page,132
name keyboard_code
title keyboard.asm   --  Procedure to mask input to read
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keyboard_code segment   para public 'code'
              assume    cs:keyboard_code
              public    keyboard            ;pass name to linker
keyboard      proc      far                 ;pascal calls are far
              push      bp                  ;save the base pointer
              cli                           ;stop interuppts
lock          mov       bp,sp               ;get the stack offset
lock          mov       bx,[bp]+10          ;get addr of string
lock          mov       dx,[bp]+8           ;get addr of length
lock          mov       si,[bp]+6           ;get number to read max
              mov       cx,si               ;save the limit for input
              mov       di,00               ;start at char number 1
              sti                           ;start interrupts
get_key:
              mov       ah,0                ;call bios for read service
              int       16h                 ;call bios
              cmp       al,0dh              ;see if this is the cr char
              je        quit                ;exit if so else continue
              mov       [bx][di],al         ;get char into parm area
              inc       di
              mov       ah,14               ;load for bios service
              int       10h                 ;bios service to display and move cursor
loop          get_key                       ;loop until di=cx=30 or find a cr (0dh)
quit:                                       ;found the end of line
              mov       bx,dx               ;get address back of length  param
              mov       [bx],di             ;move number of reads to count
              pop       bp                  ;restore the frame pointer
              ret       6                   ;cleanup stack
keyboard      endp
keyboard_code ends
              end                           ;end assembly