8位有些浪费,出现了打包的BCD,使用4位表示一个值。 二进制编码的十进制(BCD,Binary Coded Decimal)格式是用于处理人可读的数字常见方法,处理器中可以快速处理这种格式。 很多高级的BCD处理操作位于FPU中,但是处理器会包含一些简化的指令。我们来看下基本的BCD运算指令。 不打包BCD运算 不打包的BCD值:是一个字节中...
3.3. do_syscall_64 3.4. 系统调用表 3.5. 系统跳转表(sys_call_table) 4. 后记 5. 参考 前言 Linux 操作系统,为了避免用户程序非法操作设备资源,需要限制进程的操作权限,这样内核为用户程序提供了一组交互的接口,用户程序通过这组接口进行 系统调用。 本文将会通过调试方式,从用户程序到内核,理解一下系统调用...
实模式下只有shift-and-add方式的segmentation,没有paging,80286保护模式下只有table-based方式的segmentation,也没有paging。80386及其之后的处理器同时有table-based方式的segmentation和paging,其中paging是可选的。 在64-Bit Mode下,segmentation机制虽然还存在,但已经被极度弱化,可以被忽略。Compatibility Mode对segmentation...
This course teaches the x86 architecture (both 32-bit and 64-bit) through a mix of lectures and hands-on programming labs. All topics are explained in lecture format first and then the students are given programming labs in Assembly Language to reinforce the concepts and to get hands-on expe...
INT x is analogous to PUSHF; CALL dword ptr [x*4]in 16-bit environment. It was widely used in MS-DOS, functioning as a syscall vector. The registers AX/BX/CX/DX/SI/DI were filled with the arguments and then the flow jumped to the address in the Interrupt Vector Table (located at...
Hands-On x86 Assembly Language Basics 4 days All of MindShare's classroom and virtual classroom courses can be customized to fit the needs of your group. Hands-On Intel 32/64-bit x86 Architecture Course Info You Will Learn: x86 architecture basics like an overview of the instruction set, ...
KBUILD_AFLAGS += -nostdinc -D__ASSEMBLY__ -fno-PIE -m32 -pipe -msoft-float -ffreestanding -Wno-unused-function KBUILD_DEFCONFIG := i386_defconfig KBUILD_CFLAGS += -fno-pic KBUILD_CFLAGS += -nostdinc -I./arch/i386/include -I./include -I./arch/i386/include/uapi -I./include/uapi\...
https://stackoverflow.com/questions/27594297/how-to-print-a-string-to-the-terminal-in-x86-64-assembly-nasm-without-syscall This would open up: gem5 benchmarking and exploration, currently blocked on https://stackoverflow.com/questions/50364863/how-to-get-graphical-gui-output-and-user-touch-key...
调用者清理cdeclsyscalloptlink 在这些约定中,调用者自己清理栈上的变元(arguments),这样就运行了可变参数列表的实现,如printf()。 cdecl cdecl(C declaration,即C声明)是源起C语言的一种调用约定,x86架构上的许多C编译器都使用这个约定。 在cdecl中,子例程变元是在栈上传递的。EAX寄存器返回整型值和内存地址,浮点...
syscall ; sys_exit_group(0) Run Code Online (Sandbox Code Playgroud) 在Intel SnB系列中,在寻址模式下具有一个或两个组件的LEA以1c延迟运行(请参阅http://agner.org/optimize/和x86标签wiki 中的其他链接). 我在Linux上构建并运行它作为静态二进制文件,因此整个过程的用户空间perf计数器仅测量循环,启动/...