5 ms·

A bit dangerous feature to use. Carelessly used it can lead into a platform lock-in.

• anyfoo 4y ago
  This is so low-level, I think you'd just consider the respective parts "platform-dependent code", and provide alternative implementations for other platforms (possibly including a very generic one).
• verdagon 4y ago
  I'm not sure this is true, since you could simulate it on other CPUs. I believe most modern OSs don't use the top byte, so you can store things in there (as long as you clear it before trying to dereference it).
  • vardump 4y ago
    While that may be true, my experiences from Motorola 68k times still make me shiver. 68k used just bottom 24 bits for an address. Later models used full 32 bits, breaking anything that used the top 8 bits for something else. The introduced incompatibility was that bad and hard to get rid of. So pardon me for feeling uneasy.
    • irdc 4y ago
      Yes, but on the Mac (where these bits were used) the entire system participated, whereas this is per-process and needs to be explicitly enabled.