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https://git.code.sf.net/p/quake/quakeforge
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bcc5686606
Fuzzy bsearch is useful for finding an entry in a prefix sum array (value is >= ele[0], < ele[1]), and the reentrant version is good when data needs to be passed to the compare function. Adapted from the code used in pr_resolve.
98 lines
1.8 KiB
C
98 lines
1.8 KiB
C
#include <limits.h>
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#include <string.h>
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#include "QF/fbsearch.h"
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#include "bsearch.h"
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void *fbsearch (const void *key, const void *_base, size_t nmemb, size_t size,
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__compar_fn_t cmp)
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{
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// fuzzy bsearh
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const char *base = (const char *) _base;
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unsigned left = 0;
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unsigned right = nmemb - 1;
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unsigned mid;
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const void *p = 0;
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if (!nmemb) {
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return 0;
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}
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while (left != right) {
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mid = (left + right + 1) / 2;
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p = base + mid * size;
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if (cmp (key, p) < 0) {
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right = mid - 1;
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} else {
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left = mid;
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}
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}
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p = base + left * size;
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if (cmp (key, p) >= 0) {
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return (void *) p;
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}
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return 0;
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}
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void *fbsearch_r (const void *key, const void *_base, size_t nmemb, size_t size,
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__compar_d_fn_t cmp, void *arg)
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{
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// fuzzy bsearh
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const char *base = (const char *) _base;
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unsigned left = 0;
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unsigned right = nmemb - 1;
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unsigned mid;
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const void *p = 0;
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if (!nmemb) {
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return 0;
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}
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while (left != right) {
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mid = (left + right + 1) / 2;
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p = base + mid * size;
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if (cmp (key, p, arg) < 0) {
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right = mid - 1;
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} else {
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left = mid;
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}
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}
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p = base + left * size;
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if (cmp (key, p, arg) >= 0) {
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return (void *) p;
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}
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return 0;
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}
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void *
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_bsearch(const void *key, const void *_base, size_t nmemb, size_t size,
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__compar_d_fn_t cmp, void *arg)
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{
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// fuzzy bsearh
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const char *base = (const char *) _base;
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unsigned left = 0;
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unsigned right = nmemb;
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unsigned mid;
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const void *p = 0;
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int c;
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if (!nmemb) {
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return 0;
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}
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while (left != right) {
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mid = (left + right + 1) / 2;
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p = base + mid * size;
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c = cmp (key, p, arg);
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if (c == 0) {
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return (void *) p;
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}
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if (c < 0) {
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right = mid - 1;
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} else {
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left = mid;
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}
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}
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p = base + left * size;
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if (cmp (key, p, arg) == 0) {
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return (void *) p;
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}
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return 0;
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}
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