fixedpoint 1.0.1 Package Documentation

Release 1.0.1

The fixedpoint package offers several features that are widely used in DSP applications:

• Generate fixed point numbers from string literals, integers, or floating point numbers.

• Specify bit widths and signedness, or allow it to be deduced

• Various rounding methods

• Various overflow handling methods

• Configurable alerts for overflow, property mismatches, and implicit casting errors

• Arithmetic operations such as addition, subtraction, multiplication, exponentiation

• Bitwise operations AND, OR, XOR, and inversion.

• Type casting to int, float, bool, str

• Built-in string formatting (f-strings or str.format())

• Comparisons with other FixedPoint, int, or float objects

The fixedpoint package is unit-tested against MATLAB stimulus (with the fixed point toolbox), making the fixedpoint package a viable, accurate, and cost-free alternative to MATLAB.

Installation

The fixedpoint package is available on PyPI. You can install with pip:

pip install -U fixedpoint

The -U will install and/or update to the latest version.

Useful Links

• Source Code

• Bugfix/Enhancement Request

• PyPI Project

Table of Contents

Definitions

• Fixed Point Basics
  • Q Format
  • Representable Range
• The FixedPoint Class
• The FixedPointBits Class
• The PropertyResolver Class
• Functions
• Exceptions

Examples

• Initialization
  • Initializing from a float
  • Initializing from an int
  • Initializing from a str
  • Initializing from another FixedPoint
  • Initializing from other types
  • Initializers
  • overflow
    • 'clamp'
    • 'wrap'
  • rounding
    • 'convergent'
    • 'nearest'
    • 'out'
    • 'in'
    • 'up'
    • 'down'
  • overflow_alert
    • 'error'
    • 'warning'
    • 'ignore'
  • mismatch_alert
    • 'error'
    • 'warning'
    • 'ignore'
  • implicit_cast_alert
    • 'error'
    • 'warning'
    • 'ignore'
  • str_base
    • 16
    • 10
    • 8
    • 2
• Arithmetic
  • Addition
    • Unsigned
    • Signed
    • Mixed Signedness
    • Additional Examples
  • Subtraction
    • Unsigned
    • Signed
    • Mixed Signedness
  • Multiplication
    • Unsigned
    • Signed
    • Mixed Signedness
  • Exponentiation
  • Negation & Absolute Value
  • Bitwise Operations
    • Left Shift
    • Right Shift
    • AND, OR, XOR
    • Inversion
• Bit Resizing
  • resize
  • trim
  • Rounding
    • Default rounding
    • math.floor()
    • math.ceil()
    • math.trunc()
    • Rounding-induced overflow
    • Overflow-safe rounding
    • Rounding beyond the fractional bit width
  • Overflow Handling
    • Clamping/wrapping below 0 integer bits
• Context Management
  • Basic Usage
  • Context Initialization
  • Retaining the Context
• Bit Slicing
  • Bit Random Access
    • Single-Bit Random Access
    • Multi-Bit Random Access
  • Bit Mappings
• String Conversion and Formatting
  • String Conversion
  • String Formatting
    • str() Output
    • Q Format
    • FixedPoint.bits
    • Integer and Fractional Bits
    • Float Equivalent
• Miscellaneous
  • Logging Integration
    • Warnings
    • Debug Logging
  • Typing
  • Numpy Integration
  • Serialization
    • JSON
    • Pickle

Indices and tables

• Index

• Search Page

License

The fixedpoint package is released under the BSD license.

Copyright (c) 2019-2020, Schweitzer Engineering Laboratories, Inc. All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS “AS IS” AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.