1 | # Parser function for floating point hexadecimals
|
2 |
|
3 | [![license](https://img.shields.io/github/license/maurobringolf/@webassemblyjs/floating-point-hex-parser.svg)]()
|
4 | [![GitHub last commit](https://img.shields.io/github/last-commit/maurobringolf/@webassemblyjs/floating-point-hex-parser.svg)]()
|
5 | [![npm](https://img.shields.io/npm/v/@webassemblyjs/floating-point-hex-parser.svg)]()
|
6 |
|
7 | > A JavaScript function to parse floating point hexadecimals as defined by the [WebAssembly specification](https://webassembly.github.io/spec/core/text/values.html#text-hexfloat).
|
8 |
|
9 | ## Usage
|
10 |
|
11 | ```javascript
|
12 | import parseHexFloat from '@webassemblyjs/floating-point-hex-parser'
|
13 |
|
14 | parseHexFloat('0x1p-1') // 0.5
|
15 | parseHexFloat('0x1.921fb54442d18p+2') // 6.283185307179586
|
16 | ```
|
17 |
|
18 | ## Tests
|
19 |
|
20 | This module is tested in two ways. The first one is through a small set of test cases that can be found in [test/regular.test.js](https://github.com/maurobringolf/@webassemblyjs/floating-point-hex-parser/blob/master/test/regular.test.js). The second one is non-deterministic (sometimes called *fuzzing*):
|
21 |
|
22 | 1. Generate a random IEEE754 double precision value `x`.
|
23 | 1. Compute its representation `y` in floating point hexadecimal format using the C standard library function `printf` since C supports this format.
|
24 | 1. Give both values to JS testcase and see if `parseHexFloat(y) === x`.
|
25 |
|
26 | By default one `npm test` run tests 100 random samples. If you want to do more, you can set the environment variable `FUZZ_AMOUNT` to whatever number of runs you'd like. Because it uses one child process for each sample, it is really slow though. For more details about the randomized tests see [the source](https://github.com/maurobringolf/@webassemblyjs/floating-point-hex-parser/tree/master/test/fuzzing).
|
27 |
|
28 | ## Links
|
29 |
|
30 | * [maurobringolf.ch/2017/12/hexadecimal-floating-point-notation/](https://maurobringolf.ch/2017/12/hexadecimal-floating-point-notation/)
|
31 |
|
32 | * [github.com/xtuc/js-webassembly-interpreter/issues/32](https://github.com/xtuc/js-webassembly-interpreter/issues/32)
|
33 |
|
34 | * [github.com/WebAssembly/design/issues/292](https://github.com/WebAssembly/design/issues/292)
|