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Josh Weinstein jweinst1

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Focusing

On a mission to write the fastest software in the world - 中文名字：马龙

46 followers · 20 following

San Jose, CA
https://medium.com/@jweinst1

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jweinst1 / basic_probe_map.cpp

Created January 23, 2026 22:01

Basic probing map in C++

	enum class HashQueryRes {
	Empty,
	Occupied,
	Found
	};

	class HashOnlyLinearMap {

	struct KVPair {
	uint32_t _hash = 0;

jweinst1 / mmap_write_perf_tlb_Test.cpp

Last active January 23, 2026 01:15

Shows performance of TLB mmap writes across 1, 100, and 1024 pages

	#include <iostream>
	#include <vector>
	#include <unordered_map>
	#include <random>
	#include <chrono>
	#include <cstdint>
	#include <limits>
	#include <cstring>
	#include <cstdlib>
	#include <filesystem>

jweinst1 / tlb_alloc.cpp

Last active January 21, 2026 02:29

A tlb aware slot allocator

	#include <iostream>
	#include <vector>
	#include <unordered_map>
	#include <random>
	#include <chrono>
	#include <cstdint>
	#include <limits>
	#include <cstring>
	#include <cstdlib>
	#include <cstdio>

jweinst1 / level4_bench.cpp

Last active January 17, 2026 00:13

write o1 hashmap

	#include <iostream>
	#include <vector>
	#include <unordered_map>
	#include <random>
	#include <chrono>
	#include <cstdint>
	#include <limits>
	#include <cstring>

jweinst1 / 32bit_murmur_10mill.cpp

Last active January 12, 2026 04:48

hashmap for murmur3

	#include <iostream>
	#include <vector>
	#include <unordered_map>
	#include <random>
	#include <chrono>
	#include <cstdint>

	// =======================================================
	// MurmurHash3 x64 → 64-bit
	// =======================================================

jweinst1 / hamming_sep_dist.cpp

Last active December 26, 2025 22:52

and pop count of specific segments of bits for 8 bit dimension vectors

	#include <array>
	#include <cstdint>
	#include <cstddef>
	#include <cmath>
	#include <cstdio>
	#include <climits>
	#include <vector>
	#include <cassert>
	#include <random>
	#include <chrono>

jweinst1 / hamming_centers.cpp

Created December 24, 2025 00:31

sorting bit sets of numbers based on hamming distance

	#include <array>
	#include <cstdint>
	#include <cstddef>
	#include <cmath>
	#include <cstdio>
	#include <climits>
	#include <vector>
	#include <cassert>
	#include <random>
	#include <chrono>

jweinst1 / lzsort.cpp

Last active December 23, 2025 06:19

Automatic Sorting in Rust with bit RZ and LZ instructions

	#include <array>
	#include <cstdint>
	#include <cstddef>
	#include <cmath>
	#include <cstdio>
	#include <climits>
	#include <vector>
	#include <cassert>
	#include <random>
	#include <chrono>

jweinst1 / bitsorter.cpp

Last active December 19, 2025 01:39

automatic bit sorting in C++

	#include <array>
	#include <cstdint>
	#include <cstddef>
	#include <cmath>
	#include <cstdio>
	#include <climits>
	#include <vector>
	#include <cassert>
	#include <random>
	#include <chrono>

jweinst1 / add_not_bits.txt

Last active September 26, 2025 00:26

closest sub mask in a mash set

	>>> bin(0b10100 & ~0b1111)
	'0b10000'
	>>> bin(0b11000 & 0b1111)
	'0b1000'
	>>> bin(0b11000 & ~0b1111)
	'0b10000'
	>>> bin(0b01000 & ~0b1111)
	'0b0'
	>>> bin(0b11000 & ~0b1111)
	'0b10000'

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