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neorv32/rtl/core/neorv32_dcache.vhd

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2024-02-24 08:25:27 +00:00
-- #################################################################################################
-- # << NEORV32 - Processor-Internal Data Cache >> #
-- # ********************************************************************************************* #
-- # Configurable number of cache blocks (cache lines) and block size. #
-- # Cache is direct mapped (single set) and uses "write through" write strategy. #
-- # ********************************************************************************************* #
-- # BSD 3-Clause License #
-- # #
-- # The NEORV32 RISC-V Processor, https://github.com/stnolting/neorv32 #
-- # Copyright (c) 2024, Stephan Nolting. All rights reserved. #
-- # #
-- # Redistribution and use in source and binary forms, with or without modification, are #
-- # permitted provided that the following conditions are met: #
-- # #
-- # 1. Redistributions of source code must retain the above copyright notice, this list of #
-- # conditions and the following disclaimer. #
-- # #
-- # 2. Redistributions in binary form must reproduce the above copyright notice, this list of #
-- # conditions and the following disclaimer in the documentation and/or other materials #
-- # provided with the distribution. #
-- # #
-- # 3. Neither the name of the copyright holder nor the names of its contributors may be used to #
-- # endorse or promote products derived from this software without specific prior written #
-- # permission. #
-- # #
-- # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS #
-- # OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF #
-- # MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE #
-- # COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, #
-- # EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE #
-- # GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED #
-- # AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING #
-- # NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED #
-- # OF THE POSSIBILITY OF SUCH DAMAGE. #
-- #################################################################################################
library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
library neorv32;
use neorv32.neorv32_package.all;
entity neorv32_dcache is
generic (
DCACHE_NUM_BLOCKS : natural range 1 to 256; -- number of blocks (min 1), has to be a power of 2
DCACHE_BLOCK_SIZE : natural range 4 to 2**16; -- block size in bytes (min 4), has to be a power of 2
DCACHE_UC_PBEGIN : std_ulogic_vector(3 downto 0) -- begin of uncached address space (page number)
);
port (
clk_i : in std_ulogic; -- global clock, rising edge
rstn_i : in std_ulogic; -- global reset, low-active, async
cpu_req_i : in bus_req_t; -- request bus
cpu_rsp_o : out bus_rsp_t; -- response bus
bus_req_o : out bus_req_t; -- request bus
bus_rsp_i : in bus_rsp_t -- response bus
);
end neorv32_dcache;
architecture neorv32_dcache_rtl of neorv32_dcache is
-- make sure caches sizes are a power of two --
constant nblocks_valid_c : boolean := is_power_of_two_f(DCACHE_NUM_BLOCKS);
constant nblocks_pow2_c : natural := 2**index_size_f(DCACHE_NUM_BLOCKS);
constant nblocks_c : natural := cond_sel_natural_f(nblocks_valid_c, DCACHE_NUM_BLOCKS, nblocks_pow2_c);
--
constant block_size_valid_c : boolean := is_power_of_two_f(DCACHE_BLOCK_SIZE);
constant block_size_pow2_c : natural := 2**index_size_f(DCACHE_BLOCK_SIZE);
constant block_size_c : natural := cond_sel_natural_f(block_size_valid_c, DCACHE_BLOCK_SIZE, block_size_pow2_c);
-- cache layout --
constant cache_offset_size_c : natural := index_size_f(block_size_c/4); -- offset addresses full 32-bit words
-- cache memory --
component neorv32_dcache_memory
generic (
DCACHE_NUM_BLOCKS : natural; -- number of blocks (min 1), has to be a power of 2
DCACHE_BLOCK_SIZE : natural -- block size in bytes (min 4), has to be a power of 2
);
port (
-- global control --
rstn_i : in std_ulogic; -- global reset, async, low-active
clk_i : in std_ulogic; -- global clock, rising edge
clear_i : in std_ulogic; -- invalidate whole cache
hit_o : out std_ulogic; -- hit access
-- host cache access (read-only) --
host_addr_i : in std_ulogic_vector(31 downto 0); -- access address
host_rdata_o : out std_ulogic_vector(31 downto 0); -- read data
host_rstat_o : out std_ulogic; -- access status
-- ctrl cache access --
ctrl_addr_i : in std_ulogic_vector(31 downto 0); -- access address
ctrl_we_i : in std_ulogic; -- write enable (full-word)
ctrl_ben_i : in std_ulogic_vector(03 downto 0); -- byte enable
ctrl_wdata_i : in std_ulogic_vector(31 downto 0); -- write data (full word)
ctrl_wstat_i : in std_ulogic; -- access status
ctrl_rdata_o : out std_ulogic_vector(31 downto 0) -- read data
);
end component;
-- cache interface --
type cache_if_t is record
host_rdata : std_ulogic_vector(31 downto 0); -- host read data
host_rstat : std_ulogic; -- access error
ctrl_addr : std_ulogic_vector(31 downto 0); -- access address
ctrl_we : std_ulogic; -- write enable
ctrl_ben : std_ulogic_vector(03 downto 0); -- byte-enable
ctrl_rdata : std_ulogic_vector(31 downto 0); -- read data
ctrl_wdata : std_ulogic_vector(31 downto 0); -- write data
ctrl_wstat : std_ulogic; -- access error
hit : std_ulogic; -- hit access
clear : std_ulogic; -- invalidate cache
end record;
signal cache : cache_if_t;
-- control engine --
type ctrl_engine_state_t is (S_IDLE, S_CHECK, S_DOWNLOAD_REQ, S_DOWNLOAD_WAIT, S_DIRECT_REQ,
S_DIRECT_WAIT, S_RESYNC, S_RESYNC_READ, S_RESYNC_WRITE, S_RESYNC_WAIT, S_CLEAR);
type ctrl_t is record
state : ctrl_engine_state_t; -- current state
state_nxt : ctrl_engine_state_t; -- next state
addr_reg : std_ulogic_vector(31 downto 0); -- address register for block download
addr_reg_nxt : std_ulogic_vector(31 downto 0);
req_buf : std_ulogic; -- request
req_buf_nxt : std_ulogic;
clear_buf : std_ulogic; -- clear request
clear_buf_nxt : std_ulogic;
end record;
signal ctrl : ctrl_t;
begin
-- Sanity Checks --------------------------------------------------------------------------
-- -------------------------------------------------------------------------------------------
assert not ((nblocks_valid_c = false) or (block_size_valid_c = false)) report
"[NEORV32] Auto-adjusting invalid d-cache size configuration(s)." severity warning;
-- Control Engine FSM Sync ----------------------------------------------------------------
-- -------------------------------------------------------------------------------------------
ctrl_engine_sync: process(rstn_i, clk_i)
begin
if (rstn_i = '0') then
ctrl.state <= S_CLEAR; -- to reset cache information memory, which does not have an explicit reset
ctrl.addr_reg <= (others => '0');
ctrl.req_buf <= '0';
ctrl.clear_buf <= '0';
elsif rising_edge(clk_i) then
ctrl.state <= ctrl.state_nxt;
ctrl.addr_reg <= ctrl.addr_reg_nxt;
ctrl.req_buf <= ctrl.req_buf_nxt;
ctrl.clear_buf <= ctrl.clear_buf_nxt;
end if;
end process ctrl_engine_sync;
-- Control Engine FSM Comb ----------------------------------------------------------------
-- -------------------------------------------------------------------------------------------
ctrl_engine_comb: process(ctrl, cache, cpu_req_i, bus_rsp_i)
begin
-- control defaults --
ctrl.state_nxt <= ctrl.state;
ctrl.addr_reg_nxt <= ctrl.addr_reg;
-- request buffer --
ctrl.req_buf_nxt <= ctrl.req_buf or cpu_req_i.stb;
ctrl.clear_buf_nxt <= ctrl.clear_buf or cpu_req_i.fence;
-- cache defaults --
cache.clear <= '0';
cache.ctrl_addr <= ctrl.addr_reg;
cache.ctrl_we <= '0';
cache.ctrl_ben <= "1111";
cache.ctrl_wdata <= bus_rsp_i.data;
cache.ctrl_wstat <= bus_rsp_i.err;
-- host interface defaults --
cpu_rsp_o.data <= cache.host_rdata;
cpu_rsp_o.ack <= '0';
cpu_rsp_o.err <= '0';
-- peripheral bus interface defaults --
bus_req_o.addr <= ctrl.addr_reg;
bus_req_o.data <= cpu_req_i.data;
bus_req_o.ben <= cpu_req_i.ben;
bus_req_o.rw <= cpu_req_i.rw;
bus_req_o.src <= cpu_req_i.src;
bus_req_o.priv <= cpu_req_i.priv;
bus_req_o.rvso <= cpu_req_i.rvso;
bus_req_o.stb <= '0';
bus_req_o.fence <= cpu_req_i.fence;
-- fsm --
case ctrl.state is
when S_IDLE => -- wait for host access request or cache control operation
-- ------------------------------------------------------------
ctrl.addr_reg_nxt <= cpu_req_i.addr;
if (ctrl.clear_buf = '1') then -- invalidate cache
ctrl.state_nxt <= S_CLEAR;
elsif (cpu_req_i.stb = '1') or (ctrl.req_buf = '1') then
if (unsigned(cpu_req_i.addr(31 downto 28)) >= unsigned(DCACHE_UC_PBEGIN)) or (cpu_req_i.rvso = '1') then -- uncached access -> direct access
ctrl.state_nxt <= S_DIRECT_REQ;
else -- cached access
ctrl.state_nxt <= S_CHECK;
end if;
end if;
when S_CHECK => -- check if cache hit
-- ------------------------------------------------------------
ctrl.req_buf_nxt <= '0';
if (cpu_req_i.rw = '0') then -- read access
-- calculate block base address (in case we need to download it) --
ctrl.addr_reg_nxt((cache_offset_size_c+2)-1 downto 2) <= (others => '0'); -- block-aligned
ctrl.addr_reg_nxt(1 downto 0) <= "00"; -- word-aligned
--
if (cache.hit = '1') then -- HIT -> done
if (cache.host_rstat = '1') then -- erroneous read access?
cpu_rsp_o.err <= '1';
else
cpu_rsp_o.ack <= '1';
end if;
ctrl.state_nxt <= S_IDLE;
else -- cache MISS -> download block
ctrl.state_nxt <= S_DOWNLOAD_REQ;
end if;
else -- write access
if (cache.hit = '1') then -- data word in cache -> also write to cache
ctrl.state_nxt <= S_RESYNC_WRITE;
else -- write-through
ctrl.state_nxt <= S_DIRECT_REQ;
end if;
end if;
when S_DOWNLOAD_REQ => -- download new cache block: request new word
-- ------------------------------------------------------------
bus_req_o.rw <= '0'; -- read access
bus_req_o.stb <= '1'; -- request new transfer
ctrl.state_nxt <= S_DOWNLOAD_WAIT;
when S_DOWNLOAD_WAIT => -- download new cache block: wait for bus response
-- ------------------------------------------------------------
bus_req_o.rw <= '0'; -- read access
if (bus_rsp_i.ack = '1') or (bus_rsp_i.err = '1') then -- ACK or ERROR -> write to cache and get next word (store ERROR flag in cache)
cache.ctrl_we <= '1'; -- write to cache
ctrl.addr_reg_nxt <= std_ulogic_vector(unsigned(ctrl.addr_reg) + 4);
if (and_reduce_f(ctrl.addr_reg((cache_offset_size_c+2)-1 downto 2)) = '1') then -- block complete?
ctrl.state_nxt <= S_RESYNC;
else -- get next word
ctrl.state_nxt <= S_DOWNLOAD_REQ;
end if;
end if;
when S_DIRECT_REQ => -- direct uncached access: request access
-- ------------------------------------------------------------
bus_req_o.stb <= '1';
ctrl.req_buf_nxt <= '0';
ctrl.state_nxt <= S_DIRECT_WAIT;
when S_DIRECT_WAIT => -- direct uncached access: wait for bus response
-- ------------------------------------------------------------
cpu_rsp_o.data <= bus_rsp_i.data;
if (bus_rsp_i.err = '1') then
cpu_rsp_o.err <= '1';
ctrl.state_nxt <= S_IDLE;
elsif (bus_rsp_i.ack = '1') then
cpu_rsp_o.ack <= '1';
ctrl.state_nxt <= S_IDLE;
end if;
when S_RESYNC => -- re-sync host/cache access
-- ------------------------------------------------------------
ctrl.addr_reg_nxt <= cpu_req_i.addr; -- restore original access address
if (cpu_req_i.rw = '1') then -- write access
ctrl.state_nxt <= S_RESYNC_WRITE;
else -- read access
ctrl.state_nxt <= S_CHECK; -- should HIT now
end if;
when S_RESYNC_WRITE => -- finalize cached write access
-- ------------------------------------------------------------
bus_req_o.rw <= '1'; -- write access
bus_req_o.stb <= '1'; -- request new transfer
cache.ctrl_we <= '1'; -- write to cache
cache.ctrl_ben <= cpu_req_i.ben;
cache.ctrl_addr <= cpu_req_i.addr;
cache.ctrl_wdata <= cpu_req_i.data;
cache.ctrl_wstat <= '0'; -- no error possible here
ctrl.state_nxt <= S_DIRECT_WAIT;
when S_RESYNC_WAIT => -- wait for bus response
-- ------------------------------------------------------------
bus_req_o.rw <= '1'; -- write access
if (bus_rsp_i.err = '1') then
cpu_rsp_o.err <= '1';
ctrl.state_nxt <= S_IDLE;
elsif (bus_rsp_i.ack = '1') then
cpu_rsp_o.ack <= '1';
ctrl.state_nxt <= S_IDLE;
end if;
when S_CLEAR => -- invalidate all cache entries
-- ------------------------------------------------------------
ctrl.clear_buf_nxt <= '0';
cache.clear <= '1';
ctrl.state_nxt <= S_IDLE;
when others => -- undefined
-- ------------------------------------------------------------
ctrl.state_nxt <= S_IDLE;
end case;
end process ctrl_engine_comb;
-- Cache Memory ---------------------------------------------------------------------------
-- -------------------------------------------------------------------------------------------
neorv32_dcache_memory_inst: neorv32_dcache_memory
generic map (
DCACHE_NUM_BLOCKS => nblocks_c,
DCACHE_BLOCK_SIZE => block_size_c
)
port map (
-- global control --
rstn_i => rstn_i,
clk_i => clk_i,
clear_i => cache.clear,
hit_o => cache.hit,
-- host cache access --
host_addr_i => cpu_req_i.addr,
host_rdata_o => cache.host_rdata,
host_rstat_o => cache.host_rstat,
-- ctrl cache access --
ctrl_addr_i => cache.ctrl_addr,
ctrl_we_i => cache.ctrl_we,
ctrl_ben_i => cache.ctrl_ben,
ctrl_wdata_i => cache.ctrl_wdata,
ctrl_wstat_i => cache.ctrl_wstat,
ctrl_rdata_o => cache.ctrl_rdata
);
end neorv32_dcache_rtl;
-- ###########################################################################################################################################
-- ###########################################################################################################################################
-- #################################################################################################
-- # << NEORV32 - Data Cache Memory >> #
-- # ********************************************************************************************* #
-- # BSD 3-Clause License #
-- # #
-- # Copyright (c) 2023, Stephan Nolting. All rights reserved. #
-- # #
-- # Redistribution and use in source and binary forms, with or without modification, are #
-- # permitted provided that the following conditions are met: #
-- # #
-- # 1. Redistributions of source code must retain the above copyright notice, this list of #
-- # conditions and the following disclaimer. #
-- # #
-- # 2. Redistributions in binary form must reproduce the above copyright notice, this list of #
-- # conditions and the following disclaimer in the documentation and/or other materials #
-- # provided with the distribution. #
-- # #
-- # 3. Neither the name of the copyright holder nor the names of its contributors may be used to #
-- # endorse or promote products derived from this software without specific prior written #
-- # permission. #
-- # #
-- # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS #
-- # OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF #
-- # MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE #
-- # COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, #
-- # EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE #
-- # GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED #
-- # AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING #
-- # NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED #
-- # OF THE POSSIBILITY OF SUCH DAMAGE. #
-- # ********************************************************************************************* #
-- # The NEORV32 Processor - https://github.com/stnolting/neorv32 (c) Stephan Nolting #
-- #################################################################################################
library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
library neorv32;
use neorv32.neorv32_package.all;
entity neorv32_dcache_memory is
generic (
DCACHE_NUM_BLOCKS : natural; -- number of blocks (min 1), has to be a power of 2
DCACHE_BLOCK_SIZE : natural -- block size in bytes (min 4), has to be a power of 2
);
port (
-- global control --
rstn_i : in std_ulogic; -- global reset, async, low-active
clk_i : in std_ulogic; -- global clock, rising edge
clear_i : in std_ulogic; -- invalidate whole cache
hit_o : out std_ulogic; -- hit access
-- host cache access (read-only) --
host_addr_i : in std_ulogic_vector(31 downto 0); -- access address
host_rdata_o : out std_ulogic_vector(31 downto 0); -- read data
host_rstat_o : out std_ulogic; -- access status
-- ctrl cache access --
ctrl_addr_i : in std_ulogic_vector(31 downto 0); -- access address
ctrl_we_i : in std_ulogic; -- write enable
ctrl_ben_i : in std_ulogic_vector(03 downto 0); -- byte enable
ctrl_wdata_i : in std_ulogic_vector(31 downto 0); -- write data (full word)
ctrl_wstat_i : in std_ulogic; -- access status
ctrl_rdata_o : out std_ulogic_vector(31 downto 0) -- read data
);
end neorv32_dcache_memory;
architecture neorv32_dcache_memory_rtl of neorv32_dcache_memory is
-- cache layout --
constant cache_offset_size_c : natural := index_size_f(DCACHE_BLOCK_SIZE/4); -- offset addresses full 32-bit words
constant cache_index_size_c : natural := index_size_f(DCACHE_NUM_BLOCKS);
constant cache_tag_size_c : natural := 32 - (cache_offset_size_c + cache_index_size_c + 2); -- 2 additional bits for byte offset
constant cache_entries_c : natural := DCACHE_NUM_BLOCKS * (DCACHE_BLOCK_SIZE/4); -- number of 32-bit entries (per set)
-- status flag memory --
signal valid_flag : std_ulogic_vector(DCACHE_NUM_BLOCKS-1 downto 0);
signal valid : std_ulogic;
-- tag memory --
type tag_mem_t is array (0 to DCACHE_NUM_BLOCKS-1) of std_ulogic_vector(cache_tag_size_c-1 downto 0);
signal tag_mem : tag_mem_t;
signal tag : std_ulogic_vector(cache_tag_size_c-1 downto 0);
-- access address decomposition --
type acc_addr_t is record
tag : std_ulogic_vector(cache_tag_size_c-1 downto 0);
index : std_ulogic_vector(cache_index_size_c-1 downto 0);
offset : std_ulogic_vector(cache_offset_size_c-1 downto 0);
end record;
signal host_acc_addr, ctrl_acc_addr : acc_addr_t;
-- cache data memory --
type cache_mem_t is array (0 to cache_entries_c-1) of std_ulogic_vector(7 downto 0);
signal cache_data_memory_b0 : cache_mem_t; -- byte 0
signal cache_data_memory_b1 : cache_mem_t; -- byte 1
signal cache_data_memory_b2 : cache_mem_t; -- byte 2
signal cache_data_memory_b3 : cache_mem_t; -- byte 3
signal cache_err_memory : std_ulogic_vector(cache_entries_c-1 downto 0); -- access error flag
-- cache data memory access --
signal cache_rdata : std_ulogic_vector(32 downto 0);
signal cache_index : std_ulogic_vector(cache_index_size_c-1 downto 0);
signal cache_offset : std_ulogic_vector(cache_offset_size_c-1 downto 0);
signal cache_addr : std_ulogic_vector((cache_index_size_c+cache_offset_size_c)-1 downto 0); -- index & offset
begin
-- Access Address Decomposition -----------------------------------------------------------
-- -------------------------------------------------------------------------------------------
host_acc_addr.tag <= host_addr_i(31 downto 31-(cache_tag_size_c-1));
host_acc_addr.index <= host_addr_i(31-cache_tag_size_c downto 2+cache_offset_size_c);
host_acc_addr.offset <= host_addr_i(2+(cache_offset_size_c-1) downto 2); -- discard byte offset
ctrl_acc_addr.tag <= ctrl_addr_i(31 downto 31-(cache_tag_size_c-1));
ctrl_acc_addr.index <= ctrl_addr_i(31-cache_tag_size_c downto 2+cache_offset_size_c);
ctrl_acc_addr.offset <= ctrl_addr_i(2+(cache_offset_size_c-1) downto 2); -- discard byte offset
-- Status Flag Memory ---------------------------------------------------------------------
-- -------------------------------------------------------------------------------------------
status_memory: process(rstn_i, clk_i)
begin
if (rstn_i = '0') then
valid_flag <= (others => '0');
valid <= '0';
elsif rising_edge(clk_i) then
-- write access --
if (clear_i = '1') then -- invalidate entire cache
valid_flag <= (others => '0');
elsif (ctrl_we_i = '1') then -- control write access: make current block valid
valid_flag(to_integer(unsigned(cache_index))) <= '1';
end if;
-- sync read access --
valid <= valid_flag(to_integer(unsigned(cache_index)));
end if;
end process status_memory;
-- Tag Memory -----------------------------------------------------------------------------
-- -------------------------------------------------------------------------------------------
tag_memory: process(clk_i)
begin
if rising_edge(clk_i) then -- no reset to allow inferring of blockRAM
if (ctrl_we_i = '1') then -- write access
tag_mem(to_integer(unsigned(cache_index))) <= ctrl_acc_addr.tag;
else -- read access
tag <= tag_mem(to_integer(unsigned(cache_index)));
end if;
end if;
end process tag_memory;
-- hit? --
hit_o <= '1' when (host_acc_addr.tag = tag) and (valid = '1') else '0';
-- Cache Data Memory ----------------------------------------------------------------------
-- -------------------------------------------------------------------------------------------
cache_mem_access: process(clk_i)
begin
if rising_edge(clk_i) then -- no reset to allow inferring of blockRAM
-- write access --
if (ctrl_we_i = '1') and (ctrl_ben_i(0) = '1') then
cache_data_memory_b0(to_integer(unsigned(cache_addr))) <= ctrl_wdata_i(07 downto 00);
end if;
if (ctrl_we_i = '1') and (ctrl_ben_i(1) = '1') then
cache_data_memory_b1(to_integer(unsigned(cache_addr))) <= ctrl_wdata_i(15 downto 08);
end if;
if (ctrl_we_i = '1') and (ctrl_ben_i(2) = '1') then
cache_data_memory_b2(to_integer(unsigned(cache_addr))) <= ctrl_wdata_i(23 downto 16);
end if;
if (ctrl_we_i = '1') and (ctrl_ben_i(3) = '1') then
cache_data_memory_b3(to_integer(unsigned(cache_addr))) <= ctrl_wdata_i(31 downto 24);
end if;
if (ctrl_we_i = '1') then
cache_err_memory(to_integer(unsigned(cache_addr))) <= ctrl_wstat_i;
end if;
-- read access --
cache_rdata(07 downto 00) <= cache_data_memory_b0(to_integer(unsigned(cache_addr)));
cache_rdata(15 downto 08) <= cache_data_memory_b1(to_integer(unsigned(cache_addr)));
cache_rdata(23 downto 16) <= cache_data_memory_b2(to_integer(unsigned(cache_addr)));
cache_rdata(31 downto 24) <= cache_data_memory_b3(to_integer(unsigned(cache_addr)));
cache_rdata(32) <= cache_err_memory(to_integer(unsigned(cache_addr)));
end if;
end process cache_mem_access;
-- data output --
host_rdata_o <= cache_rdata(31 downto 0);
ctrl_rdata_o <= cache_rdata(31 downto 0);
host_rstat_o <= cache_rdata(32) and valid;
-- cache block ram access address --
cache_addr <= cache_index & cache_offset;
-- cache access select --
cache_index <= host_acc_addr.index when (ctrl_we_i = '0') else ctrl_acc_addr.index;
cache_offset <= host_acc_addr.offset when (ctrl_we_i = '0') else ctrl_acc_addr.offset;
end neorv32_dcache_memory_rtl;