Image Processing with MMX in Linux

Question

I want to use the MMX instruction set to optimize my Linux C program, which does lots of operations on images stored in RGB format (each RGB component is stored in an unsigned char). The operations are trivial: I subtract one image from the other pixel by pixel, and accumulate the sum of the absolute values of the differences. (basically, I have a small image, or pattern, and I'm trying to find if that pattern exists in a larger image).

I know this can be coded in assembly language using the MMX instructions to do the individual byte operations in SIMD fashion. However, is there an easier way? Maybe a library, or a higher-level interface that uses the MMX instructions?

Answer 1

Normally there is a header you #include, usually called something like intrinsics.h. This page shows how to use MMX with C. It #includes the file emmintrin.h. Maybe that file exists in Linux?

Also, if you're working on hardware that's remotely recent, you probably want to use at least SSE, if not SSE2. I believe they can be included in a similar way.