neon

I decided to continue Fast corners optimisation and stucked at _mm_movemask_epi8 SSE instruction. How can i rewrite it for ARM Neon with uint8x16_t input? I know this post is quite outdated but I found it useful to give my (validated) solution. It assumes all ones/all zeroes in every lane of the Input argument. const uint8_t __attribute__ ((aligned (16))) _Powers[16]= { 1, 2, 4, 8, 16, 32, 64, 128, 1, 2, 4, 8, 16, 32, 64, 128 }; // Set the powers of 2 (do it once for all, if applicable) uint8x16_t Powers= vld1q_u8(_Powers); // Compute the mask from the input uint64x2_t Mask= vpaddlq_u32

In ARM Cortex-A8 processor, I understand what NEON is, it is an SIMD co-processor. But is VFP(Vector Floating Point) unit, which is also a co-processor, works as a SIMD processor? If so which one is better to use? I read few links such as - Link1 Link2 . But not really very clear what they mean. They say that VFP was never intended to be used for SIMD but on Wiki I read the following - " The VFP architecture also supports execution of short vector instructions but these operate on each vector element sequentially and thus do not offer the performance of true SIMD (Single Instruction Multiple

I made my first approach with vectorization intrinsics with SSE, where there is basically only one data type __m128i . Switching to Neon I found the data types and function prototypes to be much more specific, e.g. uint8x16_t (a vector of 16 unsigned char ), uint8x8x2_t (2 vectors with 8 unsigned char each), uint32x4_t (a vector with 4 uint32_t ) etc. First I was enthusiastic (much easier to find the exact function operating on the desired data type), then I saw what a mess it was when wanting to treat the data in different ways. Using specific casting operators would take me forever. The

I am trying to implement histogram in Neon. Is it possible to vectorise ? Histogramming is almost impossible to vectorize, unfortunately. You can probably optimise the scalar code somewhat however - a common trick is to use two histograms and then combine them at the end. This allows you to overlap loads/increments/stores and thereby bury some of the serial dependencies and associated latencies. Pseudo code: init histogram 1 to all 0s init histogram 2 to all 0s loop get input value 1 get input value 2 load count for value 1 from histogram 1 load count for value 2 from histogram 2 increment

I want to build my library for armv6, and there is some neon code that I enable at runtime if the device supports it. The neon code uses neon intrinsics, and to be able to compile it, I must enable armeabi-v7a, but that affects regular c-code (it becomes broken on some low-end devices). So, if the android build system wasn't excessively intrusive, I wouldn't have to ask questions, but it seems that there is no way for me to compile one file for armv6 and the other file for arm7-neon. Can anybody give any clues if that's doable? Edit Before trying to reply and wasting internet-ink, it should be