Cosine HDL Optimized
Implement fixed-point cosine wave optimized for HDL code generation
Library
HDL Coder™ / Lookup Tables
Description
The Cosine HDL Optimized block implements a fixed-point cosine wave by using a lookup table method that exploits quarter-wave symmetry.
For the most efficient HDL implementation, configure the block with an exact power of
two as the number of elements. In the Block Parameters dialog box, for Number
of data points, specify an integer that is an exact power of two. That
is, specify the lookup table data points to be
(2^n), where n is an
integer. By default, the Number of data points is 64.
When you specify a power of two for the Number of data points, the lookup tables precede a register without reset after HDL code generation. The combination of the lookup table block and register without reset maps efficiently to RAM on the target device.
Depending on your selection of the Output formula parameter, the blocks can output these functions of the input signal:
sin(2πu)
cos(2πu)
exp(i2πu)
sin(2πu) and cos(2πu)
Use the Table data type parameter to specify the word length of the fixed-point output data type. The fraction length of the output is the output word length minus 2.
Data Type Support
The Cosine HDL Optimized block accepts signals of these data types:
Floating point
Built-in integer
Fixed point
Boolean
The output of the block is a fixed-point data type.
For more information, see Data Types Supported by Simulink (Simulink) in the Simulink® documentation.
Parameters
- Output formula
Select the signal(s) to output.
- Number of data points
Specify the number of data points to retrieve from the lookup table. The implementation is most efficient when you specify the lookup table data points to be
(2^n), where n is an integer.- Table data type
Specify the table data type. You can specify an expression that evaluates to a data type, for example,
fixdt(1,16,0).Click the Show data type assistant button
to display the Data Type
Assistant, which helps you set the table data type.- Show data type assistant
Select the mode of data type specification. If you select
Expression, enter an expression that evaluates to a data type, for example,fixdt(1,16,0).If you select
Fixed point, you can use the options in the Data Type Assistant to specify the fixed-point data type. In theFixed pointmode, you can choose binary point scaling, and specify the signedness, word length, fraction length, and the data type override setting.
Characteristics
Data Types | Double | Single | Boolean | Base Integer | Fixed-Point |
Sample Time | Inherited from driving block |
Direct Feedthrough | Yes |
Multidimensional Signals | No |
Variable-Size Signals | No |
Zero-Crossing Detection | No |
Code Generation | Yes |