server/src/common/util/cvector.c

/* vi: set ts=2:
 *
 *
 *  Eressea PB(E)M host Copyright (C) 1998-2003
 *      Christian Schlittchen (corwin@amber.kn-bremen.de)
 *      Katja Zedel (katze@felidae.kn-bremen.de)
 *      Henning Peters (faroul@beyond.kn-bremen.de)
 *      Enno Rehling (enno@eressea.de)
 *      Ingo Wilken (Ingo.Wilken@informatik.uni-oldenburg.de)
 *
 *  based on:
 *
 * Atlantis v1.0  13 September 1993 Copyright 1993 by Russell Wallace
 * Atlantis v1.7                    Copyright 1996 by Alex Schr<EFBFBD>der
 *
 * This program may not be used, modified or distributed without
 * prior permission by the authors of Eressea.
 * This program may not be sold or used commercially without prior written
 * permission from the authors.
 */

#include <config.h>
#include "cvector.h"
#include "rng.h"

#include <stdlib.h>
#include <assert.h>
#include <limits.h>
#include <memory.h>

void
cv_init(cvector * cv)
{
  cv->begin = 0;
  cv->end = 0;
  cv->space = 0;
}

cvector *
cv_kill(cvector * cv)
{
  if (cv->begin) free(cv->begin);
  cv_init(cv);
  return cv;
}

size_t
cv_size(cvector * cv)
{
  return cv->end - cv->begin;
}

void
cv_reserve(cvector * cv, size_t size)
{
  size_t count = cv->end - cv->begin;
  cv->begin = realloc(cv->begin, size * sizeof(void *));

  cv->space = size;
  cv->end = cv->begin + count;
}

void
cv_pushback(cvector * cv, void *u)
{
  if (cv->space == cv_size(cv))
    cv_reserve(cv, cv->space ? cv->space * 2 : 2);
  *(cv->end++) = u;
}

int
__cv_scramblecmp(const void *p1, const void *p2)
{
  return *((long *) p1) - *((long *) p2);
}

#define addptr(p,i)         ((void *)(((char *)p) + i))

/** randomly shuffle an array
 * for correctness, see Donald E. Knuth, The Art of Computer Programming
 */
static void
__cv_scramble(void *v1, size_t n, size_t width)
{
  size_t i;
  void * temp = malloc(width);
  for (i=0;i!=n;++i) {
    size_t j = i + (rng_int() % (n-i));
    memcpy(temp, addptr(v1, i*width), width);
    memcpy(addptr(v1, i*width), addptr(v1, j*width), width);
    memcpy(addptr(v1, j*width), temp, width);
  }
  free(temp);
}

void
v_scramble(void **begin, void **end)
{
  __cv_scramble(begin, end - begin, sizeof(void *));
}