;
|
;
|
; hello.s -- Hello, world!
|
; hello.s -- Hello, world!
|
;
|
;
|
|
|
.set tba,0xF0300000 ; terminal base address
|
.set tba,0xF0300000 ; terminal base address
|
.set tos,0xC0010000 ; top of stack
|
.set tos,0xC0020000 ; top of stack
|
|
|
; get some addresses listed in the load map
|
; get some addresses listed in the load map
|
.export reset
|
|
.export start
|
.export start
|
|
.export main
|
.export out
|
.export out
|
.export hello
|
.export hello
|
|
|
; minimal execution environment
|
; minimal execution environment
|
reset:
|
start:
|
add $29,$0,tos ; setup stack
|
add $29,$0,tos ; setup stack
|
jal start ; do useful work
|
jal main ; do useful work
|
reset1:
|
start1:
|
j reset1 ; halt by looping
|
j start1 ; halt by looping
|
|
|
; main program
|
; main program
|
start:
|
main:
|
sub $29,$29,8 ; create stack frame
|
sub $29,$29,8 ; create stack frame
|
stw $31,$29,0 ; save return register
|
stw $31,$29,0 ; save return register
|
stw $16,$29,4 ; save register variable
|
stw $16,$29,4 ; save register variable
|
add $16,$0,hello ; pointer to string
|
add $16,$0,hello ; pointer to string
|
loop:
|
loop:
|
ldbu $4,$16,0 ; get char
|
ldbu $4,$16,0 ; get char
|
beq $4,$0,stop ; null - finished
|
beq $4,$0,stop ; null - finished
|
jal out ; output char
|
jal out ; output char
|
add $16,$16,1 ; bump pointer
|
add $16,$16,1 ; bump pointer
|
j loop ; next char
|
j loop ; next char
|
stop:
|
stop:
|
ldw $31,$29,0 ; restore return register
|
ldw $31,$29,0 ; restore return register
|
ldw $16,$29,4 ; restore register variable
|
ldw $16,$29,4 ; restore register variable
|
add $29,$29,8 ; release stack frame
|
add $29,$29,8 ; release stack frame
|
jr $31 ; return
|
jr $31 ; return
|
|
|
; output a character to the terminal
|
; output a character to the terminal
|
out:
|
out:
|
add $8,$0,tba ; set I/O base address
|
add $8,$0,tba ; set I/O base address
|
out1:
|
out1:
|
ldw $9,$8,8 ; get xmtr status
|
ldw $9,$8,8 ; get xmtr status
|
and $9,$9,1 ; xmtr ready?
|
and $9,$9,1 ; xmtr ready?
|
beq $9,$0,out1 ; no - wait
|
beq $9,$0,out1 ; no - wait
|
stw $4,$8,12 ; send char
|
stw $4,$8,12 ; send char
|
jr $31 ; return
|
jr $31 ; return
|
|
|
; a very famous little string...
|
; a very famous little string...
|
hello:
|
hello:
|
.byte 0x0D, 0x0A
|
.byte 0x0D, 0x0A
|
.byte "Hello, world!"
|
.byte "Hello, world!"
|
.byte 0x0D, 0x0A
|
.byte 0x0D, 0x0A
|
.byte 0x0D, 0x0A, 0
|
.byte 0x0D, 0x0A, 0
|
|
|
