godot/core/hashfuncs.h
Hein-Pieter van Braam b696beea65 Correct hash behavior for floating point numbers
This fixes HashMap where a key or part of a key is a floating point
number. To fix this the following has been done:

* HashMap now takes an extra template argument Comparator. This class
gets used to compare keys. The default Comperator now works correctly
for common types and floating point numbets.

* Variant implements ::hash_compare() now. This function implements
nan-safe comparison for all types with components that contain floating
point numbers.

* Variant now has a VariantComparator which uses Variant::hash_compare()
safely compare floating point components of variant's types.

* The hash functions for floating point numbers will now normalize NaN
values so that all floating point numbers that are NaN hash to the same
value.

C++ module writers that want to use HashMap internally in their modules
can now also safeguard against this crash by defining their on
Comperator class that safely compares their types.

GDScript users, or writers of modules that don't use HashMap internally
in their modules don't need to do anything.

This fixes #7354 and fixes #6947.
2017-02-16 18:44:29 +01:00

154 lines
4.2 KiB
C++

/*************************************************************************/
/* hashfuncs.h */
/*************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
/* http://www.godotengine.org */
/*************************************************************************/
/* Copyright (c) 2007-2017 Juan Linietsky, Ariel Manzur. */
/* */
/* Permission is hereby granted, free of charge, to any person obtaining */
/* a copy of this software and associated documentation files (the */
/* "Software"), to deal in the Software without restriction, including */
/* without limitation the rights to use, copy, modify, merge, publish, */
/* distribute, sublicense, and/or sell copies of the Software, and to */
/* permit persons to whom the Software is furnished to do so, subject to */
/* the following conditions: */
/* */
/* The above copyright notice and this permission notice shall be */
/* included in all copies or substantial portions of the Software. */
/* */
/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */
/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY */
/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, */
/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE */
/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
/*************************************************************************/
#ifndef HASHFUNCS_H
#define HASHFUNCS_H
#include "math_funcs.h"
#include "math_defs.h"
#include "typedefs.h"
/**
* Hashing functions
*/
/**
* DJB2 Hash function
* @param C String
* @return 32-bits hashcode
*/
static inline uint32_t hash_djb2(const char *p_cstr) {
const unsigned char* chr=(const unsigned char*)p_cstr;
uint32_t hash = 5381;
uint32_t c;
while ((c = *chr++))
hash = ((hash << 5) + hash) + c; /* hash * 33 + c */
return hash;
}
static inline uint32_t hash_djb2_buffer(const uint8_t *p_buff, int p_len,uint32_t p_prev=5381) {
uint32_t hash = p_prev;
for(int i=0;i<p_len;i++)
hash = ((hash << 5) + hash) + p_buff[i]; /* hash * 33 + c */
return hash;
}
static inline uint32_t hash_djb2_one_32(uint32_t p_in,uint32_t p_prev=5381) {
return ((p_prev<<5)+p_prev)+p_in;
}
static inline uint32_t hash_one_uint64(const uint64_t p_int) {
uint64_t v=p_int;
v = (~v) + (v << 18); // v = (v << 18) - v - 1;
v = v ^ (v >> 31);
v = v * 21; // v = (v + (v << 2)) + (v << 4);
v = v ^ (v >> 11);
v = v + (v << 6);
v = v ^ (v >> 22);
return (int) v;
}
static inline uint32_t hash_djb2_one_float(float p_in,uint32_t p_prev=5381) {
union {
float f;
uint32_t i;
} u;
// Normalize +/- 0.0 and NaN values so they hash the same.
if (p_in==0.0f)
u.f=0.0;
else if (Math::is_nan(p_in))
u.f=Math_NAN;
else
u.f=p_in;
return ((p_prev<<5)+p_prev)+u.i;
}
// Overload for real_t size changes
static inline uint32_t hash_djb2_one_float(double p_in,uint32_t p_prev=5381) {
union {
double d;
uint64_t i;
} u;
// Normalize +/- 0.0 and NaN values so they hash the same.
if (p_in==0.0f)
u.d=0.0;
else if (Math::is_nan(p_in))
u.d=Math_NAN;
else
u.d=p_in;
return ((p_prev<<5)+p_prev) + hash_one_uint64(u.i);
}
template<class T>
static inline uint32_t make_uint32_t(T p_in) {
union {
T t;
uint32_t _u32;
} _u;
_u._u32=0;
_u.t=p_in;
return _u._u32;
}
static inline uint64_t hash_djb2_one_64(uint64_t p_in,uint64_t p_prev=5381) {
return ((p_prev<<5)+p_prev)+p_in;
}
template<class T>
static inline uint64_t make_uint64_t(T p_in) {
union {
T t;
uint64_t _u64;
} _u;
_u._u64=0; // in case p_in is smaller
_u.t=p_in;
return _u._u64;
}
#endif