1 # Add the first 10 numbers, and return the result in the exit code. 2 # 3 # To run: 4 # $ bootstrap/bootstrap translate apps/ex3.subx -o apps/ex3 5 # $ bootstrap/bootstrap run ex3 6 # Expected result: 7 # $ echo $? 8 # 55 9 10 == code 11 # instruction effective address register displacement immediate 12 # . op subop mod rm32 base index scale r32 13 # . 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 14 15 Entry: 16 # result: ebx = 0 17 bb/copy-to-ebx 0/imm32 18 # counter: ecx = 1 19 b9/copy-to-ecx 1/imm32 20 21 $loop: 22 # if (counter > 10) break 23 81 7/subop/compare 3/mod/direct 1/rm32/ecx . . . . . 0xa/imm32 # compare ecx 24 7f/jump-if-> $exit/disp8 25 # result += counter 26 01/add 3/mod/direct 3/rm32/ebx . . . 1/r32/ecx . . # add ecx to ebx 27 # ++counter 28 41/increment-ecx 29 # loop 30 eb/jump $loop/disp8 31 32 $exit: 33 # exit(ebx) 34 e8/call syscall_exit/disp32 35 36 # . . vim:nowrap:textwidth=0