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equals 0 o'clock, running this code should return 0.0. In practice, however, the runtime encounters a memory error. Please explain why this happens and how to modify the code.Answer:length-1 will have overflow, so instead of There are also problems with the number of signed and unsigned numbers, and when the length is particularly large, the correct result is not obtained.So instead:unsigned Ifor (i = 0; i ****************************************************************Declaration: The followin

This article is divided into 3 modules. Example---example of this directive explain ---to the point where the instructions are difficult to understand Practice ---in order to become more familiar with the directive 1.1 Signed Division instruction and take-over example:In the C language to complete the 8/2 assembly instructions are as follows:in C language to complete 8 2 of the assembly instructions are as follows:An example of a 4-byte division and take-rest operation is

Previously asked on edx code (edx Google Group) How to expand a field for course, such as adding a category field to a course.The reply says to add the field you want directly to the couesefields. Position common/lib/xmodule/course_module.py after. The field is automatically displayed in the Advanced settings. In this way I find that the field is indeed a property of course (experiment in the shell). Howeve

= dword ptr 10 h. Text: 0045ccb0. Text: 0045ccb0 push EBP. Text: 0045ccb1 mov EBP, ESP. Text: 0045ccb3 sub ESP, 414 h; Allocation variable, size 0x414. Text: 0045ccb9 mov eax, dword_5fbf64. Text: 0045 CCBE push EBX. Text: 0045 CCBF push ESI. Text: 0045ccc0 mov [EBP + var_4], eax; set the last 4 bytes of the variable to [005fbf64] And a random value.. Text: 0045ccc3 push EDI. Text: 0045ccc4 Lea eax, [EBP + widecharstr]. Text: 0045 ccca push eax. Text: 0045 cccb mov ECx, offset a_htm; ". htm". Te

push 0006af1b0 ffb5 56010000 push dword ptr ss: [EBP + 156]006af1b6 ff95 51050000 call dword ptr ss: [EBP + 551]; virtualfreeMemory released 006af1bc 8b9d 31050000 mov EBX, dword ptr ss: [EBP + 531]; EBX = 0006af1c2 0bdb or EBX, EBX006af1c4 74 08 je short drvstudy.006af1ce; EBX = 0, skip006af1c6 8b03 mov eax, dword ptr ds: [EBX]006af1c8 8785 35050000 xchg dword ptr ss: [EBP + 535], eax006af1ce 8b95 22040000 mov edX, dword ptr ss: [EBP + 422]; jump he

has played a huge role. It is no exaggeration to say that, without virtual functions, there is basically no design pattern, which cannot reflect the great superiority of the C ++ language in object-oriented design. Let's take a look at how this virtual works? [CPP] View plaincopy 76: employee P; 0040128d Lea ECx, [ebp-10h] 00401290 call @ ILT + 45 (employee: Employee) (00401032) 00401295 mov dword ptr [ebp-4], 0 77: manager m; 0040129c Lea ECx, [ebp-14h] 0040129f call @ IL

gate. Set_system_gate (0x80, system_call ); Here, we use the macro set_system_gate to associate the 0x80 interrupt with the system_call function. Here we will first look at set_system_gate regardless of system_call. In system. h: //// Set the system call function. // Parameter: n-interrupt number; addr-interrupt program offset address. // Idt [n] corresponds to the offset value of the interrupt number in the Interrupt Descriptor Table. The Interrupt Descriptor type is 15 and the privileged le

the type ). 2. General information about parameter passing when a function is called (if stdcall is not used ). For general functionsOr process. The first three parameters are placed in eax, EDX, and ECx respectively. If there are more parametersFor the class method, eax is used to store the class instance address, and EDX and ECx respectively store the first two parameters.Other parameters are added to t

process from user state to a core state, which is called the Operating system trap (operating system traps). After the process has been executed into the command, it can run the system call code in the kernel mentality. In Linux it is through soft interrupts to achieve this, on the x86 platform, this instruction is int 0x80. That is, in Linux, the interface of the system call is a special case of an interrupt handler function. The details of how to implement the system call through the interru

, which can then be used for system call pass-through Linux System calling conventionThe Linux system calls are in the kernel state with the int 0x80 instruction, the system call number passes through the EAX, the parameter is EBX, ECX, edx, EDI, ESI to pass. Writing Shellcode To write Shellcode under Linux, you can use GCC to assemble directly. s file to compile the link, generate the standard executable Elf file, but also can be directly tested, but

Author: uuk[Software name]: Total Commander[Software Version]: 7.56a[Shelling method]: new version without shelling[Programming language]: Borland Delphi 2.0 [Overlay][Tools]: OD PEID IDA[Operating platform]: Windows XP[Software introduction]: A pretty good dual-column File Management Software[Author's statement]: it is only for research purposes. Please purchase a genuine version for use.We know that Total Commander has self-verification. by tracking the CreateFile and ReadFile functions, it is

: 100000 + 400*4 + 20000 = 100000 + 1000 + 20000 = 121000. The linear address is 400000 + 121000 = 521000. (Note: all are hexadecimal numbers ). The base address can be placed in any 32-bit general-purpose register, or in any general-purpose register except ESP. The proportional factor can be 1, 2, 4, or 8. Offset is the number of immediately. For example, [EBP + EDX * 8 + 200] is a valid address expression. Of course, in most cases, it is not necessa

EBX, dword ptr [esp + 0x14] // EBX = BPush ESIMoV ESI, dword ptr [esp + 0x14] // ESI =Push EDIMoV EDI, dword ptr [esp + 0x14] // EDI = destSub ESI, EBX // ESI = A-BLea edX, dword ptr [EBX + 4 * ecx-8] // B [I]Sub EDI, EBX // EDI = DEST-BSHR ECx, 1 // Len = Len/2Movq mm7, base64 // 0x3b9aca003b9aca00Movq MM5, borrowfirst // 0x0000000100000000Movq mm6, borrownext // 0x0000000000000001Pxor mm2, mm2 // clear borrowSub_loop:Movq mm0, dword ptr [ESI +

EBX, dword ptr [esp + 0x14] // EBX = BPush ESIMoV ESI, dword ptr [esp + 0x14] // ESI =Push EDIMoV EDI, dword ptr [esp + 0x14] // EDI = destSub ESI, EBX // ESI = A-BLea edX, dword ptr [EBX + 4 * ecx-8] // B [I]Sub EDI, EBX // EDI = DEST-BSHR ECx, 1 // Len = Len/2Movq mm7, base64 // 0x3b9aca003b9aca00Movq MM5, carryfirst // 0x0000000100000000Movq mm6, carrynext // 0x0000000000000001Pxor mm2, mm2 // carry clearedAdd_loop:Movq mm0, dword ptr [ESI +

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