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Use binary search to speed up deep lookups.

This commit is contained in:
steve 2002-05-29 05:37:35 +00:00
parent 450b9ab85c
commit f704d4d3ff
1 changed files with 30 additions and 14 deletions
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44
vvp/symbols.cc
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@ -17,7 +17,7 @@
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#if !defined(WINNT)
#ident "$Id: symbols.cc,v 1.4 2001/11/02 04:48:03 steve Exp $"
#ident "$Id: symbols.cc,v 1.5 2002/05/29 05:37:35 steve Exp $"
#endif
# include "symbols.h"
@ -41,8 +41,8 @@ struct symbol_table_s {
* simple binary search to find an item. Each key represents an item.
*/
const unsigned leaf_width = 511;
const unsigned node_width = 511;
const unsigned leaf_width = 254;
const unsigned node_width = 508;
struct tree_node_ {
bool leaf_flag;
@ -274,22 +274,35 @@ static symbol_value_t find_value_(symbol_table_t tbl, struct tree_node_*cur,
}
} else {
unsigned idx = 0;
/* Do a binary search within the inner node. */
unsigned min = 0;
unsigned max = cur->count;
unsigned idx = max/2;
for (;;) {
if (idx == cur->count) {
idx -= 1;
return find_value_(tbl, cur->child[idx],
key, val, force_flag);
}
int rc = strcmp(key, node_last_key(cur->child[idx]));
if (rc <= 0) {
if (rc == 0) {
return find_value_(tbl, cur->child[idx],
key, val, force_flag);
key, val, force_flag);
}
idx += 1;
if (rc > 0) {
min = idx + 1;
if (min == cur->count)
return find_value_(tbl, cur->child[idx],
key, val, force_flag);
if (min == max)
return find_value_(tbl, cur->child[max],
key, val, force_flag);
idx = min + (max-min)/2;
} else {
max = idx;
if (idx == min)
return find_value_(tbl, cur->child[idx],
key, val, force_flag);
idx = min + (max-min)/2;
}
}
}
@ -347,6 +360,9 @@ symbol_value_t sym_get_value(symbol_table_t tbl, const char*key)
/*
* $Log: symbols.cc,v $
* Revision 1.5 2002/05/29 05:37:35 steve
* Use binary search to speed up deep lookups.
*
* Revision 1.4 2001/11/02 04:48:03 steve
* Implement split_node for symbol table (hendrik)
*