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Diffstat (limited to 'zpu/hdl/zpu4/core/zpu_core_small.vhd')
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1 files changed, 602 insertions, 0 deletions
diff --git a/zpu/hdl/zpu4/core/zpu_core_small.vhd b/zpu/hdl/zpu4/core/zpu_core_small.vhd new file mode 100644 index 0000000..9ac35a8 --- /dev/null +++ b/zpu/hdl/zpu4/core/zpu_core_small.vhd @@ -0,0 +1,602 @@ +-- ZPU +-- +-- Copyright 2004-2008 oharboe - Øyvind Harboe - oyvind.harboe@zylin.com +-- +-- The FreeBSD license +-- +-- 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. +-- +-- THIS SOFTWARE IS PROVIDED BY THE ZPU PROJECT ``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 +-- ZPU PROJECT 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 views and conclusions contained in the software and documentation +-- are those of the authors and should not be interpreted as representing +-- official policies, either expressed or implied, of the ZPU Project. + +library ieee; +use ieee.std_logic_1164.all; +use ieee.numeric_std.all; + +library work; +use work.zpu_config.all; +use work.zpupkg.all; + + +entity zpu_core is + port ( + clk : in std_logic; + -- asynchronous reset signal + reset : in std_logic; + -- this particular implementation of the ZPU does not + -- have a clocked enable signal + enable : in std_logic; + in_mem_busy : in std_logic; + mem_read : in std_logic_vector(wordSize-1 downto 0); + mem_write : out std_logic_vector(wordSize-1 downto 0); + out_mem_addr : out std_logic_vector(maxAddrBitIncIO downto 0); + out_mem_writeEnable : out std_logic; + out_mem_readEnable : out std_logic; + -- this implementation of the ZPU *always* reads and writes entire + -- 32 bit words, so mem_writeMask is tied to (others => '1'). + mem_writeMask : out std_logic_vector(wordBytes-1 downto 0); + -- Set to one to jump to interrupt vector + -- The ZPU will communicate with the hardware that caused the + -- interrupt via memory mapped IO or the interrupt flag can + -- be cleared automatically + interrupt : in std_logic; + -- Signal that the break instruction is executed, normally only used + -- in simulation to stop simulation + break : out std_logic + ); +end zpu_core; + + + +architecture behave of zpu_core is + + signal memAWriteEnable : std_logic; + signal memAAddr : unsigned(maxAddrBit downto minAddrBit); + signal memAWrite : unsigned(wordSize-1 downto 0); + signal memARead : unsigned(wordSize-1 downto 0); + signal memBWriteEnable : std_logic; + signal memBAddr : unsigned(maxAddrBit downto minAddrBit); + signal memBWrite : unsigned(wordSize-1 downto 0); + signal memBRead : unsigned(wordSize-1 downto 0); + + + + signal pc : unsigned(maxAddrBit downto 0); + signal sp : unsigned(maxAddrBit downto minAddrBit); + + -- this signal is set upon executing an IM instruction + -- the subsequence IM instruction will then behave differently. + -- all other instructions will clear the idim_flag. + -- this yields highly compact immediate instructions. + signal idim_flag : std_logic; + -- + signal busy : std_logic; + -- + signal begin_inst : std_logic; + + + signal trace_opcode : std_logic_vector(7 downto 0); + signal trace_pc : std_logic_vector(maxAddrBitIncIO downto 0); + signal trace_sp : std_logic_vector(maxAddrBitIncIO downto minAddrBit); + signal trace_topOfStack : std_logic_vector(wordSize-1 downto 0); + signal trace_topOfStackB : std_logic_vector(wordSize-1 downto 0); + + -- state machine. + type State_Type is ( + State_Fetch, + State_WriteIODone, + State_Execute, + State_StoreToStack, + State_Add, + State_Or, + State_And, + State_Store, + State_ReadIO, + State_WriteIO, + State_Load, + State_FetchNext, + State_AddSP, + State_ReadIODone, + State_Decode, + State_Resync, + State_Interrupt + ); + + type DecodedOpcodeType is ( + Decoded_Nop, + Decoded_Im, + Decoded_ImShift, + Decoded_LoadSP, + Decoded_StoreSP , + Decoded_AddSP, + Decoded_Emulate, + Decoded_Break, + Decoded_PushSP, + Decoded_PopPC, + Decoded_Add, + Decoded_Or, + Decoded_And, + Decoded_Load, + Decoded_Not, + Decoded_Flip, + Decoded_Store, + Decoded_PopSP, + Decoded_Interrupt + ); + + + + signal sampledOpcode : std_logic_vector(OpCode_Size-1 downto 0); + signal opcode : std_logic_vector(OpCode_Size-1 downto 0); + -- + signal decodedOpcode : DecodedOpcodeType; + signal sampledDecodedOpcode : DecodedOpcodeType; + + + signal state : State_Type; + -- + subtype AddrBitBRAM_range is natural range maxAddrBitBRAM downto minAddrBit; + signal memAAddr_stdlogic : std_logic_vector(AddrBitBRAM_range); + signal memAWrite_stdlogic : std_logic_vector(memAWrite'range); + signal memARead_stdlogic : std_logic_vector(memARead'range); + signal memBAddr_stdlogic : std_logic_vector(AddrBitBRAM_range); + signal memBWrite_stdlogic : std_logic_vector(memBWrite'range); + signal memBRead_stdlogic : std_logic_vector(memBRead'range); + -- + subtype index is integer range 0 to 3; + -- + signal tOpcode_sel : index; + -- + signal inInterrupt : std_logic; + + + +begin + + -- generate a trace file. + -- + -- This is only used in simulation to see what instructions are + -- executed. + -- + -- a quick & dirty regression test is then to commit trace files + -- to CVS and compare the latest trace file against the last known + -- good trace file + traceFileGenerate : if Generate_Trace generate + trace_file : trace port map ( + clk => clk, + begin_inst => begin_inst, + pc => trace_pc, + opcode => trace_opcode, + sp => trace_sp, + memA => trace_topOfStack, + memB => trace_topOfStackB, + busy => busy, + intsp => (others => 'U') + ); + end generate; + + + -- mem_writeMask is not used in this design, tie it to 1 + mem_writeMask <= (others => '1'); + + + + memAAddr_stdlogic <= std_logic_vector(memAAddr(AddrBitBRAM_range)); + memAWrite_stdlogic <= std_logic_vector(memAWrite); + memBAddr_stdlogic <= std_logic_vector(memBAddr(AddrBitBRAM_range)); + memBWrite_stdlogic <= std_logic_vector(memBWrite); + + + -- dualport_ram must be defined by the application. + -- + -- How this can be implemented is highly dependent on the FPGA + -- and synthesis technology used. + -- + -- sometimes it can be instantiated as in the + -- zpu/example/helloworld.vhd, using inference, + -- but oftentimes it must be instantiated directly + -- portmapping to part specific FPGA resources + -- + -- + -- DANGER!!!!!! If inference fails, then synthesis will try + -- to implement the memory using basic logic resources. This + -- will almost certainly cause the compiler to get "stuck" + -- since synthesising such a huge number of basic logic resources + -- will take more or less forever. + -- + -- So: if your compiler gets "stuck" then inference is not + -- the way to go. + memory : dualport_ram port map ( + clk => clk, + memAWriteEnable => memAWriteEnable, + memAAddr => memAAddr_stdlogic, + memAWrite => memAWrite_stdlogic, + memARead => memARead_stdlogic, + memBWriteEnable => memBWriteEnable, + memBAddr => memBAddr_stdlogic, + memBWrite => memBWrite_stdlogic, + memBRead => memBRead_stdlogic + ); + memARead <= unsigned(memARead_stdlogic); + memBRead <= unsigned(memBRead_stdlogic); + + + + tOpcode_sel <= to_integer(pc(minAddrBit-1 downto 0)); + + + + -- move out calculation of the opcode to a seperate process + -- to make things a bit easier to read + decodeControl : process(memBRead, pc, tOpcode_sel) + variable tOpcode : std_logic_vector(OpCode_Size-1 downto 0); + begin + + -- simplify opcode selection a bit so it passes more synthesizers + case (tOpcode_sel) is + + when 0 => tOpcode := std_logic_vector(memBRead(31 downto 24)); + + when 1 => tOpcode := std_logic_vector(memBRead(23 downto 16)); + + when 2 => tOpcode := std_logic_vector(memBRead(15 downto 8)); + + when 3 => tOpcode := std_logic_vector(memBRead(7 downto 0)); + + when others => tOpcode := std_logic_vector(memBRead(7 downto 0)); + end case; + + sampledOpcode <= tOpcode; + + if (tOpcode(7 downto 7) = OpCode_Im) then + sampledDecodedOpcode <= Decoded_Im; + elsif (tOpcode(7 downto 5) = OpCode_StoreSP) then + sampledDecodedOpcode <= Decoded_StoreSP; + elsif (tOpcode(7 downto 5) = OpCode_LoadSP) then + sampledDecodedOpcode <= Decoded_LoadSP; + elsif (tOpcode(7 downto 5) = OpCode_Emulate) then + sampledDecodedOpcode <= Decoded_Emulate; + elsif (tOpcode(7 downto 4) = OpCode_AddSP) then + sampledDecodedOpcode <= Decoded_AddSP; + else + case tOpcode(3 downto 0) is + when OpCode_Break => + sampledDecodedOpcode <= Decoded_Break; + when OpCode_PushSP => + sampledDecodedOpcode <= Decoded_PushSP; + when OpCode_PopPC => + sampledDecodedOpcode <= Decoded_PopPC; + when OpCode_Add => + sampledDecodedOpcode <= Decoded_Add; + when OpCode_Or => + sampledDecodedOpcode <= Decoded_Or; + when OpCode_And => + sampledDecodedOpcode <= Decoded_And; + when OpCode_Load => + sampledDecodedOpcode <= Decoded_Load; + when OpCode_Not => + sampledDecodedOpcode <= Decoded_Not; + when OpCode_Flip => + sampledDecodedOpcode <= Decoded_Flip; + when OpCode_Store => + sampledDecodedOpcode <= Decoded_Store; + when OpCode_PopSP => + sampledDecodedOpcode <= Decoded_PopSP; + when others => + sampledDecodedOpcode <= Decoded_Nop; + end case; -- tOpcode(3 downto 0) + end if; -- tOpcode + end process; + + + opcodeControl: process(clk, reset) + variable spOffset : unsigned(4 downto 0); + begin + + if reset = '1' then + state <= State_Resync; + break <= '0'; + sp <= unsigned(spStart(maxAddrBit downto minAddrBit)); + pc <= (others => '0'); + idim_flag <= '0'; + begin_inst <= '0'; + memAAddr <= (others => '0'); + memBAddr <= (others => '0'); + memAWriteEnable <= '0'; + memBWriteEnable <= '0'; + out_mem_writeEnable <= '0'; + out_mem_readEnable <= '0'; + memAWrite <= (others => '0'); + memBWrite <= (others => '0'); + inInterrupt <= '0'; + + elsif (clk'event and clk = '1') then + memAWriteEnable <= '0'; + memBWriteEnable <= '0'; + -- This saves ca. 100 LUT's, by explicitly declaring that the + -- memAWrite can be left at whatever value if memAWriteEnable is + -- not set. + memAWrite <= (others => DontCareValue); + memBWrite <= (others => DontCareValue); +-- out_mem_addr <= (others => DontCareValue); +-- mem_write <= (others => DontCareValue); + spOffset := (others => DontCareValue); + memAAddr <= (others => DontCareValue); + memBAddr <= (others => DontCareValue); + + out_mem_writeEnable <= '0'; + out_mem_readEnable <= '0'; + begin_inst <= '0'; + out_mem_addr <= std_logic_vector(memARead(maxAddrBitIncIO downto 0)); + mem_write <= std_logic_vector(memBRead); + + decodedOpcode <= sampledDecodedOpcode; + opcode <= sampledOpcode; + if interrupt = '0' then + inInterrupt <= '0'; -- no longer in an interrupt + end if; + + case state is + + when State_Execute => + state <= State_Fetch; + -- at this point: + -- memBRead contains opcode word + -- memARead contains top of stack + pc <= pc + 1; + + -- trace + begin_inst <= '1'; + trace_pc <= (others => '0'); + trace_pc(maxAddrBit downto 0) <= std_logic_vector(pc); + trace_opcode <= opcode; + trace_sp <= (others => '0'); + trace_sp(maxAddrBit downto minAddrBit) <= std_logic_vector(sp); + trace_topOfStack <= std_logic_vector(memARead); + trace_topOfStackB <= std_logic_vector(memBRead); + + -- during the next cycle we'll be reading the next opcode + spOffset(4) := not opcode(4); + spOffset(3 downto 0) := unsigned(opcode(3 downto 0)); + + idim_flag <= '0'; + + case decodedOpcode is + + when Decoded_Interrupt => + sp <= sp - 1; + memAAddr <= sp - 1; + memAWriteEnable <= '1'; + memAWrite <= (others => DontCareValue); + memAWrite(maxAddrBit downto 0) <= pc; + pc <= to_unsigned(32, maxAddrBit+1); -- interrupt address + report "ZPU jumped to interrupt!" severity note; + + when Decoded_Im => + idim_flag <= '1'; + memAWriteEnable <= '1'; + if (idim_flag = '0') then + sp <= sp - 1; + memAAddr <= sp-1; + for i in wordSize-1 downto 7 loop + memAWrite(i) <= opcode(6); + end loop; + memAWrite(6 downto 0) <= unsigned(opcode(6 downto 0)); + else + memAAddr <= sp; + memAWrite(wordSize-1 downto 7) <= memARead(wordSize-8 downto 0); + memAWrite(6 downto 0) <= unsigned(opcode(6 downto 0)); + end if; -- idim_flag + + when Decoded_StoreSP => + memBWriteEnable <= '1'; + memBAddr <= sp+spOffset; + memBWrite <= memARead; + sp <= sp + 1; + state <= State_Resync; + + when Decoded_LoadSP => + sp <= sp - 1; + memAAddr <= sp+spOffset; + + when Decoded_Emulate => + sp <= sp - 1; + memAWriteEnable <= '1'; + memAAddr <= sp - 1; + memAWrite <= (others => DontCareValue); + memAWrite(maxAddrBit downto 0) <= pc + 1; + -- The emulate address is: + -- 98 7654 3210 + -- 0000 00aa aaa0 0000 + pc <= (others => '0'); + pc(9 downto 5) <= unsigned(opcode(4 downto 0)); + + when Decoded_AddSP => + memAAddr <= sp; + memBAddr <= sp+spOffset; + state <= State_AddSP; + + when Decoded_Break => + report "Break instruction encountered" severity failure; + break <= '1'; + + when Decoded_PushSP => + memAWriteEnable <= '1'; + memAAddr <= sp - 1; + sp <= sp - 1; + memAWrite <= (others => DontCareValue); + memAWrite(maxAddrBit downto minAddrBit) <= sp; + + when Decoded_PopPC => + pc <= memARead(maxAddrBit downto 0); + sp <= sp + 1; + state <= State_Resync; + + when Decoded_Add => + sp <= sp + 1; + state <= State_Add; + + when Decoded_Or => + sp <= sp + 1; + state <= State_Or; + + when Decoded_And => + sp <= sp + 1; + state <= State_And; + + when Decoded_Load => + if (memARead(ioBit) = '1') then + out_mem_addr <= std_logic_vector(memARead(maxAddrBitIncIO downto 0)); + out_mem_readEnable <= '1'; + state <= State_ReadIO; + else + memAAddr <= memARead(maxAddrBit downto minAddrBit); + end if; + + when Decoded_Not => + memAAddr <= sp(maxAddrBit downto minAddrBit); + memAWriteEnable <= '1'; + memAWrite <= not memARead; + + when Decoded_Flip => + memAAddr <= sp(maxAddrBit downto minAddrBit); + memAWriteEnable <= '1'; + for i in 0 to wordSize-1 loop + memAWrite(i) <= memARead(wordSize-1-i); + end loop; + + when Decoded_Store => + memBAddr <= sp + 1; + sp <= sp + 1; + if (memARead(ioBit) = '1') then + state <= State_WriteIO; + else + state <= State_Store; + end if; + + when Decoded_PopSP => + sp <= memARead(maxAddrBit downto minAddrBit); + state <= State_Resync; + + when Decoded_Nop => + memAAddr <= sp; + + when others => + null; + + end case; -- decodedOpcode + + when State_ReadIO => + memAAddr <= sp; + if (in_mem_busy = '0') then + state <= State_Fetch; + memAWriteEnable <= '1'; + memAWrite <= unsigned(mem_read); + end if; + + when State_WriteIO => + sp <= sp + 1; + out_mem_writeEnable <= '1'; + out_mem_addr <= std_logic_vector(memARead(maxAddrBitIncIO downto 0)); + mem_write <= std_logic_vector(memBRead); + state <= State_WriteIODone; + + when State_WriteIODone => + if (in_mem_busy = '0') then + state <= State_Resync; + end if; + + when State_Fetch => + -- We need to resync. During the *next* cycle + -- we'll fetch the opcode @ pc and thus it will + -- be available for State_Execute the cycle after + -- next + memBAddr <= pc(maxAddrBit downto minAddrBit); + state <= State_FetchNext; + + when State_FetchNext => + -- at this point memARead contains the value that is either + -- from the top of stack or should be copied to the top of the stack + memAWriteEnable <= '1'; + memAWrite <= memARead; + memAAddr <= sp; + memBAddr <= sp + 1; + state <= State_Decode; + + when State_Decode => + if interrupt = '1' and inInterrupt = '0' and idim_flag = '0' then + -- We got an interrupt, execute interrupt instead of next instruction + inInterrupt <= '1'; + decodedOpcode <= Decoded_Interrupt; + end if; + -- during the State_Execute cycle we'll be fetching SP+1 + memAAddr <= sp; + memBAddr <= sp + 1; + state <= State_Execute; + + when State_Store => + sp <= sp + 1; + memAWriteEnable <= '1'; + memAAddr <= memARead(maxAddrBit downto minAddrBit); + memAWrite <= memBRead; + state <= State_Resync; + + when State_AddSP => + state <= State_Add; + + when State_Add => + memAAddr <= sp; + memAWriteEnable <= '1'; + memAWrite <= memARead + memBRead; + state <= State_Fetch; + + when State_Or => + memAAddr <= sp; + memAWriteEnable <= '1'; + memAWrite <= memARead or memBRead; + state <= State_Fetch; + + when State_Resync => + memAAddr <= sp; + state <= State_Fetch; + + when State_And => + memAAddr <= sp; + memAWriteEnable <= '1'; + memAWrite <= memARead and memBRead; + state <= State_Fetch; + + when others => + null; + + end case; -- state + + end if; -- reset, enable + end process; + + + +end behave; |
