C Language Simulation for oc reference counting and oc reference counting

C Language Simulation for oc reference counting and oc reference counting

# Include <stdio. h>

# Include <stdlib. h>

// Introduce the reference counting mechanism in c

// The problem to be solved: 1. What are the pointers to a dynamic memory?

// Set the number of dynamic memory record pointers.

// How large is the dynamic memory size to be opened up?

// If the pointer to c needs to open up n Bytes,

// In fact, n + 4 bytes should be opened

// Assume in c: void * p = xalloc (8)

// Then: in actual xalloc, you should call:

// Int * realp = malloc (12)

// Assume that the memory is as follows:

// [_]

// ^

// |

// |

// Realp p

//

// Release process: xrelease (p)

 

// This function corresponds to the alloc method of oc

Void * xalloc (int size)

{

Int * realp = malloc (size + 4 );

/** Realp = 1 ;*/

Realp [0] = 1;

Return realp + 1;

}

 

// Corresponding oc release Method

Void xrelease (void * p)

{

Int * realp = (int *) P-1;

If (realp [0] = 1)

{

Printf ("memory [% p] is actually released... \ n", p );

Free (realp );

}

Else

Realp [0] --;

}

// Retain method corresponding to oc

Void * xretain (void * p)

{

Int * realp = (int *) P-1;

Realp [0] ++;

Return p;

}

 

// RetainCount method corresponding to oc

Int xretainCount (void * p)

{

Return * (int *) P-1 );

}

 

Int main (int argc, char ** argv)

{

Int * p = xalloc (4); // The Memory count pointed to by p is: 1

Printf ("p: [% p] indicates the memory count: % d \ n", p, xretainCount (p ));

 

Int * q = xretain (p); // The Memory count pointed to by p is: 2

// Q = [p retain];

Printf ("p: [% p] indicates the memory count: % d \ n", p, xretainCount (p ));

 

Xrelease (p); // The Memory count pointed to by p is: 1

Printf ("q: [% p] indicates the memory count: % d \ n", q, xretainCount (q ));

Xrelease (q); // The Memory pointed to by q will be actually released

Return 0;

// A large-sized simulated reference counting mechanism

}