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-- #################################################################################################

-- # << NEORV32 - Main VHDL package file >>                                                        #

-- # ********************************************************************************************* #

-- # BSD 3-Clause License                                                                          #

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-- # Copyright (c) 2022, Stephan Nolting. All rights reserved.                                     #

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-- # The NEORV32 Processor - https://github.com/stnolting/neorv32              (c) Stephan Nolting #

-- #################################################################################################

library ieee;

use ieee.std_logic_1164.all;

use ieee.numeric_std.all;

package neorv32_package is

  -- Architecture Configuration -------------------------------------------------------------

  -- -------------------------------------------------------------------------------------------

  -- address space --

  constant ispace_base_c : std_ulogic_vector(31 downto 0) := x"00000000"; -- default instruction memory address space base address

  constant dspace_base_c : std_ulogic_vector(31 downto 0) := x"80000000"; -- default data memory address space base address

  -- use dedicated hardware reset value for UNCRITICAL registers --

  -- FALSE=reset value is irrelevant (might simplify HW), default; TRUE=defined LOW reset value

  constant dedicated_reset_c : boolean := false;

  -- "critical" number of implemented PMP regions --

  -- if more PMP regions (> pmp_num_regions_critical_c) are defined, another register stage is automatically inserted into the memory interfaces

  -- increasing instruction fetch & data access latency by +1 cycle but also reducing critical path length

  constant pmp_num_regions_critical_c : natural := 8; -- default=8

  -- "response time window" for processor-internal modules --

  -- = cycles after which an *unacknowledged* internal bus access will timeout and trigger a bus fault exception (min 2)

  constant max_proc_int_response_time_c : natural := 15;

  -- jtag tap - identifier --

  constant jtag_tap_idcode_version_c : std_ulogic_vector(03 downto 0) := x"0"; -- version

  constant jtag_tap_idcode_partid_c  : std_ulogic_vector(15 downto 0) := x"cafe"; -- part number

  constant jtag_tap_idcode_manid_c   : std_ulogic_vector(10 downto 0) := "00000000000"; -- manufacturer id

  -- Architecture Constants (do not modify!) ------------------------------------------------

  -- -------------------------------------------------------------------------------------------

  constant data_width_c : natural := 32; -- native data path width - do not change!

  constant hw_version_c : std_ulogic_vector(31 downto 0) := x"01060800"; -- no touchy!

  constant archid_c     : natural := 19; -- official NEORV32 architecture ID - hands off!

  -- Check if we're inside the Matrix -------------------------------------------------------

  -- -------------------------------------------------------------------------------------------

  constant is_simulation_c : boolean := false -- seems like we're on real hardware

-- pragma translate_off

-- synthesis translate_off

-- synthesis synthesis_off

-- RTL_SYNTHESIS OFF

  or true -- this MIGHT be a simulation

-- RTL_SYNTHESIS ON

-- synthesis synthesis_on

-- synthesis translate_on

-- pragma translate_on

  ;

  -- External Interface Types ---------------------------------------------------------------

  -- -------------------------------------------------------------------------------------------

  type sdata_8x32_t  is array (0 to 7) of std_ulogic_vector(31 downto 0);

  type sdata_8x32r_t is array (0 to 7) of std_logic_vector(31 downto 0); -- resolved type

  -- Internal Interface Types ---------------------------------------------------------------

  -- -------------------------------------------------------------------------------------------

  type pmp_ctrl_if_t is array (0 to 63) of std_ulogic_vector(07 downto 0);

  type pmp_addr_if_t is array (0 to 63) of std_ulogic_vector(33 downto 0);

  -- Internal Memory Types Configuration Types ----------------------------------------------

  -- -------------------------------------------------------------------------------------------

  type mem32_t is array (natural range <>) of std_ulogic_vector(31 downto 0); -- memory with 32-bit entries

  type mem8_t  is array (natural range <>) of std_ulogic_vector(07 downto 0); -- memory with 8-bit entries

  -- Helper Functions -----------------------------------------------------------------------

  -- -------------------------------------------------------------------------------------------

  function index_size_f(input : natural) return natural;

  function cond_sel_natural_f(cond : boolean; val_t : natural; val_f : natural) return natural;

  function cond_sel_int_f(cond : boolean; val_t : integer; val_f : integer) return integer;

  function cond_sel_stdulogicvector_f(cond : boolean; val_t : std_ulogic_vector; val_f : std_ulogic_vector) return std_ulogic_vector;

  function cond_sel_stdulogic_f(cond : boolean; val_t : std_ulogic; val_f : std_ulogic) return std_ulogic;

  function cond_sel_string_f(cond : boolean; val_t : string; val_f : string) return string;

  function bool_to_ulogic_f(cond : boolean) return std_ulogic;

  function bin_to_gray_f(input : std_ulogic_vector) return std_ulogic_vector;

  function gray_to_bin_f(input : std_ulogic_vector) return std_ulogic_vector;

  function or_reduce_f(a : std_ulogic_vector) return std_ulogic;

  function and_reduce_f(a : std_ulogic_vector) return std_ulogic;

  function xor_reduce_f(a : std_ulogic_vector) return std_ulogic;

  function to_hexchar_f(input : std_ulogic_vector(3 downto 0)) return character;

  function hexchar_to_stdulogicvector_f(input : character) return std_ulogic_vector;

  function bit_rev_f(input : std_ulogic_vector) return std_ulogic_vector;

  function is_power_of_two_f(input : natural) return boolean;

  function bswap32_f(input : std_ulogic_vector) return std_ulogic_vector;

  function char_to_lower_f(ch : character) return character;

  function str_equal_f(str0 : string; str1 : string) return boolean;

  function popcount_f(input : std_ulogic_vector) return natural;

  function leading_zeros_f(input : std_ulogic_vector) return natural;

  impure function mem32_init_f(init : mem32_t; depth : natural) return mem32_t;

  -- Internal (auto-generated) Configurations -----------------------------------------------

  -- -------------------------------------------------------------------------------------------

  constant def_rst_val_c : std_ulogic; -- Use a deferred constant, prevents compile error with Questa, see IEEE 1076-2008 14.4.2.1

  -- Processor-Internal Address Space Layout ------------------------------------------------

  -- -------------------------------------------------------------------------------------------

  -- Internal Instruction Memory (IMEM) and Date Memory (DMEM) --

  constant imem_base_c          : std_ulogic_vector(data_width_c-1 downto 0) := ispace_base_c; -- internal instruction memory base address

  constant dmem_base_c          : std_ulogic_vector(data_width_c-1 downto 0) := dspace_base_c; -- internal data memory base address

  --> internal data/instruction memory sizes are configured via top's generics

  -- !!! IMPORTANT: The base address of each component/module has to be aligned to the !!!

  -- !!! total size of the module's occupied address space. The occupied address space !!!

  -- !!! has to be a power of two (minimum 4 bytes). Address spaces must not overlap.  !!!

  -- Internal Bootloader ROM --

  -- Actual bootloader size is determined during runtime via the length of the bootloader initialization image

  constant boot_rom_base_c      : std_ulogic_vector(data_width_c-1 downto 0) := x"ffff0000"; -- bootloader base address, fixed!

  constant boot_rom_max_size_c  : natural := 32*1024; -- max module's address space size in bytes, fixed!

  -- On-Chip Debugger: Debug Module --

  constant dm_base_c            : std_ulogic_vector(data_width_c-1 downto 0) := x"fffff800"; -- base address, fixed!

  constant dm_size_c            : natural := 4*32*4; -- debug ROM address space size in bytes, fixed

  constant dm_code_base_c       : std_ulogic_vector(data_width_c-1 downto 0) := x"fffff800";

  constant dm_pbuf_base_c       : std_ulogic_vector(data_width_c-1 downto 0) := x"fffff880";

  constant dm_data_base_c       : std_ulogic_vector(data_width_c-1 downto 0) := x"fffff900";

  constant dm_sreg_base_c       : std_ulogic_vector(data_width_c-1 downto 0) := x"fffff980";

  -- IO: Peripheral Devices ("IO") Area --

  -- Control register(s) (including the device-enable flag) should be located at the base address of each device

  constant io_base_c            : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe00";

  constant io_size_c            : natural := 512; -- IO address space size in bytes, fixed!

  -- Custom Functions Subsystem (CFS) --

  constant cfs_base_c           : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe00"; -- base address

  constant cfs_size_c           : natural := 32*4; -- module's address space in bytes

  constant cfs_reg0_addr_c      : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe00";

  constant cfs_reg1_addr_c      : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe04";

  constant cfs_reg2_addr_c      : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe08";

  constant cfs_reg3_addr_c      : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe0c";

  constant cfs_reg4_addr_c      : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe10";

  constant cfs_reg5_addr_c      : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe14";

  constant cfs_reg6_addr_c      : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe18";

  constant cfs_reg7_addr_c      : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe1c";

  constant cfs_reg8_addr_c      : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe20";

  constant cfs_reg9_addr_c      : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe24";

  constant cfs_reg10_addr_c     : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe28";

  constant cfs_reg11_addr_c     : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe2c";

  constant cfs_reg12_addr_c     : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe30";

  constant cfs_reg13_addr_c     : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe34";

  constant cfs_reg14_addr_c     : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe38";

  constant cfs_reg15_addr_c     : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe3c";

  constant cfs_reg16_addr_c     : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe40";

  constant cfs_reg17_addr_c     : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe44";

  constant cfs_reg18_addr_c     : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe48";

  constant cfs_reg19_addr_c     : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe4c";

  constant cfs_reg20_addr_c     : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe50";

  constant cfs_reg21_addr_c     : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe54";

  constant cfs_reg22_addr_c     : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe58";

  constant cfs_reg23_addr_c     : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe5c";

  constant cfs_reg24_addr_c     : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe60";

  constant cfs_reg25_addr_c     : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe64";

  constant cfs_reg26_addr_c     : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe68";

  constant cfs_reg27_addr_c     : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe6c";

  constant cfs_reg28_addr_c     : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe70";

  constant cfs_reg29_addr_c     : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe74";

  constant cfs_reg30_addr_c     : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe78";

  constant cfs_reg31_addr_c     : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe7c";

  -- Pulse-Width Modulation Controller (PWM) --

  constant pwm_base_c           : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe80"; -- base address

  constant pwm_size_c           : natural := 16*4; -- module's address space size in bytes

  constant pwm_ctrl_addr_c      : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe80";

  constant pwm_duty0_addr_c     : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe84";

  constant pwm_duty1_addr_c     : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe88";

  constant pwm_duty2_addr_c     : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe8c";

  constant pwm_duty3_addr_c     : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe90";

  constant pwm_duty4_addr_c     : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe94";

  constant pwm_duty5_addr_c     : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe98";

  constant pwm_duty6_addr_c     : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffe9c";

  constant pwm_duty7_addr_c     : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffea0";

  constant pwm_duty8_addr_c     : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffea4";

  constant pwm_duty9_addr_c     : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffea8";

  constant pwm_duty10_addr_c    : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffeac";

  constant pwm_duty11_addr_c    : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffeb0";

  constant pwm_duty12_addr_c    : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffeb4";

  constant pwm_duty13_addr_c    : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffeb8";

  constant pwm_duty14_addr_c    : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffebc";

  -- Stream Link Interface (SLINK) --

  constant slink_base_c         : std_ulogic_vector(data_width_c-1 downto 0) := x"fffffec0"; -- base address

  constant slink_size_c         : natural := 16*4; -- module's address space size in bytes

  -- reserved --

--constant reserved_base_c      : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffff00"; -- base address

--constant reserved_size_c      : natural := 16*4; -- module's address space size in bytes

  -- Execute In Place Module (XIP) --

  constant xip_base_c           : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffff40"; -- base address

  constant xip_size_c           : natural := 4*4; -- module's address space size in bytes

  constant xip_ctrl_addr_c      : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffff40";

  constant xip_map_addr_c       : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffff44";

  constant xip_data_lo_addr_c   : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffff48";

  constant xip_data_hi_addr_c   : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffff4C";

  -- reserved --

--constant reserved_base_c      : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffff50"; -- base address

--constant reserved_size_c      : natural := 4*4; -- module's address space size in bytes

  -- General Purpose Timer (GPTMR) --

  constant gptmr_base_c         : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffff60"; -- base address

  constant gptmr_size_c         : natural := 4*4; -- module's address space size in bytes

  constant gptmr_ctrl_addr_c    : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffff60";

  constant gptmr_thres_addr_c   : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffff64";

  constant gptmr_count_addr_c   : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffff68";

--constant gptmr_reserve_addr_c : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffff6c";

  -- reserved --

--constant reserved_base_c      : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffff70"; -- base address

--constant reserved_size_c      : natural := 2*4; -- module's address space size in bytes

  -- reserved --

--constant reserved_base_c      : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffff78"; -- base address

--constant reserved_size_c      : natural := 1*4; -- module's address space size in bytes

  -- Bus Access Monitor (BUSKEEPER) --

  constant buskeeper_base_c     : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffff7c"; -- base address

  constant buskeeper_size_c     : natural := 1*4; -- module's address space size in bytes

  -- External Interrupt Controller (XIRQ) --

  constant xirq_base_c          : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffff80"; -- base address

  constant xirq_size_c          : natural := 4*4; -- module's address space size in bytes

  constant xirq_enable_addr_c   : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffff80";

  constant xirq_pending_addr_c  : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffff84";

  constant xirq_source_addr_c   : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffff88";

--constant xirq_reserved_addr_c : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffff8c";

  -- Machine System Timer (MTIME) --

  constant mtime_base_c         : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffff90"; -- base address

  constant mtime_size_c         : natural := 4*4; -- module's address space size in bytes

  constant mtime_time_lo_addr_c : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffff90";

  constant mtime_time_hi_addr_c : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffff94";

  constant mtime_cmp_lo_addr_c  : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffff98";

  constant mtime_cmp_hi_addr_c  : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffff9c";

  -- Primary Universal Asynchronous Receiver/Transmitter (UART0) --

  constant uart0_base_c         : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffffa0"; -- base address

  constant uart0_size_c         : natural := 2*4; -- module's address space size in bytes

  constant uart0_ctrl_addr_c    : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffffa0";

  constant uart0_rtx_addr_c     : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffffa4";

  -- Serial Peripheral Interface (SPI) --

  constant spi_base_c           : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffffa8"; -- base address

  constant spi_size_c           : natural := 2*4; -- module's address space size in bytes

  constant spi_ctrl_addr_c      : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffffa8";

  constant spi_rtx_addr_c       : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffffac";

  -- Two Wire Interface (TWI) --

  constant twi_base_c           : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffffb0"; -- base address

  constant twi_size_c           : natural := 2*4; -- module's address space size in bytes

  constant twi_ctrl_addr_c      : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffffb0";

  constant twi_rtx_addr_c       : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffffb4";

  -- True Random Number Generator (TRNG) --

  constant trng_base_c          : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffffb8"; -- base address

  constant trng_size_c          : natural := 1*4; -- module's address space size in bytes

  constant trng_ctrl_addr_c     : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffffb8";

  -- Watch Dog Timer (WDT) --

  constant wdt_base_c           : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffffbc"; -- base address

  constant wdt_size_c           : natural := 1*4; -- module's address space size in bytes

  constant wdt_ctrl_addr_c      : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffffbc";

  -- General Purpose Input/Output Controller (GPIO) --

  constant gpio_base_c          : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffffc0"; -- base address

  constant gpio_size_c          : natural := 4*4; -- module's address space size in bytes

  constant gpio_in_lo_addr_c    : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffffc0";

  constant gpio_in_hi_addr_c    : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffffc4";

  constant gpio_out_lo_addr_c   : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffffc8";

  constant gpio_out_hi_addr_c   : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffffcc";

  -- Secondary Universal Asynchronous Receiver/Transmitter (UART1) --

  constant uart1_base_c         : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffffd0"; -- base address

  constant uart1_size_c         : natural := 2*4; -- module's address space size in bytes

  constant uart1_ctrl_addr_c    : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffffd0";

  constant uart1_rtx_addr_c     : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffffd4";

  -- Smart LED (WS2811/WS2812) Interface (NEOLED) --

  constant neoled_base_c        : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffffd8"; -- base address

  constant neoled_size_c        : natural := 2*4; -- module's address space size in bytes

  constant neoled_ctrl_addr_c   : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffffd8";

  constant neoled_data_addr_c   : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffffdc";

  -- System Information Memory (SYSINFO) --

  constant sysinfo_base_c       : std_ulogic_vector(data_width_c-1 downto 0) := x"ffffffe0"; -- base address

  constant sysinfo_size_c       : natural := 8*4; -- module's address space size in bytes

  -- Main CPU Control Bus -------------------------------------------------------------------

  -- -------------------------------------------------------------------------------------------

  -- register file --

  constant ctrl_rf_in_mux_c     : natural :=  0; -- input source select lsb (0=MEM, 1=ALU)

  constant ctrl_rf_rs1_adr0_c   : natural :=  1; -- source register 1 address bit 0

  constant ctrl_rf_rs1_adr1_c   : natural :=  2; -- source register 1 address bit 1

  constant ctrl_rf_rs1_adr2_c   : natural :=  3; -- source register 1 address bit 2

  constant ctrl_rf_rs1_adr3_c   : natural :=  4; -- source register 1 address bit 3

  constant ctrl_rf_rs1_adr4_c   : natural :=  5; -- source register 1 address bit 4

  constant ctrl_rf_rs2_adr0_c   : natural :=  6; -- source register 2 address bit 0

  constant ctrl_rf_rs2_adr1_c   : natural :=  7; -- source register 2 address bit 1

  constant ctrl_rf_rs2_adr2_c   : natural :=  8; -- source register 2 address bit 2

  constant ctrl_rf_rs2_adr3_c   : natural :=  9; -- source register 2 address bit 3

  constant ctrl_rf_rs2_adr4_c   : natural := 10; -- source register 2 address bit 4

  constant ctrl_rf_rd_adr0_c    : natural := 11; -- destination register address bit 0

  constant ctrl_rf_rd_adr1_c    : natural := 12; -- destination register address bit 1

  constant ctrl_rf_rd_adr2_c    : natural := 13; -- destination register address bit 2

  constant ctrl_rf_rd_adr3_c    : natural := 14; -- destination register address bit 3

  constant ctrl_rf_rd_adr4_c    : natural := 15; -- destination register address bit 4

  constant ctrl_rf_wb_en_c      : natural := 16; -- write back enable

  -- alu --

  constant ctrl_alu_op0_c       : natural := 17; -- ALU operation select bit 0

  constant ctrl_alu_op1_c       : natural := 18; -- ALU operation select bit 1

  constant ctrl_alu_op2_c       : natural := 19; -- ALU operation select bit 2

  constant ctrl_alu_func0_c     : natural := 20; -- ALU function select command bit 0

  constant ctrl_alu_func1_c     : natural := 21; -- ALU function select command bit 1

  constant ctrl_alu_opa_mux_c   : natural := 22; -- operand A select (0=rs1, 1=PC)

  constant ctrl_alu_opb_mux_c   : natural := 23; -- operand B select (0=rs2, 1=IMM)

  constant ctrl_alu_unsigned_c  : natural := 24; -- is unsigned ALU operation

  constant ctrl_alu_shift_dir_c : natural := 25; -- shift direction (0=left, 1=right)

  constant ctrl_alu_shift_ar_c  : natural := 26; -- is arithmetic shift

  constant ctrl_alu_frm0_c      : natural := 27; -- FPU rounding mode bit 0

  constant ctrl_alu_frm1_c      : natural := 28; -- FPU rounding mode bit 1

  constant ctrl_alu_frm2_c      : natural := 29; -- FPU rounding mode bit 2

  -- bus interface --

  constant ctrl_bus_size_lsb_c  : natural := 30; -- transfer size lsb (00=byte, 01=half-word)

  constant ctrl_bus_size_msb_c  : natural := 31; -- transfer size msb (10=word, 11=?)

  constant ctrl_bus_rd_c        : natural := 32; -- read data request

  constant ctrl_bus_wr_c        : natural := 33; -- write data request

  constant ctrl_bus_if_c        : natural := 34; -- instruction fetch request

  constant ctrl_bus_mo_we_c     : natural := 35; -- memory address and data output register write enable

  constant ctrl_bus_mi_we_c     : natural := 36; -- memory data input register write enable

  constant ctrl_bus_unsigned_c  : natural := 37; -- is unsigned load

  constant ctrl_bus_ierr_ack_c  : natural := 38; -- acknowledge instruction fetch bus exceptions

  constant ctrl_bus_derr_ack_c  : natural := 39; -- acknowledge data access bus exceptions

  constant ctrl_bus_fence_c     : natural := 40; -- executed fence operation

  constant ctrl_bus_fencei_c    : natural := 41; -- executed fencei operation

  constant ctrl_bus_lock_c      : natural := 42; -- make atomic/exclusive access lock

  constant ctrl_bus_de_lock_c   : natural := 43; -- remove atomic/exclusive access 

  constant ctrl_bus_ch_lock_c   : natural := 44; -- evaluate atomic/exclusive lock (SC operation)

  -- co-processors --

  constant ctrl_cp_id_lsb_c     : natural := 45; -- cp select ID lsb

  constant ctrl_cp_id_hsb_c     : natural := 46; -- cp select ID "half" significant bit

  constant ctrl_cp_id_msb_c     : natural := 47; -- cp select ID msb

  -- instruction's control blocks (used by cpu co-processors) --

  constant ctrl_ir_funct3_0_c   : natural := 48; -- funct3 bit 0

  constant ctrl_ir_funct3_1_c   : natural := 49; -- funct3 bit 1

  constant ctrl_ir_funct3_2_c   : natural := 50; -- funct3 bit 2

  constant ctrl_ir_funct12_0_c  : natural := 51; -- funct12 bit 0

  constant ctrl_ir_funct12_1_c  : natural := 52; -- funct12 bit 1

  constant ctrl_ir_funct12_2_c  : natural := 53; -- funct12 bit 2

  constant ctrl_ir_funct12_3_c  : natural := 54; -- funct12 bit 3

  constant ctrl_ir_funct12_4_c  : natural := 55; -- funct12 bit 4

  constant ctrl_ir_funct12_5_c  : natural := 56; -- funct12 bit 5

  constant ctrl_ir_funct12_6_c  : natural := 57; -- funct12 bit 6

  constant ctrl_ir_funct12_7_c  : natural := 58; -- funct12 bit 7

  constant ctrl_ir_funct12_8_c  : natural := 59; -- funct12 bit 8

  constant ctrl_ir_funct12_9_c  : natural := 60; -- funct12 bit 9

  constant ctrl_ir_funct12_10_c : natural := 61; -- funct12 bit 10

  constant ctrl_ir_funct12_11_c : natural := 62; -- funct12 bit 11

  constant ctrl_ir_opcode7_0_c  : natural := 63; -- opcode7 bit 0

  constant ctrl_ir_opcode7_1_c  : natural := 64; -- opcode7 bit 1

  constant ctrl_ir_opcode7_2_c  : natural := 65; -- opcode7 bit 2

  constant ctrl_ir_opcode7_3_c  : natural := 66; -- opcode7 bit 3

  constant ctrl_ir_opcode7_4_c  : natural := 67; -- opcode7 bit 4

  constant ctrl_ir_opcode7_5_c  : natural := 68; -- opcode7 bit 5

  constant ctrl_ir_opcode7_6_c  : natural := 69; -- opcode7 bit 6

  -- CPU status --

  constant ctrl_priv_lvl_lsb_c  : natural := 70; -- privilege level lsb

  constant ctrl_priv_lvl_msb_c  : natural := 71; -- privilege level msb

  constant ctrl_sleep_c         : natural := 72; -- set when CPU is in sleep mode

  constant ctrl_trap_c          : natural := 73; -- set when CPU is entering trap execution

  constant ctrl_debug_running_c : natural := 74; -- CPU is in debug mode when set

  -- control bus size --

  constant ctrl_width_c         : natural := 75; -- control bus size

  -- Comparator Bus -------------------------------------------------------------------------

  -- -------------------------------------------------------------------------------------------

  constant cmp_equal_c : natural := 0;

  constant cmp_less_c  : natural := 1; -- for signed and unsigned comparisons

  -- RISC-V 32-Bit Instruction Word Layout --------------------------------------------------

  -- -------------------------------------------------------------------------------------------

  constant instr_opcode_lsb_c  : natural :=  0; -- opcode bit 0

  constant instr_opcode_msb_c  : natural :=  6; -- opcode bit 6

  constant instr_rd_lsb_c      : natural :=  7; -- destination register address bit 0

  constant instr_rd_msb_c      : natural := 11; -- destination register address bit 4

  constant instr_funct3_lsb_c  : natural := 12; -- funct3 bit 0

  constant instr_funct3_msb_c  : natural := 14; -- funct3 bit 2

  constant instr_rs1_lsb_c     : natural := 15; -- source register 1 address bit 0

  constant instr_rs1_msb_c     : natural := 19; -- source register 1 address bit 4

  constant instr_rs2_lsb_c     : natural := 20; -- source register 2 address bit 0

  constant instr_rs2_msb_c     : natural := 24; -- source register 2 address bit 4

  constant instr_funct7_lsb_c  : natural := 25; -- funct7 bit 0

  constant instr_funct7_msb_c  : natural := 31; -- funct7 bit 6

  constant instr_funct12_lsb_c : natural := 20; -- funct12 bit 0

  constant instr_funct12_msb_c : natural := 31; -- funct12 bit 11

  constant instr_imm12_lsb_c   : natural := 20; -- immediate12 bit 0

  constant instr_imm12_msb_c   : natural := 31; -- immediate12 bit 11

  constant instr_imm20_lsb_c   : natural := 12; -- immediate20 bit 0

  constant instr_imm20_msb_c   : natural := 31; -- immediate20 bit 21

  constant instr_csr_id_lsb_c  : natural := 20; -- csr select bit 0

  constant instr_csr_id_msb_c  : natural := 31; -- csr select bit 11

  constant instr_funct5_lsb_c  : natural := 27; -- funct5 select bit 0

  constant instr_funct5_msb_c  : natural := 31; -- funct5 select bit 4

  -- RISC-V Opcodes -------------------------------------------------------------------------

  -- -------------------------------------------------------------------------------------------

  -- alu --

  constant opcode_lui_c    : std_ulogic_vector(6 downto 0) := "0110111"; -- load upper immediate

  constant opcode_auipc_c  : std_ulogic_vector(6 downto 0) := "0010111"; -- add upper immediate to PC

  constant opcode_alui_c   : std_ulogic_vector(6 downto 0) := "0010011"; -- ALU operation with immediate (operation via funct3 and funct7)

  constant opcode_alu_c    : std_ulogic_vector(6 downto 0) := "0110011"; -- ALU operation (operation via funct3 and funct7)

  -- control flow --

  constant opcode_jal_c    : std_ulogic_vector(6 downto 0) := "1101111"; -- jump and link

  constant opcode_jalr_c   : std_ulogic_vector(6 downto 0) := "1100111"; -- jump and link with register

  constant opcode_branch_c : std_ulogic_vector(6 downto 0) := "1100011"; -- branch (condition set via funct3)

  -- memory access --

  constant opcode_load_c   : std_ulogic_vector(6 downto 0) := "0000011"; -- load (data type via funct3)

  constant opcode_store_c  : std_ulogic_vector(6 downto 0) := "0100011"; -- store (data type via funct3)

  -- system/csr --

  constant opcode_fence_c  : std_ulogic_vector(6 downto 0) := "0001111"; -- fence / fence.i

  constant opcode_syscsr_c : std_ulogic_vector(6 downto 0) := "1110011"; -- system/csr access (type via funct3)

  -- atomic memory access (A) --

  constant opcode_atomic_c : std_ulogic_vector(6 downto 0) := "0101111"; -- atomic operations (A extension)

  -- floating point operations (Zfinx-only) (F/D/H/Q) --

  constant opcode_fop_c    : std_ulogic_vector(6 downto 0) := "1010011"; -- dual/single operand instruction

  -- official "custom0/1" RISC-V opcodes - free for custom instructions --

  constant opcode_cust0_c  : std_ulogic_vector(6 downto 0) := "0001011"; -- custom instructions 0

--constant opcode_cust1_c  : std_ulogic_vector(6 downto 0) := "0101011"; -- custom instructions 1

  -- RISC-V Funct3 --------------------------------------------------------------------------

  -- -------------------------------------------------------------------------------------------

  -- control flow --

  constant funct3_beq_c    : std_ulogic_vector(2 downto 0) := "000"; -- branch if equal

  constant funct3_bne_c    : std_ulogic_vector(2 downto 0) := "001"; -- branch if not equal

  constant funct3_blt_c    : std_ulogic_vector(2 downto 0) := "100"; -- branch if less than

  constant funct3_bge_c    : std_ulogic_vector(2 downto 0) := "101"; -- branch if greater than or equal

  constant funct3_bltu_c   : std_ulogic_vector(2 downto 0) := "110"; -- branch if less than (unsigned)

  constant funct3_bgeu_c   : std_ulogic_vector(2 downto 0) := "111"; -- branch if greater than or equal (unsigned)

  -- memory access --

  constant funct3_lb_c     : std_ulogic_vector(2 downto 0) := "000"; -- load byte

  constant funct3_lh_c     : std_ulogic_vector(2 downto 0) := "001"; -- load half word

  constant funct3_lw_c     : std_ulogic_vector(2 downto 0) := "010"; -- load word

  constant funct3_lbu_c    : std_ulogic_vector(2 downto 0) := "100"; -- load byte (unsigned)

  constant funct3_lhu_c    : std_ulogic_vector(2 downto 0) := "101"; -- load half word (unsigned)

  constant funct3_sb_c     : std_ulogic_vector(2 downto 0) := "000"; -- store byte

  constant funct3_sh_c     : std_ulogic_vector(2 downto 0) := "001"; -- store half word

  constant funct3_sw_c     : std_ulogic_vector(2 downto 0) := "010"; -- store word

  -- alu --

  constant funct3_subadd_c : std_ulogic_vector(2 downto 0) := "000"; -- sub/add via funct7

  constant funct3_sll_c    : std_ulogic_vector(2 downto 0) := "001"; -- shift logical left

  constant funct3_slt_c    : std_ulogic_vector(2 downto 0) := "010"; -- set on less

  constant funct3_sltu_c   : std_ulogic_vector(2 downto 0) := "011"; -- set on less unsigned

  constant funct3_xor_c    : std_ulogic_vector(2 downto 0) := "100"; -- xor

  constant funct3_sr_c     : std_ulogic_vector(2 downto 0) := "101"; -- shift right via funct7