memb.c

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#include <string.h>

#include "memb.h"

/*---------------------------------------------------------------------------*/
void
memb_init(struct memb_blocks *m)
{
  memset(m->count, 0, m->num);
  memset(m->mem, 0, m->size * m->num);
}
/*---------------------------------------------------------------------------*/
void *
memb_alloc(struct memb_blocks *m)
{
  int i;

  for(i = 0; i < m->num; ++i) {
    if(m->count[i] == 0) {
      /* If this block was unused, we increase the reference count to
         indicate that it now is used and return a pointer to the
         memory block. */
      ++(m->count[i]);
      return (void *)((char *)m->mem + (i * m->size));
    }
  }

  /* No free block was found, so we return NULL to indicate failure to
     allocate block. */
  return NULL;
}
/*---------------------------------------------------------------------------*/
char
memb_free(struct memb_blocks *m, void *ptr)
{
  int i;
  char *ptr2;

  /* Walk through the list of blocks and try to find the block to
     which the pointer "ptr" points to. */
  ptr2 = (char *)m->mem;
  for(i = 0; i < m->num; ++i) {

    if(ptr2 == (char *)ptr) {
      /* We've found to block to which "ptr" points so we decrease the
         reference count and return the new value of it. */
      if(m->count[i] > 0) {
        /* Make sure that we don't deallocate free memory. */
        --(m->count[i]);
      }
      return m->count[i];
    }
    ptr2 += m->size;
  }
  return -1;
}
/*---------------------------------------------------------------------------*/