Either inline your functions, move them in a class, or move them to a .c file

[nfischer]

I noticed you currently have all your function implementations in a .h file. While this may seem simpler, this can cause big issues when depending on your project.

If two different .c files include your header (even though you have #pragma once), you'll doubly define your function. This is not allowed in either C or C++.

The standard way of getting around this is to move your implementations into a .c file. You'll keep your declarations in the .h. So it'll look a bit like this:

// -------------------------------
// in your .h file
#pragma once

// your includes go here (don't forget your .h file!)

__m128i _mm_load_si128 (__m128i const* address);
__m128i _mm_loadu_si128 (__m128i const* address);
// etc.

// -------------------------------
// in your .c file

// your includes go here

__m128i _mm_load_si128 (__m128i const* address)
{
    return vec_load1q (address);
}

__m128i _mm_loadu_si128 (__m128i const* address)
{
    return vec_loadu1q (address);
}

In C++, you get some extra options to work around the issue

1. inline your functions. This doesn't really fix anything, but compilers ignore the problem when you do this. C has support for inlining, but I tried it and it didn't seem to avoid the issue.
2. Move your functions into a class declaration, and implement them within the class body. This actually inlines your functions, so it's really the same as #1.

Helpful resources

• http://stackoverflow.com/questions/2458436/error-duplicate-definition-when-compiling-two-c-files-that-reference-one-heade
• http://stackoverflow.com/questions/10242357/why-cant-i-define-plain-c-functions-in-header-file
• http://stackoverflow.com/questions/28743964/c-why-do-we-include-header-files-which-declare-but-dont-define

[IvantheDugtrio]

e2657c5 fixes #1

[nfischer]

@IvantheDugtrio I think it was actually fixed in https://github.com/IvantheDugtrio/veclib/commit/e2657c5cceb18fbe6ad70d4ed5849cdfaa864bbf

Thanks for getting to this so quickly!