submachine’s gists

submachine / memhash.c

Created July 6, 2012 23:34

A toy x86_64 pointer-hash benchmark to go with the StackOverflow answer at: http://stackoverflow.com/a/11364619/274261

	#include <stdio.h>
	#include <stdlib.h>
	#include <stdint.h>
	#include <stdbool.h>

	#define HASH_BITS 10
	#define BUCKETS (1 << HASH_BITS)

	/* A half-avalanche 4 byte integer hash function, as described at:
	http://burtleburtle.net/bob/hash/integer.html */

submachine / xrenderstring.c

Created July 27, 2012 10:50

A program that takes: font, string, and renders accordingly using Xlib. Almost a verbatim copy of the one at: http://www.lemoda.net/c/xlib-text-box/index.html

	#include <string.h>
	#include <stdlib.h>
	#include <stdio.h>
	#include <X11/Xlib.h>

	/* The window which contains the text. */

	struct
	{
	int width;

submachine / omp_atomic_capture_example.c

Created September 18, 2012 09:34

An atomic 'fetch and add' using OpenMP directives

	/* Compiling with `gcc -fopenmp -m32 -O2 -S' produces:

	movl $1, %eax
	lock xaddl %eax, j
	movl %eax, i
	ret
	*/

	int i, j;
	void foo (void)

submachine / gen_rand_dag.c

Created October 9, 2012 00:37

A quick-n-dirty random DAG generator

	#include <stdio.h>
	#include <stdlib.h>
	#include <time.h>

	/* http://stackoverflow.com/q/12790337/274261 */

	/* Generates random DAGs. The key is to 'rank' the nodes, and
	only draw edges from lower ranked nodes to higher ranked ones. */

	/* Nodes/Rank: How 'fat' the DAG should be. */

submachine / keep-pushing.c

Last active December 23, 2015 17:59

Keep pushing till we run out of stack area.

	#include <stdio.h>
	#include <string.h>

	unsigned int stack_size;

	struct huge_argument /* Not the verbal kind ;). */
	{
	char x[512];
	};

submachine / hello-pthread.c

Last active December 28, 2015 18:48

A 'Hello World!' program unnecessarily using libpthread

	/*
	gcc -O0 -std=c99 -pedantic -Wall -Werror -lpthread \
	-o hello-pthread hello-pthread.c
	*/

	/* Enable 2008 edition functionality of POSIX.1,
	required for pthread_rwlock_* functions. */
	#define _POSIX_C_SOURCE 200809L

	#include <stdio.h>

submachine / glibc-tester.sh

Last active January 3, 2016 09:29

A [work in progress] script to fetch, build, and test fresh glibc sources.

	#!/bin/bash

	# TODO: Parse and report testsuite failures;
	# fetch and execute gnulib testsuite.

	GT_NAME=glibc-tester
	GT_DIR=$HOME/.$GT_NAME
	GT_CONFIG=$GT_DIR/config

	if [ ! -d $GT_DIR ]; then

submachine / tst-append-ftell.c

Last active August 29, 2015 13:57

A sequence of calls to test ftell with fseek/rewind/fread/fwrite functions while in append mode.

	#include <stdio.h>
	#include <string.h>
	#include <assert.h>
	#include <unistd.h>

	const char *data = "zzzzzzzzzz";
	const char *more_data = "aaaaaaaaaa";

	#define TEST_FILE_PATH "tst-rewind-ftell.out"

submachine / glibc-use-test-skeleton.sh

Last active August 29, 2015 14:07

[committed] script to automatically modify as many glibc test cases as possible into using test-skeleton.c

	#!/bin/bash

	SRC_DIR=~/src/glibc/

	pushd $SRC_DIR &> /dev/null \
	\|\| { echo Unable to enter directory $SRC_DIR 1>&2; exit 1; }

	let blkl=0
	let good=0
	let main=0

submachine / tst-stack-switch-x86_64-linux.c

Created February 16, 2015 23:37

A program that tests valgrind's '--max-stackframe' option on an x86-64 running Linux

	/*
	$ gcc -Wall -pedantic -o test-stack-switching test-stack-switching.c
	$ valgrind ./test-stack-switching

	Expected program output:
	> 55
	> 55
	> 55

	Expected valgrind output: Three warnings that look like;

Arjun Shankar submachine