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// Abseil absl::flat_hash_map
// Analysis of the critical path for perfectly predicted load hit.
// x86_64
// Instruction latencies have been entirely ignored.
# rdi = desired key
mov rax, qword ptr [rip + kHashSeed] # [a00] rax = per-process seed (with entropy)
add rax, rdi # [a01] rax = hash so far
Nexuapex / bit_cast.h
Created April 1, 2018 19:32
Minimal-dependencies implementation of bit_cast.
#include <string.h>
#if defined(__has_attribute)
#if __has_attribute(always_inline)
#define ALWAYS_INLINE __attribute__((always_inline))
#if defined(_MSC_VER)
// To reduce debug build overhead:
Nexuapex /
Created April 26, 2016 06:06
Sketch of a few ways to store 8 or 16 elements indexed by a packed byte array.
#include <xmmintrin.h>
#include <stdint.h>
struct ResourceTable8
uint64_t type_bits_;
uintptr_t elements_[8];
inline uint64_t mask_for_type(uint8_t type)
Nexuapex / env.cmd
Created March 6, 2015 17:18
A Python script that injects environment variables into the calling cmd.exe shell.
@echo off
rem = """
rem This is a hybrid batch and Python script. The batch (right here) invokes
rem the Python script and treats its standard output as a list of environment
rem variables to set in the current environment.
rem The -x argument causes the Python interpreter to ignore the first line.
rem The -S argument disables the implicit 'site' package import (speed go fast).
FOR /F "tokens=1,2 delims==" %%v IN ('python -x -S "%~f0" %*') DO SET %%v=%%w
GOTO :eof
Nexuapex /
Created January 8, 2015 03:15
Simple Python MPMC queue and thread pool.
from __future__ import absolute_import
import sys
import threading
import collections
class WorkerPool(object):
"""A thread pool that processes items from an unbounded work queue, for
simple multi-producer, multi-consumer processes.
Nexuapex / Microsoft C++.sublime-build
Created November 17, 2014 03:10
A simple Sublime Text 3 build system for Visual Studio 2013's C/C++ compiler.
"shell_cmd": "\"%VS120COMNTOOLS%\\..\\..\\VC\\vcvarsall.bat\" amd64 && cl /nologo \"$file\"",
"file_regex": "^(.*?)\\(([0-9+])(?:,([0-9+]))?\\)\\s+:\\s+(.*)$",
"working_dir": "${file_path}",
"selector": "source.c, source.c++"
import socket
create_socket = lambda: socket.socket(socket.AF_INET, socket.SOCK_STREAM, socket.IPPROTO_TCP)
target_port = 49400 # Any port in the ephemeral port range that no process on your machine is using.
port = 0
# Create and bind sockets, working our way through the ephemeral port space, until we get close to our target.
while not (target_port - 5 < port < target_port):
sock = create_socket()
sock.bind(('', 0))
Nexuapex /
Last active August 29, 2015 14:00
An attempt to reinvent `std::function' that ended up being about things I don't like about C++.
// Because it was possible to implement std::move and std::forward<T> as library
// functions, so that's what happened. Now this header is everywhere. This is
// 2,800 lines of kitchen sink for me.
#include <utility>
// C++ has half-decent pattern matching, but only on types. If only some of this
// energy could be thrown at language constructs like `switch'.
// Oh, right, and this relies on partial specialization, which only works on
// classes. So you get these pointless classes that contain a single typedef.
Nexuapex / inlined.h
Last active August 29, 2015 13:55
I would get behind this if I could just static_assert(size <= Size) in the placement operator new. Close but no cigar.
#include <string.h>
template <typename T, size_t Size>
class inlined
Nexuapex /
Last active December 24, 2015 01:29
There's this handy flag on Win32 heap objects called HEAP_GENERATE_EXCEPTIONS, which causes the heap manager to raise a structured exception instead of returning null on a failed allocation. But the C runtime creates its heap behind the scenes and doesn't allow you access to it, and you can't add this flag after creation anyway. Unless you are t…
#include <malloc.h>
#include <windows.h>
static HANDLE FindCrtHeap()
// Pick a block that we know is in the CRT heap.
_HEAPINFO crtEntry = {};
if (_HEAPOK != _heapwalk(&crtEntry))