2019-05-25 07:43:19 +00:00
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# Comparing arrays of numbers.
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== code
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# instruction effective address register displacement immediate
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# . op subop mod rm32 base index scale r32
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# . 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
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Entry:
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2019-05-25 07:45:31 +00:00
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# initialize heap
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# . Heap = new-segment(64KB)
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# . . push args
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68/push Heap/imm32
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68/push 0x10000/imm32/64KB
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# . . call
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e8/call new-segment/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
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2019-05-25 07:43:19 +00:00
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# for debugging: run a single test
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#? e8/call test-compare-inequal-arrays-equal-lengths/disp32
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#? 8b/copy 0/mod/indirect 5/rm32/.disp32 . . 3/r32/EBX Num-test-failures/disp32 # copy *Num-test-failures to EBX
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#? eb/jump $array-equal-main:end/disp8
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e8/call run-tests/disp32 # 'run-tests' is a function created automatically by SubX. It calls all functions that start with 'test-'.
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$array-equal-main:end:
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# syscall(exit, Num-test-failures)
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8b/copy 0/mod/indirect 5/rm32/.disp32 . . 3/r32/EBX Num-test-failures/disp32 # copy *Num-test-failures to EBX
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b8/copy-to-EAX 1/imm32/exit
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cd/syscall 0x80/imm8
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array-equal?: # a : (address array int), b : (address array int) -> EAX : boolean
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# pseudocode:
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# lena = a->length
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# if (lena != b->length) return false
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# i = 0
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# curra = a->data
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# currb = b->data
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# while i < lena
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# i1 = *curra
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# i2 = *currb
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# if (c1 != c2) return false
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# i+=4, curra+=4, currb+=4
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# return true
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#
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# registers:
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# i: ECX
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# lena: EDX
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# curra: ESI
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# currb: EDI
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# i1: EAX
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# i2: EBX
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#
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# . prolog
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55/push-EBP
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89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP
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# . save registers
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51/push-ECX
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52/push-EDX
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53/push-EBX
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56/push-ESI
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57/push-EDI
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# ESI = a
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8b/copy 1/mod/*+disp8 5/rm32/EBP . . . 6/r32/ESI 8/disp8 . # copy *(EBP+8) to ESI
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# EDI = b
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8b/copy 1/mod/*+disp8 5/rm32/EBP . . . 7/r32/EDI 0xc/disp8 . # copy *(EBP+12) to EDI
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# lena/EDX = a->length
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8b/copy 0/mod/indirect 6/rm32/ESI . . . 2/r32/EDX . . # copy *ESI to EDX
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$array-equal?:lengths:
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# if (lena != b->length) return false
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39/compare 0/mod/indirect 7/rm32/EDI . . . 2/r32/EDX . . # compare *EDI and EDX
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75/jump-if-not-equal $array-equal?:false/disp8
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# curra/ESI = a->data
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81 0/subop/add 3/mod/direct 6/rm32/ESI . . . . . 4/imm32 # add to ESI
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# currb/EDI = b->data
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81 0/subop/add 3/mod/direct 7/rm32/EDI . . . . . 4/imm32 # add to EDI
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# i/ECX = i1/EAX = i2/EBX = 0
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31/xor 3/mod/direct 1/rm32/ECX . . . 1/r32/ECX . . # clear ECX
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$array-equal?:loop:
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# if (i >= lena) return true
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39/compare 3/mod/direct 1/rm32/ECX . . . 2/r32/EDX . . # compare ECX with EDX
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7d/jump-if-greater-or-equal $array-equal?:true/disp8
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# i1 = *curra
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8b/copy 0/mod/indirect 6/rm32/ESI . . . 0/r32/EAX . . # copy *ESI to EAX
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# i2 = *currb
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8b/copy 0/mod/indirect 7/rm32/EDI . . . 3/r32/EBX . . # copy *EDI to EBX
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# if (i1 != i2) return false
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39/compare 3/mod/direct 0/rm32/EAX . . . 3/r32/EBX . . # compare EAX and EBX
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75/jump-if-not-equal $array-equal?:false/disp8
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# i += 4
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81 0/subop/add 3/mod/direct 1/rm32/ECX . . . . . 4/imm32 # add to ECX
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# currs += 4
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81 0/subop/add 3/mod/direct 6/rm32/ESI . . . . . 4/imm32 # add to ESI
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# currb += 4
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81 0/subop/add 3/mod/direct 7/rm32/EDI . . . . . 4/imm32 # add to EDI
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eb/jump $array-equal?:loop/disp8
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$array-equal?:true:
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b8/copy-to-EAX 1/imm32
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eb/jump $array-equal?:end/disp8
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$array-equal?:false:
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b8/copy-to-EAX 0/imm32
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$array-equal?:end:
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# . restore registers
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5f/pop-to-EDI
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5e/pop-to-ESI
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5b/pop-to-EBX
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5a/pop-to-EDX
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59/pop-to-ECX
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# . epilog
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89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP
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5d/pop-to-EBP
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c3/return
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# - tests
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test-compare-empty-with-empty-array:
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# . prolog
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55/push-EBP
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89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP
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# var ECX = []
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68/push 0/imm32/size
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89/copy 3/mod/direct 1/rm32/ECX . . . 4/r32/ESP . . # copy ESP to ECX
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# var EDX = []
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68/push 0/imm32/size
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89/copy 3/mod/direct 2/rm32/EDX . . . 4/r32/ESP . . # copy ESP to EDX
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# EAX = array-equal?(ECX, EDX)
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# . . push args
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52/push-EDX
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51/push-ECX
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# . . call
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e8/call array-equal?/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
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# check-ints-equal(EAX, 1, msg)
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# . . push args
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68/push "F - test-compare-empty-with-empty-array"/imm32
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68/push 1/imm32/true
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50/push-EAX
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# . . call
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e8/call check-ints-equal/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP
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# . epilog
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89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP
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5d/pop-to-EBP
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c3/return
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test-compare-empty-with-non-empty-array: # also checks length-mismatch code path
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# . prolog
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55/push-EBP
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89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP
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# var ECX = [1]
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68/push 1/imm32
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68/push 4/imm32/size
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89/copy 3/mod/direct 1/rm32/ECX . . . 4/r32/ESP . . # copy ESP to ECX
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# var EDX = []
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68/push 0/imm32/size
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89/copy 3/mod/direct 2/rm32/EDX . . . 4/r32/ESP . . # copy ESP to EDX
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# EAX = array-equal?(ECX, EDX)
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# . . push args
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52/push-EDX
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51/push-ECX
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# . . call
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e8/call array-equal?/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
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# check-ints-equal(EAX, 0, msg)
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# . . push args
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68/push "F - test-compare-empty-with-non-empty-array"/imm32
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68/push 0/imm32/false
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50/push-EAX
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# . . call
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e8/call check-ints-equal/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP
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# . epilog
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89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP
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5d/pop-to-EBP
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c3/return
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test-compare-equal-arrays:
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# . prolog
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55/push-EBP
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89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP
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# var ECX = [1, 2, 3]
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68/push 3/imm32
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68/push 2/imm32
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68/push 1/imm32
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68/push 0xc/imm32/size
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89/copy 3/mod/direct 1/rm32/ECX . . . 4/r32/ESP . . # copy ESP to ECX
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# var EDX = [1, 2, 3]
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68/push 3/imm32
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68/push 2/imm32
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68/push 1/imm32
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68/push 0xc/imm32/size
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89/copy 3/mod/direct 2/rm32/EDX . . . 4/r32/ESP . . # copy ESP to EDX
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# EAX = array-equal?(ECX, EDX)
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# . . push args
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52/push-EDX
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51/push-ECX
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# . . call
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e8/call array-equal?/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
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# check-ints-equal(EAX, 1, msg)
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# . . push args
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68/push "F - test-compare-equal-arrays"/imm32
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68/push 1/imm32/true
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50/push-EAX
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# . . call
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e8/call check-ints-equal/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP
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# . epilog
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89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP
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5d/pop-to-EBP
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c3/return
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test-compare-inequal-arrays-equal-lengths:
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# . prolog
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55/push-EBP
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89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP
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# var ECX = [1, 4, 3]
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68/push 3/imm32
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68/push 4/imm32
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68/push 1/imm32
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68/push 0xc/imm32/size
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89/copy 3/mod/direct 1/rm32/ECX . . . 4/r32/ESP . . # copy ESP to ECX
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# var EDX = [1, 2, 3]
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68/push 3/imm32
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68/push 2/imm32
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68/push 1/imm32
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68/push 0xc/imm32/size
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89/copy 3/mod/direct 2/rm32/EDX . . . 4/r32/ESP . . # copy ESP to EDX
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# EAX = array-equal?(ECX, EDX)
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# . . push args
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52/push-EDX
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51/push-ECX
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# . . call
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e8/call array-equal?/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
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# check-ints-equal(EAX, 0, msg)
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# . . push args
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68/push "F - test-compare-inequal-arrays-equal-lengths"/imm32
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68/push 0/imm32/false
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50/push-EAX
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# . . call
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e8/call check-ints-equal/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP
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# . epilog
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89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP
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5d/pop-to-EBP
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c3/return
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2019-05-25 07:45:31 +00:00
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== data
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Heap:
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# curr
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0/imm32
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# limit
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0/imm32
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2019-05-25 07:43:19 +00:00
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# . . vim:nowrap:textwidth=0
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