or1k memory checker

.org 0x100

# r3: base gpio
# r4: scratch
# r5: address to be checked
# r6: 0xaa
# r7: 0x55
# r8: 0xff
# r10: end-address 0x100000

init:
	l.movhi r3,0x9100 # r3 = base address gpio
	l.add   r4,r0,r0  # r4 = 0

	l.sb 0x0(r3),r4   # *r3 = 0, reset LEDs

	l.addi  r5,r0,0x200 # r5 = 0x200
	l.movhi r10,0x100   # r10 = 0x100000 = end address

	l.addi  r6,r0,0xaa
	l.addi  r7,r0,0x55
	l.addi  r8,r0,0xff

loop:
    # test pattern 0
    l.sb    0(r5), r0
    l.lbz   r4, 0(r5)
    l.sfne  r4, r0
    l.bf    memerr
    l.nop

    # test pattern aa
    l.sb    0(r5), r6
    l.lbz   r4, 0(r5)
    l.sfne  r4, r6
    l.bf    memerr
    l.nop

    # test pattern 55
    l.sb    0(r5), r7
    l.lbz   r4, 0(r5)
    l.sfne  r4, r7
    l.bf    memerr
    l.nop

    # test pattern ff
    l.sb    0(r5), r8
    l.lbz   r4, 0(r5)
    l.sfne  r4, r8
    l.bf    memerr
    l.nop

    # write 0 again
    l.sb   0(r5), r0

    l.addi  r5, r5, 1
    l.sfltu r5, r10
    l.bf    loop
    l.nop
    l.j     end

memerr:
    l.sb    0(r3),r8
endless:
    l.j     endless

end:
	l.nop
	l.j     end