[list -]
%INCLUDE "Along32.inc"
%INCLUDE "Macros_Along.inc"
[list +]

;---------------------------------------------------------------------
extern  isValid
; HLL prototype: bool isValid(char *string);
; This function receives the offset of a null-terminated array of
; characters. The function returns true if the string is valid and
; false otherwise.	
; Implements the following code:
;      let n = the length of the string
;      let state = 0
;      for (i = 0; i < n; ++i)
;      {
;        print state and array[i]
;        switch (state)
;        {
;          case 0: if array[i] == 'a'
;                    state = 1
;                  else if array[i] == 'b'
;                    state = 2
;                  else
;                    state = 4
;          case 1: if array[i] == 'a'
;                    state = 0
;                  else if array[i] == 'b'
;                    state = 3
;                  else
;                    state = 4
;          case 2: if array[i] == 'a'
;                    state = 3
;                  else if array[i] == 'b'
;                    state = 0
;                  else
;                    state = 4
;          case 3: if array[i] == 'a'
;                    state = 2
;                  else if array[i] == 'b'
;                    state = 1
;                  else
;                    state = 4
;          case 4: do nothing
;        } // end switch
;        print state
;      } // end for
;      return state == 1
; Receives: ESI = starting offset of array
; Returns:  bool in eax
;---------------------------------------------------------------------
        
SECTION .data
string  times   100 db 0
size    equ     $ - string
lit1    db      'Input String: ',0
lit2    db      'Status: ',0
valid   db      `Valid\n\n`,0
invalid db      `Invalid\n\n`,0
	
SECTION .bss
n       resd    1
h       resd    1
        
SECTION .text
        global  _start
_start: 
	call    ReadDec         ; read an unsigned 32-bit integer
        mov     [h],eax         ; store in h
	
mainloop:   
        cmp     dword [h], 0    ; while h > 0 do
        jle     done
	
        mov     edx,string      ;   read a string from standard input
        mov     ecx,size
        call    ReadString
	mov     dword [n],eax   ;   store length of input string in n

        mov     edx,lit1        ;   print the input string
        call    WriteString
        mov     edx,string
        call    WriteString
	mov     al,`\n`
        call    WriteChar

        mov     esi,string      ;   call isValid function
        call    isValid
	
        mov     edx,lit2        ;   print the status of the string
        call    WriteString
        cmp     eax,1
        jne     printInvalid
        mov     edx,valid
        jmp     printIt
printInvalid:
        mov     edx,invalid
printIt:
        call    WriteString
	dec     dword [h]       ;   get ready for the next iteration
        jmp     mainloop        ; end while
done:   
        Exit    {0}