grayflex.h File Reference

Gray code implementation. More...

#include "misc.h"

Go to the source code of this file.

Data Structures
struct	code
	Gray codes. More...
Defines
#define	MAXKAY   16
Functions
int	m4ri_swap_bits (int v, int l)
int	m4ri_gray_code (int i, int l)
void	m4ri_build_code (int *ord, int *inc, int l)
void	m4ri_build_all_codes (void)
	Generates global code book.
void	m4ri_destroy_all_codes (void)
int	m4ri_opt_k (int a, int b, int c)
	Return the optimal var k for the given parameters.
Variables
code **	codebook

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Detailed Description

Gray code implementation.

The Gray code is a binary numeral system where two successive values differ in only one digit.

Author:

Gregory Bard <bard@fordham.edu>

Martin Albrecht <M.R.Albrecht@rhul.ac.uk>

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Define Documentation

#define MAXKAY   16

Maximum allowed value for k.

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Function Documentation

void m4ri_build_all_codes

(

void

)

Generates global code book.

This function is called automatically when the shared library is loaded.

Warning:

Not thread safe!

void m4ri_build_code	(	int *	ord,
		int *	inc,
		int	l
	)

Fills var ord and var inc with Gray code data for a Gray code of length .

Parameters:

ord	Will hold gray code data, must be preallocated with correct size
inc	Will hold some increment data, must be preallocated with correct size
l	Logarithm of length of Gray code.

Note:

Robert Miller had the idea for a non-recursive implementation.

void m4ri_destroy_all_codes

(

void

)

Frees memory from the global code book.

This function is called automatically when the shared library is unloaded.

Warning:

Not thread safe!

int m4ri_gray_code	(	int	i,
		int	l
	)

Returns the i-th gray code entry for a gray code of length .

Parameters:

i	The ndex in the Gray code table.
l	Length of the Gray code.

Returns:

i-th Gray code entry.

int m4ri_opt_k	(	int	a,
		int	b,
		int	c
	)

Return the optimal var k for the given parameters.

If var c != 0 then var k for multiplication is returned, else var k for inversion. The optimal var k here means where is for inversion and for multiplication.

Parameters:

a	Number of rows of (first) matrix
b	Number of columns of (first) matrix
c	Number of columns of second matrix (may be 0)

Returns:

k

int m4ri_swap_bits	(	int	v,
		int	l
	)

Swaps l bits in v.

Warning:

Uppper bits of return value may contain garbage after operation.

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Variable Documentation

code** codebook

Global codebook.

Warning:

Not thread safe!