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];
      }
    }
  }
}

int
compare_ints(const void *a, const void *b)
{
  return *(const int *)a - *(const int *)b;
}

void
print_array(int *array, size_t l)
{
  int a[l];
  memcpy(a, array, sizeof(int) * l);
  qsort(a, l, sizeof(int), compare_ints);

  printf("int a[] = {");
  for (int i = 0; i < l; i++) {
    printf("%d", a[i]);
    if (i != l) {
      printf(", ");
    }
  }
  printf("};\n");
}

bool
has_span(int *array, size_t n, int x, int l)
{
  if (n == 0 || l <= 0) {
    return false;
  }

  int a[n];
  memcpy(a, array, sizeof(int) * n);
  qsort(a, n, sizeof(int), compare_ints);

  // Iterate through the array to find a span starting at x of length l
  for (size_t i = 0; i < n; i++) {
    if (a[i] == x) {
      // Check if the span can fit in the array
      if (i + l - 1 < n && a[i + l - 1] == x + l - 1) {
        return true; // Found the span
      }
    }
  }

  return false; // Span not found
}

void
print_spans(int *array, size_t n)
{
  int a[n];
  size_t start = 0;
  size_t end = 0;

  if (n == 0) {
    printf("Array is empty\n");
    return;
  }

  memcpy(a, array, sizeof(int) * n);
  qsort(a, n, sizeof(int), compare_ints);

  for (size_t i = 1; i < n; i++) {
    if (a[i] == a[i - 1] + 1) {
      end = i; // Extend the span
    } else {
      // Print the current span
      if (start == end) {
        printf("[%d] ", a[start]);
      } else {
        printf("[%d, %d] ", a[start], a[end]);
      }
      // Move to the next span
      start = i;
      end = i;
    }
  }

  // Print the last span if needed
  if (start == end) {
    printf("[%d]\n", a[start]);
  } else {
    printf("[%d, %d]\n", a[start], a[end]);
  }
}

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(stdout, 0);
  setbuf(stderr, 0);

  // int foo[] = {1, 2, 3, 5, 7, 8 ,9, 10, 21};
  // print_spans(foo, sizeof(foo) / sizeof(foo[0]));
  // exit(0);

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

  // create the sparse bitmap
  sparsemap_t *map = sparsemap(buf, sizeof(uint8_t) * 1024 * 1, 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);

  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);
#endif

  // 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++) {
    uint32_t r = __random(&prng);
    array[i] = (int)r % (4 * TEST_ARRAY_SIZE);
    if (array[i] < 0) {
      i--;
    }
    for (int j = 0; j < i; j++) {
      if (array[j] == array[i]) {
        i--;
      }
    }
  }
  // create a span of at least 8 for testing between 141 and 153
  int j = 143;
  for (i = 0; i < 8; i++) {
    uint32_t r = __random(&prng) % TEST_ARRAY_SIZE;
    array[r] = j++;
  }
  // randomize setting the bits on
  shuffle(&prng, array, TEST_ARRAY_SIZE);
  print_spans(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);
  }

//  for (size_t len = 1; len < TEST_ARRAY_SIZE; len++) {
  for (size_t len = 2; len <= 2; len++) {
    __diag("================> %lu\n", len);
    size_t l = sparsemap_span(map, 0, len);
    __diag("found span of %lu at %lu\n", len, l);
    __diag("is_span(%lu, %lu) == %s\n", l, len,
      has_span(array, TEST_ARRAY_SIZE, l, len) ? "yes" : "no");
    for (i = (int)l; i < l + len; 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, %s\n", i,
          was_set(i, array) ? "but we thought it was" : "because it wasn't");
      }
    }
  }

  return 0;
}