colematt

export PROJ_ROOT=$(pwd)
mkdir -p llvm && cd llvm

# Using Ubuntu 18.04 Prebuild Toolchain from https://releases.llvm.org/download.html
wget https://github.com/llvm/llvm-project/releases/download/llvmorg-10.0.0/clang+llvm-10.0.0-x86_64-linux-gnu-ubuntu-18.04.tar.xz \
     https://github.com/llvm/llvm-project/releases/download/llvmorg-10.0.0/clang+llvm-10.0.0-x86_64-linux-gnu-ubuntu-18.04.tar.xz.sig \
     https://releases.llvm.org/10.0.0/hans-gpg-key.asc
gpg --import hans-gpg-key.asc
gpg --verify clang+llvm-10.0.0-x86_64-linux-gnu-ubuntu-18.04.tar.xz.sig clang+llvm-10.0.0-x86_64-linux-gnu-ubuntu-18.04.tar.xz

colematt

Get elements from a multi-dimensional array

import functools
import operator
def arrget(array,tup):
	'''
	Given a tuple containing the dimensional indices, retrieve that element from a multi-dimensional array
	'''
	return functools.reduce(lambda arr, idx: operator.getitem(arr,idx), tup, array)

colematt

Allocating Multi-dimensional Arrays in C

This gist was inspired by the Geeks for Geeks' writeup How to dynamically allocate a 2D array in C? by Abhay Rathi. It has been formatted to remove interstitial ads, provide a fixed URL for links, and to modify the problem statement to match that which is commonly used in Hackerrank/Grind75/LeetCode/ACM problems where the input must be read from standard input.

Problem

We want to read input from standard input, where the nature of the input is as follows:

• On line 1, $R$: the number of rows, and $C$: the number of columns in a 2D array, space-separated and newline-terminated.
• On lines 2 through $R+1$, the row's columns, space-separated and newline-terminated.

colematt

Where does the C/C++ Compiler Find Header Files?

Ask the Preprocessor

GNU

# GNU C++ preprocessor
`gcc -print-prog-name=cc1plus` -v
# GNU C preprocessor

colematt

Adding Programs and System Calls to XV6

Adding Userspace programs

To add a userspace program that can be executed in xv6 shell, make the following additions/edits:

program.c

1. Include the headers needed to gain access to system call wrapper prototypes: types.h, user.h.
2. If you need access to struct stat, include its header: stat.h

colematt

When updating using apt-update, you get the following warnings:

$ sudo apt update
[sudo] password for matthew: 
...
Hit:10 https://packagecloud.io/slacktechnologies/slack/debian jessie InRelease                   
Fetched 9,870 B in 1s (7,957 B/s)
Reading package lists... Done
Building dependency tree... Done

colematt

\documentclass{beamer}

\begin{document}

\begin{frame}
\begin{thebibliography}{9}
\setbeamertemplate{bibliography item}[online]
\bibitem{A} ItemA
\setbeamertemplate{bibliography item}[book]
\bibitem{B} ItemB

colematt

import signal
import time

class timeout:
    def __init__(self, seconds=1, error_message='Timeout'):
        self.seconds = seconds
        self.error_message = error_message
    def handle_timeout(self, signum, frame):
        raise TimeoutError(self.error_message)
    def __enter__(self):

colematt

Get Date and Time of a History Event

By default, history will only give an event designator and command line entry. Unless the event reference is absolute, the events are relative to the current position in the history list.

history
 1995  ls S*.pdf
 1996  ls -lh S*.pdf
 1997  xdg-open System_01Jun2018_30Jun2018_0133*.pdf
 1998  ssh matthew@localhost

colematt

Keybase proof

I hereby claim:

• I am colematt on github.
• I am colematthew (https://keybase.io/colematthew) on keybase.
• I have a public key ASArTG7xdS6WqkVEnPIuqXqZ_8Ur79INXvBpEfq4lykRPQo

To claim this, I am signing this object: