Subversion Repositories eco32

;

; rom06.s -- "crossed" echo with two terminals, polled

;

        .set    tba,0xF0300000  ; terminal base address

        add     $8,$0,tba        ; set terminal base address

L1:

        ldw     $9,$8,0          ; load receiver status into $9

        and     $9,$9,1         ; check receiver ready

        beq     $9,$0,L3 ; not ready - check other terminal

        ldw     $10,$8,4        ; load receiver data into $10

L2:

        ldw     $9,$8,24        ; load transmitter status into $9

        and     $9,$9,1         ; check transmitter ready

        beq     $9,$0,L2 ; loop while not ready

        stw     $10,$8,28       ; load char into transmitter data

L3:

        ldw     $9,$8,16        ; load receiver status into $9

        and     $9,$9,1         ; check receiver ready

        beq     $9,$0,L1 ; not ready - check other terminal

        ldw     $10,$8,20       ; load receiver data into $10

L4:

        ldw     $9,$8,8         ; load transmitter status into $9

        and     $9,$9,1         ; check transmitter ready

        beq     $9,$0,L4 ; loop while not ready

        stw     $10,$8,12       ; load char into transmitter data

        j       L1              ; all over again