Showing results for December 2014 - Page 3 of 3 - The Old New Thing

Suppose you want to multiply two double-word values producing a quad-word result, but your processor supports only single-word multiplication with a double-word result. For concreteness, let's say that your processor supports 32 × 32 → 64 multiplication and you want to implement 64 × 64 → 128 multiplication. (Sound like any processor you know?) Oh...

Calling to cancel a window timer prevents messages from being generated for that timer, even if one is overdue. In other words, give this sequence of operations: no message is ever generated. Even though a timer became due during the , no timer message was generated during the sleep because timer messages are generated on demand, and nobody ...

A customer was worried that they may have a problem with their message queue filling with messages. "If my handler takes longer than the timer period, will my queue fill up with messages?" As we should know by now, timer messages are generated on demand: The WM_TIMER message is a low-priority message. The Get­Message and Peek­Message ...

Suppose your window procedure doesn't paint when it gets a message. What happens? It depends on how you don't paint. If you have an explicit handler for the message that does nothing but return without painting, then the window manager will turn around and put a new message in your queue. "And try harder this time." Remember that the rules ...

To the outside world, redline can mean to mark something for removal, or it could mean the maximum safe speed of an engine. But in the world of Microsoft design, the term redlines (pronounced as if it were written as the two words red lines, but the accent is on the red) refers to a diagram showing the exact position of visual elements. They typic...

Some time ago, we looked at how doing something can be faster than not doing it. That is, we observed the non-classical effect of the branch predictor. I took the branch out of the inner loop, but let's see how much further I can push it. The trick I'll employ today is using SIMD in order to operate on multiple pieces of data simultaneously. Ta...