I was just checking over a few pages on the wiki and came across Brendan's explanation of measuring the APIC timer rate. Some searching on Google brought up -> This Link <-. I know there are some daft patents about but

Cheers,
Adam
Your code doesn't use a slower clock to calibrate a faster clock. It uses (a simplified version of) the basic ideas present in the NTP protocol (since the early 1980's) to synchronise one clock with another.Combuster wrote:Ok, for all the people in the US who were so friendly to try my OS...
It has been common for large companies (any large (or small) company in general) to take out patents on the most simple things, not to stop competition, but in order to protect the freedom of the idea rather than down the track someone else patents it, rushes their product to the market first, and then tells them they can't use that idea.Brendan wrote:IMHO (and I'm not a lawyer), there's no way this patent would hold up in any court - it shouldn't be hard to find prior art and it's very obvious to "someone trained in the field".
As far as I can tell, in the US the patent is granted by default, and the courts decide whether or not the patent should have been granted later on.
Code: Select all
int t=timer1_ticks;
int t2=timer2_ticks;
int c=0;
while(t==timer1_ticks){}
c=t2-t;
//c is calibration variable
Doesn't determining the Local APIC's reference clock against the PIT count as calibrating a faster clock? Or is my English that badBrendan wrote:Your code doesn't use a slower clock to calibrate a faster clock.Combuster wrote:Ok, for all the people in the US who were so friendly to try my OS...
The method used to synchronise clocks by NTP could be used to synchronise a faster or slower clock (e.g. the local APIC timer) with another faster or slower clock (e.g. the PIT). This is a completely different idea to the patent, and has nothing to do with calibrating a faster clock from a slower clock (even if the code for both entirely different ideas happens to be identical, because patents cover ideas and don't cover implementation).Combuster wrote:Doesn't determining the Local APIC's reference clock against the PIT count as calibrating a faster clock? Or is my English that badBrendan wrote:Your code doesn't use a slower clock to calibrate a faster clock.Combuster wrote:Ok, for all the people in the US who were so friendly to try my OS...
No it doesn't. To infringe on the patent, you'd need to do "a series of measurement pairs" (not just one).earlz wrote:note: the following code infringes on a patent
Patent Abstract wrote:Systems and methods for efficiently and accurately determining a speed of a faster clock having unknown frequency using a slower clock having a known frequency.
[emphasis mine]Patent Claims wrote:1. A method for using a first clock to calibrate a second clock
Transfer the project in it's entirety to a fake person claiming to be base in a country not a member of the Patent Cooperation Treaty?AJ wrote:Absolutely agree. If anyone challenged me about patent infringement, I couldn't even think about putting up a defence. Of course, when I've made my millions...