program String

        include        '/home/dbarker/182/examples/Strings'

; Program takes up to 10 alphanumeric strings as input.  It will then reverse the case
; Of all letters in each string (uppercase to lower, and lowercase to upper).  Numbers
; Are not affected.  The program then prints the strings in the order opposite in which
; They were input.

; Grant Palin
; Created: 2003-02-25
; Last modified: 2003-02-25


counter1  EQU -4


        stack   100

        data

        code

String                                  ;Program start point
        call Strings

        sys EXIT

switchcase				;Switches the case of the strings

	push	fp			;push the frame pointer onto the stack so we can remember it for when we return
        mov     sp, fp  	        ;moves stack pointer into fp so we remember it for use with Params
        push    r2                      ;push what's in r2,r3,r4, and r5 onto the stack so we can retrieve it later
        push    r3                      ;in case the previous part of the program was using values stored
        push    r4                      ;see above
        push    r5                      ;see above
        push    r6
        push    r7
        push    r8
        push    r9


        lodw    counter1, fp, r2        ;load the number of strings into r2

        add     fp, counter1 -2, r9
        mov     0 , r3

loop1
        cmp     r3, r2                  ;compare r3 to r2
        be      endofswitch             ;if they are equal you are done
        lodw    0, r9, r5
        mov     0, r8
loop2
        lodbu   0, r5, r6               ;load the next byte of r5  into r6
        cmp     r6, 0
        be      endofloop
        cmp     r6, 'Z'
        bbe     uppercase
        cmp     r6, 'z'
        bbe     lowercase
        br      loop3

uppercase
        cmp     r6 , 0x40
        bbe     loop3
        br      switch

lowercase
        cmp     r6, 0x60
        bbe     loop3
        br      switch

switch
        xor     r6, 0x20, r6
        stobl   0,r5, r6
loop3   inc     r5

        br      loop2

endofloop
        inc     r3
        sub     r9, 2, r9
        br      loop1

;Pop the stack to get the parameters
;Switch the case of each string (numbers are left alone)
endofswitch

        pop        r9
        pop        r8
        pop        r7
        pop        r6
        pop        r5
        pop        r4
        pop        r3
        pop        r2
        pop        fp

        ret

putstringsreversed                      ;Reverses the order of the strings

        push       fp                   ;push the frame pointer onto the stack so we can remember it for when we return
        mov        sp, fp               ;moves stack pointer into fp so we remember it for use with Params
        push       r1
        push       r2                   ;push what's in r2,r3,r4, and r5 onto the stack so we can retrieve it later
        push       r3                   ;in case the previous part of the program was using values stored
        push       r4                   ;see above
        push       r5                   ;see above
        push       r6
        push       r7
        push       r8
        push       r9



        lodw       counter1, fp, r3     ;load the number of strings into r2

        shl        r3, 1, r4
        add        r4, 4 ,r4
        sub        fp, r4 , r4
print
        mov     PUTSTR, r1
        lodw    0, r4, r2
        sys     CONSOLE
        mov     PUTCHAR, r1
        mov     10,r2
        sys     CONSOLE
        mov     13,r2
        sys     CONSOLE
        add     r4, 2, r4
        dec     r3
        cmp     r3, 0
        be      done
        br      print
done
        pop     r9
        pop     r8
        pop     r7
        pop     r6
        pop     r5
        pop     r4
        pop     r3
        pop     r2
        pop     r1
        pop     fp
        ret

        end