diff options
Diffstat (limited to '')
| -rw-r--r-- | binary-multisearch.h | 152 |
1 files changed, 152 insertions, 0 deletions
diff --git a/binary-multisearch.h b/binary-multisearch.h new file mode 100644 index 0000000..7d8ee16 --- /dev/null +++ b/binary-multisearch.h @@ -0,0 +1,152 @@ +/* + * ISC License + * + * © 2020 Mattias Andrée <maandree@kth.se> + * + * Permission to use, copy, modify, and/or distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + */ +#ifndef BINARY_MUTLISEARCH_H +#define BINARY_MUTLISEARCH_H + +#define __STDC_WANT_LIB_EXT1__ +#include <stddef.h> +#include <stdint.h> +#include <unistd.h> +#ifndef RSIZE_MAX +# define rsize_t size_t +#endif + + +struct binary_multisearch_stack_entry { + rsize_t min; + rsize_t max; + ssize_t lmin; + ssize_t lmax; +}; + + +static ssize_t +binary_search(const void *sought, const void *list, size_t list_width, ssize_t min, + ssize_t max, int (*cmp)(const void *sought, const void *list_elem, void *data), void *data) +{ + const char *clist = list; + ssize_t mid = min; + int r; + + while (min <= max) { + mid = (ssize_t)((size_t)min + (size_t)max) / 2; + r = cmp(sought, &clist[(size_t)mid * list_width], data); + if (r < 0) + max = mid - 1; + else if (r > 0) + min = mid += 1; + else { + return mid; + } + } + + return -mid - 1; +} + + +static void +binary_multisearch(const void *sought, rsize_t sought_count, size_t sought_width, const void *list, rsize_t list_count, + size_t list_width, int (*cmp)(const void *sought_elem, const void *list_elem, void *data), void *data, + ssize_t (*search_function)(const void *sought, const void *list, size_t list_width, ssize_t min, + ssize_t max, int (*cmp)(const void *, const void *, void *), void *data), + struct binary_multisearch_stack_entry stack[restrict], ssize_t r[restrict sought_count]) +{ + struct binary_multisearch_stack_entry e; + size_t stack_i; + ssize_t pos; + const char *csought = sought; + + if (!sought_count) + return; + + stack[0].min = 0; + stack[0].max = sought_count - 1; + stack[0].lmin = 0; + stack[0].lmax = (ssize_t)list_count - 1; + stack_i = 1; + + while (stack_i) { + e = stack[--stack_i]; + while (e.max != e.min) { + stack[stack_i].max = e.max; + stack[stack_i].lmax = e.lmax; + + e.max = (e.min + e.max) / 2; + pos = search_function(&csought[e.max * sought_width], list, list_width, e.lmin, e.lmax, cmp, data); + r[e.max] = pos; + + stack[stack_i].min = e.max + 1; + stack[stack_i].lmin = pos < 0 ? -pos - 1 : pos + 1; + stack_i++; + } + } + + e.max = sought_count - 1; + r[e.max] = search_function(&csought[e.max * sought_width], list, list_width, e.lmin, e.lmax, cmp, data); +} + + +static void +binary_multisearch_online(const void *sought, rsize_t sought_count, size_t sought_width, const void *list, rsize_t list_count, + size_t list_width, int (*cmp)(const void *sought_elem, const void *list_elem, void *data), void *data, + ssize_t (*search_function)(const void *sought, const void *list, size_t list_width, ssize_t min, + ssize_t max, int (*cmp)(const void *, const void *, void *), void *data), + struct binary_multisearch_stack_entry stack[restrict], + void (*result_function)(size_t index, ssize_t position, void *data)) +{ + struct binary_multisearch_stack_entry e; + size_t stack_i; + ssize_t pos; + const char *csought = sought; + + if (!sought_count) + return; + + stack[0].min = 0; + stack[0].max = sought_count - 1; + stack[0].lmin = 0; + stack[0].lmax = (ssize_t)list_count - 1; + stack_i = 1; + + while (stack_i) { + e = stack[--stack_i]; + while (e.max != e.min) { + stack[stack_i].max = e.max; + stack[stack_i].lmax = e.lmax; + + e.max = (e.min + e.max) / 2; + pos = search_function(&csought[e.max * sought_width], list, list_width, e.lmin, e.lmax, cmp, data); + result_function(e.max, pos, data); + + stack[stack_i].min = e.max + 1; + stack[stack_i].lmin = pos < 0 ? -pos - 1 : pos + 1; + stack_i++; + } + } + + e.max = sought_count - 1; + pos = search_function(&csought[e.max * sought_width], list, list_width, e.lmin, e.lmax, cmp, data); + result_function(e.max, pos, data); +} + + +#ifndef RSIZE_MAX +# undef rsize_t +#endif + +#endif |