x86-64

I'm a CS student writing in Intel x86-64 assembly, compiling with nasm , and running on an Core i7 processor with Ubuntu 12.04 as the guest OS. Does anyone have an example of how to use XSAVE and XRSTOR ? I've read the section on XSAVE in Intel Architectures Software Developers manual several times. I tried to implement xsave in C++ and then disassemble the binary to get an understanding of what it's doing. And of course I've scoured the Internet for examples. Any suggestions would be much obliged. Finally, an answer to this question. Thanks to user: harold who helped answer the question for

How to set to 1 efficiently with AVX2 first N bits last N bits of __m256i , setting the rest to 0 ? These are 2 separate operations for tail and head of a bit range, when the range may start and end in the middle of __m256i value. The part of the range occupying full __m256i values is processed with all- 0 or all- 1 masks. The AVX2 shift instructions vpsllvd and vpsrlvd have the nice property that shift counts greater than or equal to 32 lead to zero integers within the ymm register. In other words: the shift counts are not masked, in contrast to the shift counts for the x86 scalar shift

We are using precompiled headers with GCC for our project and build them like this: gcc $(CFLAGS) precompiledcommonlib.h Now I'm building the project on OSX 10.6 and trying to use the nifty feature of building for all architectures at the same time like this: gcc $(CFLAGS) -c -arch i386 -arch x86_64 commonlib.c However, it seems this does not work for the precompiled headers: gcc $(CFLAGS) -arch i386 -arch x86_64 precompiledcommonlib.h Undefined symbols for architecture i386: "_main", referenced from: start in crt1.10.6.o ld: symbol(s) not found for architecture i386 collect2: ld returned 1

I'm having a go at writing a very light weight libc replacement library so that I can better understand the kernel - application interface. The first task is clearly getting some system call wrappers in place. I've successfully got 1 to 3 argument wrappers working but I'm struggling with a 4 argument varient. Here's my starting point: long _syscall4(long type, long a1, long a2, long a3, long a4) { long ret; asm ( "syscall" : "=a"(ret) : "a"(type), "D"(a1), "S"(a2), "d"(a3), "r10"(a4) : "c", "r11" ); return ret; } The compiler gives me the following error: error: matching constraint references

I have some gnu assembler code for the x86_64 architecture generated by a tool and there are these instructions: movq %rsp, %rbp leaq str(%rip), %rdi callq puts movl $0, %eax I can not find actual documentation on the "callq" instruction. I have looked at http://support.amd.com/TechDocs/24594.pdf which is "AMD64 Architecture Programmer’s Manual Volume 3: General-Purpose and System Instructions" but they only describe CALL near and far instructions. I have looked at documentation for gnu assembler https://sourceware.org/binutils/docs/as/index.html but could not find the section detailing the

I'm trying to understand the comment made by "Iwillnotexist Idonotexist" at SIMD optimization of cvtColor using ARM NEON intrinsics : ... why you don't use the ARM NEON intrisics that map to the VLD3 instruction? That spares you all of the shuffling, both simplifying and speeding up the code. The Intel SSE implementation requires shuffles because it lacks 2/3/4-way deinterleaving load instructions, but you shouldn't pass on them when they are available. The trouble I am having is the solution offers code that is non-interleaved, and it performs fused multiplies on floating points. I'm trying