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Line 1... |
-- #################################################################################################
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-- #################################################################################################
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-- # << NEORV32 - Machine System Timer (MTIME) >> #
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-- # << NEORV32 - Machine System Timer (MTIME) >> #
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-- # ********************************************************************************************* #
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-- # ********************************************************************************************* #
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-- # Compatible to RISC-V spec's mtime & mtimecmp. #
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-- # Compatible to RISC-V spec's 64-bit MACHINE system timer including "mtime[h]" & "mtimecmp[h]". #
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-- # Write mtime.LO first when updating the system time. System time should be written only at #
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-- # Note: The 64-bit counter and compare system is broken and de-coupled into two 32-bit systems. #
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-- # system start. RISC-V spec. exception: The MTIME interrupt is ACKed by the processor itself. #
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-- # However, the achine time cannot issue a new interrupt until the mtimecmp.HI register is #
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-- # written again. #
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-- # Note: The 64-bit time and compare system is broken and de-coupled into two 32-bit systems. #
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-- # Note: The register of this unit can only be written in WORD MODE. #
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-- # ********************************************************************************************* #
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-- # ********************************************************************************************* #
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-- # BSD 3-Clause License #
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-- # BSD 3-Clause License #
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-- # #
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-- # #
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-- # Copyright (c) 2020, Stephan Nolting. All rights reserved. #
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-- # Copyright (c) 2021, Stephan Nolting. All rights reserved. #
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-- # #
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-- # #
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-- # Redistribution and use in source and binary forms, with or without modification, are #
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-- # Redistribution and use in source and binary forms, with or without modification, are #
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-- # permitted provided that the following conditions are met: #
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-- # permitted provided that the following conditions are met: #
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-- # #
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-- # #
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-- # 1. Redistributions of source code must retain the above copyright notice, this list of #
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-- # 1. Redistributions of source code must retain the above copyright notice, this list of #
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| Line 123... |
Line 118... |
end if;
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end if;
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-- mtime high --
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-- mtime high --
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if (wren = '1') and (addr = mtime_time_hi_addr_c) then
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if (wren = '1') and (addr = mtime_time_hi_addr_c) then
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mtime_hi <= data_i;
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mtime_hi <= data_i;
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elsif ((mtime_lo_msb_ff xor mtime_lo(mtime_lo'left)) = '1') then -- mtime_lo carry?
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elsif ((mtime_lo_msb_ff xor mtime_lo(mtime_lo'left)) = '1') then -- auto increment: mtime_lo carry?
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mtime_hi <= std_ulogic_vector(unsigned(mtime_hi) + 1);
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mtime_hi <= std_ulogic_vector(unsigned(mtime_hi) + 1);
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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 wr_access;
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end process wr_access;
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| Line 145... |
Line 140... |
data_o <= mtime_lo(31 downto 00);
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data_o <= mtime_lo(31 downto 00);
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when mtime_time_hi_addr_c => -- mtime HIGH
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when mtime_time_hi_addr_c => -- mtime HIGH
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data_o <= mtime_hi;
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data_o <= mtime_hi;
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when mtime_cmp_lo_addr_c => -- mtimecmp LOW
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when mtime_cmp_lo_addr_c => -- mtimecmp LOW
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data_o <= mtimecmp_lo;
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data_o <= mtimecmp_lo;
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when others => -- mtime_cmp_hi_addr_c - mtimecmp HIGH
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when others => -- mtime_cmp_hi_addr_c -- mtimecmp HIGH
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data_o <= mtimecmp_hi;
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data_o <= mtimecmp_hi;
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end case;
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end case;
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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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