#include "random.h"
#include <stdbool.h>
#include <stdint.h>
#include "debug.h"

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Functions
static void	swap_byte (uint8_t a, uint8_t b)
	Swaps the bytes pointed to by A and B. More...

void	random_init (unsigned seed)
	Initializes or reinitializes the PRNG with the given SEED. More...

void	random_bytes (void *buf_, size_t size)
	Writes SIZE random bytes into BUF. More...

unsigned long	random_ulong (void)
	Returns a pseudo-random unsigned long. More...

Variables
static uint8_t	s [256]
	RC4-based pseudo-random number generator (PRNG). More...

static uint8_t	s_i

static uint8_t	s_j
	i, j. More...

static bool	inited
	Already initialized? More...

Function Documentation

◆ random_bytes()

void random_bytes	(	void *	buf_,
		size_t	size
	)

Writes SIZE random bytes into BUF.

Definition at line 54 of file random.c.

References buf, inited, random_init(), s, s_i, s_j, and swap_byte().

Referenced by main(), random_ulong(), seq_test(), and test_main().

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◆ random_init()

void random_init ( unsigned seed )

Initializes or reinitializes the PRNG with the given SEED.

Definition at line 34 of file random.c.

References inited, s, s_i, s_j, and swap_byte().

Referenced by consume_some_resources_and_die(), main(), parse_options(), random_bytes(), and test_main().

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◆ random_ulong()

unsigned long random_ulong ( void )

Returns a pseudo-random unsigned long.

lib/random.h

Use random_ulong() % n to obtain a random number in the range 0...n (exclusive).

Definition at line 78 of file random.c.

References random_bytes().

Referenced by consume_some_resources_and_die(), expand(), pick_pivot(), shuffle(), test(), and write_some_bytes().

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◆ swap_byte()

static void swap_byte	(	uint8_t *	a,
		uint8_t *	b
	)

inlinestatic

Swaps the bytes pointed to by A and B.

Definition at line 25 of file random.c.

Referenced by random_bytes(), and random_init().

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Variable Documentation

◆ inited

bool inited

static

Already initialized?

Definition at line 21 of file random.c.

Referenced by init(), random_bytes(), and random_init().

◆ s

uint8_t s[256]

static

RC4-based pseudo-random number generator (PRNG).

RC4 is a stream cipher. We're not using it here for its cryptographic properties, but because it is easy to implement and its output is plenty random for non-cryptographic purposes.

See http://en.wikipedia.org/wiki/RC4_(cipher) for information on RC4. RC4 state. S[].

Definition at line 17 of file random.c.

Referenced by __vprintf(), arc4_crypt(), arc4_init(), atoi(), cksum(), hash_string(), parse_octal_field(), puts(), random_bytes(), random_init(), shutdown_power_off(), strtok_r(), and udiv64().