v4.0/src/MAPPER/F_CLOSE.ASM

   1 page 80,132
   2
   3 title CP/DOS  DosFindClose  mapper
   4
   5         include find.inc
   6
   7
   8 FindSegment     segment word public 'find'
   9
  10 ; We will use the offset into the segment 'FindSegment' as the handle that we
  11 ;  return and use in subsequent FindNext and FindClose calls.  The data that is
  12 ;  in the word is the offset into the 'FindSegment' to the DTA that we should
  13 ;  use.
  14                 extrn   FindDTAs:word
  15                 extrn   FindHandles:word
  16
  17 FindSegment     ends
  18
  19
  20 ; ************************************************************************* *
  21 ; *
  22 ; *      MODULE: DosFindClose
  23 ; *
  24 ; *      FUNCTION:  Close Find Handle
  25 ; *
  26 ; *      FUNCTION: This module closes the directory handle used by CP/DOS
  27 ; *                in a find first/find next search.  Since PC/DOS does not
  28 ; *                use directory handles it will simply return to the caller
  29 ; *                removing the parameters passed on the stack.
  30 ; *
  31 ; *      CALLING SEQUENCE:
  32 ; *
  33 ; *                PUSH  WORD  DirHandle   ; Directory search handle
  34 ; *                CALL DosFindClose
  35 ; *
  36 ; *
  37 ; *      RETURN SEQUENCE:
  38 ; *
  39 ; *                IF ERROR (AX not = 0)
  40 ; *
  41 ; *                   AX = Error Code:
  42 ; *
  43 ; *
  44 ; *      MODULES CALLED:  None
  45 ; *
  46 ; *************************************************************************
  47
  48         public  DosFindClose
  49         .sall
  50         .xlist
  51         include macros.inc
  52         .list
  53
  54 str     struc
  55 old_bp    dw      ?
  56 return    dd      ?
  57 DirHandle dw      ?           ; dirctory search handle
  58 str     ends
  59
  60
  61 dosxxx  segment byte public 'dos'
  62         assume  cs:dosxxx,ds:nothing,es:nothing,ss:nothing
  63
  64 DosFindClose  proc   far
  65         Enter   DosFindClose               ; push registers
  66
  67         mov     ax,seg FindSegment         ; get address to our data
  68         mov     ds,ax
  69         assume  ds:FindSegment
  70
  71 ; Close the handle
  72
  73 ; The 'DirHandle' that the mapper returns from FindFirst, is the offset into
  74 ; 'FindSegment' of the pointer to the DTA for that Handle.  The 08000h bit
  75 ; of the pointer is used to indicate that the handle is open.  Reset the bit.
  76
  77 ; Special Logic to handle DirHandle = 1
  78
  79         mov     si,[bp].DirHandle          ; get directory hanlde
  80         cmp     si,1                       ; handle = 1??
  81         jne     CheckForClose              ; branch if not
  82
  83         mov     si,offset FindSegment:FindHandles
  84
  85 CheckForClose:
  86         test    ds:[si],OpenedHandle       ; handle is open ??
  87         jnz     OkToClose                  ; go and close if it is open
  88
  89         mov     ax,6                       ; else load error code
  90         jmp     ErrorExit                  ; return
  91
  92 OkToClose:
  93         and     ds:[si],not OpenedHandle   ; set close flag
  94         xor     ax,ax                      ; set good return code
  95
  96 ErrorExit:
  97         mexit                              ; pop registers
  98         ret     size str - 6               ; return
  99
 100 DosFindClose endp
 101
 102 dosxxx  ends
 103
 104         end