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Sqrt

Implement control-signal-based square root function

Since R2020b

  • HDL Math Sqrt Block

Description

HDL Math Sqrt Block

The Sqrt block performs the square root operation of the input data signal. 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")

Latency Considerations

You can simulate the Sqrt block with latency. This block is a masked subsystem that contains the LumpLatency MATLAB Function block. The subsystem uses this MATLAB Function block to compute the latency based on the input and output data types. The software calculates the latency of the block using the word length and fractional length of fixed-point input and output.

The block supports three latency modes. You can specify a custom latency value by setting the Latency Strategy parameter to Custom.

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. For more information, see Lump Latency for Square-root Block.

Limitations

  • The block does not support floating-point data types, such as half, single, and double.

Ports

Input

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Input signal to calculate the square root.

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

Input control signal that indicates whether the input signal is valid.

Data Types: Boolean

Output

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Output signal that is the square root of the input signal.

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

Output control signal that indicates whether output signal is valid.

Data Types: Boolean

Parameters

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Specify whether to map the blocks in your design to minimum, maximum, custom, or zero latency. For more information, see LatencyStrategy.

Programmatic Use

Block Parameter: latencyMode
Type: character vector
Values: 'Max' | 'Min' | 'Custom' | 'Zero'
Default: 'Max'

When you set Latency strategy to Custom, use this parameter to 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 Sqrt block. For more information, see CustomLatency.

Dependency

To use this parameter, set Latency strategy to Custom.

Programmatic Use

Block Parameter: customLatencyValue
Type: Integer
Values: 0 to Max latency
Default: 0

Specify the output data type. The data type can be inherited or specified directly.

Programmatic Use

Block Parameter: OutDataTypeStr
Type: character vector
Values: 'Inherit: Inherit via internal rule' | 'Inherit: Inherit via back propagation' | 'Inherit: Same as first input' | 'int8' | 'uint8' | int16 | 'uint16' | 'int32' | 'uint32' | 'int64' | 'uint64' | fixdt(1,16,0) | '<data type expression>'
Default: 'Inherit: Same as first input'

ActionReasons for Taking This ActionWhat Happens for OverflowsExample

Select this check box.

Your model has possible overflow, and you want explicit saturation protection in the generated code.

Overflows saturate to either the minimum or maximum value that the data type can represent.

The maximum value that the int8 (signed, 8-bit integer) data type can represent is 127. Any block operation result greater than this maximum value causes overflow of the 8-bit integer. With the check box selected, the block output saturates at 127. Similarly, the block output saturates at a minimum output value of -128.

Do not select this check box.

You want to optimize efficiency of your generated code.

You want to avoid overspecifying how a block handles out-of-range signals. For more information, see Troubleshoot Signal Range Errors.

Overflows wrap to the value that is representable by the data type.

The maximum value that the int8 (signed, 8-bit integer) data type can represent is 127. Any block operation result greater than this maximum value causes overflow of the 8-bit integer. With the check box cleared, the software interprets the overflow-causing value as int8, which can produce an unintended result. For example, a block result of 130 (binary 1000 0010) expressed as int8, is -126.

When you select this check box, saturation applies to every internal operation on the block, not just the output or result. Usually, the code generation process can detect when overflow is not possible. In this case, the code generator does not produce saturation code.

Programmatic Use

Block Parameter: SaturateOnIntegerOverflow
Type: character vector
Value: 'off' | 'on'
Default: 'off'

Specify the rounding mode for fixed-point operations. For more information, see Rounding.

Programmatic Use

Block Parameter: RndMeth
Type: character vector
Values: 'Zero' | 'Ceiling' | 'Floor' | 'Nearest' | 'Simplest'
Default: 'Zero'

Tips

The block supports HDL code generation using HDL Coder™. HDL Coder supports additional configuration options that affect HDL implementation and synthesized logic. For more information, see HDL Block Properties.

Algorithms

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Version History

Introduced in R2020b