Intel汇编语言程序设计(第7版)第七章编程练习题答案
1. 显示ASCII十进制数
include irvine32.inc
includelib irvine32.lib
.data
strNum BYTE "100123456789765"
.code
; EDX 偏移量
; ECX 数的长度
; EBX 小数点的偏移量
WriteScaled PROC USES edx ebx ecx
L0:
cmp ecx, ebx
jnz @F
mov al, '.'
call WriteChar
@@:
mov al, BYTE PTR [edx]
call WriteChar
inc edx
loop L0
ret
WriteScaled ENDP
start:
mov edx, OFFSET strNum
mov ecx, LENGTHOF strNum
mov ebx, 3
call WriteScaled
call WaitMsg
invoke ExitProcess, 0
end start
2. 扩展减法过程
include irvine32.inc
includelib irvine32.lib
.data
Num0 BYTE 5, 4, 7, 5, 3, 7, 8, 9, 0, 5, 8, 3, 2, 5, 7, 9
Num1 BYTE 2, 2, 5, 8, 6, 8, 7, 3, 8, 9, 0, 5, 4, 2, 8, 2
Result BYTE 64 DUP(0)
.code
Extended_Sub PROC pNum0:PTR BYTE, pNum1:PTR BYTE, dwLen:DWORD
mov esi, pNum0
mov edi, pNum1
mov ecx, dwLen
mov ebx, OFFSET Result
add esi, ecx
add edi, ecx
dec esi
dec edi
pushad
; 清除CF标志位
clc
L0:
; 进行了减法, 可能产生了借位
mov al, BYTE PTR [esi]
sbb al, BYTE PTR [edi]
; 保存标志寄存器, 主要是CF
pushfd
; 如果存在借位则加1
jnc @F
add al, 10
@@:
mov BYTE PTR [ebx + ecx - 1], al
dec esi
dec edi
popfd
loop L0
popad
ret
Extended_Sub ENDP
start:
push LENGTHOF Num0
push OFFSET Num1
push OFFSET Num0
call Extended_Sub
call WaitMsg
invoke ExitProcess, 0
end start
3. 压缩十进制转换
include irvine32.inc
includelib irvine32.lib
.data
ddata BYTE 5, 7, 2, 3
ascidata BYTE 4 DUP(0)
.code
PackedToAsc PROC CompressedDec:PTR BYTE, AsciiDec:PTR BYTE
mov esi, CompressedDec
mov ecx, 4
mov edi, AsciiDec
L0:
mov al, BYTE PTR [esi]
xor BYTE PTR [edi], al
xor BYTE PTR [edi], 30h
inc esi
inc edi
loop L0
ret
PackedToAsc ENDP
start:
push OFFSET ascidata
push OFFSET ddata
call PackedToAsc
mov ecx, 4
mov edi, OFFSET ascidata
@@:
mov al, BYTE PTR [edi]
call WriteChar
dec ecx
inc edi
test ecx, ecx
jnz @B
call WaitMsg
invoke ExitProcess, 0
end start
4. 用循环位移操作进行加密
include irvine32.inc
includelib irvine32.lib
.data
key SBYTE -2, 4, 1, 0, -3, 5, 2, -4, -4, 6
asci BYTE "Hello, world! What do you want? Do you wanna have lunch with me and your treat Ooops..", 0
.code
EncOneByte PROC USES ebx bCh:BYTE, bKey:SBYTE
mov al, bCh
movzx ebx, bKey
cmp bKey, 0
jz Ending
jl LeftShift
RightShift:
ror al, 1
dec bl
test bl, bl
jnz RightShift
jmp Ending
LeftShift:
rol al, 1
inc bl
test bl, bl
jnz LeftShift
KeyZero:
mov al, bCh
Ending:
ret
EncOneByte ENDP
DecOneByte PROC USES ebx bCh:BYTE, bKey:SBYTE
mov al, bCh
movzx ebx, bKey
cmp bKey, 0
jz Ending
jl LeftShift
RightShift:
rol al, 1
dec bl
test bl, bl
jnz RightShift
jmp Ending
LeftShift:
ror al, 1
inc bl
test bl, bl
jnz LeftShift
KeyZero:
mov al, bCh
Ending:
ret
DecOneByte ENDP
ShiftEncrypt PROC pOrigin:PTR BYTE, BufLen:DWORD
mov esi, pOrigin
mov edi, OFFSET key
mov ecx, BufLen
mov ebx, LENGTHOF key
xor edx, edx
L0:
movzx eax, BYTE PTR [edi]
push eax
movzx eax, BYTE PTR [esi]
push eax
call EncOneByte
mov BYTE PTR [esi], al
inc esi
inc edi
inc edx
cmp edx, LENGTHOF key
jnz @F
xor edx, edx
sub edi, 10
@@:
loop L0
ret
ShiftEncrypt ENDP
ShiftDecrypt PROC pOrigin:PTR BYTE, BufLen:DWORD
mov esi, pOrigin
mov edi, OFFSET key
mov ecx, BufLen
mov ebx, LENGTHOF key
xor edx, edx
L0:
movzx eax, BYTE PTR [edi]
push eax
movzx eax, BYTE PTR [esi]
push eax
call DecOneByte
mov BYTE PTR [esi], al
inc esi
inc edi
inc edx
cmp edx, LENGTHOF key
jnz @F
xor edx, edx
sub edi, 10
@@:
loop L0
ret
ShiftDecrypt ENDP
start:
; 原文打印
mov edx, OFFSET asci
mov ecx, LENGTHOF asci
call WriteString
call Crlf
; 加密后打印
push LENGTHOF asci - 1
push OFFSET asci
call ShiftEncrypt
mov edx, OFFSET asci
mov ecx, LENGTHOF asci
call WriteString
call Crlf
; 解密后打印
push LENGTHOF asci - 1
push OFFSET asci
call ShiftDecrypt
mov edx, OFFSET asci
mov ecx, LENGTHOF asci
call WriteString
call Crlf
call WaitMsg
invoke ExitProcess, 0
end start
5. 素数
include windows.inc
include kernel32.inc
includelib kernel32.lib
include msvcrt.inc
includelib msvcrt.lib
.data
ARYNUM = 1000
strPause BYTE "pause", 0
dwNumAry BYTE ARYNUM DUP(FALSE)
dwResAry DWORD ARYNUM DUP(0)
strHasFalse BYTE "有false", 0
strNoFalse BYTE "没false", 0
.code
InitAry PROC USES edi eax ecx pbAry:PTR BYTE, dwAryNum:DWORD
mov ecx, dwAryNum
mov edi, pbAry
mov al, TRUE
rep stosb
ret
InitAry ENDP
SievePrime PROC dwNum:DWORD, pAry:PTR DWORD
LOCAL @Index:DWORD, @Inner:DWORD, @MaxNum:DWORD, @bPrimeAry[ARYNUM]:BYTE
; 初始化prime数组
push ARYNUM
lea eax, @bPrimeAry
push eax
call InitAry
; 判定是否小于2, 小于2代表没有数组
mov @Index, 2
mov eax, dwNum
cmp eax, @Index
jb NoPrime
; 获取需要检测的最大值
mov @MaxNum, 31
L0:
mov ecx, @Index
push ecx
; 求Index * Index, 保存到@Inner中
mov ebx, @Index
xor edx, edx
mov eax, @Index
mul ebx
; 进行素数筛选
mov @Inner, eax
L1:
mov bl, TRUE
cmp bl, [@bPrimeAry + eax]
jne @F
mov BYTE PTR [@bPrimeAry + eax], FALSE
@@:
mov eax, @Inner
add eax, eax
mov @Inner, eax
cmp eax, ARYNUM
jbe L1
pop ecx
mov ecx, @Index
inc ecx
mov @Index, ecx
cmp ecx, @MaxNum
jbe L0
NoPrime:
xor eax, eax
Ending:
ret
SievePrime ENDP
end
6. 最大公约数(GCD)
GCD PROC x:SDWORD, y:SDWORD
cmp x, 0
jnl @F
mov ebx, -1
xor edx, edx
mov eax, x
mul ebx
mov x, eax
@@:
cmp y, 0
jnl @F
mov ebx, -1
xor edx, edx
mov eax, y
mul ebx
mov y, eax
@@:
mov eax, x
xor edx, edx
mov ebx, y
div ebx
mov x, ebx
mov y, edx
cmp edx, 0
ja @B
mov eax, x
ret
GCD ENDP
7. 位元乘法
includelib kernel32.lib
includelib user32.lib
include irvine32.inc
includelib irvine32.lib
ExitProcess PROTO STDCALL, uExitCode:DWORD
.data
strPause BYTE "pause", 0
.code
BitwiseMultiply PROC
LOCAL @dwMultiplier:DWORD
mov ecx, 20h
mov @dwMultiplier, eax
xor eax, eax
mov edx, -1
L1:
ror ebx, 1
inc edx
dec ecx
jc @F
test ecx, ecx
jnz L1
jmp Ending
@@:
mov esi, @dwMultiplier
push ecx
mov ecx, edx
shl esi, cl
pop ecx
add eax, esi
jmp L1
Ending:
ret
BitwiseMultiply ENDP
main PROC
mov eax, 21
mov ebx, 43
call BitwiseMultiply
call WriteDec
Ending:
call WaitMsg
invoke ExitProcess, 0
main ENDP
end main
8. 压缩整数乘法
includelib kernel32.lib
includelib user32.lib
include irvine32.inc
includelib irvine32.lib
ExitProcess PROTO STDCALL, uExitCode:DWORD
.data
strPause BYTE "pause", 0
NUMBITS = 4
RESULTBITS = (NUMBITS + 1)
bNum1Ary BYTE 5, 3, 2, 9
bNum2Ary BYTE 7, 4, 1, 3
bResultAry BYTE RESULTBITS DUP(0)
.code
AddPacked PROC
add esi, ecx
dec esi
add edi, ecx
dec edi
add edx, ecx
; 设置DF反向
std
L0:
lodsb
add al, BYTE PTR [edi]
cmp al, 0Ah
jb @F
sub al, 0Ah
; 进位
add BYTE PTR [edx - 1], 1
@@:
add BYTE PTR [edx], al
dec edx
dec edi
loop L0
ret
AddPacked ENDP
main PROC
mov esi, OFFSET bNum1Ary
mov edi, OFFSET bNum2Ary
mov ecx, NUMBITS
mov edx, OFFSET bResultAry
call AddPacked
mov ecx, RESULTBITS
mov edx, OFFSET bResultAry
xor eax, eax
xor esi, esi
L0:
mov al, BYTE PTR [bResultAry + esi]
call WriteDec
inc esi
loop L0
Ending:
call WaitMsg
invoke ExitProcess, 0
main ENDP
end main
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