C++反汇编入门27.处理不当的反汇编代码
# 处理不当的反汇编代码逆向工程师经常需要处理不当的反汇编代码
## 28.1反汇编于不正确起始位置(x86)
不同于ARM和MIPS架构(任何指令长度只有2个字节长度或者4个字节长度)， x86架构的指令长度是不定长的，因此，任何反汇编器从x86指令中间开始反汇编，可能会长生不正确的结果。
举个例子：
```
add , cl
dec dword ptr
dec dword ptr
inc dword ptr
fdiv st(4), st
;-------------------------------------------------------------
db 0FFh
;-------------------------------------------------------------
dec dword ptr
dec dword ptr
dec dword ptr
dec dword ptr
dec dword ptr
dec dword ptr
jmp dword ptr
;-------------------------------------------------------------
xchg eax, ebp
clc
std
;-------------------------------------------------------------
db 0FFh
db 0FFh
;-------------------------------------------------------------
mov word ptr , cs
mov word ptr , ds
mov word ptr , es
mov word ptr , fs
mov word ptr , gs
pushf
pop dword ptr
mov eax,
mov , eax
lea eax,
mov , eax
mov dword ptr , 10001h
mov eax,
mov , eax
mov eax,
mov , eax
mov eax,
mov , eax
mov eax,
mov , eax
call ds:IsDebuggerPresent
mov edi, eax
lea eax,
push eax
call sub_407663
pop ecx
test eax, eax
jnz short loc_402D7B
```
虽然上面的代码片段一开始是从错误的起始位置反汇编的，但最终，反汇编器能够自己调整到正确的轨道上。
## 28.2不正确的反汇编代码的特点
可以很容易发现它们的共同特点是：
很少出现大尺寸的指令，最常见的有x86指令的push，mov，call。 但是我们可以看到这些指令来自各个不同的指令组，有FPU指令，IN/OUT指令，少数的系统指令，一切都是因为反汇编器从一个错误的位置上开始反汇编机器码给搞砸了。
偏移量和立即数都是一些随机值，而且数值较大。
跳转到不正确的偏移地址常常会跳转到另一个指令的中间。
代码清单28.1:x86架构不正确的反汇编代码示例
```
mov bl, 0Ch
mov ecx, 0D38558Dh
mov eax, ds:2C869A86h
db 67h
mov dl, 0CCh
insb
movsb
push eax
xor , ah
fcom qword ptr
pop esp
pop ss
in eax, dx
dec ebx
push esp
lds esp,
retf
rcl dword ptr , cl
mov cl, 9Ch
mov ch, 0DFh
push cs
insb
mov esi, 0D9C65E4Dh
imul ebp, , 66h
pushf
sal dword ptr , cl
sub eax, 0AC433D64h
out 8Ch, eax
pop ss
sbb , ebx
aas
xchg cl,
jecxz short near ptr loc_58+1
xor al, 0C6h
inc edx
db 36h
pusha
stosb
test , ebx
sub al, 0D3h ; 'L'
pop eax
stosb
loc_58: ; CODE XREF: seg000:0000004A
test , eax
inc ebp
das
db 64h
pop ecx
das
hlt
pop edx
out 0B0h, al
lodsb
push ebx
cdq
out dx, al
sub al, 0Ah
sti
outsd
add dword ptr , 96FCBE4Bh
and eax, 0E537EE4Fh
inc esp
stosd
cdq
push ecx
in al, 0CBh
mov ds:0D114C45Ch, al
mov esi, 659D1985h
enter 6FE8h, 0D9h
enter 6FE6h, 0D9h
xchg eax, esi
sub eax, 0A599866Eh
retn
pop eax
dec eax
adc al, 21h ; '!'
lahf
inc edi
sub eax, 9062EE5Bh
bound eax,
loc_A2: ; CODE XREF: seg000:00000120
wait
iret
jnb short loc_D7
cmpsd
iret
jnb short loc_D7
sub ebx,
in al, 0Ch
add esp, esp
mov bl, 8Fh
xchg eax, ecx
int 67h
pop ds
pop ebx
db 36h
xor esi,
mov ebx, 0EB4F980Ch
repne add bl, dh
imul ebx, , 67A4D1EEh
xchg eax, ebp
scasb
push esp
wait
mov dl, 11h
mov ah, 29h ; ')'
fist dword ptr
loc_D7: ; CODE XREF: seg000:000000A4
; seg000:000000A8 ...
dec dword ptr
call near ptr 622FEE3Eh
sbb ax, 5A2Fh
jmp dword ptr cs:
xor ch,
inc esp
push edi
xor esp,
pop eax
int 3 ; Trap to Debugger
rcl byte ptr , cl
xor , bl
sbb al,
xor ah,
push edi
xor ah, cl
popa
cmp dword ptr , 46h ; 'F'
dec eax
in al, 69h
dec ebx
iret
or al, 6
jns short near ptr loc_D7+3
shl byte ptr , 42h
repne adc , eax
icebp
cmpsd
leave
push esi
jmp short loc_A2
and eax, 0F2E41FE9h
push esi
loop loc_14F
add ah, fs:
loc_12D: ; CODE XREF: seg000:00000169
mov dh, 0F7h
add , esp
mov edi, 79F19525h
rcl byte ptr , cl
cli
sub al, 0D2h ; 'T'
dec eax
mov ds:0A81406F5h, eax
sbb eax, 0A7AA179Ah
in eax, dx
loc_14F: ; CODE XREF: seg000:00000128
and , ah
pop ecx
push esi
mov bl, 2Dh ; '-'
in eax, 2Ch
stosd
inc edi
push esp
locret_15E: ; CODE XREF: seg000:loc_1A0
retn 0C432h
and al, 86h
cwde
and al, 8Fh
cmp ebp,
jz short loc_12D
sub bh, ch
or dword ptr , 8A16C0F7h
db 65h
insd
mov al, ds:0A3A5173Dh
dec ecx
push ds
xor al, cl
jg short loc_195
push 6Eh ; 'n'
out 0DDh, al
inc edi
sub eax, 6899BBF1h
leave
rcr dword ptr , cl
sbb ch,
loc_195: ; CODE XREF: seg000:0000017F
push es
repne sub ah,
cmc
and ch, al
loc_1A0: ; CODE XREF: seg000:00000217
jnp short near ptr locret_15E+1
or ch,
add , esi
out dx, al
db 2Eh
call far ptr 1AAh:6832F5DDh
jz short near ptr loc_1DA+1
sbb esp,
xchg eax, edi
xor , edx
loc_1C1: ; CODE XREF: seg000:00000212
cmp eax, 1BE9080h
add , edi
aad 0
imul esp, , 0A8990126h
or dword ptr , 4Bh
popf
loc_1DA: ; CODE XREF: seg000:000001B2
mov ecx, cs
aaa
mov al, 39h ; '9'
adc byte ptr , 0C7h
add , bl
retn 0DD42h
db 3Eh
mov fs:, edi
and , esp
db 64h
xchg eax, ebp
push cs
adc eax,
mov bh, 0C7h
sub eax, 0A710CBE7h
xchg eax, ecx
or eax, 51836E42h
xchg eax, ebx
inc ecx
jb short near ptr loc_21E+3
db 64h
xchg eax, esp
and dh,
mov ch, 13h
add ebx, edx
jnb short loc_1C1
db 65h
adc al, 0C5h
js short loc_1A0
sbb eax, 887F5BEEh
loc_21E: ; CODE XREF: seg000:00000207
mov eax, 888E1FD6h
mov bl, 90h
cmp , ecx
rep int 61h ; reserved for user interrupt
and edx,
fisttpqword ptr
jmp short loc_27C
fadd st, st(2)
db 3Eh
mov edx, 54C03172h
retn
db 64h
pop ds
xchg eax, esi
rcr ebx, cl
cmp , ebx
repne xor , dh
insd
adc dl,
push ss
xor , ecx
mov cl,
or , ebp
cmpsb
lodsb
iret
```
代码清单28.2:x86_64架构不正确的反汇编代码示例
```
lea esi,
loc_AF3: ; CODE XREF: seg000:0000000000000B46
rcl byte ptr , 1
lea ecx, cs:0FFFFFFFFB2A6780Fh
mov al, 96h
mov ah, 0CEh
push rsp
lods byte ptr
db2Fh ; /
pop rsp
db 64h
retf 0E993h
cmp ah,
movzx rsi, dword ptr
push 4Ah
movzx rdi, dword ptr
db9Ah
rcr byte ptr , cl
lodsd
xor , edx
xor , edx
push rbx
sbb ch,
stosd
int 87h
db 46h, 4Ch
out 33h, rax
xchg eax, ebp
test ecx, ebp
movsd
leave
push rsp
db16h
xchg eax, esi
pop rdi
loc_B3D: ; CODE XREF: seg000:0000000000000B5F
mov ds:93CA685DF98A90F9h, eax
jnz short near ptr loc_AF3+6
out dx, eax
cwde
mov bh, 5Dh ; ']'
movsb
pop rbp
db60h ; `
movsxdrbp, dword ptr
pop rbx
out 7Dh, al
add eax, 0D79BE769h
db1Fh
retf 0CAB9h
jl short near ptr loc_B3D+4
sal dword ptr , 0D3h
mov cl, 41h ; 'A'
imul eax, , 1DDE6E5h
imul ecx, ebx, 66359BCCh
xlat
db60h ; `
cmp bl,
and ebp,
stc
sub , al
jmp short loc_C05
db4Bh ; K
int 3 ; Trap to Debugger
xchg ebx,
db 0D6h
mov esp, 0C5BA61F7h
out 0A3h, al ; Interrupt Controller #2, 8259A
add al, 0A6h
pop rbx
cmp bh, fs:
and ch, cl
cmp al, 0F3h
db0Eh
xchg dh,
stosd
xor , ebx
stosb
xchg eax, ecx
push rsi
insd
fidiv word ptr
xchg eax, ecx
mov dh, 0C0h ; 'L'
xchg eax, esp
push rsi
mov dh,
xchg eax, ebp
out 9Dh, al
loc_BC0: ; CODE XREF: seg000:0000000000000C26
or , ch
int 67h ;- LIM EMS
push rdx
sub al, 43h ; 'C'
test ecx, ebp
test , cl
db 7
imul ebx, , 2BB30231h
xor ebx,
jns short near ptr loc_C56+1
ficompdword ptr
and eax, 69BEECC7h
mov esi, 37DA40F6h
imul r13, , 0FFFFFFFFF35CDD30h
or , edx
imul esi, , 0CDA42B87h
db36h ; 6
db1Fh
loc_C05: ; CODE XREF: seg000:0000000000000B86
add dh,
mov edi, 0DD3E659h
ror byte ptr , cl
xlat
db 48h
sub rsi,
db1Fh
db 6
xor , bh
cmpsb
sub esi,
pop rbp
sbb al, 62h ; 'b'
mov dl, 33h ; '3'
db4Dh ; M
db17h
jns short loc_BC0
push 0FFFFFFFFFFFFFF86h
loc_C2A: ; CODE XREF: seg000:0000000000000C8F
sub , eax
db 0FEh
cmpsb
wait
rcr byte ptr , cl
cmp bl, al
pushfq
xchg ch, cl
db4Eh ; N
db37h ; 7
mov ds:0E43F3CCD3D9AB295h, eax
cmp ebp, ecx
jl short loc_C87
retn 8574h
out 3, al ; DMA controller, 8237A-5.
; channel 1 base address and word count
loc_C4C: ; CODE XREF: seg000:0000000000000C7F
cmp al, 0A6h
wait
push 0FFFFFFFFFFFFFFBEh
db82h
ficom dword ptr
loc_C56: ; CODE XREF: seg000:0000000000000BDE
jnz short loc_C76
xchg eax, edx
db 26h
wait
iret
push rcx
db48h ; H
db9Bh
db64h ; d
db3Eh ; >
db2Fh ; /
mov al, ds:8A7490CA2E9AA728h
stc
db60h ; `
test , ebp
int 3 ; Trap to Debugger
xlat
loc_C72: ; CODE XREF: seg000:0000000000000CC6
mov bh, 98h
db2Eh ; .
db 0DFh
loc_C76: ; CODE XREF: seg000:loc_C56
jl short loc_C91
sub ecx, 13A7CCF2h
movsb
jns short near ptr loc_C4C+1
cmpsd
sub ah, ah
cdq
db6Bh ; k
db5Ah ; Z
loc_C87: ; CODE XREF: seg000:0000000000000C45
or ecx,
rep in eax, 0Eh ; DMA controller, 8237A-5.
; Clear mask registers.
; Any OUT enables all 4 channels.
cmpsb
jnb short loc_C2A
loc_C91: ; CODE XREF: seg000:loc_C76
scasd
add dl,
enter 0FFFFFFFFFFFFC733h, 7Ch
insd
mov ecx, gs
in al, dx
out 2Dh, al
mov ds:6599E434E6D96814h, al
cmpsb
push 0FFFFFFFFFFFFFFD6h
popfq
xor ecx, ebp
db 48h
insb
test al, cl
xor , cl
and al, 9Bh
db9Ah
push rsp
xor al, 8Fh
cmp eax, 924E81B9h
clc
mov bh, 0DEh
jbe short near ptr loc_C72+1
db1Eh
retn 8FCAh
db 0C4h ; -
loc_CCD: ; CODE XREF: seg000:0000000000000D22
adc eax, 7CABFBF8h
db38h ; 8
mov ebp, 9C3E66FCh
push rbp
dec byte ptr
sahf
fidivrword ptr
db1Fh
db 3Eh
xchg eax, esi
loc_CE2: ; CODE XREF: seg000:0000000000000D5E
mov ebx, 0C7AFE30Bh
clc
in eax, dx
sbb bh, bl
xchg eax, ebp
db3Fh ; ?
cmp edx, 3EC3E4D7h
push 51h
db 3Eh
pushfq
jl short loc_D17
test , ebx
db2Fh ; /
rdtsc
jns short near ptr loc_D40+4
mov ebp, 0B2BB03D8h
in eax, dx
db1Eh
fsubr dword ptr
jns short loc_D70
scasd
mov ch, 0C1h ; '+'
add edi,
db 0E7h
loc_D17: ; CODE XREF: seg000:0000000000000CF7
jp short near ptr unk_D79
scasd
cmc
sbb ebx,
fsubr dword ptr
retn
db 3
jnp short near ptr loc_CCD+4
db 36h
adc r14b, r13b
db1Fh
retf
test , ebx
cdq
or ebx, edi
test eax, 310B94BCh
ffreepst(7)
cwde
sbb esi,
push 5372CBAAh
loc_D40: ; CODE XREF: seg000:0000000000000D02
push 53728BAAh
push 0FFFFFFFFF85CF2FCh
db0Eh
retn 9B9Bh
movzx r9, dword ptr
adc , ebp
in al, 31h
db37h ; 7
jl short loc_DC5
icebp
sub esi,
clc
pop rdi
jb short near ptr loc_CE2+1
or al, 8Fh
mov ecx, 770EFF81h
sub al, ch
sub al, 73h ; 's'
cmpsd
adc bl, al
out 87h, eax ; DMA page register 74LS612:
; Channel 0 (address bits 16-23)
loc_D70: ; CODE XREF: seg000:0000000000000D0E
adc edi, ebx
db 49h
outsb
enter 33E5h, 97h
xchg eax, ebx
unk_D79 db 0FEh ; CODE XREF: seg000:loc_D17
db 0BEh
db 0E1h
db82h
loc_D7D: ; CODE XREF: seg000:0000000000000DB3
cwde
db 7
db5Ch ; \
db10h
db73h ; s
db 0A9h
db2Bh ; +
db9Fh
loc_D85: ; CODE XREF: seg000:0000000000000DD1
dec dh
jnz short near ptr loc_DD3+3
mov ds:7C1758CB282EF9BFh, al
sal ch, 91h
rol dword ptr , cl
fbstp tbyte ptr
repne mov al, ds:4BFAB3C3ECF2BE13h
pushfq
imul edx, , 8EDC09C6h
cmp , al
jg short loc_D7D
xor , edx
test eax, 14E3AD7h
insd
db38h ; 8
db80h
db 0C3h
loc_DC5: ; CODE XREF: seg000:0000000000000D57
; seg000:0000000000000DD8
cmp ah,
sbb eax, 5FC631F0h
jnb short loc_D85
loc_DD3: ; CODE XREF: seg000:0000000000000D87
call near ptr 0FFFFFFFFC03919C7h
loope near ptr loc_DC5+3
sbb al, 0C8h
std
```
代码清单28.2:ARM架构(ARM 模式)不正确的反汇编代码示例
```
BLNE 0xFE16A9D8
BGE 0x1634D0C
SVCCS 0x450685
STRNVTR5, ,#-0x964
LDCGE p6, c14, ,#0x168
STCCSLp9, c9, ,#0x14C
CMNHIPPC, R10,LSL#22
FLDMIADNV LR!, {D4}
MCR p5, 2, R2,c15,c6, 4
BLGE 0x1139558
BLGT 0xFF9146E4
STRNEBR5, ,#0xCA2
STMNEIB R5, {R0,R4,R6,R7,R9-SP,PC}
STMIA R8, {R0,R2-R4,R7,R8,R10,SP,LR}^
STRB SP, ,PC,ROR#18
LDCCS p9, c13,
LDRGE R8,
STRNEBR5, ,#-0x8C3
STCCSLp15, c9,
RSBLS LR, R2, R11,ASR LR
SVCGT 0x9B0362
SVCGT 0xA73173
STMNEDB R11!, {R0,R1,R4-R6,R8,R10,R11,SP}
STR R0, ,#-0xCE4
LDCGT p15, c8,
LDRCCBR1, ,-R7,ROR#30
BLLT 0xFED9D58C
BL 0x13E60F4
LDMVSIB R3!, {R1,R4-R7}^
USATNER10, #7, SP,LSL#11
LDRGEBLR, ,#0xE56
STRPLTR9, ,#0x567
LDRLT R11, ,#-0x29B
SVCNV 0x12DB29
MVNNVSR5, SP,LSL#25
LDCL p8, c14,
STCNELp2, c6, !
SVCNV 0x2E5A2F
BLX 0x1A8C97E
TEQGE R3, #0x1100000
STMLSIA R6, {R3,R6,R10,R11,SP}
BICPLSR12, R2, #0x5800
BNE 0x7CC408
TEQGE R2, R4,LSL#20
SUBS R1, R11, #0x28C
BICVS R3, R12, R7,ASR R0
LDRMI R7, ,R3,LSL#21
BLMI 0x1A79234
STMVCDB R6, {R0-R3,R6,R7,R10,R11}
EORMI R12, R6, #0xC5
MCRRCSp1, 0xF, R1,R3,c2
```
代码清单28.2:ARM架构(Thumb 模式)不正确的反汇编代码示例
```
LSRS R3, R6, #0x12
LDRH R1,
SUBS R0, #0x55 ; 'U'
ADR R1, loc_3C
LDR R2,
CMP R4, #0x86
SXTB R7, R4
LDR R4,
STR R4,
STR R0,
BGT 0xFFFFFF72
LDRH R7,
LDRSH R0,
LDRB R2,
DCB 0x17
DCB 0xED
STRB R3,
STR R5,
LDMIA R3, {R0-R5,R7}
ASRS R3, R2, #3
LDR R4,
SVC 0xB5
LDR R6,
LDR R5, =0xB2C5CA32
STMIA R6, {R1-R4,R6}
LDR R1,
STR R1,
BCC 0xFFFFFF70
LDR R4,
STR R5,
ORRS R5, R7
loc_3C ; DATA XREF: ROM:00000006
B 0xFFFFFF98
ASRS R4, R1, #0x1E
ADDS R1, R3, R0
STRH R7,
LDR R3,
CBZ R6, loc_90
MOVS R4, R2
LSRS R3, R4, #0x17
STMIA R6!, {R2,R4,R5}
ADDS R6, #0x42 ; 'B'
ADD R2, SP, #0x180
SUBS R5, R0, R6
BCC loc_B0
ADD R2, SP, #0x160
LSLS R5, R0, #0x1A
CMP R7, #0x45
LDR R4,
DCB 0x2F ; /
DCB 0xF4
B 0xFFFFFD18
ADD R4, SP, #0x2C0
LDR R1,
CMP R4, #0xEE
DCB0xA
DCB 0xFB
STRH R7,
LDR R3, loc_78
DCB 0xBE ; -
DCB 0xFC
MOVS R5, #0x96
DCB 0x4F ; O
DCB 0xEE
B 0xFFFFFAE6
ADD R3, SP, #0x110
loc_78 ; DATA XREF: ROM:0000006C
STR R1,
LDMIA R3!, {R2,R5-R7}
LDRB R2,
ASRS R4, R0, #0x13
BKPT 0xD1
ADDS R5, R0, R6
STR R5,
```
代码清单28.2:MIPS架构(小端序)不正确的反汇编代码示例
```
lw $t9, 0xCB3($t5)
sb $t5, 0x3855($t0)
sltiu $a2, $a0, -0x657A
ldr $t4, -0x4D99($a2)
daddi $s0, $s1, 0x50A4
lw $s7, -0x2353($s4)
bgtzl $a1, 0x17C5C
.byte 0x17
.byte 0xED
.byte 0x4B# K
.byte 0x54# T
lwc2 $31, 0x66C5($sp)
lwu $s1, 0x10D3($a1)
ldr $t6, -0x204B($zero)
lwc1 $f30, 0x4DBE($s2)
daddiu$t1, $s1, 0x6BD9
lwu $s5, -0x2C64($v1)
cop0 0x13D642D
bne $gp, $t4, 0xFFFF9EF0
lh $ra, 0x1819($s1)
sdl $fp, -0x6474($t8)
jal 0x78C0050
ori $v0, $s2, 0xC634
blez $gp, 0xFFFEA9D4
swl $t8, -0x2CD4($s2)
sltiu $a1, $k0, 0x685
sdc1 $f15, 0x5964($at)
sw $s0, -0x19A6($a1)
sltiu $t6, $a3, -0x66AD
lb $t7, -0x4F6($t3)
sd $fp, 0x4B02($a1)
.byte 0x96
.byte 0x25# %
.byte 0x4F# O
.byte 0xEE
swl $a0, -0x1AC9($k0)
lwc2 $4, 0x5199($ra)
bne $a2, $a0, 0x17308
.byte 0xD1
.byte 0xBE
.byte 0x85
.byte 0x19
swc2 $8, 0x659D($a2)
swc1 $f8, -0x2691($s6)
sltiu $s6, $t4, -0x2691
sh $t9, -0x7992($t4)
bne $v0, $t0, 0x163A4
sltiu $a3, $t2, -0x60DF
lbu $v0, -0x11A5($v1)
pref 0x1B, 0x362($gp)
pref 7, 0x3173($sp)
blez $t1, 0xB678
swc1 $f3, flt_CE4($zero)
pref 0x11, -0x704D($t4)
ori $k1, $s2, 0x1F67
swr $s6, 0x7533($sp)
swc2 $15, -0x67F4($k0)
ldl $s3, 0xF2($t7)
bne $s7, $a3, 0xFFFE973C
sh $s1, -0x11AA($a2)
bnel $a1, $t6, 0xFFFE566C
sdr $s1, -0x4D65($zero)
sd $s2, -0x24D7($t8)
scd $s4, 0x5C8D($t7)
.byte 0xA2
.byte 0xE8
.byte 0x5C# \
.byte 0xED
bgtz $t3, 0x189A0
sd $t6, 0x5A2F($t9)
sdc2 $10, 0x3223($k1)
sb $s3, 0x5744($t9)
lwr $a2, 0x2C48($a0)
beql $fp, $s2, 0xFFFF3258
```
同样重要的是要记住，巧妙地运用解压缩和解密技术(包括自修改)，可能看起来像是一段不正确的反汇编代码，但是，它是能够正确运行的(注1)。
注1: 一段代码在经过压缩或者加密之后，他的机器码全都变乱了，因此，反汇编结果得到的是一段错误的反汇编代码。但是经过一段解压缩程序或者解密程序处理之后，它就能够还原出原来的机器码，因此反汇编出来的代码和运行结果都是正确的。
## 28.3 代码的熵值
(熵在理想的情况是，压缩(或加密)文件是每字节8位；如果每字节的熵为0，它可能是任意大小的空白文件) 在这里我们可以看到当CPU(ARM模式的ARM架构或者MIPS架构)采用4个字节的指令代码的时候，在这个意义上是最有效率的。
### 28.3.1 x86
Windows 2003系统下ntoskrnl.exe文件中的.text节表：`熵 = 每字节6.662739位。 最佳的压缩方法将这个593920个字节大小的文件的大小减少16%。 `Windows 7 x64系统下ntoskrnl.exe文件中的.text节表：`熵 = 每字节6.549586位。 最佳的压缩方法将这个1685504个字节大小的文件的大小减少18%。`
### 28.3.2 ARM(Thumb模式)
AngryBirds Classic `熵 = 每字节7.058766位。 最佳的压缩方法将这个3336888个字节大小的文件的大小减少11%。`
### 28.3.3 ARM(ARM模式)
Linux Kernel 3.8.8： `熵 = 每字节6.036160位。 最佳的压缩方法将这个6946037个字节大小的文件的大小减少24%。`
### 28.3.4 MIPS(小端序)
Windows NT 4系统下user32.dll文件中的.text节表： 熵 = 每字节6.098227位。 最佳的压缩方法将这个433152个字节大小的文件的大小减少23%。
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