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signal mtime_lo : std_ulogic_vector(31 downto 0);
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signal mtime_lo : std_ulogic_vector(31 downto 0);
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signal mtime_lo_nxt : std_ulogic_vector(32 downto 0);
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signal mtime_lo_nxt : std_ulogic_vector(32 downto 0);
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signal mtime_lo_ovfl : std_ulogic_vector(00 downto 0);
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signal mtime_lo_ovfl : std_ulogic_vector(00 downto 0);
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signal mtime_hi : std_ulogic_vector(31 downto 0);
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signal mtime_hi : std_ulogic_vector(31 downto 0);
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-- comparator and IRQ trigger --
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-- comparators --
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signal cmp_lo : std_ulogic;
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signal cmp_lo_ge : std_ulogic;
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signal cmp_lo_ff : std_ulogic;
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signal cmp_lo_ge_ff : std_ulogic;
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signal cmp_hi : std_ulogic;
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signal cmp_hi_eq : std_ulogic;
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signal cmp_match_ff : std_ulogic;
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signal cmp_hi_gt : std_ulogic;
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begin
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begin
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-- Access Control -------------------------------------------------------------------------
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-- Access Control -------------------------------------------------------------------------
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-- -------------------------------------------------------------------------------------------
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-- -------------------------------------------------------------------------------------------
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mtimecmp_hi <= data_i;
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mtimecmp_hi <= data_i;
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end if;
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end if;
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end if;
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end if;
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-- mtime access buffer --
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-- mtime access buffer --
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-- wdata_buf <= data_i; -- not required, CPU wdata is stable until transfer is acknowledged
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-- wdata_buf <= data_i; -- not required, CPU wdata (=data_i) is stable until transfer is acknowledged
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mtime_lo_we <= wren and bool_to_ulogic_f(boolean(addr = mtime_time_lo_addr_c));
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mtime_lo_we <= wren and bool_to_ulogic_f(boolean(addr = mtime_time_lo_addr_c));
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mtime_hi_we <= wren and bool_to_ulogic_f(boolean(addr = mtime_time_hi_addr_c));
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mtime_hi_we <= wren and bool_to_ulogic_f(boolean(addr = mtime_time_hi_addr_c));
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-- mtime low --
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-- mtime low --
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if (mtime_lo_we = '1') then -- write access
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if (mtime_lo_we = '1') then -- write access
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end if;
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end if;
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end if;
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end if;
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end process rd_access;
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end process rd_access;
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-- system time output for cpu --
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-- system time output for cpu --
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time_o <= mtime_hi & mtime_lo;
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time_o <= mtime_hi & mtime_lo; -- NOTE: low and high words are not synchronized here!
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-- Comparator -----------------------------------------------------------------------------
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-- Comparator -----------------------------------------------------------------------------
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-- -------------------------------------------------------------------------------------------
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-- -------------------------------------------------------------------------------------------
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cmp_sync: process(clk_i)
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cmp_sync: process(clk_i)
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begin
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begin
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if rising_edge(clk_i) then
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if rising_edge(clk_i) then
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cmp_lo_ff <= cmp_lo;
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cmp_lo_ge_ff <= cmp_lo_ge;
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cmp_match_ff <= cmp_lo_ff and cmp_hi;
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irq_o <= cmp_hi_gt or (cmp_hi_eq and cmp_lo_ge_ff);
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irq_o <= cmp_lo_ff and cmp_hi and (not cmp_match_ff);
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end if;
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end if;
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end process cmp_sync;
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end process cmp_sync;
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-- test words --
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-- sub-word comparators --
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cmp_lo <= '1' when (unsigned(mtime_lo) >= unsigned(mtimecmp_lo)) else '0';
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cmp_lo_ge <= '1' when (unsigned(mtime_lo) >= unsigned(mtimecmp_lo)) else '0'; -- low-word: greater than or equal
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cmp_hi <= '1' when (unsigned(mtime_hi) >= unsigned(mtimecmp_hi)) else '0';
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cmp_hi_eq <= '1' when (unsigned(mtime_hi) = unsigned(mtimecmp_hi)) else '0'; -- high-word: equal
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cmp_hi_gt <= '1' when (unsigned(mtime_hi) > unsigned(mtimecmp_hi)) else '0'; -- high-word: greater than
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end neorv32_mtime_rtl;
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end neorv32_mtime_rtl;
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