neon

问题 Wrt my this question,I am not able to cross check the output . I am getting some wrong print statement after execution .Can someone tell me whether printf() statements are wrong or logic that I am doing is wrong . CODE: int64_t arr[2] = {227802,9896688}; int64x2_t check64_2 = vld1q_s64(arr); for(int i = 0;i < 2; i++){ printf("check64_2[%d]: %ld\n",i,check64_2[i]); } int64_t way1 = check64_2[0] + check64_2[1]; int64x1_t way2 = vset_lane_s64(vgetq_lane_s64(check64_2, 0) + vgetq_lane_s64(check64

问题 Basically I'm developing for an iPhone and I compile fine on the Mac, however I want to use NEON intrinsics to accelerate my vector math. I have experience with SSE and AVX, however I have no idea where to get the NEON header with the intrinsics from. I found only one on the net and it only worked for GCC, all the functions had some __builtin keywords behind them. I'm compiling on the xcode llvm 5.0 compiler. I know I can use ARM assembly, however I'd like to use the intrinsic functions

问题 Basically I'm developing for an iPhone and I compile fine on the Mac, however I want to use NEON intrinsics to accelerate my vector math. I have experience with SSE and AVX, however I have no idea where to get the NEON header with the intrinsics from. I found only one on the net and it only worked for GCC, all the functions had some __builtin keywords behind them. I'm compiling on the xcode llvm 5.0 compiler. I know I can use ARM assembly, however I'd like to use the intrinsic functions

问题 I want to convert a Neon 64-bit vector lane to get the n-th position(s) of non-zero (aka. 0xFF) 8-bit value(s), and then fill the rest of the vector with zeros. Here are some examples: 0 1 2 3 4 5 6 7 d0: 00 FF 00 FF 00 00 00 FF d1: 1 3 7 0 0 0 0 0 d0: 00 FF FF FF 00 00 FF 00 d1: 1 2 3 6 0 0 0 0 d0: FF FF FF FF FF FF FF FF d1: 0 1 2 3 4 5 6 7 d0: FF 00 00 00 00 00 00 00 d1: 0 0 0 0 0 0 0 0 d0: 00 00 00 00 00 00 00 00 d1: 0 0 0 0 0 0 0 0 I have the feeling that it's probably one or two bit

问题 What is the earliest version of Visual Studio (C++) that supports the ARM NEON Intrinsics, if any ? 回答1: Visual Studio 2012 supports NEON intrinsics (as well as ARMv6 intrinsics) when compiling for Windows-on-ARM. Visual Studio 2008 supported only ARMv5 DSP, XScale, and WMMX instructions when compiling for Windows Mobile. 来源： https://stackoverflow.com/questions/11839780/arm-neon-intrisics-support-in-visual-studio

问题 I want to use Neon SIMD instruction for the iphone. I heard we have to put flags "-mfloat-abi=softfp -mfpu=neon" in the "Other C Flags" field of the Target inspector, but when building I get "error: unrecognized command line option "-mfpu=neon"" . Is there anything else special that has to be done to allow this flag? (I have Xcode 3.2.1 and iphone sdk 3.1.3) Thanks !! 回答1: The NEON set is an extension on the Cortex-A series, therefore not supported in iPhone 3G. You probably cannot specify

问题 According to the arm info center vadd can be executed condtitionally however when i try vaddeq.f32 d0,d0,d1 Xcode returns 65:instruction cannot be conditional -- vaddeq.f32 d0,d0,d1 one thing i've noticed is that it seems to be only NEON instructions that give this error. VFP instructions don't produce these errors. Is there a compiler flag I have to set in order to enable NEON conditional instructions? 回答1: The ARM Architecture Reference Manual says: An ARM Advanced SIMD VADD instruction

问题 This question already has answers here : arm neon compare operations generate negative one (2 answers) Closed 3 years ago . As per the Neon documentation: If the comparison is true for a lane, the result in that lane is all bits set to one. If the comparison is false for a lane, all bits are set to zero. The return type is an unsigned integer type. I have written a small piece of code to check this and I observed the result as 0 and -1 instead of 0 and 1. Can any one tell me the reason behind

问题 unsigned char changeValue(unsigned char pArray[256],unsigned char value) { return pArray[value]; } how can I change this function with neon with about uint8x8_t?? thanks for your help!! 回答1: You can't - NEON does not have gathered loads. The only case that you can handle like this is when you want to return 8 or 16 contiguous byte values. 来源： https://stackoverflow.com/questions/11502332/arm-neon-how-can-i-change-value-with-a-index

问题 I have the following code which I would like to optimise using ARM NEON instructions. How can I implement it? Thanks for the answers unsigned char someVector[] = {1, 2, 4, 1, 2, 0, 8, 100}; unsigned char maxVal = 0, minVal = 255; for (int i = 0; i < sizeof(someVector); i++) { if (someVector[i] < minVal) { minVal = someVector[i]; } else if (someVector[i] > maxVal) { maxVal = someVector[i]; } } 回答1: Below is an highly optimized example how to find min and max in a large array. The function