Enumeration fields

Register fields can be of the type enumeration. Meaning, a field that can only take on a limited, pre-defined, and named, set of values. This is a very common and highly useful programming concept. See Wikipedia if you are unfamiliar with this: https://en.wikipedia.org/wiki/Enumerated_type

This page will show you how the set up enumeration fields in a register, and will showcase all the code that can be generated from it.

Usage in TOML

The TOML file below shows how to set up a register with two enumeration fields. See comments for rules about the different properties.

TOML that sets up a register with enumeration fields.
 1[config]
 2
 3mode = "r_w"
 4description = "Configuration register."
 5
 6# This will allocate an enumeration field named "severity_level" in the "config" register.
 7[config.severity_level]
 8
 9# The "type" property MUST be present and set to "enumeration".
10type = "enumeration"
11
12# The "description" property is OPTIONAL for an enumeration field.
13# Will default to "" if not specified.
14# The value specified MUST be a string.
15description = "Run-time configuration of severity."
16
17# The "default_value" property is OPTIONAL for an enumeration field.
18# Will default to the first enumeration element declared below, if not specified.
19# The value specified MUST be a string that matches one of the enumeration element names
20# specified below.
21default_value = "warning"
22
23# For an enumeration field there MUST be at least one enumeration element declared.
24# The name of each element is mapped below to the description of that element.
25element.info = "Informational message. Is not considered an error."
26element.warning = "Warning message. Is not considered an error."
27element.error = "Error message. Is considered an error."
28element.failure = "Failure message. Is considered an error."
29
30
31[config.packet_source]
32
33type = "enumeration"
34description = "Set input mux."
35
36element.streaming = "Process incoming streaming data."
37element.dma = "Read packets from DMA."
38element.none = "Don't send anything."

Note that the second field does not have any default value, meaning that it will automatically default to the first element (streaming).

Below you will see how you can parse this TOML file and generate artifacts from it.

Usage with Python API

The Python code below shows

  1. How to parse the TOML file listed above.

  2. How to create an identical register list when instead using the Python API.

  3. How to generate register artifacts.

Note that the result of the create_from_api call is identical to that of the parse_toml call. Meaning that using a TOML file or using the Python API is completely equivalent. You choose yourself which method you want to use in your code base.

Python code that sets up a register with enumeration fields.
 1# Standard libraries
 2import sys
 3from pathlib import Path
 4
 5# First party libraries
 6from hdl_registers.generator.c.header import CHeaderGenerator
 7from hdl_registers.generator.cpp.implementation import CppImplementationGenerator
 8from hdl_registers.generator.cpp.interface import CppInterfaceGenerator
 9from hdl_registers.generator.html.page import HtmlPageGenerator
10from hdl_registers.generator.vhdl.record_package import VhdlRecordPackageGenerator
11from hdl_registers.generator.vhdl.register_package import VhdlRegisterPackageGenerator
12from hdl_registers.parser.toml import from_toml
13from hdl_registers.register_list import RegisterList
14from hdl_registers.register_modes import REGISTER_MODES
15
16THIS_DIR = Path(__file__).parent
17
18
19def parse_toml() -> RegisterList:
20    """
21    Create the register list by parsing a TOML data file.
22    """
23    return from_toml(name="caesar", toml_file=THIS_DIR.parent / "toml" / "field_enumeration.toml")
24
25
26def create_from_api() -> RegisterList:
27    """
28    Alternative method: Create the register list by using the Python API.
29    """
30    register_list = RegisterList(name="caesar")
31
32    register = register_list.append_register(
33        name="config", mode=REGISTER_MODES["r_w"], description="Configuration register."
34    )
35
36    register.append_enumeration(
37        name="severity_level",
38        description="Run-time configuration of severity.",
39        elements={
40            "info": "Informational message. Is not considered an error.",
41            "warning": "Warning message. Is not considered an error.",
42            "error": "Error message. Is considered an error.",
43            "failure": "Failure message. Is considered an error.",
44        },
45        default_value="warning",
46    )
47
48    register.append_enumeration(
49        name="packet_source",
50        description="Set input mux.",
51        elements={
52            "streaming": "Process incoming streaming data.",
53            "dma": "Read packets from DMA.",
54            "none": "Don't send anything.",
55        },
56        default_value="streaming",
57    )
58
59    return register_list
60
61
62def generate(register_list: RegisterList, output_folder: Path):
63    """
64    Generate the artifacts that we are interested in.
65    """
66    CHeaderGenerator(register_list=register_list, output_folder=output_folder).create()
67
68    CppImplementationGenerator(register_list=register_list, output_folder=output_folder).create()
69    CppInterfaceGenerator(register_list=register_list, output_folder=output_folder).create()
70
71    HtmlPageGenerator(register_list=register_list, output_folder=output_folder).create()
72
73    VhdlRegisterPackageGenerator(register_list=register_list, output_folder=output_folder).create()
74    VhdlRecordPackageGenerator(register_list=register_list, output_folder=output_folder).create()
75
76
77def main(output_folder: Path):
78    generate(register_list=parse_toml(), output_folder=output_folder / "toml")
79    generate(register_list=create_from_api(), output_folder=output_folder / "api")
80
81
82if __name__ == "__main__":
83    main(output_folder=Path(sys.argv[1]))

See Register.append_enumeration() for more Python API details.

Generated code

See below for a description of the code that can be generated when using enumeration fields.

HTML page

See HTML file below for the human-readable documentation that is produced by the generate() call in the Python example above. Each enumeration field is documented and the description of each element is included.

See HTML code generator for more details about the HTML generator and its capabilities.

HTML page

VHDL package

The VHDL code below is produced by the generate() call in the Python example above. Click the button to expand and view the code. See VHDL code generator for instructions on how it can be used in your VHDL project.

Base register package

Some interesting things to notice:

  1. There is only one register, at index 0.

  2. The first field is two bits wide, occupying bits 1 and 0, while the second one is only one bit wide, occupying but 3.

  3. VHDL supports enumeration types natively. The elements of the enumeration are exposed to the scope of the package, and all files that include it.

  4. For each enumeration field, there are conversion functions for

    1. Converting from the enumeration type to std_logic_vector.

    2. Slicing a register value at the correct range and converting from std_logic_vector to enumeration.

Click to expand/collapse code.
Generated VHDL register package.
  1-- -----------------------------------------------------------------------------
  2-- This file is automatically generated by hdl-registers version 7.0.2-dev.
  3-- Code generator VhdlRegisterPackageGenerator version 2.0.0.
  4-- Generated 2025-01-21 20:52 at commit 3c3e6c67d817.
  5-- Register hash c2412eacf08bbf54a4f274f2d5acaec28407a34e.
  6-- -----------------------------------------------------------------------------
  7
  8library ieee;
  9use ieee.std_logic_1164.all;
 10use ieee.numeric_std.all;
 11use ieee.fixed_pkg.all;
 12
 13library register_file;
 14use register_file.register_file_pkg.all;
 15
 16
 17package caesar_regs_pkg is
 18
 19  -- ---------------------------------------------------------------------------
 20  -- The valid range of register indexes.
 21  subtype caesar_register_range is natural range 0 to 0;
 22
 23  -- ---------------------------------------------------------------------------
 24  -- The number of bits needed to address all 1 registers on a register bus.
 25  -- Note that this figure includes the lowest two address bits that are assumed zero, since
 26  -- registers are 32-bit and unaligned accesses are not supported.
 27  constant caesar_address_width : positive := 3;
 28
 29  -- Register indexes, within the list of registers.
 30  constant caesar_config : natural := 0;
 31
 32  -- Declare 'register_map' and 'regs_init' constants here but define them in
 33  -- the package body (deferred constants).
 34  -- So that functions have been elaborated when they are called.
 35  -- Needed for ModelSim compilation to pass.
 36
 37  -- To be used as the 'registers' generic of 'axi_lite_register_file.vhd'.
 38  constant caesar_register_map : register_definition_vec_t(caesar_register_range);
 39
 40  -- To be used for the 'regs_up' and 'regs_down' ports of 'axi_lite_register_file.vhd'.
 41  subtype caesar_regs_t is register_vec_t(caesar_register_range);
 42  -- To be used as the 'default_values' generic of 'axi_lite_register_file.vhd'.
 43  constant caesar_regs_init : caesar_regs_t;
 44
 45  -- To be used for the 'reg_was_read' and 'reg_was_written' ports of 'axi_lite_register_file.vhd'.
 46  subtype caesar_reg_was_accessed_t is std_ulogic_vector(caesar_register_range);
 47
 48  -- -----------------------------------------------------------------------------
 49  -- Fields in the 'config' register.
 50  -- Range of the 'severity_level' field.
 51  subtype caesar_config_severity_level is natural range 1 downto 0;
 52  -- Width of the 'severity_level' field.
 53  constant caesar_config_severity_level_width : positive := 2;
 54  -- Type for the 'severity_level' field.
 55  type caesar_config_severity_level_t is (
 56    severity_level_info,
 57    severity_level_warning,
 58    severity_level_error,
 59    severity_level_failure
 60  );
 61  -- Default value of the 'severity_level' field.
 62  constant caesar_config_severity_level_init : caesar_config_severity_level_t := severity_level_warning;
 63  -- Type for the 'severity_level' field as an SLV.
 64  subtype caesar_config_severity_level_slv_t is std_ulogic_vector(1 downto 0);
 65  -- Cast a 'severity_level' field value to SLV.
 66  function to_slv(data : caesar_config_severity_level_t) return caesar_config_severity_level_slv_t;
 67  -- Get a 'severity_level' field value from a register value.
 68  function to_caesar_config_severity_level(data : register_t) return caesar_config_severity_level_t;
 69
 70  -- Range of the 'packet_source' field.
 71  subtype caesar_config_packet_source is natural range 3 downto 2;
 72  -- Width of the 'packet_source' field.
 73  constant caesar_config_packet_source_width : positive := 2;
 74  -- Type for the 'packet_source' field.
 75  type caesar_config_packet_source_t is (
 76    packet_source_streaming,
 77    packet_source_dma,
 78    packet_source_none
 79  );
 80  -- Default value of the 'packet_source' field.
 81  constant caesar_config_packet_source_init : caesar_config_packet_source_t := packet_source_streaming;
 82  -- Type for the 'packet_source' field as an SLV.
 83  subtype caesar_config_packet_source_slv_t is std_ulogic_vector(1 downto 0);
 84  -- Cast a 'packet_source' field value to SLV.
 85  function to_slv(data : caesar_config_packet_source_t) return caesar_config_packet_source_slv_t;
 86  -- Get a 'packet_source' field value from a register value.
 87  function to_caesar_config_packet_source(data : register_t) return caesar_config_packet_source_t;
 88
 89end package;
 90
 91package body caesar_regs_pkg is
 92
 93  constant caesar_register_map : register_definition_vec_t(caesar_register_range) := (
 94    0 => (index => caesar_config, mode => r_w, utilized_width => 4)
 95  );
 96
 97  constant caesar_regs_init : caesar_regs_t := (
 98    0 => "00000000000000000000000000000001"
 99  );
100
101  -- Cast a 'severity_level' field value to SLV.
102  function to_slv(data : caesar_config_severity_level_t) return caesar_config_severity_level_slv_t is
103    constant data_int : natural := caesar_config_severity_level_t'pos(data);
104    constant result : caesar_config_severity_level_slv_t := std_ulogic_vector(
105      to_unsigned(data_int, caesar_config_severity_level_width)
106    );
107  begin
108    return result;
109  end function;
110
111  -- Get a 'severity_level' field value from a register value.
112  function to_caesar_config_severity_level(data : register_t) return caesar_config_severity_level_t is
113    constant field_slv : caesar_config_severity_level_slv_t := data(caesar_config_severity_level);
114    constant field_int : natural := to_integer(unsigned(field_slv));
115    constant result : caesar_config_severity_level_t := caesar_config_severity_level_t'val(field_int);
116  begin
117    return result;
118  end function;
119
120  -- Cast a 'packet_source' field value to SLV.
121  function to_slv(data : caesar_config_packet_source_t) return caesar_config_packet_source_slv_t is
122    constant data_int : natural := caesar_config_packet_source_t'pos(data);
123    constant result : caesar_config_packet_source_slv_t := std_ulogic_vector(
124      to_unsigned(data_int, caesar_config_packet_source_width)
125    );
126  begin
127    return result;
128  end function;
129
130  -- Get a 'packet_source' field value from a register value.
131  function to_caesar_config_packet_source(data : register_t) return caesar_config_packet_source_t is
132    constant field_slv : caesar_config_packet_source_slv_t := data(caesar_config_packet_source);
133    constant field_int : natural := to_integer(unsigned(field_slv));
134    constant result : caesar_config_packet_source_t := caesar_config_packet_source_t'val(field_int);
135  begin
136    return result;
137  end function;
138
139end package body;

Record package

The caesar_regs_down_t type is a record with a member config, the only register in this example. The type of the config member is another record with the two enumerations set up in our example: severity_level and packet_source. These are of enumeration types defined in the base register package above.

In our VHDL code we can access a field value for example like this:

if regs_down.config.packet_source = packet_source_streaming then
  result_valid <= input_valid;
elsif regs_down.config.packet_source = packet_source_dma then
  result_valid <= job_valid;
else
  -- packet_source_none
  result_valid <= '0';
end if;
Click to expand/collapse code.
Generated VHDL record package.
  1-- -----------------------------------------------------------------------------
  2-- This file is automatically generated by hdl-registers version 7.0.2-dev.
  3-- Code generator VhdlRecordPackageGenerator version 1.0.0.
  4-- Generated 2025-01-21 20:52 at commit 3c3e6c67d817.
  5-- Register hash c2412eacf08bbf54a4f274f2d5acaec28407a34e.
  6-- -----------------------------------------------------------------------------
  7
  8library ieee;
  9use ieee.fixed_pkg.all;
 10use ieee.std_logic_1164.all;
 11use ieee.numeric_std.all;
 12
 13library register_file;
 14use register_file.register_file_pkg.register_t;
 15
 16use work.caesar_regs_pkg.all;
 17
 18
 19package caesar_register_record_pkg is
 20
 21  -- -----------------------------------------------------------------------------
 22  -- Record with correctly-typed members for each field in each register.
 23  -- Fields in the 'config' register as a record.
 24  type caesar_config_t is record
 25    severity_level : caesar_config_severity_level_t;
 26    packet_source : caesar_config_packet_source_t;
 27  end record;
 28  -- Default value for the 'config' register as a record.
 29  constant caesar_config_init : caesar_config_t := (
 30    severity_level => caesar_config_severity_level_init,
 31    packet_source => caesar_config_packet_source_init
 32  );
 33  -- Convert a record of the 'config' register to SLV.
 34  function to_slv(data : caesar_config_t) return register_t;
 35  -- Convert an SLV register value to the record for the 'config' register.
 36  function to_caesar_config(data : register_t) return caesar_config_t;
 37
 38  -- -----------------------------------------------------------------------------
 39  -- Below is a record with correctly typed and ranged members for all registers, register arrays
 40  -- and fields that are in the 'down' direction.
 41  -- Record with everything in the 'down' direction.
 42  type caesar_regs_down_t is record
 43    config : caesar_config_t;
 44  end record;
 45  -- Default value of the above record.
 46  constant caesar_regs_down_init : caesar_regs_down_t := (
 47    config => caesar_config_init
 48  );
 49  -- Convert SLV register list to record with everything in the 'down' direction.
 50  function to_caesar_regs_down(data : caesar_regs_t) return caesar_regs_down_t;
 51
 52  -- ---------------------------------------------------------------------------
 53  -- Below is a record with a status bit for each readable register in the register list.
 54  -- It can be used for the 'reg_was_read' port of a register file wrapper.
 55  -- Combined status mask record for all readable register.
 56  type caesar_reg_was_read_t is record
 57    config : std_ulogic;
 58  end record;
 59  -- Default value for the above record.
 60  constant caesar_reg_was_read_init : caesar_reg_was_read_t := (
 61    others => '0'
 62  );
 63  -- Convert an SLV 'reg_was_read' from generic register file to the record above.
 64  function to_caesar_reg_was_read(
 65    data : caesar_reg_was_accessed_t
 66  ) return caesar_reg_was_read_t;
 67
 68  -- ---------------------------------------------------------------------------
 69  -- Below is a record with a status bit for each writeable register in the register list.
 70  -- It can be used for the 'reg_was_written' port of a register file wrapper.
 71  -- Combined status mask record for all writeable register.
 72  type caesar_reg_was_written_t is record
 73    config : std_ulogic;
 74  end record;
 75  -- Default value for the above record.
 76  constant caesar_reg_was_written_init : caesar_reg_was_written_t := (
 77    others => '0'
 78  );
 79  -- Convert an SLV 'reg_was_written' from generic register file to the record above.
 80  function to_caesar_reg_was_written(
 81    data : caesar_reg_was_accessed_t
 82  ) return caesar_reg_was_written_t;
 83
 84end package;
 85
 86package body caesar_register_record_pkg is
 87
 88  function to_slv(data : caesar_config_t) return register_t is
 89    variable result : register_t := (others => '-');
 90  begin
 91    result(caesar_config_severity_level) := to_slv(data.severity_level);
 92    result(caesar_config_packet_source) := to_slv(data.packet_source);
 93
 94    return result;
 95  end function;
 96
 97  function to_caesar_config(data : register_t) return caesar_config_t is
 98    variable result : caesar_config_t := caesar_config_init;
 99  begin
100    result.severity_level := to_caesar_config_severity_level(data);
101    result.packet_source := to_caesar_config_packet_source(data);
102
103    return result;
104  end function;
105
106  function to_caesar_regs_down(data : caesar_regs_t) return caesar_regs_down_t is
107    variable result : caesar_regs_down_t := caesar_regs_down_init;
108  begin
109    result.config := to_caesar_config(data(caesar_config));
110
111    return result;
112  end function;
113
114  function to_caesar_reg_was_read(
115    data : caesar_reg_was_accessed_t
116  ) return caesar_reg_was_read_t is
117    variable result : caesar_reg_was_read_t := caesar_reg_was_read_init;
118  begin
119    result.config := data(caesar_config);
120
121    return result;
122  end function;
123
124  function to_caesar_reg_was_written(
125    data : caesar_reg_was_accessed_t
126  ) return caesar_reg_was_written_t is
127    variable result : caesar_reg_was_written_t := caesar_reg_was_written_init;
128  begin
129    result.config := data(caesar_config);
130
131    return result;
132  end function;
133
134end package body;

C++

The C++ interface header and implementation code below is produced by the generate() call in the Python example above. Click the button to expand and view each code block.

The class header is skipped here, since its inclusion would make this page very long. See C++ code generator for more details and an example of how the excluded file might look.

C++ interface header

Some interesting things to notice in the interface header:

  1. The valid enumeration values are defined using a C++ enum declaration in the namespace of each field.

  2. The setters and getters for each field value use the enumeration type as argument or return value.

Click to expand/collapse code.
Generated C++ interface class code.
  1// -----------------------------------------------------------------------------
  2// This file is automatically generated by hdl-registers version 7.0.2-dev.
  3// Code generator CppInterfaceGenerator version 1.0.0.
  4// Generated 2025-01-21 20:52 at commit 3c3e6c67d817.
  5// Register hash c2412eacf08bbf54a4f274f2d5acaec28407a34e.
  6// -----------------------------------------------------------------------------
  7
  8#pragma once
  9
 10#include <sstream>
 11#include <cstdint>
 12#include <cstdlib>
 13
 14namespace fpga_regs
 15{
 16
 17  // Attributes for the 'severity_level' field in the 'config' register.
 18  namespace caesar::config::severity_level
 19  {
 20    static const auto width = 2;
 21    enum Enumeration
 22    {
 23      info = 0,
 24      warning = 1,
 25      error = 2,
 26      failure = 3,
 27    };
 28    static const auto default_value = Enumeration::warning;
 29  }
 30  // Attributes for the 'packet_source' field in the 'config' register.
 31  namespace caesar::config::packet_source
 32  {
 33    static const auto width = 2;
 34    enum Enumeration
 35    {
 36      streaming = 0,
 37      dma = 1,
 38      none = 2,
 39    };
 40    static const auto default_value = Enumeration::streaming;
 41  }
 42
 43  class ICaesar
 44  {
 45  public:
 46    // Number of registers within this register list.
 47    static const size_t num_registers = 1uL;
 48
 49    virtual ~ICaesar() {}
 50
 51    // -------------------------------------------------------------------------
 52    // Methods for the 'config' register. Mode 'Read, Write'.
 53
 54    // Getter that will read the whole register's value over the register bus.
 55    virtual uint32_t get_config() const = 0;
 56
 57    // Setter that will write the whole register's value over the register bus.
 58    virtual void set_config(
 59      uint32_t register_value
 60    ) const = 0;
 61
 62    // Getter for the 'severity_level' field in the 'config' register,
 63    // which will read register value over the register bus.
 64    virtual caesar::config::severity_level::Enumeration get_config_severity_level() const = 0;
 65    // Getter for the 'severity_level' field in the 'config' register,
 66    // given a register value.
 67    virtual caesar::config::severity_level::Enumeration get_config_severity_level_from_value(
 68      uint32_t register_value
 69    ) const = 0;
 70    // Setter for the 'severity_level' field in the 'config' register,
 71    // which will read-modify-write over the register bus.
 72    virtual void set_config_severity_level(
 73      caesar::config::severity_level::Enumeration field_value
 74    ) const = 0;
 75    // Setter for the 'severity_level' field in the 'config' register,
 76    // given a register value, which will return an updated value.
 77    virtual uint32_t set_config_severity_level_from_value(
 78      uint32_t register_value,
 79      caesar::config::severity_level::Enumeration field_value
 80    ) const = 0;
 81
 82    // Getter for the 'packet_source' field in the 'config' register,
 83    // which will read register value over the register bus.
 84    virtual caesar::config::packet_source::Enumeration get_config_packet_source() const = 0;
 85    // Getter for the 'packet_source' field in the 'config' register,
 86    // given a register value.
 87    virtual caesar::config::packet_source::Enumeration get_config_packet_source_from_value(
 88      uint32_t register_value
 89    ) const = 0;
 90    // Setter for the 'packet_source' field in the 'config' register,
 91    // which will read-modify-write over the register bus.
 92    virtual void set_config_packet_source(
 93      caesar::config::packet_source::Enumeration field_value
 94    ) const = 0;
 95    // Setter for the 'packet_source' field in the 'config' register,
 96    // given a register value, which will return an updated value.
 97    virtual uint32_t set_config_packet_source_from_value(
 98      uint32_t register_value,
 99      caesar::config::packet_source::Enumeration field_value
100    ) const = 0;
101
102  };
103
104} /* namespace fpga_regs */

C++ implementation

Note that each getter casts a uint32_t value read from the register bus to the enumeration type.

Click to expand/collapse code.
Generated C++ class implementation code.
  1// -----------------------------------------------------------------------------
  2// This file is automatically generated by hdl-registers version 7.0.2-dev.
  3// Code generator CppImplementationGenerator version 2.0.0.
  4// Generated 2025-01-21 20:52 at commit 3c3e6c67d817.
  5// Register hash c2412eacf08bbf54a4f274f2d5acaec28407a34e.
  6// -----------------------------------------------------------------------------
  7
  8#include "include/caesar.h"
  9
 10namespace fpga_regs
 11{
 12
 13#ifdef NO_REGISTER_SETTER_ASSERT
 14
 15#define _SETTER_ASSERT_TRUE(expression, message) ((void)0)
 16
 17#else // Not NO_REGISTER_SETTER_ASSERT.
 18
 19// This macro is called by the register code to check for runtime errors.
 20#define _SETTER_ASSERT_TRUE(expression, message)                                 \
 21  {                                                                              \
 22    if (!static_cast<bool>(expression)) {                                        \
 23      std::ostringstream diagnostics;                                            \
 24      diagnostics << "Tried to set value out of range in " << __FILE__ << ":"    \
 25                  << __LINE__ << ", message: " << message << ".";                \
 26      std::string diagnostic_message = diagnostics.str();                        \
 27      _assert_failed(&diagnostic_message);                                       \
 28    }                                                                            \
 29  }
 30
 31#endif // NO_REGISTER_SETTER_ASSERT.
 32
 33#ifdef NO_REGISTER_GETTER_ASSERT
 34
 35#define _GETTER_ASSERT_TRUE(expression, message) ((void)0)
 36
 37#else // Not NO_REGISTER_GETTER_ASSERT.
 38
 39// This macro is called by the register code to check for runtime errors.
 40#define _GETTER_ASSERT_TRUE(expression, message)                                 \
 41  {                                                                              \
 42    if (!static_cast<bool>(expression)) {                                        \
 43      std::ostringstream diagnostics;                                            \
 44      diagnostics << "Got read value out of range in " << __FILE__ << ":"        \
 45                  << __LINE__ << ", message: " << message << ".";                \
 46      std::string diagnostic_message = diagnostics.str();                        \
 47      _assert_failed(&diagnostic_message);                                       \
 48    }                                                                            \
 49  }
 50
 51#endif // NO_REGISTER_GETTER_ASSERT.
 52
 53#ifdef NO_REGISTER_ARRAY_INDEX_ASSERT
 54
 55#define _ARRAY_INDEX_ASSERT_TRUE(expression, message) ((void)0)
 56
 57#else // Not NO_REGISTER_ARRAY_INDEX_ASSERT.
 58
 59// This macro is called by the register code to check for runtime errors.
 60#define _ARRAY_INDEX_ASSERT_TRUE(expression, message)                            \
 61  {                                                                              \
 62    if (!static_cast<bool>(expression)) {                                        \
 63      std::ostringstream diagnostics;                                            \
 64      diagnostics << "Provided array index out of range in " << __FILE__ << ":"  \
 65                  << __LINE__ << ", message: " << message << ".";                \
 66      std::string diagnostic_message = diagnostics.str();                        \
 67      _assert_failed(&diagnostic_message);                                       \
 68    }                                                                            \
 69  }
 70
 71#endif // NO_REGISTER_ARRAY_INDEX_ASSERT.
 72
 73  Caesar::Caesar(uintptr_t base_address, bool (*assertion_handler) (const std::string*))
 74      : m_registers(reinterpret_cast<volatile uint32_t *>(base_address)),
 75        m_assertion_handler(assertion_handler)
 76  {
 77    // Empty
 78  }
 79
 80  void Caesar::_assert_failed(const std::string *message) const
 81  {
 82    m_assertion_handler(message);
 83  }
 84
 85  // ---------------------------------------------------------------------------
 86  // Methods for the 'config' register.
 87  // See interface header for documentation.
 88
 89  uint32_t Caesar::get_config() const
 90  {
 91    const size_t index = 0;
 92    const uint32_t result = m_registers[index];
 93
 94    return result;
 95  }
 96
 97  caesar::config::severity_level::Enumeration Caesar::get_config_severity_level() const
 98  {
 99    const uint32_t register_value = get_config();
100    const caesar::config::severity_level::Enumeration field_value = get_config_severity_level_from_value(register_value);
101
102    return field_value;
103  }
104
105  caesar::config::severity_level::Enumeration Caesar::get_config_severity_level_from_value(
106    uint32_t register_value
107  ) const
108  {
109    const uint32_t shift = 0uL;
110    const uint32_t mask_at_base = 0b11uL;
111    const uint32_t mask_shifted = mask_at_base << shift;
112
113    const uint32_t result_masked = register_value & mask_shifted;
114    const uint32_t result_shifted = result_masked >> shift;
115
116    caesar::config::severity_level::Enumeration field_value;
117
118    // "Cast" to the enum type.
119    field_value = caesar::config::severity_level::Enumeration(result_shifted);
120
121    return field_value;
122  }
123
124  caesar::config::packet_source::Enumeration Caesar::get_config_packet_source() const
125  {
126    const uint32_t register_value = get_config();
127    const caesar::config::packet_source::Enumeration field_value = get_config_packet_source_from_value(register_value);
128
129    return field_value;
130  }
131
132  caesar::config::packet_source::Enumeration Caesar::get_config_packet_source_from_value(
133    uint32_t register_value
134  ) const
135  {
136    const uint32_t shift = 2uL;
137    const uint32_t mask_at_base = 0b11uL;
138    const uint32_t mask_shifted = mask_at_base << shift;
139
140    const uint32_t result_masked = register_value & mask_shifted;
141    const uint32_t result_shifted = result_masked >> shift;
142
143    caesar::config::packet_source::Enumeration field_value;
144
145    // "Cast" to the enum type.
146    field_value = caesar::config::packet_source::Enumeration(result_shifted);
147
148    return field_value;
149  }
150
151  void Caesar::set_config(
152    uint32_t register_value
153  ) const
154  {
155    const size_t index = 0;
156    m_registers[index] = register_value;
157  }
158
159  void Caesar::set_config_severity_level(
160    caesar::config::severity_level::Enumeration field_value
161  ) const
162  {
163    // Get the current value of other fields by reading register on the bus.
164    const uint32_t current_register_value = get_config();
165    const uint32_t result_register_value = set_config_severity_level_from_value(current_register_value, field_value);
166    set_config(result_register_value);
167  }
168
169  uint32_t Caesar::set_config_severity_level_from_value(
170    uint32_t register_value,
171    caesar::config::severity_level::Enumeration field_value
172  ) const  {
173    const uint32_t shift = 0uL;
174    const uint32_t mask_at_base = 0b11uL;
175    const uint32_t mask_shifted = mask_at_base << shift;
176
177    const uint32_t field_value_masked = field_value & mask_at_base;
178    const uint32_t field_value_masked_and_shifted = field_value_masked << shift;
179
180    const uint32_t mask_shifted_inverse = ~mask_shifted;
181    const uint32_t register_value_masked = register_value & mask_shifted_inverse;
182
183    const uint32_t result_register_value = register_value_masked | field_value_masked_and_shifted;
184
185    return result_register_value;
186  }
187
188  void Caesar::set_config_packet_source(
189    caesar::config::packet_source::Enumeration field_value
190  ) const
191  {
192    // Get the current value of other fields by reading register on the bus.
193    const uint32_t current_register_value = get_config();
194    const uint32_t result_register_value = set_config_packet_source_from_value(current_register_value, field_value);
195    set_config(result_register_value);
196  }
197
198  uint32_t Caesar::set_config_packet_source_from_value(
199    uint32_t register_value,
200    caesar::config::packet_source::Enumeration field_value
201  ) const  {
202    const uint32_t shift = 2uL;
203    const uint32_t mask_at_base = 0b11uL;
204    const uint32_t mask_shifted = mask_at_base << shift;
205
206    const uint32_t field_value_masked = field_value & mask_at_base;
207    const uint32_t field_value_masked_and_shifted = field_value_masked << shift;
208
209    const uint32_t mask_shifted_inverse = ~mask_shifted;
210    const uint32_t register_value_masked = register_value & mask_shifted_inverse;
211
212    const uint32_t result_register_value = register_value_masked | field_value_masked_and_shifted;
213
214    return result_register_value;
215  }
216
217} /* namespace fpga_regs */

C header

The C code below is produced by the generate() call in the Python example above. The range and mask of the each field are available as constants. Note how the valid enumeration values are defined using a C enum declaration.

Click to expand/collapse code.
Generated C code.
 1// -----------------------------------------------------------------------------
 2// This file is automatically generated by hdl-registers version 7.0.2-dev.
 3// Code generator CHeaderGenerator version 1.0.0.
 4// Generated 2025-01-21 20:52 at commit 3c3e6c67d817.
 5// Register hash c2412eacf08bbf54a4f274f2d5acaec28407a34e.
 6// -----------------------------------------------------------------------------
 7
 8#ifndef CAESAR_REGS_H
 9#define CAESAR_REGS_H
10
11
12// Number of registers within this register list.
13#define CAESAR_NUM_REGS (1u)
14
15// Type for this register list.
16typedef struct caesar_regs_t
17{
18  // Mode "Read, Write".
19  uint32_t config;
20} caesar_regs_t;
21
22// Address of the 'config' register.
23// Mode 'Read, Write'.
24#define CAESAR_CONFIG_INDEX (0u)
25#define CAESAR_CONFIG_ADDR (4u * CAESAR_CONFIG_INDEX)
26// Attributes for the 'severity_level' field in the 'config' register.
27#define CAESAR_CONFIG_SEVERITY_LEVEL_SHIFT (0u)
28#define CAESAR_CONFIG_SEVERITY_LEVEL_MASK (0b11u << 0u)
29#define CAESAR_CONFIG_SEVERITY_LEVEL_MASK_INVERSE (~CAESAR_CONFIG_SEVERITY_LEVEL_MASK)
30enum CaesarConfigSeverityLevel
31{
32  CAESAR_CONFIG_SEVERITY_LEVEL_INFO = 0,
33  CAESAR_CONFIG_SEVERITY_LEVEL_WARNING = 1,
34  CAESAR_CONFIG_SEVERITY_LEVEL_ERROR = 2,
35  CAESAR_CONFIG_SEVERITY_LEVEL_FAILURE = 3,
36};
37// Attributes for the 'packet_source' field in the 'config' register.
38#define CAESAR_CONFIG_PACKET_SOURCE_SHIFT (2u)
39#define CAESAR_CONFIG_PACKET_SOURCE_MASK (0b11u << 2u)
40#define CAESAR_CONFIG_PACKET_SOURCE_MASK_INVERSE (~CAESAR_CONFIG_PACKET_SOURCE_MASK)
41enum CaesarConfigPacketSource
42{
43  CAESAR_CONFIG_PACKET_SOURCE_STREAMING = 0,
44  CAESAR_CONFIG_PACKET_SOURCE_DMA = 1,
45  CAESAR_CONFIG_PACKET_SOURCE_NONE = 2,
46};
47
48#endif // CAESAR_REGS_H