mizmar

4 ms·

1.
by mizmar 3mo ago
The seconds to calendar date conversion doesn't actually need to know about leap seconds. At the seconds representation level, the same number is repeated twice (or the smearing trategy happens). So the times before and after leap seco
2.
by mizmar 3mo ago
Yes, time() and clock_gettime(CLOCK_REALTIME) results are affected by leap seconds. New leap second will get to your system through NTP. Sadly NTP only distributes indicator flag that leap second is going to be introduced, but not the offse
3.
by mizmar 4mo ago
Clipboard on Wayland is interesting. Clients expose the content through wl_data_source and see wl_data_offer. To receive the clipboard content, they request receive on a wl_data_offer and pass a file descriptor (usually pipe() write end) to
4.
by mizmar 4mo ago
I encountered this few months back. Netcat was recv-only client connected to server that was continually sending some logs. Managed to trigger it with netcat killed with Ctrl+\ signal instead of Ctrl+C, but not consistently. My hypothesis w
5.
by mizmar 5mo ago
Great reading, thanks. Describes how to handle ±0, works with difference to avoid truncation errors. First half of the paper is arriving at this correct snippet, second part of the paper is about optimizing it. bool DawsonCompare(floa
6.
by mizmar 6mo ago
the "XOR in hash functions" mentioned at the end most certainly refers to Zobrist hashing, the actually useful XOR trick. Requires fixed-length keys. Generate random table for each byte position. Then to hash a key, for each posit
7.
by mizmar 6mo ago
Another similar trick - XOR doubly linked list: XOR the prev and next pointers (storaged size of node decreases) and you can recover the values when accessing the node from prev or next side and thus already know one of the addresses.
8.
by mizmar 6mo ago
There is another way to compare floats for rough equality that I haven't seen much explored anywhere: bit-cast to integer, strip few least significant bits and then compare for equality. This is agnostic to magnitude, unlike epsilon wh
9.
by mizmar 6mo ago
>you're assuming copy/edit don't bump mtime Incorrect, I only assume move/rename of backup to original location doesn't change it's mtime (which it doesn't with default flags or from IDE or file manager
10.
by mizmar 6mo ago
ninja fails to detect that file changed from last build - all it's mtime, ctime, inode and size can change, yet it's not detected as long as mtime is not newer than target.
11.
by mizmar 6mo ago
Similar to make, it does mtime chronological comparison of dependencies with target to determinate if dependencies changed. This is just so flawed and simple to fool by operations on filesystem that do not change mtime (move, rename): 1) pi
12.
by mizmar 6mo ago
I wouldn't call wayland-client a callback hell. All callbacks are called at expected time when you call wl_display_dispatch() (and its variants) or during wl_display_roundtrip(). GLFW also works with callbacks and nobody complains abou
13.
by mizmar 6mo ago
Wayland makes it unnecessarily difficult to make simple clients. Gnome still doesn't support server-side window decoration and libdecor is an absolute nightmare and wayland-cursor doesn't even detect the system theme properly.
14.
by mizmar 6mo ago
>and I still don't know what's the difference between them (wl_display_roundtrip() & wl_display_dispatch()) and in what order to call them on I've been struggling with this initially as well, it's pretty poorly ex
15.
by mizmar 7mo ago
I would mention stb_textedit.h, but I would not recommend it. It was an interesting thing to study. but the library has many shortcomings and is pain to integrate and use. It is used in ImGui, but somewhat modified. Just to illustrate the f
16.
by mizmar 7mo ago
It's not that bad. You need really large files to notice. The largest realistic file I'll ever touch - sqlite3 amalgamation with 270k lines and 9.1 kB - still takes only 6 ms to memmove it on my poor laptop. Any regular up-to 10k
17.
by mizmar 1y ago
It's one of the improvements they claimed in the 2019 presentation. https://youtu.be/JZE3_0qvrMg?feature=shared&t=1054 Reporting 10% speedup on find, but 15% slowdown on insert. The speedup probably comes from usin
18.
by mizmar 1y ago
Something similar is used in swiss tables - metadata bucket entries are 1 bit occupancy marker and 7 MSB bits of hash (don't remember how tombstones are represented). Metadata table is scanned first, the upper part of hash should disca