x86-64

I am trying to compile my own glibc. I have a directory glibc , which contain the glibc source code I downloaded from the internet. From that directory I typed mkdir ../build-glibc . Now from the build-glibc directory I typed ../glibc/configure , which performed the configuration. Now I'm not sure how to call make . I can't call it from glibc directory since it doesn't have the configuration set, neither I can call it from build-glibc , since makefile is not in that directory. How do I solve this problem? The Makefile is going to exist in your build-glibc directory if the configure script

I have a struct of 8-bit pixel data: struct __attribute__((aligned(4))) pixels { char r; char g; char b; char a; } I want to use SSE instructions to calculate certain things on these pixels (namely, a Paeth transformation). How can I load these pixels into an SSE register as 32-bits unsigned integers? Unpacking unsigned pixels with SSE2 Ok, using SSE2 integer intrinsics from <emmintrin.h> first load the thing into the lower 32 bits of the register: __m128i xmm0 = _mm_cvtsi32_si128(*(const int*)&pixel); Then first unpack those 8-bit values into 16-bit values in the lower 64 bits of the register

Why does this print garbage instead of exiting my program gracefully? I use system calls this way on BSD, and I wonder what would I need to make it work in Linux. int main(int argc, char **argv) { __asm ("movq $1,%rax; movq $0,%rdi; syscall"); /* exit(0) ? */ return 0; } Thanks. Why does this print garbage instead of exiting my program gracefully? Per CESA-2009-001 , "Syscall 1 is exit on i386 but write on x86_64". what would I need to make it work in Linux Use the syscall ordinals from the current unistd_64.h Hope this helps! Syscall 1 is exit on i386 but write on x86-64 I believe. EDIT: this

In my application, at one point I need to perform calculations on a large contiguous block of memory data (100s of MBs). What I was thinking was to keep prefetching the part of the block my program will touch in future, so that when I perform calculations on that portion, the data is already in the cache. Can someone give me a simple example of how to achieve this with gcc? I read _mm_prefetch somewhere, but don't know how to properly use it. Also note that I have a multicore system, but each core will be working on a different region of memory in parallel. gcc uses builtin functions as an

I am using CMake on Windows with Ninja generator cmake -G Ninja .. This uses the default Windows x86 toolchain. How to specify x64 using the Ninja generator? PS: I know how to generate x64 with Visual Studio cmake -G "Visual Studio 12 2013 Win64 .. You have to set the compiler environment accordingly before calling Ninja generation. If you have Visual Studio 2013 installed at the standard installation path you call: "C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\vcvarsall.bat" x64 cmake.exe -G "Ninja" .. Edit : Thanks for the hint from @Antwane: "Or simply run CMake command from a

This question already has an answer here: Can num++ be atomic for 'int num'? 13 answers On a multicore x86 machine, Say a thread executing on core1 increments an integer variable a at the same time thread on core 2 also increments it. Given that the initial value of a was 0, would it always be 2 in the end? Or it could have some other value? Assume that a is declared as volatile and we are not using atomic variables (such as atomic<> of C++ and built in atomic operations in gcc). If the value of a would indeed be always 2 in such event, does that mean that a long int in x86-64 would also have

I'm working on application (written in C++), which generate some machine code at runtime (Linux, x86-64 now, but I plan to migrate on ARM). Next it store generated code in memory and execute it by jumping to memory location. For a long time I had a problem with allocating executable memory, but I finally solved it using: uint8_t *memory = mmap (NULL, length, PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); So far it works, but I'm not sure if it's elegant way to do such things. I wonder how executable loader do this? This is essentially how executable loaders do things;