.386
.model flat
.code

; Algoritmo in pseudocodice
; int salvaparolaspiazzamento (char *s, char *d, unsigned char* parola1)
; *** USED subroutines (at the end of this file): SEARCH, STRLEN, STRCPY ***
; ------------------------------------------------------------------------------
; src = s
; dst = d
;
; riempire d con blank;
; len = strlen(parola1);
; if(len < 4) return(-2);       // parola1's length is less than 4 characters
; while(1){
;   pos = search(src,parola1);
;   if(pos == -1){
;       if(src==s)  return(-1); //  parola1 doesn't occur in s
;       else        return(0);  //  parola1 occurs one or more times in s
;   }
;   else{
;       src += len + pos;
;       dst += pos;
;       strcpy(parola1, dst)
;       dst += len;
;   }
; }
; ------------------------------------------------------------------------------
;int salvaparolaspiazzamento (char *s, char *d, unsigned char* parola1)

_salvaparolaspiazzamento proc
    push    ebp
    mov     ebp,esp
                                    ; save regs
    push    ebx                     ;
    push    ecx                     ;
    push    edi                     ;
    push    esi                     ;
;
    mov     esi, dword ptr[ebp+8]   ; src = s
    mov     edi, dword ptr[ebp+12]  ; dst = d
;
                                    ; fill d string with spaces:
    mov     ebx,esi                 ;   eax = strlen(ebx=d)
    call    strlen                  ;
                                    ;   build string d
    mov     byte ptr[edi+eax],0     ;   add NULL at the end of the d string, termination
    dec     eax                     ;
blfill:                             ;
    mov     byte ptr[edi+eax],' '   ;   fill with blank
    dec     eax                     ;
    jge     blfill                  ;
                                    ; if(strlen(parola1) < 4) return(-2)
    mov     ebx, dword ptr[ebp+16]  ;   *parola1
    call    strlen                  ;
    mov     ecx,eax                 ;   save strlen in to ecx
    cmp     eax,4                   ;
    jge     cerca                   ;
    mov     eax,-2                  ;
    jmp     fine                    ;
                                    ;
cerca:                              ; while(1){
    call    search                  ;   pos (stored in to eax) = search(src,parola1);
    cmp     eax, -1                 ;   if(pos == -1){
    jne     trovata                 ;
    cmp     esi,dword ptr[ebp+8]    ;       if(src==s)  return(-1);
    je      fine                    ;
    mov     eax,0                   ;       else        return(0);
    jmp     fine                    ;   }
trovata:                            ;   else{
    add     esi,eax                 ;       src += len + pos;
    add     esi,ecx                 ;
    add     edi,eax                 ;       dst += len + pos;
    call    strcpy                  ;       strcpy(parola1, dst);
    add     edi,ecx                 ;       dst += len;
    jmp     cerca                   ;   }
                                    ; }
fine:
    pop     esi                     ;   restore regs
    pop     edi                     ;
    pop     ecx                     ;
    pop     ebx                     ;

    mov     esp,ebp                 ;
    pop     ebp                     ;
    ret                             ;
_salvaparolaspiazzamento endp


search proc
; *********************************
;
;   search
;       Search for dst string in to src string,
;       returns the position of the first match.
;
;       input   esi, src string pointer; string to search in;
;               ebx, dst string pointer; string to look for;
;       output  eax, position of the first occurrence of dst in src; -1 if no match is found;
;
; *********************************
; --------------------------------;
; i = 0, j = 0
; while(1){
;   if (src[j] == NULL)     return(-1);  // No match is found
;   if (dst[i] == NULL)     return(j-i); // Match found, return match position of dst string in to src string
;   if (src[j] == dst[i])   i++;
;   else                    i = 0;
;   j++;
; }
;
; --------------------------------
    push    ecx                 ;
    push    edx                 ;
;
    mov     eax,0               ; j = 0, index of source string
    mov     edx,0               ; i = 0, index of destination string
;
ripeti:                         ; while(1) {
    mov ch, byte ptr[ebx+edx]   ;   if (dst[i] == NULL) return(i-j);
    cmp ch,0                    ;
    jne riparti                 ;
;
    sub eax,edx ; j <-(j-i)     ;
    pop edx                     ;
    pop ecx                     ;
    ret                         ;
;
riparti:
    mov cl, byte ptr[esi+eax]   ;   if (src[j] == NULL) return(-1);
    cmp cl,0                    ;
    jne compare                 ;
    mov eax,-1      ;return(-1) ;
    pop edx                     ;
    pop ecx                     ;
    ret                         ;
;
compare:
;
    cmp cl,ch                   ;   if (src[j] == dst[i])   i++;
    jne notrov                  ;   else                    i = 0;
                                ;   j++
    inc edx         ; i++       ;
    inc eax         ; j++       ;
    jmp ripeti                  ; }
;
notrov:
    inc eax         ; j++       ;
    cmp edx,0                   ;
    je riparti                  ;
    mov edx,0       ; i = 0     ;
    jmp ripeti                  ;
;
search endp


strcpy proc
; *********************************
;
;   strcpy: copy src string to dst
;           (Null is not copyed)
;   input  ebx = *src, edi = *dst
;
; *********************************
    push    ecx                     ;
    push    eax                     ;
;
    mov     eax,0                   ;
inizio:
    mov     cl,byte ptr[ebx+eax]    ;
    cmp     cl,0                    ;
    je      fine                    ;
    mov     byte ptr[edi+eax], cl   ;
    inc     eax                     ;
    jmp     inizio                  ;
fine:
    pop     eax                     ;
    pop     ecx                     ;
    ret                             ;
;
strcpy endp
;----------------------------------



strlen proc
; *********************************
;   strlen
;       input ebx = string pointer
;       output eax str length
; *********************************
    mov eax,0
inizio:
    cmp byte ptr[ebx+eax],0
    je  fine
    inc eax
    jmp inizio
fine:
    ret
;
strlen endp


end