neon

Optimizing Cortex-A8 color conversion using NEON

由 社会主义新天地 提交于 2019-12-07 05:47:54
问题 I am currently doing a color conversion routine in order to convert from YUY2 to NV12. I have a function which is quite fast, but not as fast as I would expect, mainly due to cache misses. void convert_hd(uint8_t *orig, uint8_t *result) { uint32_t width = 1280; uint32_t height = 720; uint8_t *lineOdd = orig; uint8_t *lineEven = orig + width*2; uint8_t *resultYOdd = result; uint8_t *resultYEven = result + width; uint8_t *resultUV = result + height*width; uint32_t totalLoop = height/2; while

ARM NEON assembly on Windows Phone 8 not working

由 心不动则不痛 提交于 2019-12-07 04:51:17
问题 I'm trying to call a function that is coded in ARM NEON assembly in an .s file that looks like this: AREA myfunction, code, readonly, ARM global fun align 4 fun push {r4, r5, r6, r7, lr} add r7, sp, #12 push {r8, r10, r11} sub r4, sp, #64 bic r4, r4, #15 mov sp, r4 vst1.64 {d8, d9, d10, d11}, [r4]! vst1.64 {d12, d13, d14, d15}, [r4] [....] and I'm assembling it like this: armasm.exe -32 func.s func.obj Unfortunately this doesn't work, and I'm getting illegal instruction exception when I try

Sum all elements in a quadword vector in ARM assembly with NEON

由 拜拜、爱过 提交于 2019-12-07 03:33:55
问题 Im rather new to assembly and although the arm information center is often helpful sometimes the instructions can be a little confusing to a newbie. Basically what I need to do is sum 4 float values in a quadword register and store the result in a single precision register. I think the instruction VPADD can do what I need but I'm not quite sure. 回答1: It seems that you want to get the sum of a certain length of array, and not only four float values. In that case, your code will work, but is

Battery Power Consumption between C/Renderscript/Neon Intrinsics — Video filter (Edgedetection) APK

由 扶醉桌前 提交于 2019-12-06 15:09:50
I have developed 3 C/RS/Neon-Intrinsics versions of Video Processing Algorithm using Android NDK (using C++ APIs for Renderscript). Calls to C/RS/Neon will be made to Native level on NDK side from JAVA front end. I found that for some reason Neon version consumes lot of power in comparison with C and RS versions. I used Trepn 5.0 for my power testing. Can some one clarify me regarding the power consumption level for each of these methods C , Renderscript - GPU, Neon Intrinsics. Which one consumes most ? What would be the Ideal power consumption level for RS codes ?, since GPU runs with less

Fast Gaussian blur on unsigned char image- ARM Neon Intrinsics- iOS Dev

由 ╄→尐↘猪︶ㄣ 提交于 2019-12-06 13:37:33
问题 Can someone tell me a fast function to find the gaussian blur of an image using a 5x5 mask. I need it for iOS app dev. I am working directly on the memory of the image defined as unsigned char *image_sqr_Baseaaddr = (unsigned char *) malloc(noOfPixels); for (row = 2; row < H-2; row++) { for (col = 2; col < W-2; col++) { newPixel = 0; for (rowOffset=-2; rowOffset<=2; rowOffset++) { for (colOffset=-2; colOffset<=2; colOffset++) { rowTotal = row + rowOffset; colTotal = col + colOffset; iOffset =

ARM memcpy and alignment

由 岁酱吖の 提交于 2019-12-06 11:34:46
问题 I am using the NEON memory copy with preload implementation from the ARM website with the Windows Embedded Compact 7 ARM assembler on a Cortex-A8 processor. I notice that I get datatype misalignment exceptions when I provide that function with non word aligned values For example: ; NEON memory copy with preload ALIGN LEAF_ENTRY NEONCopyPLD PLD [r1, #0xC0] VLDM r1!,{d0-d7} ;datatype misalignment VSTM r0!,{d0-d7} SUBS r2,r2,#0x40 MOV R0, #0 MOV PC, LR ENTRY_END size_t size = /* arbitrary */;

Using NEON multiply accumulate on iOS

由 寵の児 提交于 2019-12-06 10:29:27
问题 Even though I am compiling for armv7 only, NEON multiply-accumulate intrinsics appear to be being decomposed into separate multiplies and adds. I've experienced this with several versions of Xcode up to the latest 4.5, with iOS SDKs 5 through 6, and with different optimisation settings, both building through Xcode and through the commandline directly. For instance, building and disassembling some test.cpp containing #include <arm_neon.h> float32x4_t test( float32x4_t a, float32x4_t b,

ARM NEON Intrisics support in Visual Studio

由 你说的曾经没有我的故事 提交于 2019-12-06 08:19:10
What is the earliest version of Visual Studio (C++) that supports the ARM NEON Intrinsics, if any ? 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

How do I Perform Integer SIMD operations on the iPad A4 Processor?

由 跟風遠走 提交于 2019-12-06 05:07:45
问题 I feel the need for speed. Double for loops are killing my iPad apps performance. I need SIMD. How do I perform integer SIMD operations on the iPad A4 processor? Thanks, Doug 回答1: To get the fastest speed, you will have to write ARM Assembly language code that uses NEON SIMD operations, because the C compilers generally don't make very good SIMD code, so hand-written Assembly will make a big difference. I have a brief intro here: http://www.shervinemami.co.cc/iphoneAssembly.html Note that the

Alignment in VLD1

由 百般思念 提交于 2019-12-06 05:05:37
I have a question about ARM Neon VLD1 instruction's alignment. How does the alignment in the following code work? DATA .req r0 vld1.16 {d16, d17, d18, d19}, [DATA, :128]! Does the starting address of this read instruction shifts to DATA + a positive integer, such that it is the smallest multiple of 16(16 bytes = 128 bits) which is no less than DATA, or DATA itself changes to the smallest multiple of 16 no less than DATA? It is a hint to the CPU. Only thing I read about the usefulness of such hint was from a blog post on ARM's site claiming it makes the loading faster, it doesn't say how or why
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