== 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/u a/rd 10000/imm20

13/i 15/rd 0/funct3 b/rs 0/imm12

# check magic == 0xd00dfeed
37/u 6/rd edfe1/imm20
13/i 6/rd 0/funct3 6/rs dd0/imm12
3/i 5/rd 2/funct3 15/rs 0/imm12
63/b 1/funct3 5/rs1 6/rs2 38/imm13

37/u b/rd 80500/imm20
13/i b/rd 0/funct3 b/rs 14/imm12
6f/j 1/rd 88/imm21

3/i b/rd 2/funct3 15/rs 4/imm12
6f/j 1/rd 34/imm21
6f/j 1/rd a0/imm21
6f/j 1/rd 60/imm21

# exit:
# system reset (via SBI extension SRST)
# a7 = ext id, a6 = fid, a0 = 0, a1 = 0
37/u 11/rd 53525/imm20
13/i 11/rd 0/funct3 11/rs 354/imm12
33/r 10/rd 0/funct3 0/rs1 0/rs2 0/funct7
33/r a/rd 0/funct3 0/rs1 0/rs2 0/funct7
33/r b/rd 0/funct3 0/rs1 0/rs2 0/funct7
# ECALL
73/i 0/rd 0/funct3 0/rs 0/imm12

# err_magic:
37/u b/rd 80500/imm20
13/i b/rd 0/funct3 b/rs 0/imm12
6f/j 1/rd 54/imm21
6f/j 0/rd -24/imm21

# bswapw:
# byte-order-swap word in a1
# srli    a1, a0, 8
# lui     a2, 16
# addi    a2, a2, -256
# and     a1, a1, a2
13/i 5/rd 5/funct3 b/rs 8/imm12
37/u 6/rd 16/imm20
13/i 6/rd 0/funct3 6/rs -100/imm12
33/r 5/rd 7/funct3 5/rs1 6/rs2 0/funct7
#  srli    a2, a0, 24
#  or      a1, a1, a2
13/i 6/rd 5/funct3 b/rs 18/imm12
33/r 5/rd 6/funct3 5/rs1 6/rs2 0/funct7
# slli    a2, a0, 8
# lui     a3, 4080
# and     a2, a2, a3
13/i 6/rd 1/funct3 b/rs 8/imm12
37/u 7/rd ff0/imm20
33/r 6/rd 7/funct3 6/rs1 7/rs2 0/funct7
# slli    a0, a0, 24
# or      a0, a0, a2
# or      a0, a0, a1
13/i b/rd 1/funct3 b/rs 18/imm12
33/r b/rd 6/funct3 b/rs1 6/rs2 0/funct7
33/r b/rd 6/funct3 b/rs1 5/rs2 0/funct7
# ret
67/i 0/rd 0/funct3 1/rs 0/imm12

# printnl:
13/i 6/rd 0/funct3 0/rs a/imm12
# printnl:spin:
# spin if FIFO is full (thr_emtpy = UART+5 & 0x20)
3/i 7/rd 4/funct3 a/rs 5/imm12
13/i 7/rd 7/funct3 7/rs 20/imm12
63/b 0/funct3 7/rs1 0/rs2 -8/imm13
# print char
23/s 2/funct3 a/rs1 0/imm12 6/rs2
# return
67/i 0/rd 0/funct3 1/rs 0/imm12

# print:
# print:loop:
# load unsigned byte at a1
3/i 6/rd 4/funct3 b/rs 0/imm12
# break loop if zero
63/b 0/funct3 6/rs1 0/rs2 1c/imm13
# print:spin:
# spin if FIFO is full (thr_emtpy = UART+5 & 0x20)
3/i 7/rd 4/funct3 a/rs 5/imm12
13/i 7/rd 7/funct3 7/rs 20/imm12
63/b 0/funct3 7/rs1 0/rs2 -8/imm13
# print char
23/s 2/funct3 a/rs1 0/imm12 6/rs2
# increment a1
13/i b/rd 0/funct3 b/rs 1/imm12
# jump back up
6f/j 0/rd -1c/imm21
# print:break:
# return
67/i 0/rd 0/funct3 1/rs 0/imm12

# print_hex_word:
13/i 8/rd 0/funct3 b/rs 0/imm12
13/i 9/rd 0/funct3 0/rs 1c/imm12
13/i 12/rd 0/funct3 1/rs 0/imm12
# print_hex_word:loop:
# shift
33/r b/rd 5/funct3 8/rs1 9/rs2 0/funct7
6f/j 1/rd 14/imm21

# break if last shift
63/b 0/funct3 9/rs1 0/rs2 c/imm13

# subtract shift count, loop
13/i 9/rd 0/funct3 9/rs -4/imm12
6f/j 0/rd -10/imm21
# print_hex_word:break:
# return
67/i 0/rd 0/funct3 12/rs 0/imm12

# print_hex_dgt:
# a1 = a1 & 0xf
13/i b/rd 7/funct3 b/rs f/imm12
# t1 = 0x40
13/i 6/rd 0/funct3 0/rs 40/imm12

# add 0x30 (ascii '0') / 0x61 (ascii 'a')
13/i b/rd 0/funct3 b/rs 30/imm12
63/b 4/funct3 b/rs1 6/rs2 8/imm13
13/i b/rd 0/funct3 b/rs 27/imm12

# print_hex_dgt:spin:
# spin if FIFO is full (thr_emtpy = UART+5 & 0x20)
3/i 7/rd 4/funct3 a/rs 5/imm12
13/i 7/rd 7/funct3 7/rs 20/imm12
63/b 0/funct3 7/rs1 0/rs2 -8/imm13

# print char
23/s 2/funct3 a/rs1 0/imm12 b/rs2

# return
67/i 0/rd 0/funct3 1/rs 0/imm12

== 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