ch_math_utils.h File Reference

Functions for performing fixed point arithmetic. https://github.com/dmoulding/log2fix https://github.com/chmike/fpsqrt. More...

#include <stdio.h>
#include <math.h>
#include <stdint.h>

Go to the source code of this file.

Macros
#define	FIXED2FLOAT(x)   (((float)(x)) / (1 << FRACT_BITS))
#define	FIXED2INT(x)   ((x) >> FRACT_BITS)
#define	FIXED_PI   0x3243FU
#define	FIXEDDIV(x, y)   ((fixed_t)(((uint64_t)(x) << FRACT_BITS) / (y)))
#define	FIXEDMUL(x, y)   ((fixed_t)(((x) >> (FRACT_BITS / 2)) * ((y) >> (FRACT_BITS / 2))))
#define	FLOAT2FIXED(x)   ((fixed_t)((x) * (1 << FRACT_BITS)))
#define	FRACT_BITS   16
#define	INT2FIXED(x)   ((x) << FRACT_BITS)
#define	INV_LOG2_E_Q1DOT31   0x58b90bfcU
#define	Q31_TO_Q16_SHIFT_1   10
#define	Q31_TO_Q16_SHIFT_2   (Q31_TO_Q16_SHIFT_BITS - Q31_TO_Q16_SHIFT_1)
#define	Q31_TO_Q16_SHIFT_BITS   15

Typedefs
typedef uint32_t	fixed_t

Functions
fixed_t	FP_log (fixed_t x)
	Find the natural logarithm in UQ16.16 fixed-point format. More...
fixed_t	FP_log2 (fixed_t x)
	Find the base 2 logarithm in UQ16.16 fixed-point format. More...
fixed_t	FP_sqrt (fixed_t x)
int32_t	sqrt_int32 (int32_t v)
	Compute the square root of a 32-bit integer. More...

Detailed Description

Functions for performing fixed point arithmetic. https://github.com/dmoulding/log2fix https://github.com/chmike/fpsqrt.

Date

July 20, 2017

Author

nparikh

Copyright

Copyright 2017 Chirp Microsystems. All rights reserved.

Function Documentation

FP_log()

fixed_t FP_log

(

fixed_t

x

)

Find the natural logarithm in UQ16.16 fixed-point format.

Parameters

x	Find the natural log of the provided number. This number is is UQ16.16 fixed-point format.

Returns

The natural log of x in UQ16.16 format.

This function is adapted from work by dmoulding with very minor changes. The source for the original function, logfix, can be found here:

https://github.com/dmoulding/log2fix/blob/master/log2fix.c

FP_log2()

fixed_t FP_log2

(

fixed_t

x

)

Find the base 2 logarithm in UQ16.16 fixed-point format.

Parameters

x	Find the log base-2 of the provided number. This number is is UQ16.16 fixed-point format.

Returns

The log base-2 of x in UQ16.16 format.

This function is adapted from work by dmoulding with very minor changes. The source for the original function, log2fix, can be found here:

https://github.com/dmoulding/log2fix/blob/master/log2fix.c

sqrt_int32()

int32_t sqrt_int32

(

int32_t

v

)

Compute the square root of a 32-bit integer.

Parameters

x	Find the square root of the provided integer.

Returns

The square root of x as a 32-bit integer.

This function is adapted from work by chmike with very minor changes. The source for the original function, sqrt_i32, can be found here:

https://github.com/chmike/fpsqrt/blob/master/fpsqrt.c