Sin

Compute sine operation using CORDIC approximation method and simulate with latency

Since R2020b

• 

Libraries:
HDL Coder

Description

The Sin block computes the sine of input signal by using the coordinate rotation digital computer (CORDIC) approximation method. For more information, see CORDIC approximation method in Algorithms. The block has control signals that indicate whether the input and output data are valid. You can also specify the number of iterations of the algorithm and the latency strategy.

To use this block in your Simulink^® model, open the HDLMathLib library by entering this command in the MATLAB^® Command Window:

open_system('HDLMathLib')

You can simulate the Sin block with latency. For more information, Latency Considerations.

Examples

Implement Sine and Cosine Block with Control Signals

Implement the control-signal based SinCos block and use it generate HDL code.

• Open Script

Ports

Input

dataIn — Input data signal

scalar | vector

Input data signal to compute sine function, specified as a scalar or vector. The input value ranges from -2π to 2*π.

Data Types: int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | Boolean | fixed point | bus

validIn — Whether input control signal is valid

scalar

Input control signal that indicates whether the input signal is valid, specified as a scalar.

Data Types: Boolean

Output

thetaOut — Output data signal

scalar | vector

Output data signal that is the sine of the input signal, returned as a scalar or vector.

Data Types: int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | Boolean | fixed point | bus

validOut — Whether output control signal is valid

scalar

Output control signal that indicates whether output signal is valid, returned as a scalar.

Data Types: Boolean

Parameters

Number of iterations — Number of iterations for CORDIC algorithm

11 (default) | positive integer

Specify the number of iterations for CORDIC algorithm.

Programmatic Use

Block Parameter: iter

Type: character vector

Values: Integer values

Default: '11'

Latency strategy — Latency strategy

Max (default) | Min | Custom | Custom(PerIteration) | Zero

Specify whether to use minimum, maximum, custom, or zero latency. For more information, see Latency Strategy.

To use custom latency for the block, set the Latency strategy to Custom and enter the latency value in the Custom latency field.

You can also control the number of pipeline stages for the iterative algorithm. To customize the latency for iterative algorithm, set the Latency strategy to Custom(PerIteration) and enter the iterations per pipeline value in the IterationsPerPipeline field. (since R2025a)

Programmatic Use

Block Parameter: latencyMode

Type: character vector

Values: 'Max' | 'Min' | 'Custom' | 'Custom(PerIteration)' | 'Zero'

Default: 'Max'

Custom latency — Custom latency

0 (default) | positive integer

Specify the custom latency value. The latency must be a nonnegative integer in the range [0, L], where L is the maximum latency value of Sin block. For more information, see CustomLatency.

Dependency

To enable this parameter, set Latency strategy to Custom.

Programmatic Use

Block Parameter: customLatencyValue

Type: Integer

Values: 0 to Max latency

Default: 0

IterationsPerPipeline — Iterations per pipeline

1 (default) | positive integer

Since R2025a

Specify the iterations to use per each pipeline stage in the algorithm.

Dependency

To enable this parameter, set Latency strategy to Custom(PerIteration).

Programmatic Use

Block Parameter: iterationsPerPipelineValue

Type: Integer

Values: Positive integer

Default: 1

Algorithms

CORDIC

CORDIC is an acronym for coordinate rotation digital computer. The Givens rotation-based CORDIC algorithm is one of the most hardware-efficient algorithms available because it requires only iterative shift-add operations (see References). The CORDIC algorithm eliminates the need for explicit multipliers. Using CORDIC, you can calculate various functions such as sine, cosine, arc sine, arc cosine, arc tangent, and vector magnitude. You can also use this algorithm for divide, square root, hyperbolic, and logarithmic functions.

Increasing the number of CORDIC iterations can produce more accurate results, but doing so increases the expense of the computation and adds latency.

Latency Considerations

You can simulate the Sin block with latency. This block is a masked subsystem that contains a MATLAB Function block, LumpLatency. The subsystem uses this MATLAB Function block to compute the latency based on the Number of iterations. To view the function that computes the latency of the block, open the LumpLatency block in the masked subsystem. To view inside the mask, click the ⇩ icon on the block.

This table shows how the block calculates the latency based on the setting of the Latency strategy parameter:

Latency Strategy	Latency Value (L)
Max	Uses maximum latency by using the equation L = N + 1, where N is the value of the Number of iterations parameter.
Min	Uses minimum latency by using the equation L = 2 + ceil((N -1) / 3).
Custom	Specifies a custom latency value. To specify the latency, enter a value between zero and the maximum latency in the Custom latency parameter. For more information, see Custom latency.
Custom(PerIteration)	Use this setting to control the pipeline stages for the iterative algorithm. Specify the number of pipeline stages per iteration using the IterationsPerPipeline parameter. The block uses the equation L = 1 + ceil(N / K), where K is the value of the IterationsPerPipeline parameter.
Zero	The latency of the block is 0.

Pipeline Customization

The Sin block uses pipelined architectures to implement the CORDIC-based sine algorithm. By default, the block uses the maximum latency, which depends on the Number of iterations parameter. The block performs a single iteration per pipeline stage. For example, if you set the Number of iterations to 15, the latency of the block is 16, based on the latency equation in Latency Considerations. When you increase number of iterations, the latency of the block also increases.

You can customize the latency for the iterative algorithm by setting Latency strategy to Custom(PerIteration), which allows you to control the number of iterations per pipeline stages. For example, if you set the Number of iterations to 15 and you want the block to perform the iterations in three pipeline stages, then set the IterationsPerPipeline to 15/3 = 5. By using the Custom(PerIteration) latency strategy, the latency of the block reduces to 4.

References

[1] Volder, Jack E., “The CORDIC Trigonometric Computing Technique.” IRE Transactions on Electronic Computers EC-8 (1959); 330–334.

[2] Andraka, Ray “A Survey of CORDIC Algorithm for FPGA Based Computers.” Proceedings of the 1998 ACM/SIGDA Sixth International Symposium on Field Programmable Gate Arrays. Feb. 22–24 (1998): 191–200.

[3] Walther, J.S., “A Unified Algorithm for Elementary Functions,” Proceedings of the Spring Joint Computer Conference, May 18-20, 1971: 379–386.

[4] Schelin, Charles W., “Calculator Function Approximation,” The American Mathematical Monthly 90, no. 5 (1983): 317–325.

Extended Capabilities

HDL Code Generation

Generate VHDL, Verilog and SystemVerilog code for FPGA and ASIC designs using HDL Coder™.

The block supports HDL code generation using HDL Coder™. HDL Coder provides additional configuration options that affect HDL implementation and synthesized logic.

HDL Architecture

Architecture	Description
Module (default)	Generate code for the subsystem and the blocks within the subsystem.
BlackBox	Generate a black box interface. The generated HDL code includes only the input/output port definitions for the subsystem. Therefore, you can use a subsystem in your model to generate an interface to existing, manually written HDL code. The black-box interface generation for subsystems is similar to the Model block interface generation without the clock signals.
No HDL	Remove the subsystem from the generated code. You can use the subsystem in simulation, however, treat it as a “no-op” in the HDL code.

HDL Block Properties

General
AdaptivePipelining	Automatic pipeline insertion based on the synthesis tool, target frequency, and multiplier word-lengths. The default is inherit. See also AdaptivePipelining.
BalanceDelays	Detects introduction of new delays along one path and inserts matching delays on the other paths. The default is inherit. See also BalanceDelays.
ClockRatePipelining	Insert pipeline registers at a faster clock rate instead of the slower data rate. The default is inherit. See also ClockRatePipelining.
ConstrainedOutputPipeline	Number of registers to place at the outputs by moving existing delays within your design. Distributed pipelining does not redistribute these registers. The default is 0. For more details, see ConstrainedOutputPipeline.
DistributedPipelining	Pipeline register distribution, or register retiming. The default is inherit. See also DistributedPipelining.
DSPStyle	Synthesis attributes for multiplier mapping. The default is none. See also DSPStyle.
FlattenHierarchy	Remove subsystem hierarchy from generated HDL code. The default is inherit. See also FlattenHierarchy.
InputPipeline	Number of input pipeline stages to insert in the generated code. Distributed pipelining and constrained output pipelining can move these registers. The default is 0. For more details, see InputPipeline.
OutputPipeline	Number of output pipeline stages to insert in the generated code. Distributed pipelining and constrained output pipelining can move these registers. The default is 0. For more details, see OutputPipeline.
SharingFactor	Number of functionally equivalent resources to map to a single shared resource. The default is 0. See also Resource Sharing.
StreamingFactor	Number of parallel data paths, or vectors, that are time multiplexed to transform into serial, scalar data paths. The default is 0, which implements fully parallel data paths. See also Streaming.

Target Specification

This block cannot be the DUT, so the block property settings in the Target Specification tab are ignored.

Limitations

• You cannot use this block in a Synchronous Subsystem block.

• The block does not support resource sharing optimization.

Version History

Introduced in R2020b

R2025a: Control number of pipeline stages per iteration

You can control the pipeline stages for iterative algorithms by setting the LatencyStrategy parameter HDL to Custom(PerIterations), then specifying the number of pipeline stages per iteration by using the IterationsPerPipeline parameter. Use this setting to control the pipeline stages in the generated code and optimize the design for speed and resource utilization.