This library defines a fixed point numeric type FixedPoint<R>(R) and its operations.
The type is intended for embedded software. As a tuple-struct, FixedPoint is serialised cleanly and compactly. The library is no-std with dependencies on serde and, optionally defmt.
The maximum size of any fixed point representation is deliberately limited to 32 bits (signed) or 31 bits (unsigned) and floating point conversions use f32. This simplifies the code and ensures it runs well on a microcontroller. These limits can be raised by changing Float and Fixed type aliases.
The parameter R is the type of the representation on the wire and in memory. A trait Spec implemented for R gives its scaling and precision. Several types implementing Spec are provided in module unit.
For example, struct Volt(i32) defines an i32 representation of voltage. Then impl Spec for Volt gives the precision of this representation as one decimal place.
The traits defined on FixedPoint provide all representations with:
- Conversions to and from Float.
- Operations add and substract among
FixedPointof the same type and scaling by Float (ie the algebra of a linear space). - Equality and ordering.
- Debug, Display and defmt::Format.
- Parsing from strings.
- Serde.
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This code is open source software licensed under the Apache-2.0 license.
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