fhash

Fast hash map implementation in fortran

Description

Implemention of the GCC hashmap structure in Fortran. It supports any types of keys and values, as long as you set the following macros:

• FHASH_NAME;

• KEY_TYPE and VALUE_TYPE with corresponding use statements KEY_USE and VALUE_USE,

and, optionally,

• KEYS_EQUAL_FUNC: the comparison operator for the keys (defaults to either a == b or all(a == b), depending on whether the key is a scalar;

• HASH_FUNC, which takes a key and returns a hash integer. There are defaults for integers and integer arrays;

• VALUE_POINTER: when defined the values are assumed to be pointers.

Benchmarks

For

• key: integer array of size 2;

• value: double precision (64-bit) floating point;

• 10M entries,

on

• Intel(R) Core(TM) i7-6820HQ CPU @ 2.70GHz;

• Ubuntu 20.04.3 LTS,

I got

		ifort 2021	gfortran 9
insert	fhash	2.99	2.38
	C++ (STL)	2.80	2.69
clear	fhash	1.24	0.391
	C++ (STL)	0.37	0.328