(8.D.1.2) TableLookupV2
- Catherine Spain
Overview
Evenly spaced table lookup
Discussion
Multichannel input / multichannel output table lookup module. The table lookup is evenly spaced, using a variety of interpolation methods. The module performs lookup as Y=f(X) where X is the input to the module and Y is the output. The module contains a table of values which are assumed to be linearly spaced. The first value in the table corresponds to the function value at .minX. The last value in the table corresponds to the function value at .maxX. The field .interpolationType determines how the interpolation occurs.
.interpolationType = 0 - output the nearest value .interpolationType = 1 - linear interpolation between the two nearest values.
Input values outside of the range [minX maxX] are clipped.
Type Definition
typedef struct _ModuleTableLookupV2
{
ModuleInstanceDescriptor instance; // Common Audio Weaver module instance structure
INT32 L; // Number of entries in the table.
INT32 interpolationType; // Selects the type of interpolation: 0=nearest, 1=linear.
FLOAT32 minX; // X value corresponding to the first table entry.
FLOAT32 maxX; // X value corresponding to the last table entry.
FLOAT32 divisor; // Precomputed constant = (L-1)/(maxX-minX) to eliminate division on the target.
INT32 tableHeap; // Heap in which to allocate memory.
FLOAT32* table; // Table of evenly spaced values.
} ModuleTableLookupV2Class;Variables
Properties
Name | Type | Usage | isHidden | Default value | Range | Units |
L | int | const | 0 | 10 | 2:1:5000 | Â |
interpolationType | int | parameter | 0 | 1 | 0:1:1 | Â |
minX | float | parameter | 0 | -1 | -1000:1000 | Â |
maxX | float | parameter | 0 | 1 | -1000:1000 | Â |
divisor | float | state | 0 | 0 | Unrestricted | Â |
tableHeap | int | const | 1 | 2 | Unrestricted | Â |
table | float* | parameter | 0 | [10 x 1] | Unrestricted | Â |
Pins
Input Pins
Name: in
Description: audio input
Data type: float
Channel range: Unrestricted
Block size range: Unrestricted
Sample rate range: Unrestricted
Complex support: Real
Output Pins
Name: out
Description: audio output
Data type: float
MATLAB Usage
File Name: table_lookup_v2_module.m
M=table_lookup_v2_module(NAME, L, MEMHEAP)
Creates a table lookup module for use in the Audio Weaver environment.
This module has 1 multichannel input and 1 multichannel output and performs
evenly spaced table lookup using a variety of interpolation schemes.
Arguments:
NAME - name of the module.
L - size of the table.
MEMHEAP - specifies the memory heap to use to allocate the table
buffer. This is a string and follows the memory allocation
enumeration in Framework.h. Allowable values are:
'AWE_HEAP_FAST' - always use internal DM memory.
'AWE_HEAP_FASTB' - always use internal PM memory.
'AWE_HEAP_SLOW' - always use external memory (the default).
'AWE_HEAP_FAST2SLOW' - use internal memory. If this fails
then use external memory (the default).
The module performs lookup as Y=f(X) where X is the input to the module
and Y is the output. The module contains a table of values which are
assumed to be linearly spaced. The first value in the table corresponds
to the function value at .minX. The last value in the table corresponds
to the function value at .maxX. The field .interpolationType determines
how the interpolation occurs.
.interpolationType = 0, output the nearest value.
.interpolationType = 1, linear interpolation between the two nearest
values.
Input values outside of the range [minX maxX] are clipped.Â