199 lines
4.3 KiB
Markdown
199 lines
4.3 KiB
Markdown
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# CPU架构
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## 总线接口单元
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实现指令的读取功能
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实现数据的读取写入功能
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### 数据总线
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字节编址:`1Byte = 8Bit`
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总线编码: 20Bit，支持1MB的存储大小
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寄存器：16Bit，仅能描述64KB大小
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基寄存器 * 16 + 偏移寄存器 = 总线地址
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### 段寄存器
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1MB的空间分段，每段大小不超过64KB，段地址即16位寄存器地址 * 16
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程序多次运行，变化的是段寄存器，逻辑地址保持不变
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段之间可以分开也可以重合，取决于数据如何存储
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- CS
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- 存放指令的代码段地址
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- DS
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- 存放数据的数据段地址
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- SS
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- 程序堆栈段地址
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- ES
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- 附加段寄存器
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- IP
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- 专用寄存器，指令偏移地址
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- 仅由跳转类指令间接控制
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- 内部寄存器
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### 指令队列
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六字节，先进先出，跳转时刷新整个队列
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## 执行单元
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对指令进行译码，并执行
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### 通用寄存器
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寄存器描述的地址都是偏移地址，每次运行的偏移地址保持不变
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- AH + AL = AX
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- 累加器
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- BH + BL = BX
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- 基址寄存器
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- CH + CL = CX
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- 计数器
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- DH + DL = DX
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- 数据寄存器
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- SP
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- 堆栈指针寄存器
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- 会受到指令控制，不应用于其他目的
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- BP
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- 基址指针寄存器
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- SI
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- 源变址寄存器
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- 如字符串首地址
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- DI
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- 目的变址寄存器
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- 如字符串第n个元素地址
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# 程序数据
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```assembly
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assume cs:code, ds:data, ss:stack ;定义了三个段 code,data,stack 只是为了阅读的方便，用其他的名称是一样的。
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data segment
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dw 0123h, 0456h, 0789h, 0abch, 0defh, 0fedh, 0cbah, 0987h
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data ends
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stack segment
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dw 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
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stack ends
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code segment
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start: mov ax,stack # stack 段的首地址
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mov ss,ax
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mov sp, 20h;
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mov ax, data ;
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mov ds, ax; ds指向data 段的首地址
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mov bx,0
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mov cx, 8
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s: push [bx]
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add bx, 2
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loop s ;以上将data段中的0~15单元中的8个字型 数据一次入栈
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mov bx,0
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mov cx,8
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s0: pop [bx]
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add bx,2
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loop s0; 出栈，把数据放回到data段。 如此就把数据逆序了。
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mov ax, 4c00h
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int 21h ;中断调用操作系统子程序
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code ends
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end start
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```
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## 代码段
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代码数据
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## 数据段
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程序数据
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## 堆栈段
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### 标志寄存器
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ALU计算标志，中断、出错等
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状态标志
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- 进位标志CF
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- 奇偶标志PF
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- 调整标志AF
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- 零标志ZF
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- 符号标志SF
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- 溢出标志OF
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控制标志
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- 方向标志DF
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- 中断标志IF
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- 单步标志TF
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### ALU
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算术逻辑单元，核心计算单元，电路实现了基础运算的程序功能
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# 指令实例
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## 接口
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```assembly
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mov dest,src ;dest ← src
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mov al,[bx+si+6] ;指令功能：AL←[BX+SI+6]
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;[取地址存储的数据]
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```
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## 函数调用
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```assembly
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;lea 取函数地址到rax寄存器
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lea rax,[TPoint::`vcall'{0}' (07FF6C97EC00Eh)]
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TPoint::TestStaticFunction();
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00007FF61BAC9A32 call TPoint::TestStaticFunction (07FF61B95BEF1h)
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00007FF61B95BEF1 jmp TPoint::TestStaticFunction (07FF61B9A2900h)
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00007FF61B9A2900 mov eax,dword ptr [TPoint::static_int_a (07FF61BB21BA0h)]
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00007FF765B1E5AF call TPoint::Testvirtual (07FF765B068CFh)
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00007FF765B068CF jmp TPoint::Testvirtual (07FF765B529E0h)
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FuncPointer fp1 = &TPoint::Testvirtual;
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00007FF765B1E5B4 lea rax,[TPoint::`vcall'{0}' (07FF765B06663h)]
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FuncPointer fp2 = &TPoint::Testvirtua2;
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00007FF765B1E5C3 lea rax,[TPoint::`vcall'{8}' (07FF765B0600Fh)]
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0x00007ff765c8fa88 {zplus.exe!void(* TPoint::`vftable'[3])()} {
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0x00007ff765b068cf {zplus.exe!TPoint::Testvirtual(void)},
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0x00007ff765b07581}
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```
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# 编译
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```
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cl.exe -c -nologo /EHsc -Fobuild\.objs\zasm\windows\x64\release\src\main.cpp.obj src\main.cpp
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link.exe -nologo -dynamicbase -nxcompat -machine:x64 -out:build\zasm.exe
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[ 25%]: compiling.release src\main.cpp
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"C:\\Program Files\\Microsoft Visual Studio\\2022\\Community\\VC\\Tools\\MSVC\\14.36.32532\\bin\\HostX64\\x64\\cl.exe" -c -nologo /EHsc -Fobuild\.objs\zasm\windows\x64\release\src\main.cpp.obj src\main.cpp
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[ 50%]: linking.release zasm.exe
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"C:\\Program Files\\Microsoft Visual Studio\\2022\\Community\\VC\\Tools\\MSVC\\14.36.32532\\bin\\HostX64\\x64\\link.exe" -nologo -dynamicbase -nxcompat -machine:x64 -out:build\windows\x64\release\zasm.exe build\.objs\zasm\windows\x64\release\src\main.cpp.obj
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```
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