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RTL Style Parameters

You access the register transfer logic (RTL) style parameters in the HDL Code Generation > Global Settings > Coding Style tab in the Configuration Parameters dialog box.

Use “rising_edge/falling_edge” Style for Registers

Specify whether generated code uses the VHDL® rising_edge function or the falling_edge function to detect clock transitions.

Settings

Default: Off

On

Generated code uses either the rising_edge function or the falling_edge function.

For example, this following code generated from a Unit Delay block uses the rising_edge function to detect positive clock transitions:

Unit_Delay1_process : PROCESS (clk, reset)
  BEGIN
    IF reset = '1' THEN
      Unit_Delay1_out1 <= (OTHERS => '0');
    ELSIF rising_edge(clk) THEN
      IF clk_enable = '1' THEN
        Unit_Delay1_out1 <= signed(x_in);
      END IF;
    END IF; 
  END PROCESS Unit_Delay1_process;

Off

Generated code uses the 'event syntax.

For example, this code generated from a Unit Delay block uses clk'event AND clk = '1' to detect positive clock transitions:

Unit_Delay1_process : PROCESS (clk, reset)
  BEGIN
    IF reset = '1' THEN
      Unit_Delay1_out1 <= (OTHERS => '0');
    ELSIF clk'event AND clk = '1' THEN
      IF clk_enable = '1' THEN
        Unit_Delay1_out1 <= signed(x_in);
      END IF;
    END IF; 
  END PROCESS Unit_Delay1_process;

Dependency

This option is enabled when the target language is VHDL.

Command-Line Information

Property: UseRisingEdge
Type: character vector
Value: 'on' | 'off'
Default: 'off'

To set this property, use the functions hdlset_param or makehdl. To view the property value, use the function hdlget_param.

Minimize Intermediate Signals

Specify whether to optimize HDL code for debuggability or code coverage.

Settings

Default: Off

On

Optimize the code coverage by minimizing intermediate signals. For example, with this setting as off, suppose that the generated code is:

const3 <= to_signed(24, 7);
subtractor_sub_cast <= resize(const3, 8);
subtractor_sub_cast_1 <= resize(delayout, 8);
subtractor_sub_temp <= subtractor_sub_cast - subtractor_sub_cast_1;

With this setting as on, HDL Coder™ optimizes the output to:

subtractor_sub_temp <= 24 - (resize(delayout, 8));

The code generator removes the intermediate signals const3, subtractor_sub_cast, and subtractor_sub_cast_1.

Off

Optimize the code for debuggability by preserving intermediate signals.

Command-Line Information

Property: MinimizeIntermediateSignals
Type: character vector
Value: 'on' | 'off'
Default: 'off'

To set this property, use the functions hdlset_param or makehdl. To view the property value, use the function hdlget_param.

Unroll For-Generate Loops in VHDL Code

Specify whether VHDL FOR and GENERATE loops are unrolled and omitted from generated VHDL code.

Settings

Default: Off

On

Unroll and omit FOR and GENERATE loops from the generated VHDL code. (In Verilog® code, loops are always unrolled.)

Off

Include FOR and GENERATE loops in the generated VHDL code.

Command-Line Information

Property: LoopUnrolling
Type: character vector
Value: 'on' | 'off'
Default: 'off'

To set this property, use the functions hdlset_param or makehdl. To view the property value, use the function hdlget_param.

For some Simulink® blocks, by default, the HDL code is generated by using a FOR-GENERATE loop construct when you set the target language to VHDL. These Simulink blocks are:

The code generated by using a FOR-GENERATE loop has better code readability, reduced lines of code, and reduced code generation time. For example, consider the VHDL code generated for reshaping a 2-D matrix into a 1-D matrix. The example shows the code generated for the Reshape block with and without FOR-GENERATE loops.

  • Reshape block without FOR-GENERATE loop (Unroll for Generate Loops for VHDL code is enabled):

Reshape_output : PROCESS (In1_signed)
BEGIN
Reshape_out1(0) <= In1_signed(0, 0);
Reshape_out1(1) <= In1_signed(1, 0);
Reshape_out1(2) <= In1_signed(2, 0);
Reshape_out1(3) <= In1_signed(3, 0);
Reshape_out1(4) <= In1_signed(4, 0);
Reshape_out1(5) <= In1_signed(5, 0);
Reshape_out1(6) <= In1_signed(6, 0);
Reshape_out1(7) <= In1_signed(7, 0);
Reshape_out1(8) <= In1_signed(8, 0);
Reshape_out1(9) <= In1_signed(9, 0);
Reshape_out1(10) <= In1_signed(0, 1);
...

  • Reshape block with a FOR-GENERATE loop (Unroll for Generate Loops for VHDL code is disabled):

Reshape_out1GEN_LABEL1: FOR d1 IN 0 TO 1 GENERATE
  Reshape_out1GEN_LABEL: FOR d0 IN 0 TO 9 GENERATE
     Reshape_out1(d0 + (d1*10)) <= In1_signed(d0, d1);
  END GENERATE;
END GENERATE;

Tips

  • If you are using an electronic design automation (EDA) tool that does not support GENERATE loops, select the loop unrolling option to omit loops from your generated VHDL code.

  • Setting the loop unrolling option does not affect results obtained from simulation or synthesis of generated VHDL code.

Dependency

This option is enabled when the target language is VHDL.

Generate Parameterized HDL Code from Masked Subsystem

Generate reusable HDL code for subsystems that have the same tunable mask parameters, but with different values.

Settings

Default: Off

On

Generate one reusable HDL file for multiple masked subsystems that have different values for the mask parameters. HDL Coder supports scalar, vector, and matrix values as mask parameters. HDL Coder detects subsystems that have tunable mask parameters, which are sharable.

Inside the subsystem, you can use the mask parameter only in the blocks and parameters listed in the table.

Block ParameterLimitation
Constant Constant value on the Main tab in the dialog boxNone
GainGain on the Main tab in the dialog boxParameter data type must be the same for all Gain blocks.
Off

Generate a separate HDL file for each masked subsystem.

Command-Line Information

Property: MaskParameterAsGeneric
Type: character vector
Value: 'on' | 'off'
Default: 'off'

To set this property, use the functions hdlset_param or makehdl. To view the property value, use the function hdlget_param.

Restrictions for Mask Parameter Values

  • Each value must be a scalar, vector, or matrix.

  • Values must not be complex.

  • Values must not be enumerated data.

See Also

Generate Reusable Code for Subsystems

Enumerated Type Encoding Scheme

Specify the encoding scheme to represent enumeration types in the generated HDL code.

Settings

Default: default

Use a default, onehot, twohot, or binary encoding scheme to represent enumerated types in the generated HDL code.

default

The code generator uses decimal encoding in Verilog and VHDL-native enumerated types in VHDL. This example shows the Verilog code snippet of this encoding scheme for a Stateflow® Chart that has four states.

parameter 
is_Chart_IN_s_idle = 2'd0, 
is_Chart_IN_s_rx = 2'd1, 
is_Chart_IN_s_wait_0 = 2'd2, 
is_Chart_IN_s_wait_tb = 2'd3;

onehot

The code generator uses a one-hot encoding scheme where a single bit is high to represent each enumeration value. This example shows the Verilog code snippet of this encoding scheme for a Stateflow Chart that has four states.

parameter 
is_Chart_IN_s_idle = 4'b0001, 
is_Chart_IN_s_rx = 4'b0010, 
is_Chart_IN_s_wait_0 = 4'b0100, 
is_Chart_IN_s_wait_tb = 4'b1000;
This encoding scheme does not support more than 64 enumeration values or numbers of states.

twohot

The code generator uses a two-hot encoding scheme where two bits are high to represent each enumeration value. This example shows the Verilog code snippet of this encoding scheme for a Stateflow Chart that has four states.

parameter 
is_Chart_IN_s_idle = 4'b0011, 
is_Chart_IN_s_rx = 4'b0101, 
is_Chart_IN_s_wait_0 = 4'b0110, 
is_Chart_IN_s_wait_tb = 4'b1001;

binary

The code generator uses a binary encoding scheme to represent each enumeration value. This example shows the Verilog code snippet of this encoding scheme for a Stateflow Chart that has four states.

parameter 
is_Chart_IN_s_idle = 2'b00, 
is_Chart_IN_s_rx = 2'b01, 
is_Chart_IN_s_wait_0 = 2'b10, 
is_Chart_IN_s_wait_tb = 2'b11;

In VHDL, the generated code uses CONSTANT types to encode nondefault enumeration values in the generated code. For example, this code snippet shows the generated VHDL code when you use the two-hot state encoding for a Stateflow Chart that has four states.

 PACKAGE s_pkg IS
  -- Constants
  -- Two-hot encoded enumeration values for type state_type_is_Chart
  CONSTANT IN_s_idle         : std_logic_vector(3 DOWNTO 0) := 
    "0011";
  CONSTANT IN_s_rx           : std_logic_vector(3 DOWNTO 0) := 
    "0101";
  CONSTANT IN_s_wait_0       : std_logic_vector(3 DOWNTO 0) := 
    "0110";
  CONSTANT IN_s_wait_tb      : std_logic_vector(3 DOWNTO 0) := 
    "1001";

END s_pkg;

Command-Line Information

Property: EnumEncodingScheme
Type: character vector
Value: 'default' | 'onehot' | 'twohot''binary'
Default: 'default'

To set this property, use the functions hdlset_param or makehdl. To view the property value, use the function hdlget_param.

Indexing for Scalarized Port Naming

Specify the starting index for the names of scalarized vector ports. For an example, see Scalarization of Vector Ports in Generated VHDL Code.

Settings

Default: Zero-based

Zero-based

The starting index for the names of scalarized vector ports is 0. For example, if you have an input u that is a 1x10 vector of type uint16 that has been scalarized, the generated HDL code snippet might look like this code:

ENTITY Subsystem IS
  PORT( u_0        :   IN    std_logic_vector(15 DOWNTO 0);  -- uint16
        u_1        :   IN    std_logic_vector(15 DOWNTO 0);  -- uint16
        u_2        :   IN    std_logic_vector(15 DOWNTO 0);  -- uint16
        u_3        :   IN    std_logic_vector(15 DOWNTO 0);  -- uint16
        u_4        :   IN    std_logic_vector(15 DOWNTO 0);  -- uint16
        u_5        :   IN    std_logic_vector(15 DOWNTO 0);  -- uint16
        u_6        :   IN    std_logic_vector(15 DOWNTO 0);  -- uint16
        u_7        :   IN    std_logic_vector(15 DOWNTO 0);  -- uint16
        u_8        :   IN    std_logic_vector(15 DOWNTO 0);  -- uint16
        u_9        :   IN    std_logic_vector(15 DOWNTO 0);  -- uint16
        );
END Subsystem;

One-based

The starting index for the names of scalarized vector ports is 1. For example, if you have an input u that is a 1x10 vector of type uint16 that has been scalarized, the generated HDL code snippet might look like this code:

ENTITY Subsystem IS
  PORT( u_1      :   IN    std_logic_vector(15 DOWNTO 0);  -- uint16
        u_2      :   IN    std_logic_vector(15 DOWNTO 0);  -- uint16
        u_3      :   IN    std_logic_vector(15 DOWNTO 0);  -- uint16
        u_4      :   IN    std_logic_vector(15 DOWNTO 0);  -- uint16
        u_5      :   IN    std_logic_vector(15 DOWNTO 0);  -- uint16
        u_6      :   IN    std_logic_vector(15 DOWNTO 0);  -- uint16
        u_7      :   IN    std_logic_vector(15 DOWNTO 0);  -- uint16
        u_8      :   IN    std_logic_vector(15 DOWNTO 0);  -- uint16
        u_9      :   IN    std_logic_vector(15 DOWNTO 0);  -- uint16
        u_10     :   IN    std_logic_vector(15 DOWNTO 0);  -- uint16
        );
END Subsystem;

Dependency

This option is applied when the model configuration parameter Scalarize ports is set to on or DUT Level. For more information, see the Scalarize ports section of DUT Port Configuration Parameters.

Command-Line Information

Property: ScalarizedPortIndexing
Type: character vector
Value: 'Zero-based' | 'One-based'
Default: 'Zero-based'

To set this property, use the functions hdlset_param or makehdl. To view the property value, use the function hdlget_param.

Generate Record Types for Bus

Generate code with VHDL construct record types for bus signals at design-under-test (DUT) interfaces and different subsystem-level interfaces. For more information, see Generate VHDL Code with Record Types for Bus Signals.

Settings

Default: Off

On

Generate record types for bus signals in your VHDL code. For example, this code snippet shows the generated VHDL code for a subsystem where In1 and Out1 are the bus ports that are defined using the record types. 

ENTITY Subsystem IS
  PORT( clk          :   IN    std_logic;
        reset        :   IN    std_logic;
        In1          :   IN    BusObject_record;  -- record {double,double}
        Out1         :   OUT   BusObject_record  -- record {double,double}
        );
END Subsystem;
The package file defines the record BusObject_record, which consists of two bus elements with data type double.

PACKAGE Subsystem_pkg IS
  TYPE BusObject_record IS RECORD
    signal1           : std_logic_vector(63 DOWNTO 0);
    signal2           : std_logic_vector(63 DOWNTO 0);
  END RECORD BusObject_record;

END Subsystem_pkg;

Off

HDL Coder flattens the bus elements ports at the subsystem interface. This code snippet shows the generated VHDL code for the subsystem without record types:

ENTITY Subsystem IS
  PORT( clk              :   IN    std_logic;
        reset            :   IN    std_logic;
        In1_signal1      :   IN    std_logic_vector(63 DOWNTO 0);  -- double
        In1_signal2      :   IN    std_logic_vector(63 DOWNTO 0);  -- double
        Out1_signal1     :   OUT   std_logic_vector(63 DOWNTO 0);  -- double
        Out1_signal2     :   OUT   std_logic_vector(63 DOWNTO 0)  -- double
        );
END Subsystem;

Command-Line Information

Property: GenerateRecordType
Type: character vector
Value: 'on' | 'off'
Default: 'off'

To set this property, use the functions hdlset_param or makehdl. To view the property value, use the function hdlget_param.

Dependency

To enable this parameter, set Target language to VHDL.

See Also

Generate VHDL Code with Record Types for Bus Signals