vurtun

#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <arm_neon.h>

#define cast(t,p) ((t)p)
#define casts(p) cast(short,p)
#define castus(p) cast(unsigned short,p)
#define casti(p) cast(int,p)

vurtun

#include <immintrin.h>
#include <pthread.h>
#include <assert.h>
#include <string.h>

enum {
  MAX_CHAINS              = 256,
  PARTICLES_PER_CHAIN     = 16,
  SPHERES_PER_CHAIN       = 8,
  MAX_PARTICLES           = (MAX_CHAINS * PARTICLES_PER_CHAIN),

vurtun

The PdfTree is a hierarchical data structure that stores values and their associated probabilities, organized in a way that resembles a binary tree or mip-map pyramid. It allows for efficient random selection of values proportional to their probabilities (e.g., for Monte Carlo sampling in rendering or procedural generation). The tree is built as a "summed probability tree," where each level aggregates probabilities from the level below it, enabling fast traversal for sampling.

The tree is laid out linearly in probabilities, with each level concatenated. For example:
Mip 0: Original probabilities [p0, p1, p2, p3]
Mip 1: Pairwise sums [p0+p1, p2+p3]
Mip 2: Sum of mip 1 [p0+p1+p2+p3]

Mip Level Calculation:
Computes the total number of elements across all mip levels.

vurtun

#include <immintrin.h>  // AVX, includes SSE2-SSE4.2
#include <assert.h>
#include <math.h>
#include <stdint.h>
#include <pthread.h>
#include <stdlib.h>
#include <stdio.h>

// Constants
#define MAX_MDLS        256

vurtun

#include <immintrin.h> // For AVX2

#define MAX_SIZE        (64*1024)
#define BITS_PER_WORD   64
#define WORD_CNT        ((MAX_SIZE + BITS_PER_WORD - 1) / BITS_PER_WORD)  // 1024 words
#define BIT_MAP_CNT     ((WORD_CNT + BITS_PER_WORD - 1) / BITS_PER_WORD) // 16 words
#define WORD_SHIFT      6  // log2(BITS_PER_WORD)
#define WORD_MSK       (BITS_PER_WORD - 1)  // 63
#define CHUNK_CNT       (BIT_MAP_CNT/4)
#define CACHE_LINE_SIZE 64

vurtun

/* ---------------------------------------------------------------------------
 *                                Vector
 * ---------------------------------------------------------------------------
 */
/* vector */
#define opI(r,e,a,p,b,i,s,I)((r)[I]e(a)[I]p((b)[I]i(s)))
#define opsI(r,e,a,p,s,I)   ((r)[I]e(a)[I]p(s))
#define setI(d,x,I)         (d)[I]=(x)
#define dotI(a,b,I)         (a)[I]*(b)[I]
#define lerpI(r,a,b,t,I)    lerp((r)[I],(a)[I],(b)[I],t)

vurtun

#include <assert.h>
#include <math.h>
#include <stdio.h>

/* Alternative design: Iterate over path and at each point i check distance to line with points
   i + 1 and i + 2 and skip i + 1 when distance is small than epsilon. */
static float
line_dist(const float *p, const float *p1, const float *p2) {
  float dx = p2[0] - p1[0];
  float dy = p2[1] - p1[1];

vurtun

/* Problem: Directory file view ui. Files can be sorted by different properties (name, size, ...). Ui itself only needs elements
            that are currently in the visible section of the list view from x and count k. So I want to use a fixed size buffer with up to k elements 
            and walk through all files in the directory and only have the final elements in the end in the fixed size buffer.
            Temp buffers are fine for me as long as they have a fixed at compile time size. For those familiar with SQL basically this is
            a SORT BY LIMIT begin, count.
             
  Idea:     Use Floyd–Rivest algorithm with average O(n) to find the element at index x. Walk over list again and skip all elements smaller than x 
            then use heap to sort for the k smallest elements afterwards. So we have for Floyd–Rivest and heap combined O(n*log(k))

  Problem:  Find x is not directly possible since not all elements are in memory because we have only fixed size buffer. 

vurtun

// Selection algorithm
// Partial sorting

// http://www.unicode.org/Public/UCD/latest/ucd/CaseFolding.txt
switch(rune) {
case 0x0041: return 0x0061; // LATIN CAPITAL LETTER A
case 0x0042: return 0x0062; // LATIN CAPITAL LETTER B
case 0x0043: return 0x0063; // LATIN CAPITAL LETTER C
case 0x0044: return 0x0064; // LATIN CAPITAL LETTER D
case 0x0045: return 0x0065; // LATIN CAPITAL LETTER E

vurtun

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <time.h>

#define szof(a) ((int)sizeof(a))
#define cntof(a) ((int)(sizeof(a) / sizeof((a)[0])))

static void