>autoconf check for IEEE 754 floats
Autoconf man says folowing:
>it is safe to assume IEEE-754 in most portable code these days
https://www.gnu.org/software/autoconf/manual/autoconf.html#Floating-Point-Portability
> A union might be more readable
Here is union version of the patch. It's slower 10% than original cube
and dereference version. Have no idea why.
Select performance is improved as in v3.
Also I've investigated a bit why linear package failed. It's usefull
to think in terms of bijections, not in terms of arithmetic functions.
float 1 is 1065353216 hex 3f800000
FLT_MAX / ( 8 >> 3 ) is 2139095039 hex 7f7fffff
FLT_MAX / ( 8 >> 2 ) is 2130706431 hex 7effffff
FLT_MAX / ( 8 >> 1 ) is 2122317823 hex 7e7fffff
FLT_MAX / ( 8 >> 0 ) is 2113929215 hex 7dffffff
This realm borders are completly wrong.
That maens I used 800 thousands values to pack 2billions of values of
realms 1-3, and all other 2.1 bils of values to pack realm 0. Fragile
arithmetics was done wrong.
What I had to use was
Realm 3
INT32_MAX is nan (or something little less than nan)
3*INT32_MAX/4 is 3.689348e+19
Total little less than 512kk different values
Realm 2
3*INT32_MAX/4 is 3.689348e+19
INT32_MAX/2 is 2.000000e+00
Total 512kk different values
Realm 1
INT32_MAX/2 is 2.000000e+00
INT32_MAX/4 is 1.084202e-19
Total 512kk different values
Realm 0
INT32_MAX/4 is 1.084202e-19
0 is 0.000000e+00
Total 512kk different values
Though I hadn't tested it yet. I'm not sure, BTW, hardcoding this
consts is a good idea.
Best regards, Andrey Borodin, Octonica & Ural Federal University.
diff --git a/contrib/cube/cube.c b/contrib/cube/cube.c
index 3feddef..ded639b 100644
--- a/contrib/cube/cube.c
+++ b/contrib/cube/cube.c
@@ -91,14 +91,16 @@ PG_FUNCTION_INFO_V1(cube_enlarge);
/*
** For internal use only
*/
-int32 cube_cmp_v0(NDBOX *a, NDBOX *b);
-bool cube_contains_v0(NDBOX *a, NDBOX *b);
-bool cube_overlap_v0(NDBOX *a, NDBOX *b);
-NDBOX *cube_union_v0(NDBOX *a, NDBOX *b);
-void rt_cube_size(NDBOX *a, double *sz);
-NDBOX *g_cube_binary_union(NDBOX *r1, NDBOX *r2, int *sizep);
-bool g_cube_leaf_consistent(NDBOX *key, NDBOX *query, StrategyNumber
strategy);
-bool g_cube_internal_consistent(NDBOX *key, NDBOX *query,
StrategyNumber strategy);
+static int32 cube_cmp_v0(NDBOX *a, NDBOX *b);
+static bool cube_contains_v0(NDBOX *a, NDBOX *b);
+static bool cube_overlap_v0(NDBOX *a, NDBOX *b);
+static NDBOX *cube_union_v0(NDBOX *a, NDBOX *b);
+static float pack_float(float actualValue, int realm);
+static void rt_cube_size(NDBOX *a, double *sz);
+static void rt_cube_edge(NDBOX *a, double *sz);
+static NDBOX *g_cube_binary_union(NDBOX *r1, NDBOX *r2, int *sizep);
+static bool g_cube_leaf_consistent(NDBOX *key, NDBOX *query,
StrategyNumber strategy);
+static bool g_cube_internal_consistent(NDBOX *key, NDBOX *query,
StrategyNumber strategy);
/*
** Auxiliary funxtions
@@ -419,7 +421,32 @@ g_cube_decompress(PG_FUNCTION_ARGS)
}
PG_RETURN_POINTER(entry);
}
+/*
+ * Function to pack floats of different realms
+ * This function serves to pack bit flags inside float type
+ * Resulted value represent can be from four different "realms"
+ * Every value from realm 3 is greater than any value from realms 2,1 and 0.
+ * Every value from realm 2 is less than every value from realm 3 and greater
+ * than any value from realm 1 and 0, and so on. Values from the same realm
+ * loose two bits of precision. This technique is possible due to floating
+ * point numbers specification according to IEEE 754: exponent bits are highest
+ * (excluding sign bits, but here penalty is always positive). If float a is
+ * greater than float b, integer A with same bit representation as a is greater
+ * than integer B with same bits as b.
+ */
+static float
+pack_float(float actualValue, int realm)
+{
+ union
+ {
+ float fp;
+ int32 bits;
+ } buffer;
+ buffer.fp = actualValue;
+ buffer.bits = (buffer.bits >> 2) + (INT32_MAX / 4) * realm;
+ return buffer.fp;
+}
/*
** The GiST Penalty method for boxes
@@ -428,6 +455,11 @@ g_cube_decompress(PG_FUNCTION_ARGS)
Datum
g_cube_penalty(PG_FUNCTION_ARGS)
{
+ /* REALM 0: No extension is required, volume is zero, return edge
*/
+ /* REALM 1: No extension is required, return nonzero volume
*/
+ /* REALM 2: Volume extension is zero, return nonzero edge extension
*/
+ /* REALM 3: Volume extension is nonzero, return it
*/
+
GISTENTRY *origentry = (GISTENTRY *) PG_GETARG_POINTER(0);
GISTENTRY *newentry = (GISTENTRY *) PG_GETARG_POINTER(1);
float *result = (float *) PG_GETARG_POINTER(2);
@@ -441,9 +473,33 @@ g_cube_penalty(PG_FUNCTION_ARGS)
rt_cube_size(DatumGetNDBOX(origentry->key), &tmp2);
*result = (float) (tmp1 - tmp2);
- /*
- * fprintf(stderr, "penalty\n"); fprintf(stderr, "\t%g\n", *result);
- */
+ if( *result == 0 )
+ {
+ double tmp3 = tmp1; /* remember entry volume */
+ rt_cube_edge(ud, &tmp1);
+ rt_cube_edge(DatumGetNDBOX(origentry->key), &tmp2);
+ *result = (float) (tmp1 - tmp2);
+ if( *result == 0 )
+ {
+ if( tmp3 != 0 )
+ {
+ *result = pack_float(tmp3, 1); /* REALM 1 */
+ }
+ else
+ {
+ *result = pack_float(tmp1, 0); /* REALM 0 */
+ }
+ }
+ else
+ {
+ *result = pack_float(*result, 2); /* REALM 2 */
+ }
+ }
+ else
+ {
+ *result = pack_float(*result, 3); /* REALM 3 */
+ }
+
PG_RETURN_FLOAT8(*result);
}
@@ -626,7 +682,7 @@ g_cube_same(PG_FUNCTION_ARGS)
/*
** SUPPORT ROUTINES
*/
-bool
+static bool
g_cube_leaf_consistent(NDBOX *key,
NDBOX *query,
StrategyNumber strategy)
@@ -658,7 +714,7 @@ g_cube_leaf_consistent(NDBOX *key,
return (retval);
}
-bool
+static bool
g_cube_internal_consistent(NDBOX *key,
NDBOX *query,
StrategyNumber strategy)
@@ -688,7 +744,7 @@ g_cube_internal_consistent(NDBOX *key,
return (retval);
}
-NDBOX *
+static NDBOX *
g_cube_binary_union(NDBOX *r1, NDBOX *r2, int *sizep)
{
NDBOX *retval;
@@ -701,7 +757,7 @@ g_cube_binary_union(NDBOX *r1, NDBOX *r2, int *sizep)
/* cube_union_v0 */
-NDBOX *
+static NDBOX *
cube_union_v0(NDBOX *a, NDBOX *b)
{
int i;
@@ -875,25 +931,40 @@ cube_size(PG_FUNCTION_ARGS)
PG_RETURN_FLOAT8(result);
}
-void
+static void
rt_cube_size(NDBOX *a, double *size)
{
int i;
+ double result = 0;
- if (a == (NDBOX *) NULL)
- *size = 0.0;
- else
+ if (a != (NDBOX *) NULL)
+ {
+ result = 1.0;
+ for (i = 0; i < DIM(a); i++)
+ result *= UR_COORD(a, i) - LL_COORD(a, i);
+ }
+ *size = Abs(result);
+ return;
+}
+
+static void
+rt_cube_edge(NDBOX *a, double *size)
+{
+ int i;
+ double result = 0;
+
+ if (a != (NDBOX *) NULL)
{
- *size = 1.0;
for (i = 0; i < DIM(a); i++)
- *size = (*size) * Abs(UR_COORD(a, i) - LL_COORD(a, i));
+ result += Abs(UR_COORD(a, i) - LL_COORD(a, i));
}
+ *size = result;
return;
}
/* make up a metric in which one box will be 'lower' than the other
-- this can be useful for sorting and to determine uniqueness */
-int32
+static int32
cube_cmp_v0(NDBOX *a, NDBOX *b)
{
int i;
@@ -1080,7 +1151,7 @@ cube_ge(PG_FUNCTION_ARGS)
/* Contains */
/* Box(A) CONTAINS Box(B) IFF pt(A) < pt(B) */
-bool
+static bool
cube_contains_v0(NDBOX *a, NDBOX *b)
{
int i;
@@ -1150,7 +1221,7 @@ cube_contained(PG_FUNCTION_ARGS)
/* Overlap */
/* Box(A) Overlap Box(B) IFF (pt(a)LL < pt(B)UR) && (pt(b)LL < pt(a)UR) */
-bool
+static bool
cube_overlap_v0(NDBOX *a, NDBOX *b)
{
int i;
--
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