blob: f9df870382f3c1f71dcc1f4ef91b455015cfb62d (
plain) (
tree)
|
|
## add the first 10 numbers, and return the result in the exit code
#
# To run:
# $ subx translate ex3.subx ex3
# $ subx run ex3
# Expected result:
# $ echo $?
# 55
== 0x08048054 # code segment, after leaving room for ELF header
# instruction effective address operand displacement immediate
# op subop mod rm32 base index scale r32
# 1-3 bytes 3 bits 2 bits 3 bits 3 bits 3 bits 2 bits 2 bits 0/1/2/4 bytes 0/1/2/4 bytes
# result: EBX = 0
# 0: e_entry = 0x08048054
bb 0/imm32 # copy 0 to EBX
# counter: ECX = 1
b9 1/imm32 # copy 1 to ECX
# 10: loop: 0x0804805e
# while (ECX <= 10)
81 7/subop/compare 3/mod/direct 1/rm32/ecx 10/imm32 # compare ECX, 10/imm
7f 10/disp8 # jump-if-greater exit
# EBX += ECX
01 3/mod/direct 3/rm32/ebx 1/r32/ecx # add ECX to EBX
# ECX++
81 0/subop/add 3/mod/direct 1/rm32/ecx 1/imm32 # add 1 to ECX
# loop
eb -18/disp8 # jump loop
# 28: exit: 0x08048070
# exit(EBX)
b8 1/imm32 # copy 1 to EAX
cd 0x80/imm8 # int 80h
# vim:ft=subx:nowrap
|