;Chris Ruskai

TITLE CharacterSearch.asm



INCLUDE Irvine32.inc



PrepareMap PROTO,
    string: PTR BYTE,
    map: PTR BYTE



CharacterSearch PROTO,
        map: PTR BYTE,
        char: BYTE

.data
stringMap byte 32 dup(0)
testString byte "hello, assembly language programming!",0
msg1 byte " is not in the string.",0
msg2 byte " is in the string.",0

;Code test driver
.code
    main PROC





    INVOKE PrepareMap, addr testString, addr stringMap

    ;Generate Random Characters
    call Randomize
    mov esi, 0
    L1:
    cmp esi, 9
    JG L2
    mov eax, 25
    call RandomRange
    add eax, 97d
    call WriteChar
    INVOKE CharacterSearch, addr stringMap, al
    inc esi
    JMP L1

    L2:


    exit
    main ENDP



    ;PrepareMap Procedure. Takes the test string and the map as parameters.
    PrepareMap PROC USES ECX EBX EAX EDX ESI EDI EBP, string: PTR BYTE, map: PTR BYTE


    ;mov string offsets and set counter
    mov esi, string
    mov edi, map
    mov edx, map
    mov ebp, 0


;for(int i = 0; i < strlength; i++)
ForLoop:

    ;length of string
    cmp ebp, 32
    ;end loop if i >= 32
    JGE L9

    ;map[(string[i])>>3] |= 1<<( (string[i]) &7)

    ;map[(string[i]>>3]
    LeftSide:

        mov al, [esi]
        movzx eax, al
        shr eax, 3
        add edi, eax


    ;1 << ((string[i]) &7)
    RightSide:
        mov cl, [esi]
        AND cl, 7
        mov bl, 1
        shl bl, cl

    ; LefSide |= RightSide
    OrStatement:
        OR [edi], bl
        inc ebp
        inc esi
        mov edi, edx
        add edi, 1
        inc edx





        ;Restart loop
        JMP ForLoop



    ;End Loop
    L9:
        ret
    PrepareMap Endp




    CharacterSearch PROC map: PTR BYTE, char: BYTE

    ;map[ch >> 3]
    LeftSide:
        ;mov al, char
        ;call WriteChar
        mov edi, map
        mov cl, char
        shr cl, 3
        add [edi], cl

    ;(1 << ((string[i]) & 7)
    RightSide:
        mov cl, char
        AND cl, 7
        mov al, 1
        shl al, cl

    ;LeftSide & RightSide
    AndStatement:
        mov bl, [edi]
        AND bl, al

    ;If AndStatement != 0, character is here.
    IfStatement:
        cmp bl, 0
        JE NotIn
        mov edx, offset msg2
        call WriteString
        call crlf
        JMP L9

    ;Else, not in string.
    NotIn:
        mov edx, offset msg1
        call WriteString
        call crlf

    ;end proc
    L9:
    ret
    CharacterSearch endp


    END main