v4.0/src/CMD/FC/MOVE.ASM

   1 ;
   2 ; memory routines
   3 ;
   4
   5 .xlist
   6 include version.inc
   7 include cmacros.inc
   8 .list
   9
  10 sBegin  code
  11 assumes cs,code
  12
  13 cProc   Move,<PUBLIC>,<DS,SI,DI>
  14 parmD   src
  15 parmD   dst
  16 parmW   count
  17 cBegin
  18         mov     cx,count
  19         jcxz    NoByte                  ; No characters to move
  20         les     di,dst                  ; grab pointers
  21         lds     si,src
  22         cld
  23         mov     ax,ds
  24         cmp     ax,Seg_dst
  25         jnz     SimpleMove              ; segments are NOT the same, no opt
  26         cmp     si,di                   ; is the start of source before dest
  27         jb      TestMove                ; yes, try to optimize
  28
  29 SimpleMove:
  30         shr     cx,1
  31         rep     movsw
  32         jnc     NoByte
  33         movsb
  34         jmp     short NoByte
  35
  36 TestMove:
  37         mov     ax,di
  38         sub     ax,si                   ; ax = difference between regions
  39         cmp     ax,cx                   ; is difference greater than region?
  40         jae     SimpleMove              ; yes, no optimize
  41         mov     ax,cx                   ; optimize by copying down from top
  42         dec     ax
  43         add     di,ax
  44         add     si,ax
  45         std
  46         rep     movsb                   ; no word optimization here
  47
  48 NoByte:
  49         cld
  50 cEnd
  51
  52 cProc   Fill,<PUBLIC>,<DI>
  53 parmD   dst
  54 parmB   value
  55 parmW   count
  56 cBegin
  57         cld
  58         les     di,dst
  59         mov     al,value
  60         mov     ah,value
  61         mov     cx,count
  62         shr     cx,1
  63         jcxz    fill1
  64         rep     stosw
  65 fill1:
  66         jnc     fill2
  67         stosb
  68 fill2:
  69 cEnd
  70
  71 sEnd
  72
  73 end