shafik

What is the Strict Aliasing Rule and Why do we care?

(OR Type Punning, Undefined Behavior and Alignment, Oh My!)

What is strict aliasing? First we will describe what is aliasing and then we can learn what being strict about it means.

In C and C++ aliasing has to do with what expression types we are allowed to access stored values through. In both C and C++ the standard specifies which expression types are allowed to alias which types. The compiler and optimizer are allowed to assume we follow the aliasing rules strictly, hence the term strict aliasing rule. If we attempt to access a value using a type not allowed it is classified as undefined behavior(UB). Once we have undefined behavior all bets are off, the results of our program are no longer reliable.

Unfortunately with strict aliasing violations, we will often obtain the results we expect, leaving the possibility the a future version of a compiler with a new optimization will break code we th

igrr

#include <stdio.h>
#include "esp_err.h"
#include "driver/ledc.h"
#include "driver/periph_ctrl.h"


void app_main()
{
    periph_module_enable(PERIPH_LEDC_MODULE);

NeoCat

// ESP8266 Pins
//  4(SDA) --- AMG8833 SDA
//  5(SCL) --- AMG8833 SCL
//  13     --- LED (Anode) via 100ohm

#include <pgmspace.h>
#include <ESP8266WiFi.h>
#include <WiFiClient.h>
#include <ESP8266WebServer.h>
#include <WebSocketsServer.h>

mbinna

Effective Modern CMake

Getting Started

For a brief user-level introduction to CMake, watch C++ Weekly, Episode 78, Intro to CMake by Jason Turner. LLVM’s CMake Primer provides a good high-level introduction to the CMake syntax. Go read it now.

After that, watch Mathieu Ropert’s CppCon 2017 talk Using Modern CMake Patterns to Enforce a Good Modular Design (slides). It provides a thorough explanation of what modern CMake is and why it is so much better than “old school” CMake. The modular design ideas in this talk are based on the book [Large-Scale C++ Software Design](https://www.amazon.de/Large-Scale-Soft

niclasmattsson

Nothing here, just a Gist hack to display the title correctly on Gist.
(Prefix the title of this file with a dot on Gist.)

heiko-r

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "esp_system.h"
#include "esp_log.h"
#include "bt.h"
#include "bta_api.h"

#include "esp_gap_ble_api.h"
#include "esp_bt_main.h"

chriseth

// This file is MIT Licensed.
//
// Copyright 2017 Christian Reitwiessner
// Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
// The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF O

xxlukas42

void setup() {
  Serial.begin(115200);
}
 
void loop() {
 
    int measurement = 0;

    measurement = hallRead();
 

pjobson

Unbricking a Buffalo WZR-HP-G300NH

TFTP recovery in OSX 10.13

Similar steps can be used under Linux, I have no idea how to Windows anymore. This will probably work for similar Buffalo WZR routers, though your milage may vary. These directions flash the router back to stock Buffalo branded DDWRT.

When these routers brick they tend to go into a kind of reboot mode. At the begining of the reboot, the TFTP server is available for a brief period of time, then all of the lights flash and the unit reboots. We're exploiting the short period of time where the router is in TFTP mode at the start of the reboot. You can try to do a put via TFTP at the begining of this cycle, even if your router has been plugged in for awhile.

Back to Stock Buffalo Branded DDWRT

beevelop

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