* Samuel Finocchio - 255380
* 09/05/2018
* Excercise 3

; Looping until reaching GUARD
GUARD EQU 3

STRUCT_OFFSET EQU 8
ENERGY_OFFSET EQU 0
TAC_OFFSET EQU 4
DEC_OFFSET EQU 6

START:
    ; Using D0 as index
    CLR d0

    ; Using D1 as total
    CLR d1

    ; Using D2 as x0
    CLR d2

    ; A0 pointing to X
    MOVE.L #X, a0

    ; Addres of a2 is the string
    MOVE.L #s, a2

WHILE_LOOP:

    ; Compares the string A2 of Index D0: A2[D0] to 'T'
    cmpi.b #'T', (a2,d0)

    ; Jumps to Dekyon case if true
    BEQ TAKYON_LABEL

    ; Compare the string A2 of Index D0: A2[D0] to 'D'
    cmpi.b #'D', (a2,d0)

    ; Jumps to Takyon if true
    BEQ DEKYON_LABEL

    ; If none of the above is true we jump to the end of the while loop
    BRA END_WHILE_LOOP

    DEKYON_LABEL:
        ; Cloning A0 in A3 to 'easily' work with the indexing
        MOVE.L a0, a3

        ; Adding 6 bytes offset to read the Dekyon attribute in the struct
        ADD.L #DEC_OFFSET, a3

        ; Copying the first 2 bytes starting from the offsetted memory address to the x0 index to read the Dekyon attribute
        MOVE.W (a3), d2

        BRA LOOP_DEFAULT


    TAKYON_LABEL:
        ; Cloning A0 in A3 to 'easily' work with the indexing
        MOVE.L a0, a3

        ; Adding 4 bytes offset to read the TAKYON attribute in the struct
        ADD.L #TAC_OFFSET, a3

        ; Copying the first 2 bytes starting from the offsetted memory address to the x0 index to read the takyon attribute
        MOVE.W (a3), d2

        BRA LOOP_DEFAULT ; Added for simmetry ( No need )

    LOOP_DEFAULT:
        ; Incrementing index d0 (i)
        ADDI #1,d0

        ; Cloning A0 in A3 to 'easily' work with the indexing
        MOVE.L a0, a3

        ; Size multiplied by the x0 index
        MULS #STRUCT_OFFSET, d2

        ; Offsetting by x0 * 8 the X struct
        ADD.L d2, a3

        ; A3 now pointes to X[x0]

        ; A3.L refers to the first 4 bits of A3 (X struct array of position x0) in particular the element energy, the sum is added in d1 (total)
        ADD.L (a3),d1

        ; Indexing the next element of the struct array A0, adding 8 bytes ( sizeof (struct array) )
        ADD.L #8,a0

        ; Loops again
        BRA WHILE_LOOP

END_WHILE_LOOP:

    ADDI #10,d0


    SIMHALT

; Struct declaration
x: dcb.b 800,$00
; Char array declaration
s: dc.b  'T','D','T'
; Declaring total
total: ds.l 0

    END    START