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hilbert3d(): enforce input range rather than aborting. #13

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hilbert3d(): enforce input range rather than aborting. #13

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41 changes: 35 additions & 6 deletions structures/hilbert.c
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@
#include <stdio.h>
#include <stdint.h>
#include <assert.h>
#include <math.h>

#include "hilbert.h"

Expand Down Expand Up @@ -107,9 +108,18 @@ uint64_t hilbert3d(float x,float y,float z) {
uint64_t s = 0;
uint32_t m,ux,uy,uz,ut;

assert(x >= 1.0f && x < 2.0f);
assert(y >= 1.0f && y < 2.0f);
assert(z >= 1.0f && z < 2.0f);
const float fMax = nextafterf(2.0f, 0.0f); /* floating point
number just less
than 2.0 */

if(x < 1.0f) x = 1.0f;
else if(x > fMax) x = fMax;

if(y < 1.0f) y = 1.0f;
else if(y > fMax) y = fMax;

if(z < 1.0f) z = 1.0f;
else if(z > fMax) z = fMax;

ux = (*(uint32_t *)&x)>>2;
uy = (*(uint32_t *)&y)>>2;
Expand Down Expand Up @@ -140,6 +150,11 @@ uint64_t hilbert3d(float x,float y,float z) {
else {
ux = ~ux;
uy = ~uy;
/* trq suggested change:
ut = ux;
ux = ~uy;
uy = ~ut;
*/
if (uz&m) {
s |= 4;
}
Expand Down Expand Up @@ -171,6 +186,12 @@ uint64_t hilbert3d(float x,float y,float z) {
uy = ux;
ux = ~uz;
uz = ~ut;
/* trq suggested change:
ut = uy;
uy = ~uz;
uz = ~ut;
*/

s |= 7;
}
else {
Expand All @@ -195,10 +216,18 @@ __uint128_t hilbert3d_double(double x,double y,double z) {
__uint128_t s = 0;
uint64_t m,ux,uy,uz,ut;

assert(x >= 1.0 && x < 2.0);
assert(y >= 1.0 && y < 2.0);
assert(z >= 1.0 && z < 2.0);
const double fMax = nextafterf(2.0, 0.0); /* floating point number
just less than 2.0 */

if(x < 1.0) x = 1.0;
else if(x > fMax) x = fMax;

if(y < 1.0) y = 1.0;
else if(y > fMax) y = fMax;

if(z < 1.0) z = 1.0;
else if(z > fMax) z = fMax;

/* We can only use 42 bits. Lose the last 10 bits. */
ux = (*(uint64_t *)&x)>>10;
uy = (*(uint64_t *)&y)>>10;
Expand Down