## add the first 10 numbers, and return the result in the exit code # # To run: # $ subx translate ex3.subx -o ex3 # $ subx run ex3 # Expected result: # $ echo $? # 55 == code # 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 bb/copy 0/imm32 # copy 0 to EBX # counter: ECX = 1 b9/copy 1/imm32 # copy 1 to ECX $loop: # while (counter <= 10) 81 7/subop/compare 3/mod/direct 1/rm32/ECX 0xa/imm32 # compare ECX, 10/imm 7f/jump-if-greater $exit/disp8 # result += counter 01/add 3/mod/direct 3/rm32/EBX 1/r32/ECX # add ECX to EBX # ++counter 81 0/subop/add 3/mod/direct 1/rm32/ECX 1/imm32 # add 1 to ECX # loop eb/jump $loop/disp8 $exit: # exit(EBX) b8/copy 1/imm32 # copy 1 to EAX cd/syscall 0x80/imm8 # vim:ft=subx:nowrap