Subversion Repositories eco32

;

; hello.s -- Hello, world!

;

        .set    tba,0xF0300000          ; terminal base address

        .set    tos,0xC0020000          ; top of stack

        ; get some addresses listed in the load map

        .export start

        .export main

        .export out

        .export hello

        ; minimal execution environment

start:

        add     $29,$0,tos               ; setup stack

        jal     main                    ; do useful work

start1:

        j       start1                  ; halt by looping

        ; main program

main:

        sub     $29,$29,8               ; create stack frame

        stw     $31,$29,0                ; save return register

        stw     $16,$29,4               ; save register variable

        add     $16,$0,hello             ; pointer to string

loop:

        ldbu    $4,$16,0         ; get char

        beq     $4,$0,stop               ; null - finished

        jal     out                     ; output char

        add     $16,$16,1               ; bump pointer

        j       loop                    ; next char

stop:

        ldw     $31,$29,0                ; restore return register

        ldw     $16,$29,4               ; restore register variable

        add     $29,$29,8               ; release stack frame

        jr      $31                     ; return

        ; output a character to the terminal

out:

        add     $8,$0,tba                ; set I/O base address

out1:

        ldw     $9,$8,8                 ; get xmtr status

        and     $9,$9,1                 ; xmtr ready?

        beq     $9,$0,out1               ; no - wait

        stw     $4,$8,12                ; send char

        jr      $31                     ; return

        ; a very famous little string...

hello:

        .byte   0x0D, 0x0A

        .byte   "Hello, world!"

        .byte   0x0D, 0x0A

        .byte   0x0D, 0x0A, 0