DOSSEG 
; A Assembler program that does something
; Author: Curt Hill
; Purpose: Demonstrate string instructions  
;Data section
       .model large
       .stack 100h
       .586
       .data
; Line to make it easy to count blanks
numline   db 13,10,'123456789012345678901234567890123456789012345678901234567890'
          db 13,10,'$'
greeting  db 'This program demonstrates string instructions',13,10,'$'
farewell  db 'This program is complete.  ',13,10,'$'
tabmsg    db 'Display a table:',13,10,'$'
summsg    db 'Sum of table is '
sumslot   db '                      ',13,10,'$'       
c_str     db 'Null terminated string. ->',0,'<- (After the null)',13,10,'$'
lodsmsg   db 'Use LODS/STOS to add two arrays',13,10,'$'
lenline   db 'Length used: '
blank     db 64 dup (?),8 dup (' '),13,10,'$'
buffer    db 100 dup (' '),13,10,'$' 
               dd  9999
tab1      dd -2,5,1509,-210,10
               dd  -9999
tab2      dd -4,9,1,-100,225492
resTab    dd 5 dup (0)
       .code
; Here is the code
start:
          mov    ax,@data  ; Address the data
          mov    ds,ax
   ;       mov    es,ds     -- Nope this won't work
          mov    es,ax      ; but this does 

   ; Greeting
          mov    ah,9
          lea    dx,greeting
          int    21h   

;
;
;     Display a table demonstrating LODS
          lea    ax,tab1
          lea    bx,blank
          call   displaytab

          mov    ah,9
          lea    dx,tabmsg
          int    21H 

          lea    dx,blank
          int    21H 

;     Show the sum of the table
          lea    eax,tab1
          mov    ecx,5
          call   sumtable
          lea    ebx,sumslot
          call   int_to_str
          mov    ah,9
          lea    dx,summsg
          int    21h


          lea    ax,tab2
          lea    bx,blank
          call   displaytab
          mov    ah,9
          lea    dx,blank
          int    21H 

;     Add two tables      
          lea    ax,tab1
          lea    bx,tab2
          lea    cx,restab
          call   addtabp

;     Display the result
          lea    ax,restab
          lea    bx,blank
          call   displaytab
          mov    ah,9
          lea    dx,blank
          int    21H 

;
; Find a null
;
          lea    dx,numline       ; Print number line
          mov    ah,9
          int    21h
          lea    dx,c_str         ; Print the line
          int    21h

          lea    ax,blank         ; Clear the line
          mov    cx,64
          call   clearp
          xor    eax,eax          ; print header lines
          lea    ax,c_str
          mov    cx,200
          call   findnullp        ; find the null
          lea    bx,blank
          call   int_to_str
          mov    ah,9
          lea    dx,lenline
          int    21h          

;
; Skip blanks
;

          lea    bx,blank         ; Clear the line
          mov    cx,64
          call   clearp
          mov    blank+41,'X'     ; Put a nonblank in
          lea    dx,numline       ; Print number line
          mov    ah,9
          int    21h
          lea    dx,blank         ; Print the line
          int    21h

          lea    ax,blank
          mov    cx,64
          call   skipblnkp

          lea    bx,blank
          call   int_to_str

          lea    dx,lenline
          mov    ah,9
          int    21h


;
;  All done
;
          mov    ah,9
          lea    dx,farewell
          int    21h   

          mov    ax,4c00h  ; Leave the program
          int    21h




;
; Subroutines
;
  
;
; sumtable - find the sum of a table
;
;   eax - address of table, return value
;   cx - maximum count
sumtable proc    near
         push    si
         push    cx
         push    ebx
         xor     ebx,ebx
         mov     esi,eax 
summer:
         lodsd
         add     ebx,eax
         loop    summer 
; Restore registers
         mov     eax,ebx 
         pop     ebx
         pop     cx
         pop     si
         ret
sumtable endp 
   
;
; findnullp - find null character in a string
;
;   ax - address of first table, return length
;   cx - maximum count
findnullp proc    near
;         push    eax
          push    bx
          push    cx
          push    di
          
          mov     di,ax
          mov     bx,ax
          xor     al,al
   repnz  scasb 
          mov     ax,di
          sub     ax,bx
         

          pop     di
          pop     cx
          pop     bx
;         pop     eax
          ret
findnullp    endp    
         
;
; skipblnkp - find first non-blank character in a string
;
;   ax - address of first table, return length
;   cx - maximum count
skipblnkp proc    near
;         push    eax
         push    bx
         push    cx
         push    di
          
         mov     di,ax
         mov     bx,ax
         mov     al,' '
     repe  scasb 
         mov     ax,di
         sub     ax,bx
         

         pop     di
         pop     cx
         pop     bx
;         pop     eax
         ret
skipblnkp   endp    
         
;
; AddTab - add two tables
;
;   ax - address of first table
;   bx - address of second table
;   cx - address of result table  
addtabp  proc    near
         push    eax
         push    bx
         push    cx
         push    edx
         push    si
         push    di

         mov     di,cx
         mov     cx,5
         mov     si,ax
         xor     edx,edx         

       ;   registers in the loop:
       ;     eax move destination location
       ;     bx/si address of two tables
       ;     cx - count
       ;     edx - temp location for tab1 entry
addloop1:
         lodsd        ; move tab1 to eax
         xchg    bx,si 
         mov     edx,eax
         lodsd
         add     eax,edx
         stosd
         loop    addloop1

         pop     di
         pop     si
         pop     edx
         pop     cx
         pop     bx
         pop     eax
         ret
addtabp   endp    
;          
;  Make a string representation of a table of length 5
;          
;       AX contains address of table
;       BX contains address of line
displaytab proc   near
          push   eax
          push   bx
          push   cx
          push   si
          mov    cx,64
          call   clearp
          mov    si,ax
          mov    cx,5
          
dtloop:   lodsd              ; load into eax
          call   int_to_str  ; convert to string
          inc    bx          ; allow one blank between    
          loop   dtloop  

          pop    si
          pop    cx
          pop    bx
          pop    eax
          ret 
displaytab  endp   

;
;  Clear an area with blanks
;
;    BX contains line
;    CX contains count
clearp    proc   near
          push   ax
          push   bx
          push   cx          
          push   di

          mov    di,bx
          mov    al,' '
         rep stosb          

          pop    di
          pop    cx
          pop    bx
          pop    ax
          ret
clearp  endp ;   clearp          
;
;
;
          include int2str.asm

; Last line of assembly is end
          end