jboner

Latency Comparison Numbers (~2012)
----------------------------------
L1 cache reference                           0.5 ns
Branch mispredict                            5   ns
L2 cache reference                           7   ns                      14x L1 cache
Mutex lock/unlock                           25   ns
Main memory reference                      100   ns                      20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy             3,000   ns        3 us
Send 1K bytes over 1 Gbps network       10,000   ns       10 us
Read 4K randomly from SSD*             150,000   ns      150 us          ~1GB/sec SSD

leommoore

File Magic Numbers

Magic numbers are the first bits of a file which uniquely identify the type of file. This makes programming easier because complicated file structures need not be searched in order to identify the file type.

For example, a jpeg file starts with ffd8 ffe0 0010 4a46 4946 0001 0101 0047 ......JFIF.....G ffd8 shows that it's a JPEG file, and ffe0 identify a JFIF type structure. There is an ascii encoding of "JFIF" which comes after a length code, but that is not necessary in order to identify the file. The first 4 bytes do that uniquely.

This gives an ongoing list of file-type magic numbers.

Image Files

protrolium

ffmpeg

Converting Audio into Different Formats / Sample Rates

Minimal example: transcode from MP3 to WMA:
ffmpeg -i input.mp3 output.wma

You can get the list of supported formats with:
ffmpeg -formats

You can get the list of installed codecs with:

zuyu

sudo apt update && \
sudo apt install build-essential software-properties-common -y && \
sudo add-apt-repository ppa:ubuntu-toolchain-r/test -y && \
sudo apt update && \
sudo apt install gcc-6 g++-6 -y && \
sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-6 60 --slave /usr/bin/g++ g++ /usr/bin/g++-6 && \
gcc -v

straker

Basic Snake HTML and JavaScript Game

Snake is a fun game to make as it doesn't require a lot of code (less than 100 lines with all comments removed). This is a basic implementation of the snake game, but it's missing a few things intentionally and they're left as further exploration for the reader.

Further Exploration

• Score
• When the snake eats an apple, the score should increase by one. Use context.fillText() to display the score to the screen

atenni

Problem: When linking to the raw version of a gist, the link changes with each revision.

Solution:

To return the first file from a gist: https://gist.github.com/[gist_user]/[gist_id]/raw/

• Example: https://gist.github.com/atenni/5604522/raw/
• Works even when you change the filename.

To get a file from multi–file gist: https://gist.github.com/[gist_user]/[gist_id]/raw/[file_name]

tamask

import os
import sys
import bpy

output = None
input = None
info = None
error = None
write = None

senderle

So you want to modify the text of a PDF by hand...

If you, like me, resent every dollar spent on commercial PDF tools, you might want to know how to change the text content of a PDF without having to pay for Adobe Acrobat or another PDF tool. I didn't see an obvious open-source tool that lets you dig into PDF internals, but I did discover a few useful facts about how PDFs are structured that I think may prove useful to others (or myself) in the future. They are recorded here. They are surely not universally applicable --
the PDF standard is truly Byzantine -- but they worked for my case.

shawndumas

[mergetool]
    prompt = false
    keepBackup = false
    keepTemporaries = false

[merge]
    tool = winmerge

[mergetool "winmerge"]
    name = WinMerge

mucar

var colorArray = ['#FF6633', '#FFB399', '#FF33FF', '#FFFF99', '#00B3E6', 
		  '#E6B333', '#3366E6', '#999966', '#99FF99', '#B34D4D',
		  '#80B300', '#809900', '#E6B3B3', '#6680B3', '#66991A', 
		  '#FF99E6', '#CCFF1A', '#FF1A66', '#E6331A', '#33FFCC',
		  '#66994D', '#B366CC', '#4D8000', '#B33300', '#CC80CC', 
		  '#66664D', '#991AFF', '#E666FF', '#4DB3FF', '#1AB399',
		  '#E666B3', '#33991A', '#CC9999', '#B3B31A', '#00E680', 
		  '#4D8066', '#809980', '#E6FF80', '#1AFF33', '#999933',
		  '#FF3380', '#CCCC00', '#66E64D', '#4D80CC', '#9900B3', 
		  '#E64D66', '#4DB380', '#FF4D4D', '#99E6E6', '#6666FF'];