the
  31 ;    fixit routine.  Services provided include initialise, allocate and
  32 ;    blkmov to the memory.
  33 ;
  34 ;******************************************************************************
  35 .lfcond
  36 .386p
  37
  38         page
  39 ;******************************************************************************
  40 ;               P U B L I C   D E C L A R A T I O N S
  41 ;******************************************************************************
  42         public      pool_initialise
  43         public      get_buffer
  44
  45         page
  46 ;******************************************************************************
  47 ;                       L O C A L   C O N S T A N T S
  48 ;******************************************************************************
  49 ;
  50
  51 ;******************************************************************************
  52 ;                       INCLUDE FILES
  53 ;******************************************************************************
  54     include  vdmseg.inc     ; segment definitions
  55
  56         page
  57 ;******************************************************************************
  58 ;                       E X T E R N A L    R E F E R E N C E S
  59 ;******************************************************************************
  60 ;
  61 ;
  62         page
  63 ;******************************************************************************
  64 ;                       S E G M E N T   D E F I N I T I O N
  65 ;******************************************************************************
  66
  67 ;*************************************************************************
  68 ;
  69 ; DATA
  70 ;
  71 ;*************************************************************************
  72
  73 LAST   SEGMENT
  74
  75 ext_start   dw      0000h           ; start of the pool of extended memory
  76             dw      0010h           ; 24 bit address
  77
  78 ext_size    dw      0               ; size
  79             dw      0               ;
  80
  81 LAST   ENDS
  82
  83 ;*************************************************************************
  84 ;
  85 ; CODE
  86 ;
  87 ;*************************************************************************
  88 LAST   SEGMENT
  89 assume  cs:LAST, DS:DGROUP, ES:DGROUP
  90
  91
  92 ;******************************************************************************
  93 ;*** Pool Initialise *** Give this memory manager the memory it is to play    ;
  94 ;                        with.                                                ;
  95 ;                                                                             ;
  96 ;   INPUTS:  AX = start offset of the extended memory in K                    ;
  97 ;            CX = size of the memory                                          ;
  98 ;                                                                             ;
  99 ;   OUTPUTS: None                                                             ;
 100 ;                                                                             ;
 101 ;   USES:    None                                                             ;
 102 ;                                                                             ;
 103 ;   AUTHOR:  ISP (ISP) Sep 1, 1988                            ;
 104 ;                                                                             ;
 105 ;*****************************************************************************;
 106
 107 Pool_Initialise     proc    near
 108 ;
 109         push    dx
 110         push    cx
 111         push    ax
 112 ;
 113         push    cx                   ; save size of memory
 114         xor     dx,dx
 115         mov     cx,1024
 116         mul     cx          ; dx:ax size in bytes offset from 1M
 117 ;
 118         add     ax,cs:[ext_start]    ; add it to 1M
 119         adc     dx,cs:[ext_start+2]  ;
 120 ;
 121         mov     cs:[ext_start],ax    ;
 122         mov     cs:[ext_start+2],dx  ;
 123 ;
 124         pop     ax                  ; get size into ax
 125         xor     dx,dx               ;
 126         mul     cx
 127 ;
 128         mov     cs:[ext_size],ax
 129         mov     cs:[ext_size+2],dx
 130 ;
 131         pop     ax
 132         pop     cx
 133         pop     dx
 134 ;
 135         ret
 136 ;
 137 Pool_Initialise     endp
 138
 139
 140
 141 ;******************************************************************************
 142 ;***Get buffer*** Give some poor beggar the memory he is asking for           ;
 143 ;                                                                             ;
 144 ;   INPUTS:  cx = size of buffer required in bytes                                                              ;
 145 ;                                                                             ;
 146 ;   OUTPUTS: DX:AX = address of buffer                                        ;
 147 ;            cx = size allocated
 148 ;                                                                             ;
 149 ;   USES:    None                                                             ;
 150 ;                                                                             ;
 151 ;   AUTHOR:  ISP (ISP) Sep 1, 1988                            ;
 152 ;                                                                             ;
 153 ;*****************************************************************************;
 154
 155 Get_Buffer          proc    near
 156 ;
 157     ;
 158     ; assume that the memory is present, put start address in dx:ax
 159     ;
 160         mov     dx,cs:[ext_start+2]
 161         mov     ax,cs:[ext_start]
 162     ;
 163     ; then proceed to determine if it really exists
 164     ;
 165         push    eax
 166         xor     eax,eax
 167         mov     ax,cx
 168         cmp     eax, dword ptr cs:[ext_size]
 169         ja      no_mem
 170     ;
 171     ; it does exist, adjust the size and the start address
 172     ;
 173         sub     dword ptr cs:[ext_size],eax
 174         add     dword ptr cs:[ext_start],eax
 175 ;
 176         pop     eax
 177         clc
 178         ret
 179
 180 no_mem:
 181         pop     eax
 182         stc
 183         ret
 184 Get_buffer          endp
 185
 186 LAST   ENDS
 187         end