Measter

My Adventures in MMIO Abstraction

Some years ago, I came across a simple Roguelike on Reddit called coreRL. It's very simplistic; levels are just a box with two walls, only one enemy type with basic AI, no health or character attributes, and the only goal is to see how far you can get before you die. Having nothing better to do, I thought it'd be a fun little project to write a port for an Arduino Nano. The only inputs needed are the four movement keys, and the display can just be a basic SSD1306-driven 128x64 OLED panel.

I could, of course, do this in C++. The language is a known quantity for the ATmega328P that powers the Arduino Nano. The toolchain is mature, as are the abstractions for interacting with the onboard peripherals. There are also libraries

munificent

#include <time.h> //  Robert Nystrom
#include <stdio.h> // @munificentbob
#include <stdlib.h> //     for Ginny
#define  r return    //    2008-2019
#define  l(a, b, c, d) for (i y=a;y\
<b; y++) for (int x = c; x < d; x++)
typedef int i;const i H=40;const i W
=80;i m[40][80];i g(i x){r rand()%x;
}void cave(i s){i w=g(10)+5;i h=g(6)
+3;i t=g(W-w-2)+1;i u=g(H-h-2)+1;l(u

josevalim

# You will need fswatch installed (available in homebrew and friends)
# The command below will run tests and wait until fswatch writes something.
# The --stale flag will only run stale entries, it requires Elixir v1.3.
fswatch lib/ test/ | mix test --stale --listen-on-stdin

aaronjensen

# ATTENTION: This is now supported in plug_cowboy as of 2.1.0:
# https://hexdocs.pm/plug_cowboy/Plug.Cowboy.Drainer.html

defmodule DrainStop do
  @moduledoc """
  DrainStop Attempts to gracefully shutdown an endpoint when a normal shutdown
  occurs. It first shuts down the acceptor, ensuring that no new requests can be
  made. It then waits for all pending requests to complete. If the timeout
  expires before this happens, it stops waiting, allowing the supervision tree
  to continue its shutdown order.

kommen

defmodule Mp3Info do
  def duration(data) do
    compute_duration(data, 0, 0)
  end

  defp compute_duration(data, offset, duration) when byte_size(data) > offset do
    case decode_header_at_offset(offset, data) do
      {:ok, length, {samplerate, samples}} ->
        compute_duration(data, offset + length, duration + (samples / samplerate))

drmalex07

README

Services declared as oneshot are expected to take some action and exit immediatelly (thus, they are not really services, no running processes remain). A common pattern for these type of service is to be defined by a setup and a teardown action.

Let's create a example foo service that when started creates a file, and when stopped it deletes it.

Define setup/teardown actions

Create executable file /opt/foo/setup-foo.sh:

jjgod

- (void)drawRect:(NSRect)dirtyRect {
	CGContextRef context = [[NSGraphicsContext currentContext] graphicsPort];
	CGContextSetTextMatrix(context, CGAffineTransformIdentity);

	CTFontRef font = CTFontCreateUIFontForLanguage(kCTFontUIFontSystem, 12.0, NULL);
	
	// Use this to find out the feature identifiers we use below.
	CFTypeRef features = CTFontCopyAttribute(font, kCTFontFeaturesAttribute);
	NSLog(@"%@", features);
	CFRelease(features);

loderunner

Profiling an application in Mac OS X

Finding which process to profile

If your system is running slowly, perhaps a process is using too much CPU time and won't let other processes run smoothly. To find out which processes are taking up a lot of CPU time, you can use Apple's Activity Monitor.

The CPU pane shows how processes are affecting CPU (processor) activity:

jspahrsummers

/// Observes a run loop to detect any stalling or blocking that occurs.
///
/// This class is thread-safe.
@interface GHRunLoopWatchdog : NSObject

/// Initializes the receiver to watch the specified run loop, using a default
/// stalling threshold.
- (id)initWithRunLoop:(CFRunLoopRef)runLoop;

/// Initializes the receiver to detect when the specified run loop blocks for

xhacker

find . ! -path . -maxdepth 1 -type d -exec sh -c '(cd {} && pwd && git pull)' ';'