universal ring buffer.

Macros
#define	zRingClass(ring_t, cell_t)
	generate ring buffer class. More...
#define	zRingSize(y)   (y)->size
#define	zRingBuf(y)   ( (y)->buf )
#define	zRingElemSize(y)   sizeof(*zRingBuf(y))
#define	zRingHead(y)   ( &zRingBuf(y)[(y)->head] )
#define	zRingElem(y, i)   ( &zRingBuf(y)[((y)->head+(i)) % (y)->size] )
#define	zRingSetElem(a, i, d)   memcpy( zRingElem(a,i), (d), zRingElemSize(a) )
#define	zRingReset(y)   ( (y)->head = 0 );
#define	zRingInit(y)
#define	zRingAlloc(y, type, size)
	allocate an array. More...
#define	zRingFree(y)
#define	zRingIncHead(y)
#define	zRingDecHead(y)

Detailed Description

Macro Definition Documentation

zRingClass

#define zRingClass	(		ring_t,
			cell_t
	)

Value:

typedef struct{\
  int size;\
  int head;\
  cell_t *buf;\
} ring_t

generate ring buffer class.

A macro zRingClass() can generate a new ring buffer class, which consists of the total number of elements, the current head of the ring buffer, and the pointer to the ring buffer. ring_t is the class name to be defined. cell_t is the class name of the data to be arrayed.

To allocate and free a ring buffer, use zRingAlloc() and zRingFree().

The number of elements is acquired by zRingSize(). The actual array head can be accessed by zRingBuf(). But, the ring buffer conceptually conceal the body array. zRingHead() is preferable to be used, instead. It allows to access to the data at the current head. An elements after some elements the head can be safely accessed by zRingElem() and zRingSetElem().

zRingReset() resets the head position to the actual head of the array.

To advance and get back the head, use zRingIncHead() and zRingDecHead(), respectively.

zRingSize

#define zRingSize

(

y

)

(y)->size

zRingBuf

#define zRingBuf

(

y

)

( (y)->buf )

zRingElemSize

#define zRingElemSize

(

y

)

sizeof(*zRingBuf(y))

zRingHead

#define zRingHead

(

y

)

( &zRingBuf(y)[(y)->head] )

zRingElem

#define zRingElem	(		y,
			i
	)		( &zRingBuf(y)[((y)->head+(i)) % (y)->size] )

zRingSetElem

#define zRingSetElem	(		a,
			i,
			d
	)		memcpy( zRingElem(a,i), (d), zRingElemSize(a) )

zRingReset

#define zRingReset

(

y

)

( (y)->head = 0 );

zRingInit

#define zRingInit

(

y

)

Value:

do{\
  zRingSize(y) = (y)->head = 0;\
  zRingBuf(y) = NULL;\
} while(0)

zRingAlloc

#define zRingAlloc	(		y,
			type,
			size
	)

Value:

do{\
  zRingInit( y );\
  if( !( zRingBuf(y) = zAlloc(type,size) ) )\
    ZALLOCERROR();\
  else\
    zRingSize(y) = (size);\
} while(0)

allocate an array.

Parameters

y	ring buffer class instance to be created.
type	the data type of the array cells.
s	the size of the array.

zRingFree

#define zRingFree

(

y

)

Value:

do{\
  zFree( zRingBuf(y) );\
  zRingInit( y );\
} while(0)

zRingIncHead

#define zRingIncHead

(

y

)

Value:

do{\
  if( ++(y)->head >= zRingSize(y) ) (y)->head = 0;\
} while(0)

zRingDecHead

#define zRingDecHead

(

y

)

Value:

do{\
  if( --(y)->head < 0 ) (y)->head = zRingSize(y) - 1;\
} while(0)