Q-NOTE QN-7000HX Technical Information download pdf (Page 11)

Software Performance Optimization Methods

XAPP1206 v1.1 June 12, 2014 www.xilinx.com 11

In addition to these open source libraries, NEON is also popular with commercial providers,

including those shown in Tabl e 5:

Using Compiler Automatic Vectorization

This section describes:

• How to enable automatic vectorization with GCC, which is used in Xilinx SDK and Linux

development

• How small modifications to source code can lead to large improvements in software

performance

Introduction

The easiest way to optimize for NEON is through use of compilers. GCC has several

optimization levels, along with a wide range of individual options to enable or disable particular

optimizations.

Compiler optimization levels are set using the command line option -On, as follows:

• -O0. (default). No optimization is performed. Each line of source code is mapped directly

to the corresponding instructions in the executable file. This provides the clearest view for

source level debugging but the lowest level of performance.

• -O1. Enables the most common forms of optimization that do not require decisions

regarding size or speed. It can often produce a faster executable than -O0.

• -O2. Enables further optimizations, such as instruction scheduling. Again, optimizations

that have potential speed versus size implications are not being employed here.

• -O3. Enables more aggressive optimizations, such as aggressive function inlining, and it

typically increases speed at the expense of image size. Moreover, this option enables

-ftree-vectorize, causing the compiler to attempt to automatically generate NEON

Table 5: NEON 3rd Party Ecosystem

Provider Project and Description

Sasken Communication

Technologies

H.264, VC1, MPEG-4

Skype On2 VP6 video, SILK audio (v1.08+)

Ittiam Systems MPEG-4, MPEG-2, H.263, H.264, WMV9, VC1, DD

Aricent MPEG-4, H.263, H.264, WMV9, audio

Tata Elxsi H.264, VC1

SPIRIT DSP TeamSpirit® Voice and Video Engine

VisualOn H.264, H.263, S.263, WMV, RealVideo, VC-1

Dolby Multichannel audio processing, MS10/11

Adobe Adobe Flash products

Techno Mathematical Co., Ltd.

(TMC)

MPEG-4

drawElements 2D GUI library

ESPICO Audio: low bitrate and digital theater, consulting

CoreCodec CoreAVC, CoreMVC, CoreAAC, x264

DSP Concepts NEON optimized audio and signal processing libraries

Ace Thought Technologies NEON video and audio

1 2 ... 6 7 8 9 10 11 12 13 14 15 16 ... 27 28

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