如何加速浮点到整数的转换?
我们在项目中进行了大量的浮点到整数转换.基本上是这样的
We're doing a great deal of floating-point to integer number conversions in our project. Basically, something like this
for(int i = 0; i < HUGE_NUMBER; i++)
int_array[i] = float_array[i];
执行转换的默认 C 函数非常耗时.
The default C function which performs the conversion turns out to be quite time consuming.
是否有任何解决方法(可能是手动调整功能)可以稍微加快进程?我们不太关心精度.
Is there any work around (maybe a hand tuned function) which can speed up the process a little bit? We don't care much about a precision.
推荐答案
这里的大多数其他答案只是试图消除循环开销.
Most of the other answers here just try to eliminate loop overhead.
只有 deft_code 的答案 触及了真正问题的核心――将浮点数转换为整数是在 x86 处理器上价格高得惊人.deft_code 的解决方案是正确的，尽管他没有给出引用或解释.
Only deft_code's answer gets to the heart of what is likely the real problem -- that converting floating point to integers is shockingly expensive on an x86 processor. deft_code's solution is correct, though he gives no citation or explanation.
这里是技巧的来源，有一些解释以及特定于您是要向上、向下还是向零舍入的版本:了解您的 FPU
Here is the source of the trick, with some explanation and also versions specific to whether you want to round up, down, or toward zero: Know your FPU
很抱歉提供一个链接，但实际上这里写的任何内容，除了复制那篇出色的文章，都不会使事情变得清晰.
Sorry to provide a link, but really anything written here, short of reproducing that excellent article, is not going to make things clear.
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