cortex-a8 | 易学教程

ARM芯片介绍

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ARM芯片介绍作者：nbnb001 原文网址： http://bbs.imp3.net/thread-894970-1-1.html 翻译来源: http://www.ruanyifeng.com/blog/2010/10/arm_chips.html 一、ARM9系列较小的核心面积带来较低的成本，相对比较省电，但难以冲击更高的频率，总体效能有限。 1. 威盛WM8505/WM8505+ 主频：300MHz/400MHz 内存：128M DDR2，16bit 工艺：65nm工艺 Linpack测试：测试：1-1.25MFlops（Android 1.6系统）视频处理：只有JPEG硬解，视频支持很弱，无3D加速代表机型：国美飞触1代，山寨VIA平板【点评】价格低廉大概是这个方案的唯一优点，不知道国美是怎么忽悠把这个机器卖到999元的...... ARM9 300MHz的主频，自然不用指望有多好的性能，上网都勉勉强强吧。超频的400MHz版本，发热比较大，性能提升又实在有限。视频能力很弱，也不能当MP4用，最多只能当个Android入门机器玩玩。淘宝售价低至500-600元，7寸屏。如果不是囊中羞涩到一定程度，实在不推荐这个芯片的机器。真要入门的话，收个二手的智器Q5也比这个好。性能★☆☆☆☆ 视频★☆☆☆☆ 2. 瑞芯微RK2808 主频：600MHz 内存

ARM Cortex-A8: Whats the difference between VFP and NEON

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问题 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

How to measure program execution time in ARM Cortex-A8 processor?

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I'm using an ARM Cortex-A8 based processor called as i.MX515. There is linux Ubuntu 9.10 distribution. I'm running a very big application written in C and I'm making use of gettimeofday(); functions to measure the time my application takes. main() { gettimeofday(start); .... .... .... gettimeofday(end); } This method was sufficient to look at what blocks of my application was taking what amount of time. But, now that, I'm trying to optimize my code very throughly, with the gettimeofday() method of calculating time, I see a lot of fluctuation between successive runs (Run before and after my

How to measure program execution time in ARM Cortex-A8 processor?

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问题 I\'m using an ARM Cortex-A8 based processor called as i.MX515. There is linux Ubuntu 9.10 distribution. I\'m running a very big application written in C and I\'m making use of gettimeofday(); functions to measure the time my application takes. main() { gettimeofday(start); .... .... .... gettimeofday(end); } This method was sufficient to look at what blocks of my application was taking what amount of time. But, now that, I\'m trying to optimize my code very throughly, with the gettimeofday()