== code 0x80400000
# main:
# print device tree info.
# OpenSBI calls us with a1 set to the start of the DTB
# load 0x10000000 (UART0) into a0
37/7 0a/5 10000/20

13/7 15/5 0/3 0b/5 000/12

# check magic == 0xd00dfeed
37/7 06/5 edfe1/20
13/7 06/5 0/3 06/5 dd0/12
03/7 05/5 2/3 15/5 000/12
63/7 0/1 c/4 1/3 05/5 06/5 01/6 0/1

37/7 0b/5 80500/20
13/7 0b/5 0/3 0b/5 014/12
6f/7 01/5 00/8 0/1 044/10 0/1

03/7 0b/5 2/3 15/5 004/12
6f/7 01/5 00/8 0/1 01a/10 0/1
6f/7 01/5 00/8 0/1 050/10 0/1
6f/7 01/5 00/8 0/1 030/10 0/1

# exit:
# system reset (via SBI extension SRST)
# a7 = ext id, a6 = fid, a0 = 0, a1 = 0
37/7 11/5 53525/20
13/7 11/5 0/3 11/5 354/12
33/7 10/5 0/3 00/5 00/5 00/7
33/7 0a/5 0/3 00/5 00/5 00/7
33/7 0b/5 0/3 00/5 00/5 00/7
# ECALL
73/7 00/5 0/3 00/5 000/12

# err_magic:
37/7 0b/5 80500/20
13/7 0b/5 0/3 0b/5 000/12
6f/7 01/5 00/8 0/1 02a/10 0/1
6f/7 00/5 ff/8 1/1 3ee/10 1/1

# bswapw:
# byte-order-swap word in a1
# srli    a1, a0, 8
# lui     a2, 16
# addi    a2, a2, -256
# and     a1, a1, a2
13/7 05/5 5/3 0b/5 008/12
37/7 06/5 00016/20
13/7 06/5 0/3 06/5 f00/12
33/7 05/5 7/3 05/5 06/5 00/7
#  srli    a2, a0, 24
#  or      a1, a1, a2
13/7 06/5 5/3 0b/5 018/12
33/7 05/5 6/3 05/5 06/5 00/7
# slli    a2, a0, 8
# lui     a3, 4080
# and     a2, a2, a3
13/7 06/5 1/3 0b/5 008/12
37/7 07/5 00ff0/20
33/7 06/5 7/3 06/5 07/5 00/7
# slli    a0, a0, 24
# or      a0, a0, a2
# or      a0, a0, a1
13/7 0b/5 1/3 0b/5 018/12
33/7 0b/5 6/3 0b/5 06/5 00/7
33/7 0b/5 6/3 0b/5 05/5 00/7
# ret
67/7 00/5 0/3 01/5 000/12

# printnl:
13/7 06/5 0/3 00/5 00a/12
# printnl:spin:
# spin if FIFO is full (thr_emtpy = UART+5 & 0x20)
03/7 07/5 4/3 0a/5 005/12
13/7 07/5 7/3 07/5 020/12
63/7 1/1 c/4 0/3 07/5 00/5 3f/6 1/1
# print char
23/7 00/5 2/3 0a/5 06/5 00/7
# return
67/7 00/5 0/3 01/5 000/12

# print:
# print:loop:
# load unsigned byte at a1
03/7 06/5 4/3 0b/5 000/12
# break loop if zero
63/7 0/1 e/4 0/3 06/5 00/5 00/6 0/1
# print:spin:
# spin if FIFO is full (thr_emtpy = UART+5 & 0x20)
03/7 07/5 4/3 0a/5 005/12
13/7 07/5 7/3 07/5 020/12
63/7 1/1 c/4 0/3 07/5 00/5 3f/6 1/1
# print char
23/7 00/5 2/3 0a/5 06/5 00/7
# increment a1
13/7 0b/5 0/3 0b/5 001/12
# jump back up
6f/7 00/5 ff/8 1/1 3f2/10 1/1
# print:break:
# return
67/7 00/5 0/3 01/5 000/12

# print_hex_word:
13/7 08/5 0/3 0b/5 000/12
13/7 09/5 0/3 00/5 01c/12
13/7 12/5 0/3 01/5 000/12
# print_hex_word:loop:
# shift
33/7 0b/5 5/3 08/5 09/5 00/7
6f/7 01/5 00/8 0/1 00a/10 0/1

# break if last shift
63/7 0/1 6/4 0/3 09/5 00/5 00/6 0/1

# subtract shift count, loop
13/7 09/5 0/3 09/5 ffc/12
6f/7 00/5 ff/8 1/1 3f8/10 1/1
# print_hex_word:break:
# return
67/7 00/5 0/3 12/5 000/12

# print_hex_dgt:
# a1 = a1 & 0xf
13/7 0b/5 7/3 0b/5 00f/12
# t1 = 0x40
13/7 06/5 0/3 00/5 040/12

# add 0x30 (ascii '0') / 0x61 (ascii 'a')
13/7 0b/5 0/3 0b/5 030/12
63/7 0/1 4/4 4/3 0b/5 06/5 00/6 0/1
13/7 0b/5 0/3 0b/5 027/12

# print_hex_dgt:spin:
# spin if FIFO is full (thr_emtpy = UART+5 & 0x20)
03/7 07/5 4/3 0a/5 005/12
13/7 07/5 7/3 07/5 020/12
63/7 1/1 c/4 0/3 07/5 00/5 3f/6 1/1

# print char
23/7 00/5 2/3 0a/5 0b/5 00/7

# return
67/7 00/5 0/3 01/5 000/12

== data 0x80500000
# E_MAGIC:
# "Invalid DTB magic!\n\0"
49/8 6e/8 76/8 61/8 6c/8 69/8 64/8 20/8 44/8 54/8 42/8 20/8 6d/8 61/8 67/8 69/8 63/8 21/8 a/8 0/8
# S_TOTALSZ:
54/8 6f/8 74/8 61/8 6c/8 20/8 53/8 69/8 7a/8 65/8 3a/8 20/8 0/8