Summary

The Fixed Point Math Library simplifies writing fixed point algorithms, supporting both Q15 and Q16 data formats. Using the simple, C callable functions contained in the library complex fixed point mathematical operations can be easily executed. The library is built into the MPLAB C Compiler and is part of every install.

Description
The Fixed Point Math Library contains functions for manipulating Q15 and Q16 integers. The 16-bit Language Tools document details the operation of the Q15 and Q16 formats and explains each function in detail.

Features
• Free library included with MPLAB compiler

• Compatible with the Microchip PIC24and dsPIC families
• Over 30 math functions for working with Q15 or Q16 data

• Detailed explanation of Q formatted data

• Detailed description of each function

• Highly optimized functions for fast execution

Devices Supported
All processors in the PIC24and dsPIC DSC family

Getting Started
• Download and install MPLAB and the free trial version of the C compiler

• See Chapter 5 of the 16-bit Language Tools Library for complete documentation of the Fixed Point Math Library

• Start writing Q formatted math code!

Common Fixed Point Math Functions

Function

Description

_Q1Xabs*

Absolute value of a Q15/Q16 value

_Q1Xsin*

Sin of a Q15/Q16 number

_Q1Xcos*

Cos of a Q15/Q16 number

_Q1Xtan*

Tan of a Q15/Q16 number

_Q1Xasin*

Arc sin of a Q15/Q16 value

_Q1Xacos*

Arc cos of a Q15/Q16 value

_Q1Xatan*

Arc tan of a Q15/Q16 value

_Q1Xadd*

Sums two Q15/Q16 values, taking care of overflow and underflow

_Q1Xsub*

Subtracts two Q15/Q16 values, taking care of overflow and underflow

_Q1Xlog*

Log of a Q15/Q16 number

_Q1Xatoi*

Converts ASCII number to a Q15/Q16 number

_Q1Xftoi*

Converts a single precision floating point number to a Q1X value

_itoaQ1X*

Converts a Q1X value to an ASCII encoded number

_itofQ1X*

Converts Q1X value to a floating point value

*- function name contains either Q15 or Q16 depending on the variable type

A complete list of fixed point math functions is available in the 16-Bit Language Tool Libraries document