Data Structures
struct	EGpermIt_t
	Structure to store the information relevant to the permutation iterator. More...
Files
file	eg_perm_it.c
file	eg_perm_it.ex.c
file	eg_perm_it.h
Defines
#define	__PERM_IT_NO_INLINE__ 0
	choose a macro or function definition of EGpermItNext
#define	EG_PERMIT_DBG 0
	Debug level for the heap.
#define	EGpermItClear(__gc)
	free all internally allocated memory for the given EGpermIt_t structure.
#define	EGpermItGetChange(__gc) ((const int)((__gc)->changed_pos))
	return which position in the permutation changed in the last iteration.
#define	EGpermItGetSize(__gc) ((const int)((__gc)->sz))
	Return the number of bits for the given permutation iterator.
#define	EGpermItGetTuple(__gc) ((const int*const)((__gc)->tuple))
	Return a constant pointer to the current tuple.
#define	EGpermItInit(__gc, __sz)
	Initialize a binary permutation iterator, and set the iterator to the zero position.
#define	EGpermItNext(__prit)
	move to the next permutation, if no next string exists (i.e. we finish the loop), return 0, otherwise return 1.
#define	EGpermItReset(__gc)
	Reset an initialized permutation iterator to the zero position.
Typedefs
typedef struct EGpermIt_t	EGpermIt_t
	Structure to store the information relevant to the permutation iterator.
Functions
int	main (int argc, char **argv)
	main function
void	prit_usage (char *program)
	given a number, print to standard output a gray code on n bits.

Detailed Description

Here we define an implementation of knuth'__EGs plain changes iterator for permutations of $n$ different elements as defined in ``The Art of Computer Programming, Chapter 7.2.1.2''. We use an algorithms that perform single swaps in each step, the last position of the swap is stored.

Define Documentation

#define __PERM_IT_NO_INLINE__ 0

choose a macro or function definition of EGpermItNext

Definition at line 119 of file eg_perm_it.h.

#define EG_PERMIT_DBG 0

Debug level for the heap.

Definition at line 44 of file eg_perm_it.h.

#define EGpermItClear ( __gc )

Value:

do{\
  EGpermIt_t*const __EGgcit = (__gc);\
  EGfree(__EGgcit->tuple);\
  EGfree(__EGgcit->o_focus);\
  EGfree(__EGgcit->c_focus);\
  memset(__EGgcit,0,sizeof(EGpermIt_t));}while(0)

free all internally allocated memory for the given EGpermIt_t structure.

Parameters:

__gc

pointer to a permutation iterator structure (EGpermIt_t)

Examples:: eg_perm_it.ex.c.

Definition at line 90 of file eg_perm_it.h.

Referenced by main().

#define EGpermItGetChange ( __gc ) ((const int)((__gc)->changed_pos))

return which position in the permutation changed in the last iteration.

Parameters:

__gc

pointer to a permutation iterator structure (EGpermIt_t)

Examples:: eg_perm_it.ex.c.

Definition at line 115 of file eg_perm_it.h.

Referenced by main().

#define EGpermItGetSize ( __gc ) ((const int)((__gc)->sz))

Return the number of bits for the given permutation iterator.

Parameters:

__gc

pointer to a permutation iterator structure (EGpermIt_t)

Returns:: number of bits for the iterator

Definition at line 102 of file eg_perm_it.h.

#define EGpermItGetTuple ( __gc ) ((const int*const)((__gc)->tuple))

Return a constant pointer to the current tuple.

Parameters:

__gc

pointer to a permutation iterator structure (EGpermIt_t)

Returns:: pointer to an array containing the current tuple

Examples:: eg_perm_it.ex.c.

Definition at line 108 of file eg_perm_it.h.

Referenced by main().

#define EGpermItInit	(	__gc,
		__sz
	)

Value:

do{\
  EGpermIt_t*const __EGgcit = (__gc);\
  const int __EGgcsz = __EGgcit->sz = ((int)(__sz));\
  __EGgcit->tuple = EGsMalloc(int,__EGgcsz);\
  __EGgcit->o_focus = EGsMalloc(int,__EGgcsz);\
  __EGgcit->c_focus = EGsMalloc(int,__EGgcsz);\
  EGpermItReset(__EGgcit);}while(0)

Initialize a binary permutation iterator, and set the iterator to the zero position.

Parameters:

	__gc	pointer to a permutation iterator structure (EGpermIt_t)
	__sz	number of bits to be used in the iterator.

Examples:: eg_perm_it.ex.c.

Definition at line 77 of file eg_perm_it.h.

Referenced by main().

#define EGpermItNext ( __prit )

move to the next permutation, if no next string exists (i.e. we finish the loop), return 0, otherwise return 1.

Parameters:

__EGprit

pointer to a permutation iterator structure (EGpermIt_t)

Returns:: zero if no next string exists, otherwise 1.

Examples:: eg_perm_it.ex.c.

Definition at line 129 of file eg_perm_it.h.

Referenced by main().

#define EGpermItReset ( __gc )

Value:

do{\
  EGpermIt_t*const __EGgcit2 = (__gc);\
  register int __EGgci = __EGgcit2->sz;\
  while(__EGgci--){__EGgcit2->tuple[__EGgci] = __EGgci;\
  __EGgcit2->o_focus[__EGgci]=1;\
  __EGgcit2->c_focus[__EGgci]=0;}\
  __EGgcit2->changed_pos=0;}while(0)