223 lines
10 KiB
Plaintext
223 lines
10 KiB
Plaintext
# Comparing 'regular' length-prefixed strings.
|
|
|
|
== 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: # run all tests
|
|
#? e8/call test-compare-equal-strings/disp32
|
|
e8/call run-tests/disp32 # 'run-tests' is a function created automatically by SubX. It calls all functions that start with 'test-'.
|
|
# 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
|
|
|
|
string-equal?: # s : (addr array byte), benchmark : (addr array byte) -> eax : boolean
|
|
# pseudocode:
|
|
# if (s->length != benchmark->length) return false
|
|
# currs = s->data
|
|
# currb = benchmark->data
|
|
# maxs = &s->data[s->length]
|
|
# while currs < maxs
|
|
# c1 = *currs
|
|
# c2 = *currb
|
|
# if (c1 != c2) return false
|
|
# ++currs, ++currb
|
|
# return true
|
|
#
|
|
# registers:
|
|
# currs: esi
|
|
# maxs: ecx
|
|
# currb: edi
|
|
# c1: eax
|
|
# c2: ebx
|
|
#
|
|
# . prologue
|
|
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
|
|
56/push-esi
|
|
57/push-edi
|
|
# esi = s
|
|
8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 6/r32/esi 8/disp8 . # copy *(ebp+8) to esi
|
|
# edi = benchmark
|
|
8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 7/r32/edi 0xc/disp8 . # copy *(ebp+12) to edi
|
|
# ecx = s->length
|
|
8b/copy 0/mod/indirect 6/rm32/esi . . . 1/r32/ecx . . # copy *esi to ecx
|
|
$string-equal?:lengths:
|
|
# if (ecx != benchmark->length) return false
|
|
39/compare 0/mod/indirect 7/rm32/edi . . . 1/r32/ecx . . # compare *edi and ecx
|
|
75/jump-if-not-equal $string-equal?:false/disp8
|
|
# var currs/esi : (addr byte) = s->data
|
|
81 0/subop/add 3/mod/direct 6/rm32/esi . . . . . 4/imm32 # add to esi
|
|
# var maxs/ecx : (addr byte) = &s->data[s->length]
|
|
01/add 3/mod/direct 1/rm32/ecx . . . 6/r32/esi . . # add esi to ecx
|
|
# var currb/edi : (addr byte) = benchmark->data
|
|
81 0/subop/add 3/mod/direct 7/rm32/edi . . . . . 4/imm32 # add to edi
|
|
# var c1/eax : byte = 0
|
|
31/xor 3/mod/direct 0/rm32/eax . . . 0/r32/eax . . # clear eax
|
|
# var c2/edx : byte = 0
|
|
31/xor 3/mod/direct 2/rm32/edx . . . 2/r32/edx . . # clear edx
|
|
$string-equal?:loop:
|
|
# if (currs >= maxs) return true
|
|
39/compare 3/mod/direct 6/rm32/esi . . . 1/r32/ecx . . # compare esi with ecx
|
|
73/jump-if-greater-or-equal-unsigned $string-equal?:true/disp8
|
|
# c1 = *currs
|
|
8a/copy-byte 0/mod/indirect 6/rm32/esi . . . 0/r32/AL . . # copy byte at *esi to AL
|
|
# c2 = *currb
|
|
8a/copy-byte 0/mod/indirect 7/rm32/edi . . . 2/r32/DL . . # copy byte at *edi to DL
|
|
# if (c1 != c2) return false
|
|
39/compare 3/mod/direct 0/rm32/eax . . . 2/r32/edx . . # compare eax and edx
|
|
75/jump-if-not-equal $string-equal?:false/disp8
|
|
# ++currs
|
|
46/increment-esi
|
|
# ++currb
|
|
47/increment-edi
|
|
eb/jump $string-equal?:loop/disp8
|
|
$string-equal?:true:
|
|
b8/copy-to-eax 1/imm32
|
|
eb/jump $string-equal?:end/disp8
|
|
$string-equal?:false:
|
|
b8/copy-to-eax 0/imm32
|
|
$string-equal?:end:
|
|
# . restore registers
|
|
5f/pop-to-edi
|
|
5e/pop-to-esi
|
|
5a/pop-to-edx
|
|
59/pop-to-ecx
|
|
# . epilogue
|
|
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-string:
|
|
# eax = string-equal?("", "")
|
|
# . . push args
|
|
68/push ""/imm32
|
|
68/push ""/imm32
|
|
# . . call
|
|
e8/call string-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-string"/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
|
|
c3/return
|
|
|
|
test-compare-empty-with-non-empty-string: # also checks length-mismatch code path
|
|
# eax = string-equal?("", "Abc")
|
|
# . . push args
|
|
68/push "Abc"/imm32
|
|
68/push ""/imm32
|
|
# . . call
|
|
e8/call string-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-string"/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
|
|
c3/return
|
|
|
|
test-compare-equal-strings:
|
|
# eax = string-equal?("Abc", "Abc")
|
|
# . . push args
|
|
68/push "Abc"/imm32
|
|
68/push "Abc"/imm32
|
|
# . . call
|
|
e8/call string-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-strings"/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
|
|
c3/return
|
|
|
|
test-compare-inequal-strings-equal-lengths:
|
|
# eax = string-equal?("Abc", "Adc")
|
|
# . . push args
|
|
68/push "Adc"/imm32
|
|
68/push "Abc"/imm32
|
|
# . . call
|
|
e8/call string-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-strings-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
|
|
c3/return
|
|
|
|
# helper for later tests
|
|
check-strings-equal: # s : (addr array byte), expected : (addr array byte), msg : (addr array byte)
|
|
# . prologue
|
|
55/push-ebp
|
|
89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp
|
|
# . save registers
|
|
50/push-eax
|
|
# var eax : boolean = string-equal?(s, expected)
|
|
# . . push args
|
|
ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 0xc/disp8 . # push *(ebp+12)
|
|
ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 8/disp8 . # push *(ebp+8)
|
|
# . . call
|
|
e8/call string-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
|
|
ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 0x10/disp8 . # push *(ebp+16)
|
|
68/push 1/imm32
|
|
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
|
|
$check-strings-equal:end:
|
|
# . restore registers
|
|
58/pop-to-eax
|
|
# . epilogue
|
|
89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp
|
|
5d/pop-to-ebp
|
|
c3/return
|
|
|
|
# test the helper
|
|
test-check-strings-equal:
|
|
# check-strings-equal?("Abc", "Abc")
|
|
# . . push args
|
|
68/push "Abc"/imm32
|
|
68/push "Abc"/imm32
|
|
# . . call
|
|
e8/call check-strings-equal/disp32
|
|
# . . discard args
|
|
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
|
|
c3/return
|
|
|
|
# . . vim:nowrap:textwidth=0
|