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pervognsen /
Last active January 27, 2024 19:54
Shift-based DFAs

A traditional table-based DFA implementation looks like this:

uint8_t table[NUM_STATES][256]

uint8_t run(const uint8_t *start, const uint8_t *end, uint8_t state) {
    for (const uint8_t *s = start; s != end; s++)
        state = table[state][*s];
    return state;
# Here's a probably-not-new data structure I discovered after implementing weight-balanced trees with
# amortized subtree rebuilds (e.g.
# and realizing it was silly to turn a subtree into a sorted array with an in-order traversal only as an
# aid in constructing a balanced subtree in linear time. Why not replace the subtree by the sorted array and
# use binary search when hitting that leaf array? Then you'd defer any splitting of the array until inserts and
# deletes hit that leaf array. Only in hindsight did I realize this is similar to the rope data structure for strings.
# Unlike ropes, it's a key-value search tree for arbitrary ordered keys.
# The main attraction of this data structure is its simplicity (on par with a standard weight-balanced tree) and that it
# coalesces subtrees into contiguous arrays, which reduces memory overhead and boosts the performance of in-order traversals
//! Container for resources, that can be any type. This is inspired by Shred and AnyMap.
//! AnyMap didn't fill my usecase as there is no way to borrow mutably 2 values for different
//! keys. (`get_mut(&mut self)`).
//! This container is using interior mutability with `RefCell` to allow this usecase.
//! Downcasting trait does not work with pure rust so I am using a crate called `downcast_rs` to
//! do it.
//! How to use.
rygorous / rast.c
Created March 2, 2020 01:56
Simple watertight triangle rasterizer
// ---- triangle rasterizer
static RADINLINE S64 det2x2(S32 a, S32 b, S32 c, S32 d)
S64 r = (S64) a*d - (S64) b*c;
return r >> SUBPIXEL_SHIFT;
rygorous / gist:b434cf2916be5c9573796b5f96671cbe
Last active November 30, 2022 04:32
2x interleaved rANS encoder/decoder from BitKnit
#include <stdint.h>
// RAD-esque types
typedef size_t UINTa;
typedef uint8_t U8;
typedef uint16_t U16;
typedef uint32_t U32;
rygorous / gist:1d3c1614f9fab50149502e3339ebde83
Last active July 13, 2021 18:28
BiDi processing excerpt
// Rule N0:
// "Any number of characters that had original bidirectional character type NSM prior to
// the application of W1 that immediately follow a paired bracket which changed to L or R
// under N0 should change to match the type of their preceding bracket."
// We don't store the character types as they were before W1 persistently. However, we do
// store the initial character types before any of the rules get applied (since they're
// required for processing of rules L1/L2). Now the only relevant way that a NSM type
// can get modified prior to rule W1 is due to directional overrides. But this can't
// affect us: if there's directional overrides active around the bracket pair, e.g.
rygorous / weak_solutions.txt
Created January 11, 2016 05:07
All hail Sobolev!
Alright, so the basic problem is you have some system with a behavior
described by a differential equation, but you either know that no
classical (smooth) solution exists, or you think it might but aren't sure.
For example, say you need 2nd derivatives somewhere but you know the
problem must have C^2 discontinuities elsewhere because you have
constraints that enforce them! Another example is you have
poles/singularities but don't know where. (If you know in advance that
you're gonna have poles in a specific location, you can exclude that
location from consideration by removing it from your domain; but if you
agnoster /
Last active April 6, 2024 22:35
My ZSH Theme


A ZSH theme optimized for people who use:

  • Solarized
  • Git
  • Unicode-compatible fonts and terminals (I use iTerm2 + Menlo)

For Mac users, I highly recommend iTerm 2 + Solarized Dark

fogus /
Created April 30, 2012 13:02 — forked from viktorklang/
Minimalist Java Actors
// ©2012 Viktor Klang
// 5,804 bytes compressed.
package java.klang
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.Executor;
import java.util.concurrent.RejectedExecutionException;
import java.util.concurrent.atomic.AtomicBoolean;
public class Actor {
rygorous / gist:2203834
Created March 26, 2012 08:03
float->sRGB8 using SSE2 (and a table)
// float->sRGB8 conversions - two variants.
// by Fabian "ryg" Giesen
// I hereby place this code in the public domain.
// Both variants come with absolute error bounds and a reversibility and monotonicity
// guarantee (see test driver code below). They should pass D3D10 conformance testing
// (not that you can verify this, but still). They are verified against a clean reference
// implementation provided below, and the test driver checks all floats exhaustively.