Skip to content
  • Home Home Home, current page.
  • Moments Moments Moments, current page.

Saved searches

  • Remove
  • In this conversation
    Verified accountProtected Tweets @
Suggested users
  • Verified accountProtected Tweets @
  • Verified accountProtected Tweets @
  • Language: English
    • Bahasa Indonesia
    • Bahasa Melayu
    • Català
    • Čeština
    • Dansk
    • Deutsch
    • English UK
    • Español
    • Filipino
    • Français
    • Hrvatski
    • Italiano
    • Magyar
    • Nederlands
    • Norsk
    • Polski
    • Português
    • Română
    • Slovenčina
    • Suomi
    • Svenska
    • Tiếng Việt
    • Türkçe
    • Ελληνικά
    • Български език
    • Русский
    • Српски
    • Українська мова
    • עִבְרִית
    • العربية
    • فارسی
    • मराठी
    • हिन्दी
    • বাংলা
    • ગુજરાતી
    • தமிழ்
    • ಕನ್ನಡ
    • ภาษาไทย
    • 한국어
    • 日本語
    • 简体中文
    • 繁體中文
  • Have an account? Log in
    Have an account?
    · Forgot password?

    New to Twitter?
    Sign up
RichFelker's profile
Rich Felker
Rich Felker
Rich Felker
@RichFelker

Tweets

Rich Felker

@RichFelker

Yeah, I do @musllibc, FOSS & infosec stuff. But now is not the time for a mostly-/only-tech Twitter feed.

musl-libc.org
Joined March 2014

Tweets

  • © 2018 Twitter
  • About
  • Help Center
  • Terms
  • Privacy policy
  • Cookies
  • Ads info
Dismiss
Previous
Next

Go to a person's profile

Saved searches

  • Remove
  • In this conversation
    Verified accountProtected Tweets @
Suggested users
  • Verified accountProtected Tweets @
  • Verified accountProtected Tweets @

Promote this Tweet

Block

  • Tweet with a location

    You can add location information to your Tweets, such as your city or precise location, from the web and via third-party applications. You always have the option to delete your Tweet location history. Learn more

    Your lists

    Create a new list


    Under 100 characters, optional

    Privacy

    Copy link to Tweet

    Embed this Tweet

    Embed this Video

    Add this Tweet to your website by copying the code below. Learn more

    Add this video to your website by copying the code below. Learn more

    Hmm, there was a problem reaching the server.

    By embedding Twitter content in your website or app, you are agreeing to the Twitter Developer Agreement and Developer Policy.

    Preview

    Why you're seeing this ad

    Log in to Twitter

    · Forgot password?
    Don't have an account? Sign up »

    Sign up for Twitter

    Not on Twitter? Sign up, tune into the things you care about, and get updates as they happen.

    Sign up
    Have an account? Log in »

    Two-way (sending and receiving) short codes:

    Country Code For customers of
    United States 40404 (any)
    Canada 21212 (any)
    United Kingdom 86444 Vodafone, Orange, 3, O2
    Brazil 40404 Nextel, TIM
    Haiti 40404 Digicel, Voila
    Ireland 51210 Vodafone, O2
    India 53000 Bharti Airtel, Videocon, Reliance
    Indonesia 89887 AXIS, 3, Telkomsel, Indosat, XL Axiata
    Italy 4880804 Wind
    3424486444 Vodafone
    » See SMS short codes for other countries

    Confirmation

     

    Welcome home!

    This timeline is where you’ll spend most of your time, getting instant updates about what matters to you.

    Tweets not working for you?

    Hover over the profile pic and click the Following button to unfollow any account.

    Say a lot with a little

    When you see a Tweet you love, tap the heart — it lets the person who wrote it know you shared the love.

    Spread the word

    The fastest way to share someone else’s Tweet with your followers is with a Retweet. Tap the icon to send it instantly.

    Join the conversation

    Add your thoughts about any Tweet with a Reply. Find a topic you’re passionate about, and jump right in.

    Learn the latest

    Get instant insight into what people are talking about now.

    Get more of what you love

    Follow more accounts to get instant updates about topics you care about.

    Find what's happening

    See the latest conversations about any topic instantly.

    Never miss a Moment

    Catch up instantly on the best stories happening as they unfold.

    1. whitequark‏ @whitequark 29 Apr 2017

      every new uC family I touch has an increasingly more contrived way of operating GPIOs. in 2022 I expect to have to solve a sudokupic.twitter.com/pxvNYr8KxE

      4 replies 15 retweets 54 likes
    2. whitequark‏ @whitequark 29 Apr 2017
      Replying to @whitequark

      a) not really helping b) your own register definition files place GPIO_DATA 0x3FC past its actual position in memory whypic.twitter.com/RPA1iwNlSk

      1 reply 0 retweets 2 likes
    3. whitequark‏ @whitequark 29 Apr 2017
      Replying to @whitequark

      oh I see, the idea is that by placing GPIO_DATA at 0x3FC you get a mask of 0xFF, which effectively makes it a boring old GPIO state register

      3 replies 0 retweets 4 likes
    4. whitequark‏ @whitequark 29 Apr 2017
      Replying to @whitequark

      the helpful diagram they made is inverted. they drew it like the written value is a mask but the address is the mask do you hate developers

      1 reply 0 retweets 11 likes
    5. new299‏ @new299 29 Apr 2017
      Replying to @whitequark

      It's not that they hate developers, it's just that they don't think about them at all.

      1 reply 0 retweets 4 likes
    6. Rich Felker‏ @RichFelker 29 Apr 2017
      Replying to @new299 @whitequark

      On the contrary it seems they actually DID think about developers, and the fact that independent code needs to be able to access gpio bits.

      1 reply 0 retweets 0 likes
    7. Rich Felker‏ @RichFelker 29 Apr 2017
      Replying to @RichFelker @new299 @whitequark

      Without such a scheme, you need all access to gpio mediated through a gpio driver that ensures drivers don't clobber each other's changes.

      2 replies 0 retweets 0 likes
    8. William D. Jones‏ @cr1901 29 Apr 2017
      Replying to @RichFelker @new299 @whitequark

      I don't see how this prevents clobbering when "threads" won't know of each other's writes.

      1 reply 0 retweets 0 likes
      Rich Felker‏ @RichFelker 29 Apr 2017
      Replying to @cr1901 @new299 @whitequark

      It's assuming each driver does its own synchronization with itself or is single-threaded; that's trivial to satisfy.

      12:52 PM - 29 Apr 2017
      2 replies 0 retweets 0 likes
        1. Rich Felker‏ @RichFelker 29 Apr 2017
          Replying to @RichFelker @cr1901 and

          What's nontrivial is synchronizing access to a gpio register between independent drivers that don't know about each other.

          0 replies 0 retweets 0 likes
          Thanks. Twitter will use this to make your timeline better. Undo
          Undo
        1. New conversation
        2. William D. Jones‏ @cr1901 29 Apr 2017
          Replying to @RichFelker

          What does "it's" in "It's assuming" referring to. Unfortunately I'm lost now :(.

          1 reply 0 retweets 0 likes
        3. Rich Felker‏ @RichFelker 29 Apr 2017
          Replying to @cr1901

          It = my tweet/my point.

          1 reply 0 retweets 0 likes
        4. William D. Jones‏ @cr1901 29 Apr 2017
          Replying to @RichFelker

          Well two drivers (I hope!) aren't going to use the same GPIO line to send/recv data simultaneously, so I don't understand >>

          1 reply 0 retweets 0 likes
        5. William D. Jones‏ @cr1901 29 Apr 2017
          Replying to @cr1901 @RichFelker

          why this is a problem as long as each driver shifts GPIO locations to be changed/masks to the correct positions before writing.

          1 reply 0 retweets 0 likes
        6. Rich Felker‏ @RichFelker 29 Apr 2017
          Replying to @cr1901

          A single mmio address hosts multiple (up to 32) gpio lines.

          1 reply 0 retweets 0 likes
        7. William D. Jones‏ @cr1901 29 Apr 2017
          Replying to @RichFelker

          So each driver reserves a chunk of those lines ahead of time, and every time a write is required, shift to the appriopriate >>

          1 reply 0 retweets 0 likes
        8. William D. Jones‏ @cr1901 29 Apr 2017
          Replying to @cr1901 @RichFelker

          GPIO lines to modify, then send a mask for the other lines to NOT modify them... oh, wait... that's not atomic

          1 reply 0 retweets 0 likes
        9. William D. Jones‏ @cr1901 29 Apr 2017
          Replying to @cr1901 @RichFelker

          (why is it called "RMW" in the case where you send the mask at the same time? From the hardware POV, we're >>

          1 reply 0 retweets 0 likes
        10. 1 more reply

      Loading seems to be taking a while.

      Twitter may be over capacity or experiencing a momentary hiccup. Try again or visit Twitter Status for more information.

        Promoted Tweet

        false

        • © 2018 Twitter
        • About
        • Help Center
        • Terms
        • Privacy policy
        • Cookies
        • Ads info