5 releases

0.0.4	Mar 14, 2024
0.0.3	Mar 10, 2024
0.0.2	Mar 7, 2024
0.0.1	Feb 20, 2024
0.0.0	Dec 3, 2023

#679 in Algorithms

1,147 downloads per month
Used in 3 crates (2 directly)

GPL-3.0-or-later

230KB
7K SLoC

NaNVM

Float64

Sign, 1	Exponent, 11	Fraction, 52	Value
0	000	0_0000_0000_0000	number
	...		number
	7FF	0_0000_0000_0000	+Inf
		...	reserved
		8_0000_0000_0000	NaN
		...	reserved
1	000	0_0000_0000_0000	number
	...		number
	7FF	0_0000_0000_0000	-Inf
		...	reserved

Value

exponent == 0x7FF is used for special values (53 bits):

Special value, 53 bits	Value	# of values
00_0000_0000_0000	+Inf	1
...	reserved	2^51-1
08_0000_0000_0000	Nan	1
...	reserver	2^51-1
10_0000_0000_0000	-Inf	1
...	reserved	2^52-1

Pointers

45 bits = 48 bits - 3 bits of alignment.

We need, at least, two types of pointers:

&string,
&object.

null is a separate value, so our pointers have 2^45 - 1 values.

Array Index

2^32 - 1 values.

Bool

2 values.

Number Extension

prefix
0111_1111_1111_0	Infinity
0111_1111_1111_1	NaN
1111_1111_1111_0	-Infinity
1111_1111_1111_1	Extension

Extension Types

const EXTENSION_MASK: u64 = 0xFFF8_0000_0000_0000;

const PTR_MASK: u64 = EXTENSION | 0x4_0000_0000_0000;
const NULL: u64 = PTR_MASK;

const STR_MASK: u64 = EXTENSION | 0x2_0000_0000_0000;

const STR_PTR_MASK: u64 = PTR_MASK | STR_MASK;

const FALSE: u64 = EXTENSION;
const TRUE: u64 = FALSE | 1;

String

type String16 = Rc<[u16]>;

Object

type Object = Rc<[Value]>

Array

type Array = Rc<[Value]>;

nanvm-lib