<div dir="auto"><div><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sun, Aug 30, 2020, 6:53 PM Peter Constable <<a href="mailto:pgcon6@msn.com">pgcon6@msn.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">This describes symbols used in various languages:<br>
<br>
<a href="https://en.wikipedia.org/wiki/Exponentiation#In_programming_languages" rel="noreferrer noreferrer" target="_blank">https://en.wikipedia.org/wiki/Exponentiation#In_programming_languages</a><br>
<br>
There isn't a perfect answer. I think the best answer is whatever would be most intuitive / less likely to be mis-interpreted.<br></blockquote></div></div><div dir="auto"><br></div><div dir="auto">Which happens to be "**". What's the problem again?</div><div dir="auto"><br></div><div dir="auto"><br></div><div dir="auto"><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
-----Original Message-----<br>
From: Peter Constable <<a href="mailto:pgcon6@msn.com" target="_blank" rel="noreferrer">pgcon6@msn.com</a>> <br>
Sent: Sunday, August 30, 2020 5:43 PM<br>
To: Peter Constable <<a href="mailto:pgcon6@msn.com" target="_blank" rel="noreferrer">pgcon6@msn.com</a>>; Laurence Penney <<a href="mailto:lorp@lorp.org" target="_blank" rel="noreferrer">lorp@lorp.org</a>>; MPEG OT Spec list (<a href="mailto:mpeg-otspec@lists.aau.at" target="_blank" rel="noreferrer">mpeg-otspec@lists.aau.at</a>) <<a href="mailto:mpeg-otspec@lists.aau.at" target="_blank" rel="noreferrer">mpeg-otspec@lists.aau.at</a>><br>
Subject: exponentiation (was RE: [MPEG-OTSPEC] "font directory" / "offset table" / "table directory"<br>
<br>
Separate topic:<br>
<br>
In the description of cmap format 4, "**" is used as an exponentiation operator in the description of the searchRange field, but it appears some younger readers don't recognize that notation from older programming languages. So, I different notation should be used, preferably one that would be readily understood by readers who might or might not be familiar different language. (This will apply also to description of a similar field in the table directory (aka offset table).)<br>
<br>
One possibility is to use pow(). E.g., <br>
<br>
2 * pow(2, floor(log2(segCount)))<br>
<br>
<br>
Another is to use "^". E.g., <br>
<br>
2 * (2 ^ floor(log2(segCount)))<br>
<br>
(I'd keep the extra parens to avoid any uncertainty regarding operator precedence.)<br>
<br>
<br>
There may be other possibilities.<br>
<br>
Recommendations?<br>
<br>
<br>
Peter<br>
<br>
-----Original Message-----<br>
From: mpeg-otspec <<a href="mailto:mpeg-otspec-bounces@lists.aau.at" target="_blank" rel="noreferrer">mpeg-otspec-bounces@lists.aau.at</a>> On Behalf Of Peter Constable<br>
Sent: Sunday, August 30, 2020 5:32 PM<br>
To: Laurence Penney <<a href="mailto:lorp@lorp.org" target="_blank" rel="noreferrer">lorp@lorp.org</a>>; MPEG OT Spec list (<a href="mailto:mpeg-otspec@lists.aau.at" target="_blank" rel="noreferrer">mpeg-otspec@lists.aau.at</a>) <<a href="mailto:mpeg-otspec@lists.aau.at" target="_blank" rel="noreferrer">mpeg-otspec@lists.aau.at</a>><br>
Subject: Re: [MPEG-OTSPEC] "font directory" / "offset table" / "table directory"<br>
<br>
I had considered "^", but that is bitwise XOR in C, Python and other languages du jour. I'm open to input, though.<br>
<br>
(This is yet another topic.)<br>
<br>
-----Original Message-----<br>
From: mpeg-otspec <<a href="mailto:mpeg-otspec-bounces@lists.aau.at" target="_blank" rel="noreferrer">mpeg-otspec-bounces@lists.aau.at</a>> On Behalf Of Laurence Penney<br>
Sent: Sunday, August 30, 2020 1:39 PM<br>
To: MPEG OT Spec list (<a href="mailto:mpeg-otspec@lists.aau.at" target="_blank" rel="noreferrer">mpeg-otspec@lists.aau.at</a>) <<a href="mailto:mpeg-otspec@lists.aau.at" target="_blank" rel="noreferrer">mpeg-otspec@lists.aau.at</a>><br>
Subject: Re: [MPEG-OTSPEC] "font directory" / "offset table" / "table directory"<br>
<br>
> On 30 Aug 2020, at 20:43, Peter Constable <<a href="mailto:pgcon6@msn.com" target="_blank" rel="noreferrer">pgcon6@msn.com</a>> wrote:<br>
> <br>
> Separating the fingerprint from the rest of the structure would end up being messy in describing the organization of TTCs … it feels cleaner to say the offsets are to the table directory of each font resource, and that the font resource beings with sfntVersion.<br>
<br>
Yes, that makes sense.<br>
<br>
>> To avoid confusion it may be helpful to provide pseudocode for calculating them.<br>
> <br>
> There are similar fields in cmap format 4, and they are described with formulae. E.g., "2 × (2**floor(log2(segCount)))". Now, one of the issues opened on that chapter is that someone wasn't familiar with the Fortran "**" operator and so misunderstood the intent. It seems like something less language specific is needed. Taking that in mind, something similar could be done here. E.g., "pow(floor(log2(numTables)), 2) × 16". Or include both prose description and formula.<br>
<br>
Good point, "**" is not clear to whippersnappers.<br>
<br>
BTW the two definitions can be made identical apart from the factors 16 (for table directory) and 2 (for cmap). Please also consider an asterisk (*) over the typographic multiply sign, unless the whole thing uses math typography, and also consider the ascii circumflex (^) over pow().<br>
<br>
- Laurence<br>
<br>
_______________________________________________<br>
mpeg-otspec mailing list<br>
<a href="mailto:mpeg-otspec@lists.aau.at" target="_blank" rel="noreferrer">mpeg-otspec@lists.aau.at</a><br>
<a href="https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.aau.at%2Fmailman%2Flistinfo%2Fmpeg-otspec&data=02%7C01%7C%7Cab8f76cb75d54fc434d908d84d46be45%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637344313512313008&sdata=zOeGdidOuD3jmfkz5ABGblbmlkiNH%2FShfsj8kUPXJos%3D&reserved=0" rel="noreferrer noreferrer" target="_blank">https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.aau.at%2Fmailman%2Flistinfo%2Fmpeg-otspec&data=02%7C01%7C%7Cab8f76cb75d54fc434d908d84d46be45%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637344313512313008&sdata=zOeGdidOuD3jmfkz5ABGblbmlkiNH%2FShfsj8kUPXJos%3D&reserved=0</a><br>
_______________________________________________<br>
mpeg-otspec mailing list<br>
<a href="mailto:mpeg-otspec@lists.aau.at" target="_blank" rel="noreferrer">mpeg-otspec@lists.aau.at</a><br>
<a href="https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.aau.at%2Fmailman%2Flistinfo%2Fmpeg-otspec&data=02%7C01%7C%7Cab8f76cb75d54fc434d908d84d46be45%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637344313512323001&sdata=9ujsTE%2BuUWHq1wwNHc1OZSipr9CUCVV9WN%2FE3gRFwEc%3D&reserved=0" rel="noreferrer noreferrer" target="_blank">https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.aau.at%2Fmailman%2Flistinfo%2Fmpeg-otspec&data=02%7C01%7C%7Cab8f76cb75d54fc434d908d84d46be45%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637344313512323001&sdata=9ujsTE%2BuUWHq1wwNHc1OZSipr9CUCVV9WN%2FE3gRFwEc%3D&reserved=0</a><br>
_______________________________________________<br>
mpeg-otspec mailing list<br>
<a href="mailto:mpeg-otspec@lists.aau.at" target="_blank" rel="noreferrer">mpeg-otspec@lists.aau.at</a><br>
<a href="https://lists.aau.at/mailman/listinfo/mpeg-otspec" rel="noreferrer noreferrer" target="_blank">https://lists.aau.at/mailman/listinfo/mpeg-otspec</a><br>
</blockquote></div></div></div>