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John Carmack's Unusual Fast Inverse Square Root (Quake III)

...s derived is something of a mystery. To quote Gary Tarolli: Which actually is doing a floating point computation in integer - it took a long time to figure out how and why this works, and I can't remember the details anymore. A slightly better constant, developed by an expert mathemat...
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BLE(二)信道&数据包&协议栈格式 - 创客硬件开发 - 清泛IT社区,...

...一定频率范围下的频带资源(Frequency Band); BLE的市场定位是个体和民用,因此使用免费的ISM频段(频率范围是2.400-2.4835 GHz); 为了同时支持多个设备,将整个频带分为40份,每份的带宽为2MHz,称作RF Channel。 所以经过上面...
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What is the “FS”/“GS” register intended for?

...dows and Linux. The original intention behind the segment registers was to allow a program to access many different (large) segments of memory that were intended to be independent and part of a persistent virtual store. The idea was taken from the 1966 Multics operating system, that treated files a...
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Performance optimization strategies of last resort [closed]

...erformance questions on this site already, but it occurs to me that almost all are very problem-specific and fairly narrow. And almost all repeat the advice to avoid premature optimization. ...
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Is PHP compiled or interpreted?

... He means the utility called php (or on windows php.exe) is compiled. – sepp2k Oct 3 '09 at 20:02 7 ...
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基于PECL OAuth打造微博应用 - 更多技术 - 清泛网 - 专注C/C++及内核技术

...rOAuth改的,一旦多平台集成,很容易出现命名冲突之类的问题。 既然官方SDK不给力,那我们只能发扬自力更生的革命精神了!好消息是PHP本身已经有了一个标准的OAuth实现:PECL OAuth!下面以此为例来讲解一下: 说明:首先需...
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warning C4996 - c++1y / stl - 清泛IT社区,为创新赋能!

...可能会产生诸如内存泄露、缓冲区溢出、非法访问等安全问题。这些函数如:strcpy、strcat等。对于这些问题,VC2005建议使用这些函数的更高级的安全版本,即在这些函数名后面加了一个_s的函数。这些安全版本函数使用起来更有...
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地图组件(高德地图) · App Inventor 2 中文网

...标。 此功能的可用性和准确性取决于用户是否启用了定位服务以及可用的位置提供商。 用户纬度 如果启用了显示用户位置,则返回用户的纬度。 用户经度 如果启用了显示用户位置,则返回用户的经度。 可见性 ...
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C++ 打开文件,以清空覆盖的方式 - C/C++ - 清泛网 - 专注C/C++及内核技术

... 以追加的方式打开文件 ios::ate:    文件打开后定位到文件尾,ios:app就包含有此属性 ios::binary:  以二进制方式打开文件,缺省的方式是文本方式。两种方式的区别见前文 ios::in:    文件以输入方式打开(...
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How does one write code that best utilizes the CPU cache to improve performance?

... The cache is there to reduce the number of times the CPU would stall waiting for a memory request to be fulfilled (avoiding the memory latency), and as a second effect, possibly to reduce the overall amount of data that needs to be transfered (preserving memory bandwidth). Techniques for ...