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Try to reduce the number of malloc() for user-defined functions. Begin

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transfering built-in functions over to the user-define function
mechanism. (CVS 399)

FossilOrigin-Name: c4f9e017b449d4036fa8d2bf77b931d4c31d74f7
This commit is contained in:
drh
2002-02-27 19:50:59 +00:00
parent 1350b030c1
commit dd5baa95e8
5 changed files with 78 additions and 30 deletions
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52
src/func.c
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@@ -16,7 +16,7 @@
** sqliteRegisterBuildinFunctions() found at the bottom of the file.
** All other code has file scope.
**
** $Id: func.c,v 1.4 2002/02/27 19:00:22 drh Exp $
** $Id: func.c,v 1.5 2002/02/27 19:50:59 drh Exp $
*/
#include <ctype.h>
#include <math.h>
@@ -47,6 +47,44 @@ static void lowerFunc(sqlite_func *context, int argc, const char **argv){
}
}
/*
** An instance of the following structure holds the context of a
** sum() or avg() aggregate computation.
*/
typedef struct SumCtx SumCtx;
struct SumCtx {
double sum; /* Sum of terms */
};
/*
** Routines used to compute the sum or average.
*/
static void sumStep(sqlite_func *context, int argc, const char **argv){
SumCtx *p;
double x;
if( argc<1 ) return;
p = sqlite_aggregate_context(context, sizeof(*p));
if( p==0 ) return;
x = argv[0] ? atof(argv[0]) : 0.0;
p->sum += x;
}
static void sumFinalize(sqlite_func *context){
SumCtx *p;
p = sqlite_aggregate_context(context, sizeof(*p));
if( p ){
sqlite_set_result_double(context, p->sum);
}
}
static void avgFinalize(sqlite_func *context){
SumCtx *p;
double rN;
p = sqlite_aggregate_context(context, sizeof(*p));
rN = sqlite_aggregate_count(context);
if( p && rN>0.0 ){
sqlite_set_result_double(context, p->sum/rN);
}
}
/*
** An instance of the following structure holds the context of a
** variance or standard deviation computation.
@@ -55,7 +93,6 @@ typedef struct StdDevCtx StdDevCtx;
struct StdDevCtx {
double sum; /* Sum of terms */
double sum2; /* Sum of the squares of terms */
int n; /* Number of terms seen so far */
};
/*
@@ -67,20 +104,21 @@ static void stdDevStep(sqlite_func *context, int argc, const char **argv){
if( argc<1 ) return;
p = sqlite_aggregate_context(context, sizeof(*p));
if( p==0 ) return;
x = atof(argv[0]);
x = argv[0] ? atof(argv[0]) : 0.0;
p->sum += x;
p->sum2 += x*x;
p->n++;
}
static void stdDevFinalize(sqlite_func *context){
double rN = sqlite_aggregate_count(context);
StdDevCtx *p = sqlite_aggregate_context(context, sizeof(*p));
if( p && p->n>1 ){
double rN = p->n;
if( p && rN>1.0 ){
sqlite_set_result_double(context,
sqrt((p->sum2 - p->sum*p->sum/rN)/(rN-1.0)));
}
}
/*
** This function registered all of the above C functions as SQL
** functions. This should be the only routine in this file with
@@ -90,4 +128,6 @@ void sqliteRegisterBuildinFunctions(sqlite *db){
sqlite_create_function(db, "upper", 1, upperFunc, 0);
sqlite_create_function(db, "lower", 1, lowerFunc, 0);
sqlite_create_aggregate(db, "stddev", 1, stdDevStep, stdDevFinalize, 0);
sqlite_create_aggregate(db, "x_sum", 1, sumStep, sumFinalize, 0);
sqlite_create_aggregate(db, "x_avg", 1, sumStep, avgFinalize, 0);
}