clausecker

UNIX famously uses fork+exec to create processes, a simple API that is nevertheless quite tricky to use correctly and that comes with a bunch of problems. The alternative, spawn, as used by VMS, Windows NT and recently POSIX, fixes many of these issues but it overly complex and makes it hard to add new features.

prepare() is a proposed API to simplify process creation. When calling prepare(), the current thread enters “preparation state.” That means, a nascent process is created and the current thread is moved to the context of this process, but without changing memory maps (this is similar to how vfork() works). Inside the nascent process, you can configure the environment as desired and then call prep_execve() to execute a new program. On success, prep_execve() leaves preparation state, moving the current thread back to the parent's process context and returns (!) the pid of the now grownup child. You can also use prep_exit() to abort the child without executing a new process, it similarly returns the pid

clausecker

/*
 * biastest.c -- bias test for arc4ranom_uniform()
 * written by Robert Clausecker <[email protected]>
 */

#include <assert.h>
#include <limits.h>
#include <math.h>
#include <signal.h>
#include <stdatomic.h>

clausecker

/* test the behaviour of rdffr with extending loads */

#include <assert.h>
#include <arm_sve.h>
#include <sys/mman.h>
#include <stdio.h>
#include <unistd.h>

int main()
{

clausecker

	# MMX caeasar chiffre implementation
	# for i686 with MMX
	# signature:
	# caesar(out, in, len, key)
	# key is between 0 and 25

	.section .text
	.globl caesar
	.type caesar,@function
	.align 16

clausecker

	// getnumericvalue(ptr)
	.section .text
	.type getnumericvalue, @function
	.globl getnumericvalue
getnumericvalue:
	xor %eax, %eax		// digit counter

	// process string until we reach cache-line alignment
	test $64-1, %dil	// is ptr aligned to 64 byte?
	jz 0f

clausecker

	// b:a = a+b+c, v31.16b used for scratch space
	.macro csa, a, b, c
	eor v31.16b, \a\().16b, \b\().16b
	eor \a\().16b, v31.16b, \c\().16b
	bit \b\().16b, \c\().16b, v31.16b
	.endm

	// d:a = a+b+c
	.macro csac a, b, c, d
	eor \d\().16b, \a\().16b, \b\().16b

clausecker

#include "textflag.h"

// func PospopcntMem(counts *[8]int32, buf []byte)
TEXT ·PospopcntMem(SB),NOSPLIT,$0-32
	MOVQ counts+0(FP), DI
	MOVQ buf_base+8(FP), SI		// SI = &buf[0]
	MOVQ buf_len+16(FP), CX		// CX = len(buf)

	SUBQ $32, CX			// pre-subtract 32 bit from CX
	JL scalar

clausecker

#define _XOPEN_SOURCE 700
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

extern void pospopcnt_reg(int accum[8], const char *buf, size_t len);
extern void pospopcnt_mem(int accum[8], const char *buf, size_t len);

extern void

clausecker

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>

extern int
main(int argc, char *argv[])
{
	ssize_t count;
	int flags;

clausecker

/* parallel wc(1) demo program */
/* cc -O3 -fopenmp -o wc wc.c */
#include <ctype.h>
#include <unistd.h>
#include <omp.h>
#include <stdlib.h>
#include <stdio.h>
#include <stdbool.h>
#include <sys/stat.h>