; ------------------------------------------------------------------
; --  _____       ______  _____                                    -
; -- |_   _|     |  ____|/ ____|                                   -
; --   | |  _ __ | |__  | (___    Institute of Embedded Systems    -
; --   | | | '_ \|  __|  \___ \   Zurich University of             -
; --  _| |_| | | | |____ ____) |  Applied Sciences                 -
; -- |_____|_| |_|______|_____/   8401 Winterthur, Switzerland     -
; ------------------------------------------------------------------
; --
; -- sumdiff.s
; --
; -- CT1 P05 Summe und Differenz
; --
; -- $Id$
; ------------------------------------------------------------------
;Directives
        PRESERVE8
        THUMB

; ------------------------------------------------------------------
; -- Symbolic Literals
; ------------------------------------------------------------------
ADDR_DIP_SWITCH_7_0     EQU     0x60000200
ADDR_DIP_SWITCH_15_8    EQU     0x60000201
ADDR_LED_7_0            EQU     0x60000100
ADDR_LED_15_8           EQU     0x60000101
ADDR_LED_23_16          EQU     0x60000102
ADDR_LED_31_24          EQU     0x60000103

; ------------------------------------------------------------------
; -- myCode
; ------------------------------------------------------------------
        AREA MyCode, CODE, READONLY

main    PROC
        EXPORT main

user_prog
        ; STUDENTS: To be programmed

        ; Load Operand A
        LDR R3, =ADDR_DIP_SWITCH_15_8
        LDRB R0, [R3]

        ; Load Operand B
        LDR R3, =ADDR_DIP_SWITCH_7_0
        LDRB R1, [R3]

        ; Shift
        LSLS R0, #24
        LSLS R1, #24

        ; Summe an den LEDs L7 - L0
        ADDS R2, R0, R1
        MRS R4, APSR
        LSRS R2, #24
        LDR R3, =ADDR_LED_7_0
        STRB R2, [R3]

        ; Auslesen APSR
        LSRS R4, #24
        LDR R3, =ADDR_LED_15_8
        STRB R4, [R3]

        ; Summe an den LEDs L7 - L0
        SUBS R2, R0, R1
        MRS R4, APSR
        LSRS R2, #24
        LDR R3, =ADDR_LED_23_16
        STRB R2, [R3]

        ; Auslesen APSR
        LSRS R4, #24
        LDR R3, =ADDR_LED_31_24
        STRB R4, [R3]




        ; END: To be programmed
        B       user_prog
        ALIGN
; ------------------------------------------------------------------
; End of code
; ------------------------------------------------------------------
        ENDP
        END