Computer Science from the Bottom Up (2016)

Re:Computer Science from the Bottom Up (2016) by Exuma on Sunday December 29, 2019 @02:28AM (#21904608)

Hey, so this is a great work you did. One thing perhaps you can explain... I've stared at this example now for like 30 minutes...

https://www.bottomupcs.com/chapter01.xhtml

Section on "Masking"

How do you get 0x09 or 0x90?

I get how using <memory> & <mask> = <extracted data>...

so:

10100101

11110000

10100000

But I have yet to see how this is 0x90 or 0x09, perhaps I'm misunderstanding. I'm trying to understand the 'shift' piece of it

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Re:Computer Science from the Bottom Up (2016) by 314 on Sunday December 29, 2019 @02:38AM (#21904645)

It’s a typo: he meant 0xa0 or 0x0a and the shift is the four positions to the right to extract the top nybble of the byte.

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Re:Computer Science from the Bottom Up (2016) by delsarto on Sunday December 29, 2019 @03:49AM (#21904887)

Thanks, I believe this should be clearer with https://github.com/ianw/bottomupcs/commit/d8dfd3dc6be5795f4b...

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Re:Computer Science from the Bottom Up (2016) by 314 on Sunday December 29, 2019 @04:51AM (#21905077)

Great resource - very detailed and your style is clear and readable. I'd happily recommend this to anybody who is studying an OS course (and in fact emailed a link to some people who teach similar courses to see if they would use it as background reading).

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Re:Computer Science from the Bottom Up (2016) by Exuma on Tuesday December 31, 2019 @11:55AM (#21922443)

It appears this section might be incomplete:

Branch Prediction

pipeline flush, predict taken, predict not taken, branch delay slots

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Re:Computer Science from the Bottom Up (2016) by Exuma on Sunday December 29, 2019 @03:04AM (#21904737)

Awesome, thank you... I thought I was going insane. So you shift 4 times correct?

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