sparsemap/examples/ex_4.c

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

#include "../include/sparsemap.h"

#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wvariadic-macros"
#define __diag(...)                                                \
  do {                                                             \
    fprintf(stderr, "%s:%d:%s(): ", __FILE__, __LINE__, __func__); \
    fprintf(stderr, __VA_ARGS__);                                  \
  } while (0)
#pragma GCC diagnostic pop

#define SEED

/* https://burtleburtle.net/bob/rand/smallprng.html */
typedef struct rnd_ctx {
  uint32_t a;
  uint32_t b;
  uint32_t c;
  uint32_t d;
} rnd_ctx_t;
#define __rot(x, k) (((x) << (k)) | ((x) >> (32 - (k))))
uint32_t
__random(rnd_ctx_t *x)
{
  uint32_t e = x->a - __rot(x->b, 27);
  x->a = x->b ^ __rot(x->c, 17);
  x->b = x->c + x->d;
  x->c = x->d + e;
  x->d = e + x->a;
  return x->d;
}

void
__random_seed(rnd_ctx_t *x, uint32_t seed)
{
  uint32_t i;
  x->a = 0xf1ea5eed, x->b = x->c = x->d = seed;
  for (i = 0; i < 20; ++i) {
    (void)__random(x);
  }
}

void
shuffle(rnd_ctx_t *prng, int *array, size_t n)
{
  size_t i, j;

  if (n > 1) {
    for (i = n - 1; i > 0; i--) {
      j = (unsigned int)(__random(prng) % (i + 1));
      // XOR swap algorithm
      if (i != j) { // avoid self-swap leading to zero-ing the element
        array[i] = array[i] ^ array[j];
        array[j] = array[i] ^ array[j];
        array[i] = array[i] ^ array[j];
      }
    }
  }
}

bool
was_set(size_t bit, const int array[])
{
  for (int i = 0; i < 1024; i++) {
    if (array[i] == (int)bit) {
      return true;
    }
  }
  return false;
}

#define TEST_ARRAY_SIZE 1024

int
main(void)
{
  int i = 0;
  size_t rank;
  rnd_ctx_t prng;
  int array[TEST_ARRAY_SIZE];

  // disable buffering
  setbuf(stderr, 0);

  // start with a 1KiB buffer, TEST_ARRAY_SIZE bits
  uint8_t *buf = calloc(TEST_ARRAY_SIZE, sizeof(uint8_t));

  // create the sparse bitmap
  sparsemap_t *map = sparsemap(buf, sizeof(uint8_t) * TEST_ARRAY_SIZE, 0);

#if 0
  for (i = 0; i < 8; i++) sparsemap_set(map, i, true);
  rank = sparsemap_rank(map, 0, 8);
  __diag("rank was %lu at offset 0\n", rank);
  assert(rank == 8);
  for (i = 0; i < 8; i++) {
    bool set = sparsemap_is_set(map, i);
    if (set) {
      __diag("verified %d was set, %s\n", i,
        was_set(i, array) ? "but we thought it was" : "because it wasn't");
    } else {
      __diag("darn, %d was not really set, %s\n", i,
        was_set(i, array) ? "but we thought it was" : "because it wasn't");
    }
  }
  __diag("and %d was %s", i, sparsemap_is_set(map, i + 1) ? "set" : "not set");
  rank = sparsemap_span(map, 0, 8);
  __diag("span was found at %lu\n", rank);
  sparsemap_clear(map);

  for (i = 2; i < 7; i++) sparsemap_set(map, i, true);
  rank = sparsemap_rank(map, 0, 10);
  __diag("rank was %lu between [0, 10]\n", rank);
  assert(rank == 5);
  sparsemap_clear(map);
#endif

  for (i = 2049; i < 2057; i++) sparsemap_set(map, i, true);
  rank = sparsemap_rank(map, 2049, 2058);
  __diag("rank was %lu at offset 108\n", rank);
  assert(rank == 8);
  for (i = 2049; i < 2057; i++) {
    bool set = sparsemap_is_set(map, i);
    if (set) {
      __diag("verified %d was set\n", i);
    } else {
      __diag("darn, %d was not really set\n", i);
    }
  }
  __diag("and %d was %s", i, sparsemap_is_set(map, i + 1) ? "set" : "not set");
  rank = sparsemap_rank(map, 2048, 2060);
  __diag("rank was %lu at offset 109\n", rank);
  //rank = sparsemap_span(map, 2048, 8);
  //__diag("span was found at %lu\n", rank);
  sparsemap_clear(map);

  // seed the PRNG
#ifdef SEED
  __random_seed(&prng, 8675309);
#else
  __random_seed(&prng, (unsigned int)time(NULL) ^ getpid());
#endif

  for (i = 0; i < TEST_ARRAY_SIZE; i++) {
    array[i] = (int)__random(&prng) % TEST_ARRAY_SIZE + 1;
    if (array[i] < 0) {
      i--;
    }
  }
  // randomize setting the bits on
  shuffle(&prng, array, TEST_ARRAY_SIZE);

  // set all the bits on in a random order
  for (i = 0; i < TEST_ARRAY_SIZE; i++) {
    //__diag("set %d\n", array[i]);
    sparsemap_set(map, array[i], true);
    assert(sparsemap_is_set(map, array[i]) == true);
  }

  size_t len  = 6;
  size_t l = sparsemap_span(map, 0, len);
  __diag("found span of %d at %lu starting from 0\n", len, l);
  for (i = (int)l; i < l + len; i++) {
    bool set = sparsemap_is_set(map, i);
    if (set) {
      __diag("verified %lu was set\n", i);
    } else {
      __diag("darn, %lu was not really set, %s\n", i,
        was_set(i, array) ? "but we thought it was" : "because it wasn't");
    }
  }

  return 0;
}