https://github.com/haukex/fp2conv
FP2 Conversion Library
https://github.com/haukex/fp2conv
arduino c campbellscientific perl5 python3
Last synced: 3 months ago
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FP2 Conversion Library
- Host: GitHub
- URL: https://github.com/haukex/fp2conv
- Owner: haukex
- License: gpl-3.0
- Created: 2023-03-26T12:10:56.000Z (about 2 years ago)
- Default Branch: main
- Last Pushed: 2023-03-26T18:06:27.000Z (about 2 years ago)
- Last Synced: 2025-01-19T17:33:42.928Z (5 months ago)
- Topics: arduino, c, campbellscientific, perl5, python3
- Language: C
- Homepage:
- Size: 35.2 KB
- Stars: 0
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE.txt
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README
fp2conv
=======
"FP2" is a 16-bit data type that is defined to store values
from +/-0.001 to +/-7999 (up to 4 significant digits).
**NOTE:** This data type is not my invention; it is already used on
numerous embedded devices.
This library provides functions to convert these data types to and
from strings, see `fp2conv.h` for details. The data type is defined
as follows:
| bit 15 (MSB) | bits 14 - 13 | bits 12 - 0 (LSB) |
| :------------------ | :--------------: | ----------------: |
| sign (0=pos, 1=neg) | decimal position | significand |
The meanings of bits 14-13 (decimal position) are defined as follows:
| bit 14 | bit 13 | dec. pos. | value range |
| -----: | -----: | --------: | -----------------: |
| 0 | 0 | `XXXX.` | +/-800 to +/-7999. |
| 0 | 1 | `XXX.X` | +/- 80 to +/-799.9 |
| 1 | 0 | `XX.XX` | +/- 8 to +/-79.99 |
| 1 | 1 | `X.XXX` | 0 to +/-7.999 |
Note that identical values can be represented in different ways. This
library uses the above value range to decide the storage format, thus
for example the integer 1 is stored as `0x63E8`, even though it could
also be stored as `0x4064`, `0x200A`, or `0x0001`. As one exception,
zero (0) is stored as `0x0000`. Note the conversion from FP2 to string
can handle all of the aforementioned values.
Though theoretically 13 bits can store values from 0 to 8191,
this data type defines the maximum value at 7999; in addition,
the following special values are defined:
| Value | FP2 bytes |
| ------ | --------- |
| +Inf | `0x1FFF` |
| -Inf | `0x9FFF` |
| NaN | `0x9FFE` |
| Fail\* | `0xFFFF` |
\* This is not part of the original specification, but as far as I can
tell this value should never occur otherwise, so this code uses it to
indicate that the conversion could not be performed.
Compilation
-----------
Using the provided `Makefile`, you can simply run `make` to build
`libfp2conv.so`, and `make test` to build and run `test_fp2conv.c`.
The library and headers can be installed via `sudo make install`.
Tested on Linux with gcc 7.5.0.
Arduino
-------
The `fp2conv.c` / `fp2conv.h` files were tested to be working on an
Arduino MKR series board with a SAMD21 processor
using the Arduino IDE 2.0.0.
The source files can be installed to your local Arduino library path
with `make ardulibinst`, assuming the default environment on Linux.
Python
------
Simple Python bindings are provided in `pyfp2conv.py` with tests in `tests/`.
Tested on Python 3.10 on Linux.
Perl
----
Simple Perl FFI bindings are provided in `lib/Data/FP2.pm` with tests in `t/`.
The CPAN module `FFI::Platypus` is required.
Tested on Perl 5.34 and 5.28 on Linux.
Note: If `FFI::Platypus` fails to build due to a missing `xlocale.h`,
a workaround is: `cd /usr/include && sudo ln -si locale.h xlocale.h`
Tests
-----
All tests can be run via the included shell script `prove.sh`.
Author, Copyright, and License
------------------------------
Copyright (c) 2022 Hauke Daempfling
at the Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB),
Berlin, Germany,
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see .