yet another partitioning function for quicksort

qsort_part.c

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

//#define DEBUG

int compares = 0, swaps = 0;

void dumps(void *d, int c) {
  int i;
  for (i = 0; i < c; i++)
    printf("%s ", *((char **) d + i));
  printf("\n");
}

int (*partition)(void *, int, int, int, int (*)(const void *, const void *));

int partition_2(void *data, int low, int high, int size, int (*cmp)(const void *, const void *)) {
  int i = low;
  int j = high - 1;
  char buf[size];

  memcpy(buf, data + j * size, size);

  int d = 1;
  while (i < j) {
    compares++;
    void *addr = d ? data + size * i : data + size * j;
    void *dest = d ? data + size * j : data + size * i;
    if (d ^ (cmp(buf, addr) > 0)) {
      swaps++;
      memcpy(dest, addr, size);
      d = !d;
    }
    if (d)
      i++;
    else
      j--;
  }

  memcpy(data + size * i, buf, size);

  return i;
}

int partition_1(void *data, int low, int high, int size, int (*cmp)(const void *, const void *)) {
  char buf[size];
  void *pivot = data + size * (high-1);

  int i = low - 1, j;
  for (j = low; j < high-1; j++) {
    compares++;
    if (cmp(data + size * j, pivot) <= 0) {
      i++;
      swaps++;
      memcpy(buf, data + size * j, size);
      memcpy(data + size * j, data + size * i, size);
      memcpy(data + size * i, buf, size);
    }
  }
  i++;
  swaps++;
  memcpy(buf, pivot, size);
  memcpy(pivot, data + size * i, size);
  memcpy(data + size * i, buf, size);
  return i;
}

void qsort(void *data, size_t count, size_t size, int (*cmp)(const void *, const void *)) {
  if (count < 2)
    return;

  int i = partition(data, 0, count, size, cmp);
#ifdef DEBUG
  printf("partition at pos %d\n", i);
  dumps(data, count);
#endif
  qsort(data, i, size, cmp);
  qsort(data + size * (i + 1), count-i-1, size, cmp);
}

int scmp(const void *a, const void *b) {
#ifdef DEBUG
  printf("%s vs %s\n", *(char **)a, *(char **)b);
#endif
  return strcmp(*(char **)a, *(char **)b);
}

int main(int argc, char **argv) {
  int i;
  char **d = malloc(sizeof(char *) * (argc-1));

  memcpy(d, argv+1, (argc-1)*sizeof(char *));
  partition = partition_1;
  dumps(d, argc-1);
  qsort(d, argc-1, sizeof(char *), scmp);
  dumps(d, argc-1);
  printf("Original partition: compares: %d, swaps: %d\n", compares, swaps);

  compares = 0;
  swaps = 0;
  memcpy(d, argv+1, (argc-1)*sizeof(char *));
  partition = partition_2;
  qsort(d, argc-1, sizeof(char *), scmp);
  dumps(d, argc-1);
  printf("Modified partition: compares: %d, swaps: %d\n", compares, swaps);
}