icache.py add missing funciton bodies, add missing return statment, fix

[soc.git] / src / soc / experiment / icache.py

"""ICache

based on Anton Blanchard microwatt icache.vhdl

Set associative icache

TODO (in no specific order):
* Add debug interface to inspect cache content
* Add snoop/invalidate path
* Add multi-hit error detection
* Pipelined bus interface (wb or axi)
* Maybe add parity? There's a few bits free in each BRAM row on Xilinx
* Add optimization: service hits on partially loaded lines
* Add optimization: (maybe) interrupt reload on fluch/redirect
* Check if playing with the geometry of the cache tags allow for more
  efficient use of distributed RAM and less logic/muxes. Currently we
  write TAG_BITS width which may not match full ram blocks and might
  cause muxes to be inferred for "partial writes".
* Check if making the read size of PLRU a ROM helps utilization

"""
from enum import Enum, unique
from nmigen import (Module, Signal, Elaboratable, Cat, Array, Const)
from nmigen.cli import main
from nmigen.cli import rtlil
from nmutil.iocontrol import RecordObject
from nmutil.byterev import byte_reverse
from nmutil.mask import Mask
from nmigen.utils import log2_int
from nmutil.util import Display

from soc.experiment.mem_types import (Fetch1ToICacheType,
                                      ICacheToDecode1Type,
                                      MMUToICacheType)

from soc.experiment.wb_types import (WB_ADDR_BITS, WB_DATA_BITS,
                                     WB_SEL_BITS, WBAddrType, WBDataType,
                                     WBSelType, WBMasterOut, WBSlaveOut,
                                     WBMasterOutVector, WBSlaveOutVector,
                                     WBIOMasterOut, WBIOSlaveOut)

from soc.experiment.cache_ram import CacheRam
from soc.experiment.plru import PLRU

# for test
from nmigen_soc.wishbone.sram import SRAM
from nmigen import Memory
from nmigen.cli import rtlil
if True:
    from nmigen.back.pysim import Simulator, Delay, Settle
else:
    from nmigen.sim.cxxsim import Simulator, Delay, Settle
from nmutil.util import wrap



SIM            = 0
LINE_SIZE      = 64
# BRAM organisation: We never access more than wishbone_data_bits
# at a time so to save resources we make the array only that wide,
# and use consecutive indices for to make a cache "line"
#
# ROW_SIZE is the width in bytes of the BRAM (based on WB, so 64-bits)
ROW_SIZE       = WB_DATA_BITS // 8
# Number of lines in a set
NUM_LINES      = 32
# Number of ways
NUM_WAYS       = 4
# L1 ITLB number of entries (direct mapped)
TLB_SIZE       = 64
# L1 ITLB log_2(page_size)
TLB_LG_PGSZ    = 12
# Number of real address bits that we store
REAL_ADDR_BITS = 56
# Non-zero to enable log data collection
LOG_LENGTH     = 0

ROW_SIZE_BITS  = ROW_SIZE * 8
# ROW_PER_LINE is the number of row
# (wishbone) transactions in a line
ROW_PER_LINE   = LINE_SIZE // ROW_SIZE
# BRAM_ROWS is the number of rows in
# BRAM needed to represent the full icache
BRAM_ROWS      = NUM_LINES * ROW_PER_LINE
# INSN_PER_ROW is the number of 32bit
# instructions per BRAM row
INSN_PER_ROW   = ROW_SIZE_BITS // 32

# Bit fields counts in the address
#
# INSN_BITS is the number of bits to
# select an instruction in a row
INSN_BITS      = log2_int(INSN_PER_ROW)
# ROW_BITS is the number of bits to
# select a row
ROW_BITS       = log2_int(BRAM_ROWS)
# ROW_LINEBITS is the number of bits to
# select a row within a line
ROW_LINE_BITS   = log2_int(ROW_PER_LINE)
# LINE_OFF_BITS is the number of bits for
# the offset in a cache line
LINE_OFF_BITS  = log2_int(LINE_SIZE)
# ROW_OFF_BITS is the number of bits for
# the offset in a row
ROW_OFF_BITS   = log2_int(ROW_SIZE)
# INDEX_BITS is the number of bits to
# select a cache line
INDEX_BITS     = log2_int(NUM_LINES)
# SET_SIZE_BITS is the log base 2 of
# the set size
SET_SIZE_BITS  = LINE_OFF_BITS + INDEX_BITS
# TAG_BITS is the number of bits of
# the tag part of the address
TAG_BITS       = REAL_ADDR_BITS - SET_SIZE_BITS
# WAY_BITS is the number of bits to
# select a way
WAY_BITS       = log2_int(NUM_WAYS)
TAG_RAM_WIDTH  = TAG_BITS * NUM_WAYS

#     -- L1 ITLB.
#     constant TLB_BITS : natural := log2(TLB_SIZE);
#     constant TLB_EA_TAG_BITS : natural := 64 - (TLB_LG_PGSZ + TLB_BITS);
#     constant TLB_PTE_BITS : natural := 64;
TLB_BITS        = log2_int(TLB_SIZE)
TLB_EA_TAG_BITS = 64 - (TLB_LG_PGSZ + TLB_BITS)
TLB_PTE_BITS    = 64

# architecture rtl of icache is
#constant ROW_SIZE_BITS : natural := ROW_SIZE*8;
#-- ROW_PER_LINE is the number of row (wishbone
#-- transactions) in a line
#constant ROW_PER_LINE  : natural := LINE_SIZE / ROW_SIZE;
#-- BRAM_ROWS is the number of rows in BRAM
#-- needed to represent the full
#-- icache
#constant BRAM_ROWS     : natural := NUM_LINES * ROW_PER_LINE;
#-- INSN_PER_ROW is the number of 32bit instructions per BRAM row
#constant INSN_PER_ROW  : natural := ROW_SIZE_BITS / 32;
#-- Bit fields counts in the address
#
#-- INSN_BITS is the number of bits to select
#-- an instruction in a row
#constant INSN_BITS     : natural := log2(INSN_PER_ROW);
#-- ROW_BITS is the number of bits to select a row
#constant ROW_BITS      : natural := log2(BRAM_ROWS);
#-- ROW_LINEBITS is the number of bits to
#-- select a row within a line
#constant ROW_LINEBITS  : natural := log2(ROW_PER_LINE);
#-- LINE_OFF_BITS is the number of bits for the offset
#-- in a cache line
#constant LINE_OFF_BITS : natural := log2(LINE_SIZE);
#-- ROW_OFF_BITS is the number of bits for the offset in a row
#constant ROW_OFF_BITS  : natural := log2(ROW_SIZE);
#-- INDEX_BITS is the number of bits to select a cache line
#constant INDEX_BITS    : natural := log2(NUM_LINES);
#-- SET_SIZE_BITS is the log base 2 of the set size
#constant SET_SIZE_BITS : natural := LINE_OFF_BITS + INDEX_BITS;
#-- TAG_BITS is the number of bits of the tag part of the address
#constant TAG_BITS      : natural := REAL_ADDR_BITS - SET_SIZE_BITS;
#-- WAY_BITS is the number of bits to select a way
#constant WAY_BITS     : natural := log2(NUM_WAYS);

#-- Example of layout for 32 lines of 64 bytes:
#--
#-- ..  tag    |index|  line  |
#-- ..         |   row   |    |
#-- ..         |     |   | |00| zero          (2)
#-- ..         |     |   |-|  | INSN_BITS     (1)
#-- ..         |     |---|    | ROW_LINEBITS  (3)
#-- ..         |     |--- - --| LINE_OFF_BITS (6)
#-- ..         |         |- --| ROW_OFF_BITS  (3)
#-- ..         |----- ---|    | ROW_BITS      (8)
#-- ..         |-----|        | INDEX_BITS    (5)
#-- .. --------|              | TAG_BITS      (53)
   # Example of layout for 32 lines of 64 bytes:
   #
   # ..  tag    |index|  line  |
   # ..         |   row   |    |
   # ..         |     |   | |00| zero          (2)
   # ..         |     |   |-|  | INSN_BITS     (1)
   # ..         |     |---|    | ROW_LINEBITS  (3)
   # ..         |     |--- - --| LINE_OFF_BITS (6)
   # ..         |         |- --| ROW_OFF_BITS  (3)
   # ..         |----- ---|    | ROW_BITS      (8)
   # ..         |-----|        | INDEX_BITS    (5)
   # .. --------|              | TAG_BITS      (53)

#subtype row_t is integer range 0 to BRAM_ROWS-1;
#subtype index_t is integer range 0 to NUM_LINES-1;
#subtype way_t is integer range 0 to NUM_WAYS-1;
#subtype row_in_line_t is unsigned(ROW_LINEBITS-1 downto 0);
#
#-- The cache data BRAM organized as described above for each way
#subtype cache_row_t is std_ulogic_vector(ROW_SIZE_BITS-1 downto 0);
#
#-- The cache tags LUTRAM has a row per set. Vivado is a pain and will
#-- not handle a clean (commented) definition of the cache tags as a 3d
#-- memory. For now, work around it by putting all the tags
#subtype cache_tag_t is std_logic_vector(TAG_BITS-1 downto 0);
#  type cache_tags_set_t is array(way_t) of cache_tag_t;
#  type cache_tags_array_t is array(index_t) of cache_tags_set_t;
#constant TAG_RAM_WIDTH : natural := TAG_BITS * NUM_WAYS;
#subtype cache_tags_set_t is std_logic_vector(TAG_RAM_WIDTH-1 downto 0);
#type cache_tags_array_t is array(index_t) of cache_tags_set_t;
def CacheTagArray():
    return Array(Signal(TAG_RAM_WIDTH) for x in range(NUM_LINES))

#-- The cache valid bits
#subtype cache_way_valids_t is std_ulogic_vector(NUM_WAYS-1 downto 0);
#type cache_valids_t is array(index_t) of cache_way_valids_t;
#type row_per_line_valid_t is array(0 to ROW_PER_LINE - 1) of std_ulogic;
def CacheValidBitsArray():
    return Array(Signal(NUM_WAYS) for x in range(NUM_LINES))

def RowPerLineValidArray():
    return Array(Signal() for x in range(ROW_PER_LINE))


#attribute ram_style : string;
#attribute ram_style of cache_tags : signal is "distributed";
   # TODO to be passed to nigmen as ram attributes
   # attribute ram_style : string;
   # attribute ram_style of cache_tags : signal is "distributed";


#subtype tlb_index_t is integer range 0 to TLB_SIZE - 1;
#type tlb_valids_t is array(tlb_index_t) of std_ulogic;
#subtype tlb_tag_t is std_ulogic_vector(TLB_EA_TAG_BITS - 1 downto 0);
#type tlb_tags_t is array(tlb_index_t) of tlb_tag_t;
#subtype tlb_pte_t is std_ulogic_vector(TLB_PTE_BITS - 1 downto 0);
#type tlb_ptes_t is array(tlb_index_t) of tlb_pte_t;
def TLBValidBitsArray():
    return Array(Signal() for x in range(TLB_SIZE))

def TLBTagArray():
    return Array(Signal(TLB_EA_TAG_BITS) for x in range(TLB_SIZE))

def TLBPTEArray():
    return Array(Signal(TLB_PTE_BITS) for x in range(TLB_SIZE))


#-- Cache RAM interface
#type cache_ram_out_t is array(way_t) of cache_row_t;
# Cache RAM interface
def CacheRamOut():
    return Array(Signal(ROW_SIZE_BITS) for x in range(NUM_WAYS))

#-- PLRU output interface
#type plru_out_t is array(index_t) of
# std_ulogic_vector(WAY_BITS-1 downto 0);
# PLRU output interface
def PLRUOut():
    return Array(Signal(WAY_BITS) for x in range(NUM_LINES))

#     -- Return the cache line index (tag index) for an address
#     function get_index(addr: std_ulogic_vector(63 downto 0))
#      return index_t is
#     begin
#         return to_integer(unsigned(
#          addr(SET_SIZE_BITS - 1 downto LINE_OFF_BITS)
#         ));
#     end;
# Return the cache line index (tag index) for an address
def get_index(addr):
    return addr[LINE_OFF_BITS:SET_SIZE_BITS]

#     -- Return the cache row index (data memory) for an address
#     function get_row(addr: std_ulogic_vector(63 downto 0))
#       return row_t is
#     begin
#         return to_integer(unsigned(
#          addr(SET_SIZE_BITS - 1 downto ROW_OFF_BITS)
#         ));
#     end;
# Return the cache row index (data memory) for an address
def get_row(addr):
    return addr[ROW_OFF_BITS:SET_SIZE_BITS]

#     -- Return the index of a row within a line
#     function get_row_of_line(row: row_t) return row_in_line_t is
#       variable row_v : unsigned(ROW_BITS-1 downto 0);
#     begin
#       row_v := to_unsigned(row, ROW_BITS);
#         return row_v(ROW_LINEBITS-1 downto 0);
#     end;
# Return the index of a row within a line
def get_row_of_line(row):
    return row[:ROW_LINE_BITS]

#     -- Returns whether this is the last row of a line
#     function is_last_row_addr(addr: wishbone_addr_type;
#      last: row_in_line_t
#     )
#      return boolean is
#     begin
#       return unsigned(
#        addr(LINE_OFF_BITS-1 downto ROW_OFF_BITS)
#       ) = last;
#     end;
# Returns whether this is the last row of a line
def is_last_row_addr(addr, last):
    return addr[ROW_OFF_BITS:LINE_OFF_BITS] == last

#     -- Returns whether this is the last row of a line
#     function is_last_row(row: row_t;
#      last: row_in_line_t) return boolean is
#     begin
#       return get_row_of_line(row) = last;
#     end;
# Returns whether this is the last row of a line
def is_last_row(row, last):
    return get_row_of_line(row) == last

#     -- Return the address of the next row in the current cache line
#     function next_row_addr(addr: wishbone_addr_type)
#       return std_ulogic_vector is
#       variable row_idx : std_ulogic_vector(ROW_LINEBITS-1 downto 0);
#       variable result  : wishbone_addr_type;
#     begin
#       -- Is there no simpler way in VHDL to generate that 3 bits adder ?
#       row_idx := addr(LINE_OFF_BITS-1 downto ROW_OFF_BITS);
#       row_idx := std_ulogic_vector(unsigned(row_idx) + 1);
#       result := addr;
#       result(LINE_OFF_BITS-1 downto ROW_OFF_BITS) := row_idx;
#       return result;
#     end;
# Return the address of the next row in the current cache line
def next_row_addr(addr):
    row_idx = addr[ROW_OFF_BITS:LINE_OFF_BITS] + 1
    return addr[ROW_OFF_BITS:LINE_OFF_BITS].eq(row_idx)

#     -- Return the next row in the current cache line. We use a dedicated
#     -- function in order to limit the size of the generated adder to be
#     -- only the bits within a cache line (3 bits with default settings)
#     function next_row(row: row_t) return row_t is
#       variable row_v   : std_ulogic_vector(ROW_BITS-1 downto 0);
#       variable row_idx : std_ulogic_vector(ROW_LINEBITS-1 downto 0);
#       variable result  : std_ulogic_vector(ROW_BITS-1 downto 0);
#     begin
#       row_v := std_ulogic_vector(to_unsigned(row, ROW_BITS));
#       row_idx := row_v(ROW_LINEBITS-1 downto 0);
#       row_v(ROW_LINEBITS-1 downto 0) :=
#        std_ulogic_vector(unsigned(row_idx) + 1);
#       return to_integer(unsigned(row_v));
#     end;
# Return the next row in the current cache line. We use a dedicated
# function in order to limit the size of the generated adder to be
# only the bits within a cache line (3 bits with default settings)
def next_row(row):
    row_idx = row[:ROW_LINE_BITS]
    return row[:ROW_LINE_BITS].eq(row_idx + 1)

#     -- Read the instruction word for the given address in the
#     -- current cache row
#     function read_insn_word(addr: std_ulogic_vector(63 downto 0);
#                           data: cache_row_t) return std_ulogic_vector is
#       variable word: integer range 0 to INSN_PER_ROW-1;
#     begin
#         word := to_integer(unsigned(addr(INSN_BITS+2-1 downto 2)));
#       return data(31+word*32 downto word*32);
#     end;
# Read the instruction word for the given address
# in the current cache row
def read_insn_word(addr, data):
    word = addr[2:INSN_BITS+3]
    return data.word_select(word, 32)

#     -- Get the tag value from the address
#     function get_tag(
#      addr: std_ulogic_vector(REAL_ADDR_BITS - 1 downto 0)
#     )
#      return cache_tag_t is
#     begin
#         return addr(REAL_ADDR_BITS - 1 downto SET_SIZE_BITS);
#     end;
# Get the tag value from the address
def get_tag(addr):
    return addr[SET_SIZE_BITS:REAL_ADDR_BITS]

#     -- Read a tag from a tag memory row
#     function read_tag(way: way_t; tagset: cache_tags_set_t)
#      return cache_tag_t is
#     begin
#       return tagset((way+1) * TAG_BITS - 1 downto way * TAG_BITS);
#     end;
# Read a tag from a tag memory row
def read_tag(way, tagset):
    return tagset[way * TAG_BITS:(way + 1) * TAG_BITS]

#     -- Write a tag to tag memory row
#     procedure write_tag(way: in way_t;
#      tagset: inout cache_tags_set_t; tag: cache_tag_t) is
#     begin
#       tagset((way+1) * TAG_BITS - 1 downto way * TAG_BITS) := tag;
#     end;
# Write a tag to tag memory row
def write_tag(way, tagset, tag):
    tagset[way * TAG_BITS:(way + 1) * TAG_BITS] = tag

#     -- Simple hash for direct-mapped TLB index
#     function hash_ea(addr: std_ulogic_vector(63 downto 0))
#      return tlb_index_t is
#         variable hash : std_ulogic_vector(TLB_BITS - 1 downto 0);
#     begin
#         hash := addr(TLB_LG_PGSZ + TLB_BITS - 1 downto TLB_LG_PGSZ)
#                 xor addr(
#                  TLB_LG_PGSZ + 2 * TLB_BITS - 1 downto
#                  TLB_LG_PGSZ + TLB_BITS
#                 )
#                 xor addr(
#                  TLB_LG_PGSZ + 3 * TLB_BITS - 1 downto
#                  TLB_LG_PGSZ + 2 * TLB_BITS
#                 );
#         return to_integer(unsigned(hash));
#     end;
# Simple hash for direct-mapped TLB index
def hash_ea(addr):
    hsh = addr[TLB_LG_PGSZ:TLB_LG_PGSZ + TLB_BITS] ^ addr[
           TLB_LG_PGSZ + TLB_BITS:TLB_LG_PGSZ + 2 * TLB_BITS
          ] ^ addr[
           TLB_LG_PGSZ + 2 * TLB_BITS:TLB_LG_PGSZ + 3 * TLB_BITS
          ]
    return hsh

# begin
#
#     assert LINE_SIZE mod ROW_SIZE = 0;
#     assert ispow2(LINE_SIZE) report "LINE_SIZE not power of 2"
#      severity FAILURE;
#     assert ispow2(NUM_LINES) report "NUM_LINES not power of 2"
#      severity FAILURE;
#     assert ispow2(ROW_PER_LINE) report "ROW_PER_LINE not power of 2"
#      severity FAILURE;
#     assert ispow2(INSN_PER_ROW) report "INSN_PER_ROW not power of 2"
#      severity FAILURE;
#     assert (ROW_BITS = INDEX_BITS + ROW_LINEBITS)
#       report "geometry bits don't add up" severity FAILURE;
#     assert (LINE_OFF_BITS = ROW_OFF_BITS + ROW_LINEBITS)
#       report "geometry bits don't add up" severity FAILURE;
#     assert (REAL_ADDR_BITS = TAG_BITS + INDEX_BITS + LINE_OFF_BITS)
#       report "geometry bits don't add up" severity FAILURE;
#     assert (REAL_ADDR_BITS = TAG_BITS + ROW_BITS + ROW_OFF_BITS)
#       report "geometry bits don't add up" severity FAILURE;
#
#     sim_debug: if SIM generate
#     debug: process
#     begin
#       report "ROW_SIZE      = " & natural'image(ROW_SIZE);
#       report "ROW_PER_LINE  = " & natural'image(ROW_PER_LINE);
#       report "BRAM_ROWS     = " & natural'image(BRAM_ROWS);
#       report "INSN_PER_ROW  = " & natural'image(INSN_PER_ROW);
#       report "INSN_BITS     = " & natural'image(INSN_BITS);
#       report "ROW_BITS      = " & natural'image(ROW_BITS);
#       report "ROW_LINEBITS  = " & natural'image(ROW_LINEBITS);
#       report "LINE_OFF_BITS = " & natural'image(LINE_OFF_BITS);
#       report "ROW_OFF_BITS  = " & natural'image(ROW_OFF_BITS);
#       report "INDEX_BITS    = " & natural'image(INDEX_BITS);
#       report "TAG_BITS      = " & natural'image(TAG_BITS);
#       report "WAY_BITS      = " & natural'image(WAY_BITS);
#       wait;
#     end process;
#     end generate;

# Cache reload state machine
@unique
class State(Enum):
    IDLE     = 0
    CLR_TAG  = 1
    WAIT_ACK = 2

#     type reg_internal_t is record
#       -- Cache hit state (Latches for 1 cycle BRAM access)
#       hit_way   : way_t;
#       hit_nia   : std_ulogic_vector(63 downto 0);
#       hit_smark : std_ulogic;
#       hit_valid : std_ulogic;
#
#       -- Cache miss state (reload state machine)
#         state            : state_t;
#         wb               : wishbone_master_out;
#       store_way        : way_t;
#         store_index      : index_t;
#       store_row        : row_t;
#         store_tag        : cache_tag_t;
#         store_valid      : std_ulogic;
#         end_row_ix       : row_in_line_t;
#         rows_valid       : row_per_line_valid_t;
#
#         -- TLB miss state
#         fetch_failed     : std_ulogic;
#     end record;
class RegInternal(RecordObject):
    def __init__(self):
        super().__init__()
        # Cache hit state (Latches for 1 cycle BRAM access)
        self.hit_way      = Signal(NUM_WAYS)
        self.hit_nia      = Signal(64)
        self.hit_smark    = Signal()
        self.hit_valid    = Signal()

        # Cache miss state (reload state machine)
        self.state        = Signal(State)
        self.wb           = WBMasterOut()
        self.store_way    = Signal(NUM_WAYS)
        self.store_index  = Signal(NUM_LINES)
        self.store_row    = Signal(BRAM_ROWS)
        self.store_tag    = Signal(TAG_BITS)
        self.store_valid  = Signal()
        self.end_row_ix   = Signal(ROW_LINE_BITS)
        self.rows_valid   = RowPerLineValidArray()

        # TLB miss state
        self.fetch_failed = Signal()

# -- 64 bit direct mapped icache. All instructions are 4B aligned.
#
# entity icache is
#     generic (
#         SIM : boolean := false;
#         -- Line size in bytes
#         LINE_SIZE : positive := 64;
#         -- BRAM organisation: We never access more
#         -- than wishbone_data_bits
#         -- at a time so to save resources we make the
#         -- array only that wide,
#         -- and use consecutive indices for to make a cache "line"
#         --
#         -- ROW_SIZE is the width in bytes of the BRAM (based on WB,
#         -- so 64-bits)
#         ROW_SIZE  : positive := wishbone_data_bits / 8;
#         -- Number of lines in a set
#         NUM_LINES : positive := 32;
#         -- Number of ways
#         NUM_WAYS  : positive := 4;
#         -- L1 ITLB number of entries (direct mapped)
#         TLB_SIZE : positive := 64;
#         -- L1 ITLB log_2(page_size)
#         TLB_LG_PGSZ : positive := 12;
#         -- Number of real address bits that we store
#         REAL_ADDR_BITS : positive := 56;
#         -- Non-zero to enable log data collection
#         LOG_LENGTH : natural := 0
#         );
#     port (
#         clk          : in std_ulogic;
#         rst          : in std_ulogic;
#
#         i_in         : in Fetch1ToIcacheType;
#         i_out        : out IcacheToDecode1Type;
#
#         m_in         : in MmuToIcacheType;
#
#         stall_in     : in std_ulogic;
#       stall_out    : out std_ulogic;
#       flush_in     : in std_ulogic;
#       inval_in     : in std_ulogic;
#
#         wishbone_out : out wishbone_master_out;
#         wishbone_in  : in wishbone_slave_out;
#
#         log_out      : out std_ulogic_vector(53 downto 0)
#         );
# end entity icache;
# 64 bit direct mapped icache. All instructions are 4B aligned.
class ICache(Elaboratable):
    """64 bit direct mapped icache. All instructions are 4B aligned."""
    def __init__(self):
        self.i_in           = Fetch1ToICacheType()
        self.i_out          = ICacheToDecode1Type()

        self.m_in           = MMUToICacheType()

        self.stall_in       = Signal()
        self.stall_out      = Signal()
        self.flush_in       = Signal()
        self.inval_in       = Signal()

        self.wb_out         = WBMasterOut()
        self.wb_in          = WBSlaveOut()

        self.log_out        = Signal(54)


#     -- Generate a cache RAM for each way
#     rams: for i in 0 to NUM_WAYS-1 generate
#       signal do_read  : std_ulogic;
#       signal do_write : std_ulogic;
#       signal rd_addr  : std_ulogic_vector(ROW_BITS-1 downto 0);
#       signal wr_addr  : std_ulogic_vector(ROW_BITS-1 downto 0);
#       signal dout     : cache_row_t;
#       signal wr_sel   : std_ulogic_vector(ROW_SIZE-1 downto 0);
#     begin
#       way: entity work.cache_ram
#           generic map (
#               ROW_BITS => ROW_BITS,
#               WIDTH => ROW_SIZE_BITS
#               )
#           port map (
#               clk     => clk,
#               rd_en   => do_read,
#               rd_addr => rd_addr,
#               rd_data => dout,
#               wr_sel  => wr_sel,
#               wr_addr => wr_addr,
#               wr_data => wishbone_in.dat
#               );
#       process(all)
#       begin
#           do_read <= not (stall_in or use_previous);
#           do_write <= '0';
#           if wishbone_in.ack = '1' and replace_way = i then
#               do_write <= '1';
#           end if;
#           cache_out(i) <= dout;
#           rd_addr <=
#            std_ulogic_vector(to_unsigned(req_row, ROW_BITS));
#           wr_addr <=
#            std_ulogic_vector(to_unsigned(r.store_row, ROW_BITS));
#             for i in 0 to ROW_SIZE-1 loop
#                 wr_sel(i) <= do_write;
#             end loop;
#       end process;
#     end generate;
    def rams(self, m, r, cache_out, use_previous, replace_way, req_row):
        comb = m.d.comb

        wb_in, stall_in = self.wb_in, self.stall_in

        do_read  = Signal()
        do_write = Signal()
        rd_addr  = Signal(ROW_BITS)
        wr_addr  = Signal(ROW_BITS)
        _d_out   = Signal(ROW_SIZE_BITS)
        wr_sel   = Signal(ROW_SIZE)

        for i in range(NUM_WAYS):
            way = CacheRam(ROW_BITS, ROW_SIZE_BITS)
            comb += way.rd_en.eq(do_read)
            comb += way.rd_addr.eq(rd_addr)
            comb += way.rd_data_o.eq(_d_out)
            comb += way.wr_sel.eq(wr_sel)
            comb += way.wr_addr.eq(wr_addr)
            comb += way.wr_data.eq(wb_in.dat)

            comb += do_read.eq(~(stall_in | use_previous))
            comb += do_write.eq(0)

            with m.If(wb_in.ack & (replace_way == i)):
                comb += do_write.eq(1)

            comb += cache_out[i].eq(_d_out)
            comb += rd_addr.eq(req_row)
            comb += wr_addr.eq(r.store_row)
            for j in range(ROW_SIZE):
                comb += wr_sel[j].eq(do_write)

#     -- Generate PLRUs
#     maybe_plrus: if NUM_WAYS > 1 generate
#     begin
#       plrus: for i in 0 to NUM_LINES-1 generate
#           -- PLRU interface
#           signal plru_acc    : std_ulogic_vector(WAY_BITS-1 downto 0);
#           signal plru_acc_en : std_ulogic;
#           signal plru_out    : std_ulogic_vector(WAY_BITS-1 downto 0);
#
#       begin
#           plru : entity work.plru
#               generic map (
#                   BITS => WAY_BITS
#                   )
#               port map (
#                   clk => clk,
#                   rst => rst,
#                   acc => plru_acc,
#                   acc_en => plru_acc_en,
#                   lru => plru_out
#                   );
#
#           process(all)
#           begin
#               -- PLRU interface
#               if get_index(r.hit_nia) = i then
#                   plru_acc_en <= r.hit_valid;
#               else
#                   plru_acc_en <= '0';
#               end if;
#               plru_acc <=
#                std_ulogic_vector(to_unsigned(r.hit_way, WAY_BITS));
#               plru_victim(i) <= plru_out;
#           end process;
#       end generate;
#     end generate;
    def maybe_plrus(self, m, r, plru_victim):
        comb = m.d.comb

        with m.If(NUM_WAYS > 1):
            for i in range(NUM_LINES):
                plru_acc_i  = Signal(WAY_BITS)
                plru_acc_en = Signal()
                plru_out    = Signal(WAY_BITS)
                plru        = PLRU(WAY_BITS)
                comb += plru.acc_i.eq(plru_acc_i)
                comb += plru.acc_en.eq(plru_acc_en)
                comb += plru.lru_o.eq(plru_out)

                # PLRU interface
                with m.If(get_index(r.hit_nia) == i):
                    comb += plru.acc_en.eq(r.hit_valid)

                with m.Else():
                    comb += plru.acc_en.eq(0)

                comb += plru.acc_i.eq(r.hit_way)
                comb += plru_victim[i].eq(plru.lru_o)

#     -- TLB hit detection and real address generation
#     itlb_lookup : process(all)
#         variable pte : tlb_pte_t;
#         variable ttag : tlb_tag_t;
#     begin
#         tlb_req_index <= hash_ea(i_in.nia);
#         pte := itlb_ptes(tlb_req_index);
#         ttag := itlb_tags(tlb_req_index);
#         if i_in.virt_mode = '1' then
#             real_addr <= pte(REAL_ADDR_BITS - 1 downto TLB_LG_PGSZ) &
#                          i_in.nia(TLB_LG_PGSZ - 1 downto 0);
#             if ttag = i_in.nia(63 downto TLB_LG_PGSZ + TLB_BITS) then
#                 ra_valid <= itlb_valids(tlb_req_index);
#             else
#                 ra_valid <= '0';
#             end if;
#             eaa_priv <= pte(3);
#         else
#             real_addr <= i_in.nia(REAL_ADDR_BITS - 1 downto 0);
#             ra_valid <= '1';
#             eaa_priv <= '1';
#         end if;
#
#         -- no IAMR, so no KUEP support for now
#         priv_fault <= eaa_priv and not i_in.priv_mode;
#         access_ok <= ra_valid and not priv_fault;
#     end process;
    # TLB hit detection and real address generation
    def itlb_lookup(self, m, tlb_req_index, itlb_ptes, itlb_tags,
                    real_addr, itlb_valid_bits, ra_valid, eaa_priv,
                    priv_fault, access_ok):
        comb = m.d.comb

        i_in = self.i_in

        pte  = Signal(TLB_PTE_BITS)
        ttag = Signal(TLB_EA_TAG_BITS)

        comb += tlb_req_index.eq(hash_ea(i_in.nia))
        comb += pte.eq(itlb_ptes[tlb_req_index])
        comb += ttag.eq(itlb_tags[tlb_req_index])

        with m.If(i_in.virt_mode):
            comb += real_addr.eq(Cat(
                     i_in.nia[:TLB_LG_PGSZ],
                     pte[TLB_LG_PGSZ:REAL_ADDR_BITS]
                    ))

            with m.If(ttag == i_in.nia[TLB_LG_PGSZ + TLB_BITS:64]):
                comb += ra_valid.eq(itlb_valid_bits[tlb_req_index])

            with m.Else():
                comb += ra_valid.eq(0)

        with m.Else():
            comb += real_addr.eq(i_in.nia[:REAL_ADDR_BITS])
            comb += ra_valid.eq(1)
            comb += eaa_priv.eq(1)

        # No IAMR, so no KUEP support for now
        comb += priv_fault.eq(eaa_priv & ~i_in.priv_mode)
        comb += access_ok.eq(ra_valid & ~priv_fault)

#     -- iTLB update
#     itlb_update: process(clk)
#         variable wr_index : tlb_index_t;
#     begin
#         if rising_edge(clk) then
#             wr_index := hash_ea(m_in.addr);
#             if rst = '1' or
#              (m_in.tlbie = '1' and m_in.doall = '1') then
#                 -- clear all valid bits
#                 for i in tlb_index_t loop
#                     itlb_valids(i) <= '0';
#                 end loop;
#             elsif m_in.tlbie = '1' then
#                 -- clear entry regardless of hit or miss
#                 itlb_valids(wr_index) <= '0';
#             elsif m_in.tlbld = '1' then
#                 itlb_tags(wr_index) <=
#                  m_in.addr(63 downto TLB_LG_PGSZ + TLB_BITS);
#                 itlb_ptes(wr_index) <= m_in.pte;
#                 itlb_valids(wr_index) <= '1';
#             end if;
#         end if;
#     end process;
    # iTLB update
    def itlb_update(self, m, itlb_valid_bits, itlb_tags, itlb_ptes):
        comb = m.d.comb
        sync = m.d.sync

        m_in = self.m_in

        wr_index = Signal(TLB_SIZE)
        comb += wr_index.eq(hash_ea(m_in.addr))

        with m.If(m_in.tlbie & m_in.doall):
            # Clear all valid bits
            for i in range(TLB_SIZE):
                sync += itlb_valid_bits[i].eq(0)

        with m.Elif(m_in.tlbie):
            # Clear entry regardless of hit or miss
            sync += itlb_valid_bits[wr_index].eq(0)

        with m.Elif(m_in.tlbld):
            sync += itlb_tags[wr_index].eq(
                     m_in.addr[TLB_LG_PGSZ + TLB_BITS:64]
                    )
            sync += itlb_ptes[wr_index].eq(m_in.pte)
            sync += itlb_valid_bits[wr_index].eq(1)

#     -- Cache hit detection, output to fetch2 and other misc logic
#     icache_comb : process(all)
    # Cache hit detection, output to fetch2 and other misc logic
    def icache_comb(self, m, use_previous, r, req_index, req_row,
                    req_tag, real_addr, req_laddr, cache_valid_bits,
                    cache_tags, access_ok, req_is_hit,
                    req_is_miss, replace_way, plru_victim, cache_out):
#       variable is_hit  : std_ulogic;
#       variable hit_way : way_t;
        comb = m.d.comb

        i_in, i_out, wb_out = self.i_in, self.i_out, self.wb_out
        flush_in, stall_out = self.flush_in, self.stall_out

        is_hit  = Signal()
        hit_way = Signal(NUM_WAYS)
#     begin
#         -- i_in.sequential means that i_in.nia this cycle
#         -- is 4 more than last cycle.  If we read more
#         -- than 32 bits at a time, had a cache hit last
#         -- cycle, and we don't want the first 32-bit chunk
#         -- then we can keep the data we read last cycle
#         -- and just use that.
#         if unsigned(i_in.nia(INSN_BITS+2-1 downto 2)) /= 0 then
#             use_previous <= i_in.sequential and r.hit_valid;
#         else
#             use_previous <= '0';
#         end if;
        # i_in.sequential means that i_in.nia this cycle is 4 more than
        # last cycle.  If we read more than 32 bits at a time, had a
        # cache hit last cycle, and we don't want the first 32-bit chunk
        # then we can keep the data we read last cycle and just use that.
        with m.If(i_in.nia[2:INSN_BITS+2] != 0):
            comb += use_previous.eq(i_in.sequential & r.hit_valid)

        with m.Else():
            comb += use_previous.eq(0)

#       -- Extract line, row and tag from request
#         req_index <= get_index(i_in.nia);
#         req_row <= get_row(i_in.nia);
#         req_tag <= get_tag(real_addr);
        # Extract line, row and tag from request
        comb += req_index.eq(get_index(i_in.nia))
        comb += req_row.eq(get_row(i_in.nia))
        comb += req_tag.eq(get_tag(real_addr))

#       -- Calculate address of beginning of cache row, will be
#       -- used for cache miss processing if needed
#       req_laddr <=
#        (63 downto REAL_ADDR_BITS => '0') &
#        real_addr(REAL_ADDR_BITS - 1 downto ROW_OFF_BITS) &
#        (ROW_OFF_BITS-1 downto 0 => '0');
        # Calculate address of beginning of cache row, will be
        # used for cache miss processing if needed
        comb += req_laddr.eq(Cat(
                 Const(0b0, ROW_OFF_BITS),
                 real_addr[ROW_OFF_BITS:REAL_ADDR_BITS],
                 Const(0, REAL_ADDR_BITS)
                ))

#       -- Test if pending request is a hit on any way
#       hit_way := 0;
#       is_hit := '0';
#       for i in way_t loop
#           if i_in.req = '1' and
#                 (cache_valids(req_index)(i) = '1' or
#                  (r.state = WAIT_ACK and
#                   req_index = r.store_index and
#                   i = r.store_way and
#                   r.rows_valid(req_row mod ROW_PER_LINE) = '1')) then
#               if read_tag(i, cache_tags(req_index)) = req_tag then
#                   hit_way := i;
#                   is_hit := '1';
#               end if;
#           end if;
#       end loop;
        # Test if pending request is a hit on any way
        for i in range(NUM_WAYS):
            with m.If(i_in.req &
                      (cache_valid_bits[req_index][i] |
                       ((r.state == State.WAIT_ACK)
                        & (req_index == r.store_index)
                        & (i == r.store_way)
                        & r.rows_valid[req_row % ROW_PER_LINE]))):
                with m.If(read_tag(i, cache_tags[req_index]) == req_tag):
                    comb += hit_way.eq(i)
                    comb += is_hit.eq(1)

#       -- Generate the "hit" and "miss" signals
#       -- for the synchronous blocks
#       if i_in.req = '1' and access_ok = '1' and flush_in = '0'
#        and rst = '0' then
#           req_is_hit  <= is_hit;
#           req_is_miss <= not is_hit;
#       else
#           req_is_hit  <= '0';
#           req_is_miss <= '0';
#       end if;
#       req_hit_way <= hit_way;
        # Generate the "hit" and "miss" signals
        # for the synchronous blocks
        with m.If(i_in.req & access_ok & ~flush_in):
            comb += req_is_hit.eq(is_hit)
            comb += req_is_miss.eq(~is_hit)

        with m.Else():
            comb += req_is_hit.eq(0)
            comb += req_is_miss.eq(0)

#       -- The way to replace on a miss
#       if r.state = CLR_TAG then
#           replace_way <=
#            to_integer(unsigned(plru_victim(r.store_index)));
#       else
#           replace_way <= r.store_way;
#       end if;
        # The way to replace on a miss
        with m.If(r.state == State.CLR_TAG):
            comb += replace_way.eq(plru_victim[r.store_index])

        with m.Else():
            comb += replace_way.eq(r.store_way)

#       -- Output instruction from current cache row
#       --
#       -- Note: This is a mild violation of our design principle of
#       -- having pipeline stages output from a clean latch. In this
#       -- case we output the result of a mux. The alternative would
#       -- be output an entire row which I prefer not to do just yet
#       -- as it would force fetch2 to know about some of the cache
#       -- geometry information.
#       i_out.insn <= read_insn_word(r.hit_nia, cache_out(r.hit_way));
#       i_out.valid <= r.hit_valid;
#       i_out.nia <= r.hit_nia;
#       i_out.stop_mark <= r.hit_smark;
#       i_out.fetch_failed <= r.fetch_failed;
        # Output instruction from current cache row
        #
        # Note: This is a mild violation of our design principle of
        # having pipeline stages output from a clean latch. In this
        # case we output the result of a mux. The alternative would
        # be output an entire row which I prefer not to do just yet
        # as it would force fetch2 to know about some of the cache
        # geometry information.
        comb += i_out.insn.eq(
                 read_insn_word(r.hit_nia, cache_out[r.hit_way])
                )
        comb += i_out.valid.eq(r.hit_valid)
        comb += i_out.nia.eq(r.hit_nia)
        comb += i_out.stop_mark.eq(r.hit_smark)
        comb += i_out.fetch_failed.eq(r.fetch_failed)

#       -- Stall fetch1 if we have a miss on cache or TLB
#       -- or a protection fault
#       stall_out <= not (is_hit and access_ok);
        # Stall fetch1 if we have a miss on cache or TLB
        # or a protection fault
        comb += stall_out.eq(~(is_hit & access_ok))

#       -- Wishbone requests output (from the cache miss reload machine)
#       wishbone_out <= r.wb;
        # Wishbone requests output (from the cache miss reload machine)
        comb += wb_out.eq(r.wb)
#     end process;

#     -- Cache hit synchronous machine
#     icache_hit : process(clk)
    # Cache hit synchronous machine
    def icache_hit(self, m, use_previous, r, req_is_hit, req_hit_way,
                   req_index, req_tag, real_addr):
        sync = m.d.sync

        i_in, stall_in = self.i_in, self.stall_in
        flush_in       = self.flush_in

#     begin
#         if rising_edge(clk) then
#             -- keep outputs to fetch2 unchanged on a stall
#             -- except that flush or reset sets valid to 0
#             -- If use_previous, keep the same data as last
#             -- cycle and use the second half
#             if stall_in = '1' or use_previous = '1' then
#                 if rst = '1' or flush_in = '1' then
#                     r.hit_valid <= '0';
#             end if;
        # keep outputs to fetch2 unchanged on a stall
        # except that flush or reset sets valid to 0
        # If use_previous, keep the same data as last
        # cycle and use the second half
        with m.If(stall_in | use_previous):
            with m.If(flush_in):
                sync += r.hit_valid.eq(0)
#             else
#                 -- On a hit, latch the request for the next cycle,
#                 -- when the BRAM data will be available on the
#                 -- cache_out output of the corresponding way
#                 r.hit_valid <= req_is_hit;
#                 if req_is_hit = '1' then
#                     r.hit_way <= req_hit_way;
        with m.Else():
            # On a hit, latch the request for the next cycle,
            # when the BRAM data will be available on the
            # cache_out output of the corresponding way
            sync += r.hit_valid.eq(req_is_hit)

            with m.If(req_is_hit):
                sync += r.hit_way.eq(req_hit_way)

#                     report "cache hit nia:" & to_hstring(i_in.nia) &
#                         " IR:" & std_ulogic'image(i_in.virt_mode) &
#                         " SM:" & std_ulogic'image(i_in.stop_mark) &
#                         " idx:" & integer'image(req_index) &
#                         " tag:" & to_hstring(req_tag) &
#                         " way:" & integer'image(req_hit_way) &
#                         " RA:" & to_hstring(real_addr);
                print(f"cache hit nia:{i_in.nia}, " \
                      f"IR:{i_in.virt_mode}, " \
                      f"SM:{i_in.stop_mark}, idx:{req_index}, " \
                      f"tag:{req_tag}, way:{req_hit_way}, " \
                      f"RA:{real_addr}")
#                 end if;
#           end if;
#             if stall_in = '0' then
#                 -- Send stop marks and NIA down regardless of validity
#                 r.hit_smark <= i_in.stop_mark;
#                 r.hit_nia <= i_in.nia;
#             end if;
        with m.If(~stall_in):
            # Send stop marks and NIA down regardless of validity
            sync += r.hit_smark.eq(i_in.stop_mark)
            sync += r.hit_nia.eq(i_in.nia)
#       end if;
#     end process;

#     -- Cache miss/reload synchronous machine
#     icache_miss : process(clk)
    # Cache miss/reload synchronous machine
    def icache_miss(self, m, cache_valid_bits, r, req_is_miss,
                    req_index, req_laddr, req_tag, replace_way,
                    cache_tags, access_ok, real_addr):
        comb = m.d.comb
        sync = m.d.sync

        i_in, wb_in, m_in  = self.i_in, self.wb_in, self.m_in
        stall_in, flush_in = self.stall_in, self.flush_in
        inval_in           = self.inval_in

#       variable tagset    : cache_tags_set_t;
#       variable stbs_done : boolean;

        tagset    = Signal(TAG_RAM_WIDTH)
        stbs_done = Signal()

#     begin
#         if rising_edge(clk) then
#           -- On reset, clear all valid bits to force misses
#             if rst = '1' then
        # On reset, clear all valid bits to force misses
#               for i in index_t loop
#                   cache_valids(i) <= (others => '0');
#               end loop;
#                 r.state <= IDLE;
#                 r.wb.cyc <= '0';
#                 r.wb.stb <= '0';
#               -- We only ever do reads on wishbone
#               r.wb.dat <= (others => '0');
#               r.wb.sel <= "11111111";
#               r.wb.we  <= '0';

        # We only ever do reads on wishbone
        comb += r.wb.sel.eq(~0) # set to all 1s

#               -- Not useful normally but helps avoiding
#               -- tons of sim warnings
#               r.wb.adr <= (others => '0');

#             else

#                 -- Process cache invalidations
#                 if inval_in = '1' then
#                     for i in index_t loop
#                         cache_valids(i) <= (others => '0');
#                     end loop;
#                     r.store_valid <= '0';
#                 end if;
        # Process cache invalidations
        with m.If(inval_in):
            for i in range(NUM_LINES):
                sync += cache_valid_bits[i].eq(~1) # NO just set to zero.
                                                   # look again: others == 0

            sync += r.store_valid.eq(0)

#               -- Main state machine
#               case r.state is
            # Main state machine
            with m.Switch(r.state):

#               when IDLE =>
                with m.Case(State.IDLE):
#                     -- Reset per-row valid flags,
#                     -- only used in WAIT_ACK
#                     for i in 0 to ROW_PER_LINE - 1 loop
#                         r.rows_valid(i) <= '0';
#                     end loop;
                    # Reset per-row valid flags,
                    # only used in WAIT_ACK
                    for i in range(ROW_PER_LINE):
                        sync += r.rows_valid[i].eq(0)

#                   -- We need to read a cache line
#                   if req_is_miss = '1' then
#                       report "cache miss nia:" & to_hstring(i_in.nia) &
#                             " IR:" & std_ulogic'image(i_in.virt_mode) &
#                           " SM:" & std_ulogic'image(i_in.stop_mark) &
#                           " idx:" & integer'image(req_index) &
#                           " way:" & integer'image(replace_way) &
#                           " tag:" & to_hstring(req_tag) &
#                             " RA:" & to_hstring(real_addr);
                    # We need to read a cache line
                    with m.If(req_is_miss):
                        # XXX no, do not use "f".  use sync += Display
                        # and use %d for integer, %x for hex.
                        print(f"cache miss nia:{i_in.nia} " \
                              f"IR:{i_in.virt_mode} " \
                              f"SM:{i_in.stop_mark} " \
                              F"idx:{req_index} " \
                              f"way:{replace_way} tag:{req_tag} " \
                              f"RA:{real_addr}")

#                       -- Keep track of our index and way for
#                       -- subsequent stores
#                       r.store_index <= req_index;
#                       r.store_row <= get_row(req_laddr);
#                       r.store_tag <= req_tag;
#                       r.store_valid <= '1';
#                       r.end_row_ix <=
#                        get_row_of_line(get_row(req_laddr)) - 1;
                        # Keep track of our index and way
                        # for subsequent stores
                        sync += r.store_index.eq(req_index)
                        sync += r.store_row.eq(get_row(req_laddr))
                        sync += r.store_tag.eq(req_tag)
                        sync += r.store_valid.eq(1)
                        sync += r.end_row_ix.eq(
                                 get_row_of_line(
                                  get_row(req_laddr)
                                 ) - 1
                                )

#                       -- Prep for first wishbone read. We calculate the
#                       -- address of the start of the cache line and
#                       -- start the WB cycle.
#                       r.wb.adr <= req_laddr(r.wb.adr'left downto 0);
#                       r.wb.cyc <= '1';
#                       r.wb.stb <= '1';
                        # Prep for first wishbone read.
                        # We calculate the
                        # address of the start of the cache line and
                        # start the WB cycle.
                        sync += r.wb.adr.eq(
                                 req_laddr[:r.wb.adr]
                                )
                        sync += r.wb.cyc.eq(1)
                        sync += r.wb.stb.eq(1)

#                       -- Track that we had one request sent
#                       r.state <= CLR_TAG;
                        # Track that we had one request sent
                        sync += r.state.eq(State.CLR_TAG)
#                   end if;

#               when CLR_TAG | WAIT_ACK =>
                with m.Case(State.CLR_TAG, State.WAIT_ACK):
#                     if r.state = CLR_TAG then
                    with m.If(r.state == State.CLR_TAG):
#                         -- Get victim way from plru
#                       r.store_way <= replace_way;
                        # Get victim way from plru
                        sync += r.store_way.eq(replace_way)
#
#                       -- Force misses on that way while
#                       -- reloading that line
#                       cache_valids(req_index)(replace_way) <= '0';
                        # Force misses on that way while
                        # realoading that line
                        sync += cache_valid_bits[
                                 req_index
                                ][replace_way].eq(0)

#                       -- Store new tag in selected way
#                       for i in 0 to NUM_WAYS-1 loop
#                           if i = replace_way then
#                               tagset := cache_tags(r.store_index);
#                               write_tag(i, tagset, r.store_tag);
#                               cache_tags(r.store_index) <= tagset;
#                           end if;
#                       end loop;
                        for i in range(NUM_WAYS):
                            with m.If(i == replace_way):
                                comb += tagset.eq(
                                         cache_tags[r.store_index]
                                        )
                                sync += write_tag(
                                         i, tagset, r.store_tag
                                        )
                                sync += cache_tags[r.store_index].eq(
                                         tagset
                                        )

#                         r.state <= WAIT_ACK;
                        sync += r.state.eq(State.WAIT_ACK)
#                     end if;

#                   -- Requests are all sent if stb is 0
#                   stbs_done := r.wb.stb = '0';
                    # Requests are all sent if stb is 0
                    comb += stbs_done.eq(r.wb.stb == 0)

#                   -- If we are still sending requests,
#                   -- was one accepted ?
#                   if wishbone_in.stall = '0' and not stbs_done then
                    # If we are still sending requests,
                    # was one accepted?
                    with m.If(~wb_in.stall & ~stbs_done):
#                       -- That was the last word ? We are done sending.
#                       -- Clear stb and set stbs_done so we can handle
#                       -- an eventual last ack on the same cycle.
#                       if is_last_row_addr(r.wb.adr, r.end_row_ix) then
#                           r.wb.stb <= '0';
#                           stbs_done := true;
#                       end if;
                        # That was the last word ?
                        # We are done sending.
                        # Clear stb and set stbs_done
                        # so we can handle
                        # an eventual last ack on
                        # the same cycle.
                        with m.If(is_last_row_addr(
                                  r.wb.adr, r.end_row_ix)):
                            sync += r.wb.stb.eq(0)
                            stbs_done.eq(1)

#                       -- Calculate the next row address
#                       r.wb.adr <= next_row_addr(r.wb.adr);
                        # Calculate the next row address
                        sync += r.wb.adr.eq(next_row_addr(r.wb.adr))
#                   end if;

#                   -- Incoming acks processing
#                   if wishbone_in.ack = '1' then
                    # Incoming acks processing
                    with m.If(wb_in.ack):
#                         r.rows_valid(r.store_row mod ROW_PER_LINE)
#                          <= '1';
                        sync += r.rows_valid[
                                 r.store_row & ROW_PER_LINE
                                ].eq(1)

#                       -- Check for completion
#                       if stbs_done and
#                        is_last_row(r.store_row, r.end_row_ix) then
                        # Check for completion
                        with m.If(stbs_done & is_last_row(
                                  r.store_row, r.end_row_ix)):
#                           -- Complete wishbone cycle
#                           r.wb.cyc <= '0';
                            # Complete wishbone cycle
                            sync += r.wb.cyc.eq(0)

#                           -- Cache line is now valid
#                           cache_valids(r.store_index)(replace_way) <=
#                            r.store_valid and not inval_in;
                            # Cache line is now valid
                            sync += cache_valid_bits[
                                     r.store_index
                                    ][relace_way].eq(
                                     r.store_valid & ~inval_in
                                    )

#                           -- We are done
#                           r.state <= IDLE;
                            # We are done
                            sync += r.state.eq(State.IDLE)
#                       end if;

#                       -- Increment store row counter
#                       r.store_row <= next_row(r.store_row);
                        # Increment store row counter
                        sync += store_row.eq(next_row(r.store_row))
#                   end if;
#               end case;
#           end if;
#
#             -- TLB miss and protection fault processing
#             if rst = '1' or flush_in = '1' or m_in.tlbld = '1' then
#                 r.fetch_failed <= '0';
#             elsif i_in.req = '1' and access_ok = '0' and
#              stall_in = '0' then
#                 r.fetch_failed <= '1';
#             end if;
        # TLB miss and protection fault processing
        with m.If('''TODO nmigen rst''' | flush_in | m_in.tlbld):
            sync += r.fetch_failed.eq(0)

        with m.Elif(i_in.req & ~access_ok & ~stall_in):
            sync += r.fetch_failed.eq(1)
#       end if;
#     end process;

#     icache_log: if LOG_LENGTH > 0 generate
    def icache_log(self, m, req_hit_way, ra_valid, access_ok,
                   req_is_miss, req_is_hit, lway, wstate, r):
        comb = m.d.comb
        sync = m.d.sync

        wb_in, i_out       = self.wb_in, self.i_out
        log_out, stall_out = self.log_out, self.stall_out

#         -- Output data to logger
#         signal log_data    : std_ulogic_vector(53 downto 0);
#     begin
#         data_log: process(clk)
#             variable lway: way_t;
#             variable wstate: std_ulogic;
        # Output data to logger
        for i in range(LOG_LENGTH):
            # Output data to logger
            log_data = Signal(54)
            lway     = Signal(NUM_WAYS)
            wstate   = Signal()

#         begin
#             if rising_edge(clk) then
#                 lway := req_hit_way;
#                 wstate := '0';
            comb += lway.eq(req_hit_way)
            comb += wstate.eq(0)

#                 if r.state /= IDLE then
#                     wstate := '1';
#                 end if;
            with m.If(r.state != State.IDLE):
                sync += wstate.eq(1)

#                 log_data <= i_out.valid &
#                             i_out.insn &
#                             wishbone_in.ack &
#                             r.wb.adr(5 downto 3) &
#                             r.wb.stb & r.wb.cyc &
#                             wishbone_in.stall &
#                             stall_out &
#                             r.fetch_failed &
#                             r.hit_nia(5 downto 2) &
#                             wstate &
#                             std_ulogic_vector(to_unsigned(lway, 3)) &
#                             req_is_hit & req_is_miss &
#                             access_ok &
#                             ra_valid;
            sync += log_data.eq(Cat(
                     ra_valid, access_ok, req_is_miss, req_is_hit,
                     lway, wstate, r.hit_nia[2:6],
                     r.fetch_failed, stall_out, wb_in.stall, r.wb.cyc,
                     r.wb.stb, r.wb.adr[3:6], wb_in.ack, i_out.insn,
                     i_out.valid
                    ))
#             end if;
#         end process;
#         log_out <= log_data;
            comb += log_out.eq(log_data)
#     end generate;
# end;

    def elaborate(self, platform):

        m                = Module()
        comb             = m.d.comb

        # Storage. Hopefully "cache_rows" is a BRAM, the rest is LUTs
        cache_tags       = CacheTagArray()
        cache_valid_bits = CacheValidBitsArray()

#     signal itlb_valids : tlb_valids_t;
#     signal itlb_tags : tlb_tags_t;
#     signal itlb_ptes : tlb_ptes_t;
#     attribute ram_style of itlb_tags : signal is "distributed";
#     attribute ram_style of itlb_ptes : signal is "distributed";
        itlb_valid_bits  = TLBValidBitsArray()
        itlb_tags        = TLBTagArray()
        itlb_ptes        = TLBPTEArray()
        # TODO to be passed to nmigen as ram attributes
        # attribute ram_style of itlb_tags : signal is "distributed";
        # attribute ram_style of itlb_ptes : signal is "distributed";

#     -- Privilege bit from PTE EAA field
#     signal eaa_priv  : std_ulogic;
        # Privilege bit from PTE EAA field
        eaa_priv         = Signal()

#     signal r : reg_internal_t;
        r                = RegInternal()

#     -- Async signals on incoming request
#     signal req_index   : index_t;
#     signal req_row     : row_t;
#     signal req_hit_way : way_t;
#     signal req_tag     : cache_tag_t;
#     signal req_is_hit  : std_ulogic;
#     signal req_is_miss : std_ulogic;
#     signal req_laddr   : std_ulogic_vector(63 downto 0);
        # Async signal on incoming request
        req_index        = Signal(NUM_LINES)
        req_row          = Signal(BRAM_ROWS)
        req_hit_way      = Signal(NUM_WAYS)
        req_tag          = Signal(TAG_BITS)
        req_is_hit       = Signal()
        req_is_miss      = Signal()
        req_laddr        = Signal(64)

#     signal tlb_req_index : tlb_index_t;
#     signal real_addr     : std_ulogic_vector(
#                             REAL_ADDR_BITS - 1 downto 0
#                            );
#     signal ra_valid      : std_ulogic;
#     signal priv_fault    : std_ulogic;
#     signal access_ok     : std_ulogic;
#     signal use_previous  : std_ulogic;
        tlb_req_index    = Signal(TLB_SIZE)
        real_addr        = Signal(REAL_ADDR_BITS)
        ra_valid         = Signal()
        priv_fault       = Signal()
        access_ok        = Signal()
        use_previous     = Signal()

#     signal cache_out   : cache_ram_out_t;
        cache_out        = CacheRamOut()

#     signal plru_victim : plru_out_t;
#     signal replace_way : way_t;
        plru_victim      = PLRUOut()
        replace_way      = Signal(NUM_WAYS)

        # call sub-functions putting everything together, using shared
        # signals established above
        self.rams(m, r, cache_out, use_previous, replace_way, req_row)
        self.maybe_plrus(m, r, plru_victim)
        self.itlb_lookup(m, tlb_req_index, itlb_ptes, itlb_tags,
                         real_addr, itlb_valid_bits, ra_valid, eaa_priv,
                         priv_fault, access_ok)
        self.itlb_update(m, itlb_valid_bits, itlb_tags, itlb_ptes)
        self.icache_comb(m, use_previous, r, req_index, req_row,
                         req_tag, real_addr, req_laddr, cache_valid_bits,
                         cache_tags, access_ok, req_is_hit, req_is_miss,
                         replace_way, plru_victim, cache_out)
        self.icache_hit(m, use_previous, r, req_is_hit, req_hit_way,
                        req_index, req_tag, real_addr)
        self.icache_miss(m, cache_valid_bits, r, req_is_miss, req_index,
                         req_laddr, req_tag, replace_way, cache_tags,
                         access_ok, real_addr)
        #self.icache_log(m, log_out, req_hit_way, ra_valid, access_ok,
        #                req_is_miss, req_is_hit, lway, wstate, r)

        return m


# icache_tb.vhdl
#
# library ieee;
# use ieee.std_logic_1164.all;
#
# library work;
# use work.common.all;
# use work.wishbone_types.all;
#
# entity icache_tb is
# end icache_tb;
#
# architecture behave of icache_tb is
#     signal clk          : std_ulogic;
#     signal rst          : std_ulogic;
#
#     signal i_out        : Fetch1ToIcacheType;
#     signal i_in         : IcacheToDecode1Type;
#
#     signal m_out        : MmuToIcacheType;
#
#     signal wb_bram_in   : wishbone_master_out;
#     signal wb_bram_out  : wishbone_slave_out;
#
#     constant clk_period : time := 10 ns;
# begin
#     icache0: entity work.icache
#         generic map(
#             LINE_SIZE => 64,
#             NUM_LINES => 4
#             )
#         port map(
#             clk => clk,
#             rst => rst,
#             i_in => i_out,
#             i_out => i_in,
#             m_in => m_out,
#             stall_in => '0',
#           flush_in => '0',
#             inval_in => '0',
#             wishbone_out => wb_bram_in,
#             wishbone_in => wb_bram_out
#             );
#
#     -- BRAM Memory slave
#     bram0: entity work.wishbone_bram_wrapper
#         generic map(
#             MEMORY_SIZE   => 1024,
#             RAM_INIT_FILE => "icache_test.bin"
#             )
#         port map(
#             clk => clk,
#             rst => rst,
#             wishbone_in => wb_bram_in,
#             wishbone_out => wb_bram_out
#             );
#
#     clk_process: process
#     begin
#         clk <= '0';
#         wait for clk_period/2;
#         clk <= '1';
#         wait for clk_period/2;
#     end process;
#
#     rst_process: process
#     begin
#         rst <= '1';
#         wait for 2*clk_period;
#         rst <= '0';
#         wait;
#     end process;
#
#     stim: process
#     begin
#         i_out.req <= '0';
#         i_out.nia <= (others => '0');
#       i_out.stop_mark <= '0';
#
#         m_out.tlbld <= '0';
#         m_out.tlbie <= '0';
#         m_out.addr <= (others => '0');
#         m_out.pte <= (others => '0');
#
#         wait until rising_edge(clk);
#         wait until rising_edge(clk);
#         wait until rising_edge(clk);
#         wait until rising_edge(clk);
#
#         i_out.req <= '1';
#         i_out.nia <= x"0000000000000004";
#
#         wait for 30*clk_period;
#         wait until rising_edge(clk);
#
#         assert i_in.valid = '1' severity failure;
#         assert i_in.insn = x"00000001"
#           report "insn @" & to_hstring(i_out.nia) &
#           "=" & to_hstring(i_in.insn) &
#           " expected 00000001"
#           severity failure;
#
#         i_out.req <= '0';
#
#         wait until rising_edge(clk);
#
#         -- hit
#         i_out.req <= '1';
#         i_out.nia <= x"0000000000000008";
#         wait until rising_edge(clk);
#         wait until rising_edge(clk);
#         assert i_in.valid = '1' severity failure;
#         assert i_in.insn = x"00000002"
#           report "insn @" & to_hstring(i_out.nia) &
#           "=" & to_hstring(i_in.insn) &
#           " expected 00000002"
#           severity failure;
#         wait until rising_edge(clk);
#
#         -- another miss
#         i_out.req <= '1';
#         i_out.nia <= x"0000000000000040";
#
#         wait for 30*clk_period;
#         wait until rising_edge(clk);
#
#         assert i_in.valid = '1' severity failure;
#         assert i_in.insn = x"00000010"
#           report "insn @" & to_hstring(i_out.nia) &
#           "=" & to_hstring(i_in.insn) &
#           " expected 00000010"
#           severity failure;
#
#         -- test something that aliases
#         i_out.req <= '1';
#         i_out.nia <= x"0000000000000100";
#         wait until rising_edge(clk);
#         wait until rising_edge(clk);
#         assert i_in.valid = '0' severity failure;
#         wait until rising_edge(clk);
#
#         wait for 30*clk_period;
#         wait until rising_edge(clk);
#
#         assert i_in.valid = '1' severity failure;
#         assert i_in.insn = x"00000040"
#           report "insn @" & to_hstring(i_out.nia) &
#           "=" & to_hstring(i_in.insn) &
#           " expected 00000040"
#           severity failure;
#
#         i_out.req <= '0';
#
#         std.env.finish;
#     end process;
# end;
def icache_sim(dut):
    i_out, i_in, m_out, m_in = dut.i_out, dut.i_in, dut.m_out, dut.m_in

    yield i_out.req.eq(0)
    yield i_out.nia.eq(~1)
    yield i_out.stop_mark.eq(0)
    yield m_out.tlbld.eq(0)
    yield m_out.tlbie.eq(0)
    yield m_out.addr.eq(~1)
    yield m_out.pte.eq(~1)
    yield
    yield
    yield
    yield
    yield i_out.req.eq(1)
    yield i_out.nia.eq(Const(0x0000000000000004, 64))
    for i in range(30):
        yield
    yield
    assert i_in.valid
    assert i_in.insn == Const(0x00000001, 32), \
        ("insn @%x=%x expected 00000001" % i_out.nia, i_in.insn)
    yield i_out.req.eq(0)
    yield

    # hit
    yield i_out.req.eq(1)
    yield i_out.nia.eq(Const(0x0000000000000008, 64))
    yield
    yield
    assert i_in.valid
    assert i_in.insn == Const(0x00000002, 32), \
        ("insn @%x=%x expected 00000002" % i_out.nia, i_in.insn)
    yield

    # another miss
    yield i_out.req(1)
    yield i_out.nia.eq(Const(0x0000000000000040, 64))
    for i in range(30):
        yield
    yield
    assert i_in.valid
    assert i_in.insn == Const(0x00000010, 32), \
        ("insn @%x=%x expected 00000010" % i_out.nia, i_in.insn)

    # test something that aliases
    yield i_out.req.eq(1)
    yield i_out.nia.eq(Const(0x0000000000000100, 64))
    yield
    yield
    assert i_in.valid
    for i in range(30):
        yield
    yield
    assert i_in.valid
    assert i_in.insn == Const(0x00000040, 32), \
         ("insn @%x=%x expected 00000040" % i_out.nia, i_in.insn)
    yield i_out.req.eq(0)


def test_icache():
    dut = ICache()

    m = Module()
    m.submodules.icache = dut

    # nmigen Simulation
    sim = Simulator(m)
    sim.add_clock(1e-6)

    sim.add_sync_process(wrap(icache_sim(dut)))
    with sim.write_vcd('test_icache.vcd'):
        sim.run()

if __name__ == '__main__':
    dut = ICache()
    vl = rtlil.convert(dut, ports=[])
    with open("test_icache.il", "w") as f:
        f.write(vl)

    test_icache()