; Peter Hutnick
; COSC 2425, section 27540
; Project
; December 10, 2001

.model small            ; Set memory model
.stack 100h             ; Ask for a 200h byte stack
.386                    ; Use 386 features

node struc              ; Label the start of the struct definition
   txt db 14 dup(?)     ; The data element of the node
   next dw 0            ; The link pointer
node ends               ; end of struct

inputbuffer struc
   max    db 13
   total  db 0
   buffer db 14 dup(?)
inputbuffer ends

.data                   ; Begin data segment
start dw 0              ; Pointer to the first node in the list (queue)
input_msg db "Please enter a string (up to 13 characters)",'$'
evendata
input_buffer inputbuffer <>

.code                   ; Begin code segment

main proc               ; Begin the main procedure

   mov ax,@data         ; Place the address of the begining of the data
                        ; segment in AX,
                        ; because we can't set DS directly from memory.
   mov ds,ax            ; Set the DS to the begining of the data segment

   mov bx,1000h         ; I need a 100h byte heap
   mov ax,4a00h         ; Tell DOS that when I int 21h I want to allocate heap
   int 21h              ; Tell DOS to go ahead an allocate the heap


call AllocNode
; queue up five strings
; display them
; remove a node, display the string and de-alloc, five times, one line each.

 
   mov ah, 4Ch          ; Tell DOS that when I int 21h I want to terminate
                        ; the program.
   int 21h              ; Tell DOS to go ahead and terminate the program

main endp               ; label the end of the main procedure

AllocNode proc ; does not attach to list

   push ax
   push bx

   mov bx,1
   mov ah,48h
   int 21h

   call PopulateNode

   pop bx
   pop ax
   ret

; The carry on error is just "passed through" from the int 21h.  IOW, this
; function "returns" carry on alloc error without doing anything!

AllocNode endp   

PutNode proc

   push ax
   push bx
   push es
   push si

   mov bx,start
   mov start,ax
   mov es,ax
   xor si,si
   mov es:[si].next,bx

   pop si
   pop es
   pop bx
   pop ax

   ret

PutNode endp

GetNode proc

;   push whatever

   ; traverse list to node with null pointer

   ; set ES to that node and call freenode

;   pop whatever

GetNode endp

ListNodes proc

;   push whatever

   ; traverse list outputing each string (with a newline)

;   pop whatever

ListNodes endp

FreeNode proc

   push ax

   mov ah,49h
   int 21h

   pop ax
   ret

FreeNode endp

PopulateNode proc

   pushf
   push ax
   push dx

   mov ah,9
   mov dx,offset input_msg
   int 21h

   mov input_buffer.max,13
   mov dx, offset input_buffer
   mov ah,0ah
   int 21h

   pop dx
   pop ax
   popf

   ret

PopulateNode endp

end main                ; Label the end of the program, and tell the assembler
                        ; what proc to start with (main).