locate first span of length 'n' using rank and select #3
2 changed files with 194 additions and 0 deletions
192
examples/ex_4.c
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192
examples/ex_4.c
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#include <assert.h>
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#include <stdarg.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <time.h>
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#include <unistd.h>
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#include "../include/sparsemap.h"
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#pragma GCC diagnostic push
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#pragma GCC diagnostic ignored "-Wvariadic-macros"
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#define __diag(...) \
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do { \
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fprintf(stderr, "%s:%d:%s(): ", __FILE__, __LINE__, __func__); \
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fprintf(stderr, __VA_ARGS__); \
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} while (0)
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#pragma GCC diagnostic pop
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#define SEED
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/* https://burtleburtle.net/bob/rand/smallprng.html */
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typedef struct rnd_ctx {
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uint32_t a;
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uint32_t b;
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uint32_t c;
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uint32_t d;
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} rnd_ctx_t;
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#define __rot(x, k) (((x) << (k)) | ((x) >> (32 - (k))))
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uint32_t
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__random(rnd_ctx_t *x)
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{
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uint32_t e = x->a - __rot(x->b, 27);
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x->a = x->b ^ __rot(x->c, 17);
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x->b = x->c + x->d;
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x->c = x->d + e;
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x->d = e + x->a;
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return x->d;
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}
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void
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__random_seed(rnd_ctx_t *x, uint32_t seed)
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{
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uint32_t i;
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x->a = 0xf1ea5eed, x->b = x->c = x->d = seed;
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for (i = 0; i < 20; ++i) {
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(void)__random(x);
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}
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}
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void
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shuffle(rnd_ctx_t *prng, int *array, size_t n)
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{
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size_t i, j;
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if (n > 1) {
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for (i = n - 1; i > 0; i--) {
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j = (unsigned int)(__random(prng) % (i + 1));
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// XOR swap algorithm
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if (i != j) { // avoid self-swap leading to zero-ing the element
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array[i] = array[i] ^ array[j];
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array[j] = array[i] ^ array[j];
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array[i] = array[i] ^ array[j];
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}
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}
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}
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}
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bool
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was_set(size_t bit, int array[])
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{
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for (int i = 0; i < 1024; i++) {
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if (array[i] == bit)
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return true;
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}
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return false;
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}
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#define TEST_ARRAY_SIZE 1024
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int
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main(void)
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{
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int i = 0;
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size_t rank;
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rnd_ctx_t prng;
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int array[TEST_ARRAY_SIZE];
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// disable buffering
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setbuf(stderr, 0);
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// start with a 1KiB buffer, TEST_ARRAY_SIZE bits
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uint8_t *buf = calloc(TEST_ARRAY_SIZE, sizeof(uint8_t));
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// create the sparse bitmap
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sparsemap_t *map = sparsemap(buf, sizeof(uint8_t) * TEST_ARRAY_SIZE, 0);
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for (i = 0; i < 8; i++)
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sparsemap_set(map, i, true);
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rank = sparsemap_rank(map, 0, 8);
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__diag("rank was %lu at offset 0\n", rank);
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assert(rank == 8);
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for (i = 0; i < 8; i++) {
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bool set = sparsemap_is_set(map, i);
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if (set)
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__diag("verified %d was set, %s\n", i,
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was_set(i, array) ? "but we thought it was" : "because it wasn't");
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else
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__diag("darn, %d was not really set, %s\n", i,
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was_set(i, array) ? "but we thought it was" : "because it wasn't");
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}
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__diag("and %d was %s", i, sparsemap_is_set(map, i + 1) ? "set" : "not set");
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rank = sparsemap_span(map, 0, 8);
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__diag("span was found at %lu\n", rank);
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sparsemap_clear(map);
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for (i = 1; i < 9; i++)
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sparsemap_set(map, i, true);
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rank = sparsemap_rank(map, 0, 10);
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__diag("rank was %lu at offset 1\n", rank);
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assert(rank == 8);
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for (i = 100; i < 108; i++) {
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bool set = sparsemap_is_set(map, i);
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if (set)
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__diag("verified %d was set, %s\n", i,
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was_set(i, array) ? "but knew that" : "because it wasn't");
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else
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__diag("darn, %d was not set, %s\n", i,
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was_set(i, array) ? "and yet we did set it" : "because it wasn't");
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}
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__diag("and %d was %s", i, sparsemap_is_set(map, i + 1) ? "set" : "not set");
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rank = sparsemap_rank(map, 109, 8);
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__diag("rank was %lu at offset 109\n", rank);
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rank = sparsemap_span(map, 0, 8);
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__diag("span was found at %lu\n", rank);
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sparsemap_clear(map);
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for (i = 2049; i < 2057; i++)
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sparsemap_set(map, i, true);
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rank = sparsemap_rank(map, 2048, 8);
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__diag("rank was %lu at offset 108\n", rank);
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assert(rank == 8);
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for (i = 100; i < 108; i++) {
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bool set = sparsemap_is_set(map, i);
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if (set)
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__diag("verified %d was set, %s\n", i,
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was_set(i, array) ? "but we thought it was" : "because it wasn't");
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else
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__diag("darn, %d was not really set, %s\n", i,
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was_set(i, array) ? "but we thought it was" : "because it wasn't");
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}
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__diag("and %d was %s", i, sparsemap_is_set(map, i + 1) ? "set" : "not set");
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rank = sparsemap_rank(map, 2048, 2060);
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__diag("rank was %lu at offset 109\n", rank);
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rank = sparsemap_span(map, 2048, 8);
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__diag("span was found at %lu\n", rank);
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sparsemap_clear(map);
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// seed the PRNG
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#ifdef SEED
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__random_seed(&prng, 8675309);
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#else
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__random_seed(&prng, (unsigned int)time(NULL) ^ getpid());
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#endif
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for (i = 0; i < TEST_ARRAY_SIZE; i++) {
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array[i] = (int)__random(&prng) % 7000 + 1;
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if (array[i] < 0)
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i--;
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}
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// randomize setting the bits on
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shuffle(&prng, array, TEST_ARRAY_SIZE);
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// set all the bits on in a random order
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for (i = 0; i < TEST_ARRAY_SIZE; i++) {
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//__diag("set %d\n", array[i]);
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sparsemap_set(map, array[i], true);
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assert(sparsemap_is_set(map, array[i]) == true);
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}
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size_t l = sparsemap_span(map, 0, 8);
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__diag("found span of 8 at %lu starting from 0\n", l);
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for (i = l; i < l + 8; i++) {
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bool set = sparsemap_is_set(map, l + i);
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if (set)
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__diag("verified %lu was set\n", l + i);
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else
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__diag("darn, %lu was not really set, %s\n", l + i,
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was_set(l + i, array) ? "but we thought it was" : "because it wasn't");
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}
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return 0;
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}
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@ -118,4 +118,6 @@ size_t sparsemap_select(sparsemap_t *map, size_t n);
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/* Counts the set bits in the range [offset, idx]. */
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/* Counts the set bits in the range [offset, idx]. */
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size_t sparsemap_rank(sparsemap_t *map, size_t offset, size_t idx);
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size_t sparsemap_rank(sparsemap_t *map, size_t offset, size_t idx);
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size_t sparsemap_span(sparsemap_t *map, size_t loc, size_t len);
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#endif
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#endif
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Loading…
Reference in a new issue