movw

16-bit registers, the head address register is also set to 16 bits, the cylinder address register unchanged. This allows the register space available in the LBA address to be raised from 28 bits to 48 bits (16+16+16), the number of sectors that can be addressed is 281,474,976,710,655 (65,536x65,535x65,536), and the capacity of the entire hard drive is 281. 474,976,710,655x512=144,115,188,075,855,872 byte, approximately equal to 144PB (1pb=1000,000,000,000,000 bytes). The 48-bit LBA addressing c

a 7-bit value, the new Pixel will perform an exclusive or operation with the content of the current pixel. --------------------------------------------------------------------------- Example: [cpp] # This program draws a straight line in graphics mode. #2012-12-24 # guzhoudiaoke@126.com. section. text. global _ start. code16 _ start: jmp main clear_screen: # clear screen function movb $0x06, % ah # function no. 0x06 movb $0, % al # Roll up all rows, movb $0, % ch # movb $0 in the upper left cor

Grub Source Analysis-1 This chapter begins the analysis of Grub's source code, version 2.02. When the system starts, the BIOS loads the first sector of the hard drive (assuming boot from the hard disk) into the memory 0x7c00 location, which corresponds to the start function in grub (assuming grub boot), as shown below. first part of boot startGrub-core/boot/i386/pc/boot. S start:jmp local (AFTER_BPB) ... Local (AFTER_BPB): CLI. org grub_boot_machine_drive_check boot_drive_check:jmp 3f testb $0x

. NOP). */ . Byte 0x80, 0xca The first is the CLI directive, disabling interrupts and then displaying the 80CA binary code. Look at the annotation, the meaning of this 80ca is Orb $0x80,%dl. The value of the DL register is 80. DL = 00h 1st floppy disk ("Drive A:") DL = 01h 2nd floppy disk ("Drive B:") dl = 80h 1st hard disk DL = 81H 2nd hard Disk Because we are a disk-loaded MBR, we have 0x80 in our DL. Next Analysis: LJMP $, $ABS (Real_start) Real_start:/

the CPU is working in real mode. CLD # String Operations increment This instruction is used to specify the direction in which the pointer moves after a string processing operation that occurs. # Set up the important data segment registers (DS, ES, SS). Xorw %ax,%ax # Segment number zero movw %ax,%ds #-Data Segment movw %ax,%es #- > Extra

The OS development environment has been set up in the previous section. Now let's write a simple guide Code Right First, let's talk about the operating system boot process:After the PC power-on self-check, the content of 0 head, 0 track, and 1 Sector of the boot device will be loaded to the memory 0x7c00, and then the Boot Code will be directed to it. I just briefly said, please google for details. Boot. s Code highlighting produced by Actipro CodeHighlighter (freeware)http://www.CodeHigh

the grammar of at-the-T, for two reasons, the first is that at/T grammar is a common standard in the Linux world, and the other is that the AT/t syntax is actually easier to understand in some concepts (such as memory addressing mode). There are assembly language basis of the people, at and T Grammar quickly, mainly have the following: ① assembly instructions followed by the length of the operation of the suffix, such as MOV instructions, if the operand is 8 bits, then with MOVB, if the operand

counter channel 0 to send an interrupt request signal to the interrupt controller every 10 ms.25 movb $0x36, % Al # control word: Set channel 0 to work in Mode 3. The initial count value is binary.26 movl $0x43, % edX #8253 Chip Control Word register write port.27 outb % Al, % DX28 movl $ latch, % eax # The initial count value is set to latch (1193180/100), that is, the frequency is 100Hz.29 movl $0x40, % edX # port of channel 0.30 outb % Al, % DX # Write the initial count value to channel 0 tw

The bootstrap can be considered as the first code to run after the PC is powered on. It is a 16-bit code that runs in real mode with a length of 512 bytes. In fact, after the machine is started, it will first run 0xffff0 (or 0xfffffff0 in some documents, I am not familiar with BIOS:-() BIOS code in ROM, and then jump to 0x07c00 to execute the boot program. 1. First, a complete sample code is provided. This Code only describes the execution process of the Bootstrap program. It does not have the f

This piece of updated code is more, so it is not convenient to all posted out ... Specific code everyone directly into the group to find it (OS0.3) In addition, I configured the Bochs virtual machine, so that everyone can be downloaded to use the Bochs virtual machine directly debugging. Now I'll just post the main code,,,,,, Setupasm. S (here, jump to C function direct call on it) Start32: # Segment Register for each segment in initialize protected mode

The types and functions of left-shift and right-hand commands:left shift instruction: the left shift command moves the bit bits of the operand to the left n bits, and the vacated bits are filled with 0.The left-shift directive contains SAL and SHL, and the two instructions are the same, and the vacated bits are filled with 0.where to move Sal's instruction usage:. section. Text.global _start_start:movb $0b11111111,%al #8字节 salb $,%al movw $0b11111111,

hard disk, and is also referred to as a boot record because it only takes up less (512 bytes) of storage space. In addition, the boot record includes a 64-byte partition table and a 2-byte label that identifies the end of a valid boot record (0x55 0xAA). However, this boot loader is no longer performed from Linux2.6, which can be learned from the Header.s file (the assembly syntax for the gas format under Linux can be referencedGas LearningSeries):[CPP] View Plain Copy bootseg=0x07c0 /*original

initialization, such as dividing the stack and heap space. Let's look at the lines of code at the end. 292 # Zero the BSS293 movw $ __bss_start, % di294 movw $ _ end + 3, % CX295 xorl % eax, % eax296 subw % Di, % CX297 shrw $2, % CX298 rep; stosl299300 # Jump to C code (shocould not return)301 calll main The 292-298 line of code is used to initialize the. BBS segment to 0. We know that in the concept of ge

field.(Using one kernel stack per CPU saves the patch and the reload, but makesThe kernel ring0 code uninterruptable. Actually... who wantsInterrupt the task Switcher in a critical section ?) PS2: the code in unoptimized inline GCC assembly: asm("_kernel_lbl_int_00:");asm(" pushl $0");asm(" jmp _kernel_lbl_to_kernel");[...]asm("_kernel_lbl_int_40:");asm(" pushl $0"); /* filler for the err code */asm(" pushl $64"); /* irq number */asm(" jmp _kernel_lbl_to_kernel");[.

User state__asm__ ("Movl%%esp,%%eax\n\t" \ "PUSHL $0x17\n\t" \ //press into the original SS (point to Idle code snippet, low two bits for cpl= 3, on behalf of user state) "PUSHL%%eax\n\t" \ //press into the original Esp pushfl\n\t "\ //press into the original flags " PUSHL $0x0f\n\t "\ // pressed into the original CS (point to Idle code snippet, low two-bit represents cpl= 3, on behalf of the user "PUSHL $1f\n\t" \ //press into the original EIP, point to the code fol

# DEFINE _ set_gate (gate_addr, type, DPL, ADDR, SEG )/Do {/Int _ D0, _ D1 ;/_ ASM _ volatile _ ("movw % dx, % ax/n/t "/"Movw % 4, % dx/n/t "/"Movl % eax, % 0/n/t "/"Movl % edX, % 1 "/: "= M" (* (long *) (gate_addr ))),/"= M" (* (1 + (long *) (gate_addr), "= A" (_ D0), "= D" (_ D1)/: "I" (short) (0x8000 + (DPL "3" (char *) (ADDR), "2" (SEG) } While (0) Analysis:Output:* (Gate_addr) 0%* (1 + gate_addr) 1%D

\n\t" \"Pushl $0x17\n\t" \//pressure into the original SS (point to Idle code segment, low two-bit representative cpl=3, representing user state)"PUSHL%%eax\n\t" \//pressed into the original ESP"pushfl\n\t" \//pressed into the original flags"PUSHL $0x0f\n\t"///press into the original CS (point to the Idle code segment, low two representative cpl=3, representative user state)"PUSHL $1f\n\t" \//pressed into the original EIP, pointing to the code behind the iret directive /* The above stack operati

DJGPP uses the assembly syntax of the ATT format. It's a little different from the usual Intel format syntax. The main differences are as follows: The att syntax reverses the position of the source and destination operands, and the purpose operand is after the source operand. The register operand must have a% prefix, and the immediate operand must have a prefix of $ sign. The size of the memory operand depends on the last character of the opcode. They are B (8-bit), W (16-bit), and L (32-bit).

directly ignore it.__attribute__ ((constructor))StaticvoidGjalertcontrollerpatchentry(void) {Staticdispatch_once_t Oncetoken; Dispatch_once (oncetoken, ^{@autoreleasepool {>= iOS8.if (Objc_getclass ("Uialertcontroller")) {Return } Class *alertcontroller =NULL;#If Target_cpu_arm __asm ("MOVW%0,: lower16: (_objc_class_uialertcontroller-(lpc0+4)) \ n""Movt%0,: upper16: (_objc_class_uialertcontroller-(lpc0+4)) \ n""Lpc0:add%0, PC":"=r" (Alertcontroller))

EAX, ECX,EDX,EBX can be 32bit,16bit,8bit accessed as follows:|||The test code is as follows:1 . Section. Data2 Output:3. Asciz"Value is:%x\n"4 Val:5.int 06 7 . Section. Text8 . Globl Main9 Main:Ten NOP One movl $0x12345678,%eax AMOVL $0,%ecx - MOVW%ax,%cx - PUSHW%cx the PUSHL $output - Pagerprintf -Addl $6,%esp - +MOVL $1,%eax -MOVL $0,%EBX + int$0x80My computer is a small-format (MSB in the high-level), so the expected output