When I continuously do "step into",it switches between different threads. But how's that scheduled in visual studio,how does it know which thread to activate for next instruction? ...
I have problems accessing the process command line from Linux 64 bit Assembly program. To reproduce this with minimal code, I made this 32-bit program which prints first 5 characters of the program name: .section .text .globl _start _start: movl %esp, %ebp movl $4, %eax # write movl $1, %ebx # stdout movl 4(%ebp), ...
I have multiple threads accessing variables. I know how to write spinlocks and use the Threading.Interlocked methods to increment etc. variables. However, I want to perform the equivalent of: a = Math.Min(a, b) or a = a | 10 ... but without using a critical section. Is this possible? I know the 2nd line is possible in assembler, but ...
Hi, in reflection, the private field can be access via getDeclaredField() and setAccessible(true). How to access the private field of a outside class via Objectweb ASM bytecode API? I set to get the private field from something like, via Field current = sourceObject.getDeclaredField(privateFieldName); Field.setAccessible(true); Type so...
Hello! So I'm learning to program in an assembly language for an abstract machine wich is very similar to an URM Machine. An URM machine has 3 basic instructions (or 4 in some literature): To zero a register: Z(r) To increment a register: S(r) To Jump to a line or label if registers r1 and r2 contain the same val...
I'm writing a small bootloader for an x86 based PC. The problem is that the CPU is somehow still active after executing these instructions: sti hlt sti is supposed to disable interrupts for the next instruction hlt is supposed to completely halt the processor Since they're used together, I assumed they would just 'freeze' the compute...
I've read that the INT 3 (0xCC) is used for software breakpoints. It is set by (for instance) a debugger by overwriting the actual program code in memory. I've also read that INT 3 is a "trap" not "fault" exception meaning the address pushed on the stack is the address of the instruction following the INT3 instruction. How does the debug...
Hi, I have a problem with the MASM32 assembler The following code is a Hello World example that I copied from the MASM32 tutorial: .model small .stack .data message db "Hello world!", "$" .code _main proc mov ax,seg message mov ds,ax mov ah,09 lea dx,message int 21h mov ax,4c00h int ...
Listing 7.1 The Decryptor of the Cascade Virus lea si, Start ; position to decrypt (dynamically set) mov sp, 0682 ; length of encrypted body (1666 bytes) Decrypt: xor [si],si ; decryption key/counter 1 xor [si],sp ; decryption key/counter 2 inc si ; increment one counter dec sp ; decrement the other jnz De...
Suppose, in a debugging session I have an address which unfortunately points to some rubbish. And I want to examine memory around it to see what's located near. As expected, the following error occurs: (gdb) x/64 $t5 0x842da7ac: Cannot access memory at address 0x842da7ac So, the question is: is there any way to read a range of add...
I wonder if there is a way to restrict invoke call to a function? Let me make it clear. [Assembly:a1] Class A { function Af(); } [Assembly:a2] Class B { function Bf(){ //load Assembly a1 //InvokeMember to Af } } After compilation I will have 2 assemblies. Now if I distribute to client, anyone can copy assembly...
I want to count the number of bits in a binary number that are set. For example, user enter the number 97 which is 01100001 in binary. The program should give me that 3 bits are set using MIPS ISA. I am able to achieve this in C, but I don't know how to achieve it using assembly code. Any ideas? Thanks in advance for all the help. ...
My goal is to have a rule that file.asm should be built exactly the same as file.ASM (or similar variations e.g. file.[aA][sS][mM]). I would like to avoid stepping on a convention that I'm unaware of. Case-sensitive File Extension Convention Examples: Assembly Files with .S and .s extensions are treated differently under GNU Assembler...
Computers recognize different file systems. My question is, where exactly does this information get stored in a memory device (the specific location if any). Or does it not get stored anywhere & rather an operating system tests the system (memory device) against a known set of file systems (like ext3, ntfs, etc) ? With reference to the ...
I am currently in the process of writing a compiler and I seem to have run into some problems getting it to output code that executes in a decent timeframe. A brief overview of the compiler: 7Basic is a compiler that aims to compile 7Basic code directly into machine code for the target architecture / platform. Currently 7Basic gener...
I have some code that basically needs to use a small expression in an assembly statement, where the expression is fairly trivial like i*4, but GCC doesn't seem to realize that at compile time (tried no -O flag, and -O3). Neither "i" nor "n" constraints work in the following snippet for the third usage. #include <stdint.h> #include <st...
Is it faster to access a global or object variable? In C++, I'm referring to the difference between ::foo and this->foo In x86 assembler, this basically translates to mov eax, offset foo vs mov eax, dword ptr[edx+foo] All data in both cases is expected to be in cache. (I know the difference if any will be tiny, and one shou...
I am experiencing a crash, and while investigating I found myself totally blocked by the following code: 0000000000000a00 <_IO_vfprintf>: a00: 55 push %rbp a01: 48 89 e5 mov %rsp,%rbp a04: 41 57 push %r15 a06: 41 56 push %r14 a08: ...
I'm working on some code which contains some (compiler generated) chunks of assembly code that we've identified are speed bottle necks. I know enough about assembly to muddle through and look for manual optimizations - I'm wondering, though, if there are any good, online guides that offer reusable techniques to be used in hand-optimizi...
Hi, I am trying to learn low-level development. By putting 0 in ebx and 1 in eax (for exit() syscall) and calling int 0x80, it should exit the program. I have a simple c program that runs fine, but when I paste this in, instead of exiting as expected, I get a segmantation fault. Why does this happen? THANK YOU! __asm__ ("xor %ebx, ...