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Portability: Use stack-allocated arrays only if the compiler supports them.

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This commit is contained in:
Bruno Haible
2003-04-10 10:26:05 +00:00
parent bfefa088aa
commit f619dea2f5
5 changed files with 61 additions and 6 deletions
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40
src/search.cc
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@@ -31,9 +31,33 @@
#include <limits.h> /* defines INT_MIN, INT_MAX, UINT_MAX */
#include "options.h"
#include "hash-table.h"
#include "config.h"
/* ============================== Portability ============================== */
/* Assume ISO C++ 'for' scoping rule. */
#define for if (0) ; else for
/* Dynamically allocated array with dynamic extent:
Example:
DYNAMIC_ARRAY (my_array, int, n);
...
FREE_DYNAMIC_ARRAY (my_array);
Attention: depending on your implementation my_array is either the array
itself or a pointer to the array! Always use my_array only as expression!
*/
#if HAVE_DYNAMIC_ARRAY
#define DYNAMIC_ARRAY(var,eltype,size) eltype var[size]
#define FREE_DYNAMIC_ARRAY(var)
#else
#define DYNAMIC_ARRAY(var,eltype,size) eltype *var = new eltype[size]
#define FREE_DYNAMIC_ARRAY(var) delete[] var
#endif
/* ================================ Theory ================================= */
/* The most general form of the hash function is
hash (keyword) = sum (asso_values[keyword[i] + alpha_inc[i]] : i in Pos)
@@ -589,7 +613,7 @@ Search::find_alpha_inc ()
}
}
unsigned int indices[nindices];
DYNAMIC_ARRAY (indices, unsigned int, nindices);
{
unsigned int j = 0;
PositionIterator iter = _key_positions.iterator(_max_key_len);
@@ -608,8 +632,8 @@ Search::find_alpha_inc ()
/* Perform several rounds of searching for a good alpha increment.
Each round reduces the number of artificial collisions by adding
an increment in a single key position. */
unsigned int best[_max_key_len];
unsigned int tryal[_max_key_len];
DYNAMIC_ARRAY (best, unsigned int, _max_key_len);
DYNAMIC_ARRAY (tryal, unsigned int, _max_key_len);
do
{
/* An increment of 1 is not always enough. Try higher increments
@@ -644,6 +668,8 @@ Search::find_alpha_inc ()
}
}
while (current_duplicates_count > duplicates_goal);
FREE_DYNAMIC_ARRAY (tryal);
FREE_DYNAMIC_ARRAY (best);
if (option[DEBUG])
{
@@ -661,6 +687,7 @@ Search::find_alpha_inc ()
}
fprintf (stderr, "\n");
}
FREE_DYNAMIC_ARRAY (indices);
}
_alpha_inc = current;
@@ -1003,7 +1030,7 @@ Search::count_possible_collisions (EquivalenceClass *partition, unsigned int c)
Return the sum of this expression over all equivalence classes. */
unsigned int sum = 0;
unsigned int m = _max_selchars_length;
unsigned int split_cardinalities[m+1];
DYNAMIC_ARRAY (split_cardinalities, unsigned int, m + 1);
for (EquivalenceClass *cls = partition; cls; cls = cls->_next)
{
for (unsigned int i = 0; i <= m; i++)
@@ -1025,6 +1052,7 @@ Search::count_possible_collisions (EquivalenceClass *partition, unsigned int c)
for (unsigned int i = 0; i <= m; i++)
sum -= split_cardinalities[i] * split_cardinalities[i];
}
FREE_DYNAMIC_ARRAY (split_cardinalities);
return sum;
}
@@ -1231,7 +1259,7 @@ Search::find_asso_values ()
}
unsigned int iterations = 0;
unsigned int iter[k];
DYNAMIC_ARRAY (iter, unsigned int, k);
for (unsigned int i = 0; i < k; i++)
iter[i] = 0;
unsigned int ii = (_jump != 0 ? k - 1 : 0);
@@ -1384,6 +1412,8 @@ Search::find_asso_values ()
ii = 0;
}
}
FREE_DYNAMIC_ARRAY (iter);
if (option[DEBUG])
{
fprintf (stderr, "Step %u chose _asso_values[", stepno);