# Comparing arrays of numbers. == code # instruction effective address register 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 Entry: # initialize heap # . Heap = new-segment(64KB) # . . push args 68/push Heap/imm32 68/push 0x10000/imm32/64KB # . . call e8/call new-segment/disp32 # . . discard args 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP # for debugging: run a single test #? e8/call test-compare-inequal-arrays-equal-lengths/disp32 #? 8b/copy 0/mod/indirect 5/rm32/.disp32 . . 3/r32/EBX Num-test-failures/disp32 # copy *Num-test-failures to EBX #? eb/jump $array-equal-main:end/disp8 e8/call run-tests/disp32 # 'run-tests' is a function created automatically by SubX. It calls all functions that start with 'test-'. $array-equal-main:end: # syscall(exit, Num-test-failures) 8b/copy 0/mod/indirect 5/rm32/.disp32 . . 3/r32/EBX Num-test-failures/disp32 # copy *Num-test-failures to EBX b8/copy-to-EAX 1/imm32/exit cd/syscall 0x80/imm8 array-equal?: # a : (address array int), b : (address array int) -> EAX : boolean # pseudocode: # lena = a->length # if (lena != b->length) return false # i = 0 # curra = a->data # currb = b->data # while i < lena # i1 = *curra # i2 = *currb # if (c1 != c2) return false # i+=4, curra+=4, currb+=4 # return true # # registers: # i: ECX # lena: EDX # curra: ESI # currb: EDI # i1: EAX # i2: EBX # # . prolog 55/push-EBP 89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP # . save registers 51/push-ECX 52/push-EDX 53/push-EBX 56/push-ESI 57/push-EDI # ESI = a 8b/copy 1/mod/*+disp8 5/rm32/EBP . . . 6/r32/ESI 8/disp8 . # copy *(EBP+8) to ESI # EDI = b 8b/copy 1/mod/*+disp8 5/rm32/EBP . . . 7/r32/EDI 0xc/disp8 . # copy *(EBP+12) to EDI # lena/EDX = a->length 8b/copy 0/mod/indirect 6/rm32/ESI . . . 2/r32/EDX . . # copy *ESI to EDX $array-equal?:lengths: # if (lena != b->length) return false 39/compare 0/mod/indirect 7/rm32/EDI . . . 2/r32/EDX . . # compare *EDI and EDX 75/jump-if-not-equal $array-equal?:false/disp8 # curra/ESI = a->data 81 0/subop/add 3/mod/direct 6/rm32/ESI . . . . . 4/imm32 # add to ESI # currb/EDI = b->data 81 0/subop/add 3/mod/direct 7/rm32/EDI . . . . . 4/imm32 # add to EDI # i/ECX = i1/EAX = i2/EBX = 0 31/xor 3/mod/direct 1/rm32/ECX . . . 1/r32/ECX . . # clear ECX $array-equal?:loop: # if (i >= lena) return true 39/compare 3/mod/direct 1/rm32/ECX . . . 2/r32/EDX . . # compare ECX with EDX 7d/jump-if-greater-or-equal $array-equal?:true/disp8 # i1 = *curra 8b/copy 0/mod/indirect 6/rm32/ESI . . . 0/r32/EAX . . # copy *ESI to EAX # i2 = *currb 8b/copy 0/mod/indirect 7/rm32/EDI . . . 3/r32/EBX . . # copy *EDI to EBX # if (i1 != i2) return false 39/compare 3/mod/direct 0/rm32/EAX . . . 3/r32/EBX . . # compare EAX and EBX 75/jump-if-not-equal $array-equal?:false/disp8 # i += 4 81 0/subop/add 3/mod/direct 1/rm32/ECX . . . . . 4/imm32 # add to ECX # currs += 4 81 0/subop/add 3/mod/direct 6/rm32/ESI . . . . . 4/imm32 # add to ESI # currb += 4 81 0/subop/add 3/mod/direct 7/rm32/EDI . . . . . 4/imm32 # add to EDI eb/jump $array-equal?:loop/disp8 $array-equal?:true: b8/copy-to-EAX 1/imm32 eb/jump $array-equal?:end/disp8 $array-equal?:false: b8/copy-to-EAX 0/imm32 $array-equal?:end: # . restore registers 5f/pop-to-EDI 5e/pop-to-ESI 5b/pop-to-EBX 5a/pop-to-EDX 59/pop-to-ECX # . epilog 89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP 5d/pop-to-EBP c3/return # - tests test-compare-empty-with-empty-array: # . prolog 55/push-EBP 89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP # var ECX = [] 68/push 0/imm32/size 89/copy 3/mod/direct 1/rm32/ECX . . . 4/r32/ESP . . # copy ESP to ECX # var EDX = [] 68/push 0/imm32/size 89/copy 3/mod/direct 2/rm32/EDX . . . 4/r32/ESP . . # copy ESP to EDX # EAX = array-equal?(ECX, EDX) # . . push args 52/push-EDX 51/push-ECX # . . call e8/call array-equal?/disp32 # . . discard args 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP # check-ints-equal(EAX, 1, msg) # . . push args 68/push "F - test-compare-empty-with-empty-array"/imm32 68/push 1/imm32/true 50/push-EAX # . . call e8/call check-ints-equal/disp32 # . . discard args 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP # . epilog 89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP 5d/pop-to-EBP c3/return test-compare-empty-with-non-empty-array: # also checks length-mismatch code path # . prolog 55/push-EBP 89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP # var ECX = [1] 68/push 1/imm32 68/push 4/imm32/size 89/copy 3/mod/direct 1/rm32/ECX . . . 4/r32/ESP . . # copy ESP to ECX # var EDX = [] 68/push 0/imm32/size 89/copy 3/mod/direct 2/rm32/EDX . . . 4/r32/ESP . . # copy ESP to EDX # EAX = array-equal?(ECX, EDX) # . . push args 52/push-EDX 51/push-ECX # . . call e8/call array-equal?/disp32 # . . discard args 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP # check-ints-equal(EAX, 0, msg) # . . push args 68/push "F - test-compare-empty-with-non-empty-array"/imm32 68/push 0/imm32/false 50/push-EAX # . . call e8/call check-ints-equal/disp32 # . . discard args 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP # . epilog 89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP 5d/pop-to-EBP c3/return test-compare-equal-arrays: # . prolog 55/push-EBP 89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP # var ECX = [1, 2, 3] 68/push 3/imm32 68/push 2/imm32 68/push 1/imm32 68/push 0xc/imm32/size 89/copy 3/mod/direct 1/rm32/ECX . . . 4/r32/ESP . . # copy ESP to ECX # var EDX = [1, 2, 3] 68/push 3/imm32 68/push 2/imm32 68/push 1/imm32 68/push 0xc/imm32/size 89/copy 3/mod/direct 2/rm32/EDX . . . 4/r32/ESP . . # copy ESP to EDX # EAX = array-equal?(ECX, EDX) # . . push args 52/push-EDX 51/push-ECX # . . call e8/call array-equal?/disp32 # . . discard args 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP # check-ints-equal(EAX, 1, msg) # . . push args 68/push "F - test-compare-equal-arrays"/imm32 68/push 1/imm32/true 50/push-EAX # . . call e8/call check-ints-equal/disp32 # . . discard args 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP # . epilog 89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP 5d/pop-to-EBP c3/return test-compare-inequal-arrays-equal-lengths: # . prolog 55/push-EBP 89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP # var ECX = [1, 4, 3] 68/push 3/imm32 68/push 4/imm32 68/push 1/imm32 68/push 0xc/imm32/size 89/copy 3/mod/direct 1/rm32/ECX . . . 4/r32/ESP . . # copy ESP to ECX # var EDX = [1, 2, 3] 68/push 3/imm32 68/push 2/imm32 68/push 1/imm32 68/push 0xc/imm32/size 89/copy 3/mod/direct 2/rm32/EDX . . . 4/r32/ESP . . # copy ESP to EDX # EAX = array-equal?(ECX, EDX) # . . push args 52/push-EDX 51/push-ECX # . . call e8/call array-equal?/disp32 # . . discard args 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP # check-ints-equal(EAX, 0, msg) # . . push args 68/push "F - test-compare-inequal-arrays-equal-lengths"/imm32 68/push 0/imm32/false 50/push-EAX # . . call e8/call check-ints-equal/disp32 # . . discard args 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP # . epilog 89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP 5d/pop-to-EBP c3/return == data Heap: # curr 0/imm32 # limit 0/imm32 # . . vim:nowrap:textwidth=0