Log2Fract32

Overview

Computes the log base 2 using a fast polynomial approximation.

Discussion

Computes the log base 2 using a polynomial approximation. The input format is Q9.23 as well as the output (values in the range +/- 256) The function computes the absolute value of the input before computing the log. The output will always be in the ranage [8 -23]. The results are accurate to within 1.326392691030e-3 (in Q9.23).

For negative inputs the function takes the absolute value. An input of 0 returns -256.

Module Pack

Standard

ClassID

classID = 153

Type Definition

typedef struct _ModuleLog2Fract32
{
ModuleInstanceDescriptor instance;            // Common Audio Weaver module instance structure
} ModuleLog2Fract32Class;

Pins

Input Pins


Name	in
Description	Input signal
Data type	fract32
Channel range	Unrestricted
Block size range	Unrestricted
Sample rate range	Unrestricted
Complex support	Real

Output Pins


Name	out
Description	Output signal
Data Type	fract32

Matlab Usage

File Name: log2_fract32_module.m 
 M = log2_fract32_module(NAME) 
 Creates an Audio Weaver module that computes the log base 2 using a 
 polynomial approximation.  The input is in Q9.23 format and the output in 
 Q9.23.  Arguments: 
    NAME - name of the module.