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-- Seth Henry 04/16/20 Added the OPEN8_BUS_TYPE record to simplify
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-- Seth Henry 04/16/20 Added the OPEN8_BUS_TYPE record to simplify
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-- peripheral connections.
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-- peripheral connections.
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-- Seth Henry 10/21/20 Modified the write data path to use separate
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-- Seth Henry 10/21/20 Modified the write data path to use separate
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-- enumerated states rather than reuse the .reg field
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-- enumerated states rather than reuse the .reg field
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-- to improve performance.
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-- to improve performance.
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-- Seth Henry 10/23/20 Moved CPU internal constants to o8_cpu.vhd
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library ieee;
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library ieee;
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use ieee.std_logic_1164.all;
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use ieee.std_logic_1164.all;
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use ieee.std_logic_arith.all;
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use ieee.std_logic_arith.all;
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generic(
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generic(
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Program_Start_Addr : ADDRESS_TYPE := x"8000";
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Program_Start_Addr : ADDRESS_TYPE := x"8000";
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ISR_Start_Addr : ADDRESS_TYPE := x"FFF0";
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ISR_Start_Addr : ADDRESS_TYPE := x"FFF0";
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Stack_Start_Addr : ADDRESS_TYPE := x"03FF";
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Stack_Start_Addr : ADDRESS_TYPE := x"03FF";
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Allow_Stack_Address_Move : boolean := false;
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Allow_Stack_Address_Move : boolean := false;
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Stack_Xfer_Flag : integer := 4;
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Enable_Auto_Increment : boolean := false;
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Enable_Auto_Increment : boolean := false;
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BRK_Implements_WAI : boolean := false;
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BRK_Implements_WAI : boolean := false;
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Enable_NMI : boolean := true;
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Enable_NMI : boolean := true;
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RTI_Ignores_GP_Flags : boolean := false;
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RTI_Ignores_GP_Flags : boolean := false;
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Default_Interrupt_Mask : DATA_TYPE := x"FF";
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Default_Interrupt_Mask : DATA_TYPE := x"FF";
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-- This function is used to calculate RAM parameters, but is generally
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-- This function is used to calculate RAM parameters, but is generally
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-- useful for making things more generic.
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-- useful for making things more generic.
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function ceil_log2 (x : in natural) return natural;
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function ceil_log2 (x : in natural) return natural;
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-------------------------------------------------------------------------------
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-- Internal constants and type declarations.
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--
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-- These are only used in the actual model, and aren't generally useful for
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-- external application.
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-------------------------------------------------------------------------------
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subtype OPCODE_TYPE is std_logic_vector(4 downto 0);
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subtype SUBOP_TYPE is std_logic_vector(2 downto 0);
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-- All opcodes should be identical to the opcode used by the assembler
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-- In this case, they match the original V8/ARC uRISC ISA
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constant OP_INC : OPCODE_TYPE := "00000";
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constant OP_ADC : OPCODE_TYPE := "00001";
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constant OP_TX0 : OPCODE_TYPE := "00010";
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constant OP_OR : OPCODE_TYPE := "00011";
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constant OP_AND : OPCODE_TYPE := "00100";
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constant OP_XOR : OPCODE_TYPE := "00101";
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constant OP_ROL : OPCODE_TYPE := "00110";
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constant OP_ROR : OPCODE_TYPE := "00111";
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constant OP_DEC : OPCODE_TYPE := "01000";
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constant OP_SBC : OPCODE_TYPE := "01001";
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constant OP_ADD : OPCODE_TYPE := "01010";
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constant OP_STP : OPCODE_TYPE := "01011";
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constant OP_BTT : OPCODE_TYPE := "01100";
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constant OP_CLP : OPCODE_TYPE := "01101";
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constant OP_T0X : OPCODE_TYPE := "01110";
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constant OP_CMP : OPCODE_TYPE := "01111";
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constant OP_PSH : OPCODE_TYPE := "10000";
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constant OP_POP : OPCODE_TYPE := "10001";
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constant OP_BR0 : OPCODE_TYPE := "10010";
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constant OP_BR1 : OPCODE_TYPE := "10011";
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constant OP_DBNZ : OPCODE_TYPE := "10100"; -- USR
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constant OP_INT : OPCODE_TYPE := "10101";
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constant OP_MUL : OPCODE_TYPE := "10110"; -- USR2
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constant OP_STK : OPCODE_TYPE := "10111";
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constant OP_UPP : OPCODE_TYPE := "11000";
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constant OP_STA : OPCODE_TYPE := "11001";
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constant OP_STX : OPCODE_TYPE := "11010";
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constant OP_STO : OPCODE_TYPE := "11011";
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constant OP_LDI : OPCODE_TYPE := "11100";
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constant OP_LDA : OPCODE_TYPE := "11101";
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constant OP_LDX : OPCODE_TYPE := "11110";
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constant OP_LDO : OPCODE_TYPE := "11111";
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-- OP_STK uses the lower 3 bits to further refine the instruction by
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-- repurposing the source register field. These "sub opcodes" take
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-- the place of the register select for the OP_STK opcode
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constant SOP_RSP : SUBOP_TYPE := "000";
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constant SOP_RTS : SUBOP_TYPE := "001";
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constant SOP_RTI : SUBOP_TYPE := "010";
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constant SOP_BRK : SUBOP_TYPE := "011";
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constant SOP_JMP : SUBOP_TYPE := "100";
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constant SOP_SMSK : SUBOP_TYPE := "101";
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constant SOP_GMSK : SUBOP_TYPE := "110";
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constant SOP_JSR : SUBOP_TYPE := "111";
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type CPU_STATES is (
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-- Instruction fetch & Decode
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IPF_C0, IPF_C1, IPF_C2, IDC_C0,
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-- Branching
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BRN_C1, DBNZ_C1, JMP_C1, JMP_C2,
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-- Loads
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LDA_C1, LDA_C2, LDA_C3, LDA_C4, LDI_C1,
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LDO_C1, LDO_C2, LDX_C1, LDX_C2, LDX_C3, LDX_C4,
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-- Stores
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STA_C1, STA_C2, STA_C3, STO_C1, STO_C2, STO_C3, STX_C1, STX_C2,
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-- 2-cycle math
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MUL_C1, UPP_C1,
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-- Stack
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PSH_C1, POP_C1, POP_C2, POP_C3, POP_C4,
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-- Subroutines & Interrupts
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WAI_Cx, WAH_Cx, BRK_C1,
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ISR_C1, ISR_C2, ISR_C3, JSR_C1, JSR_C2,
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RTS_C1, RTS_C2, RTS_C3, RTS_C4, RTS_C5, RTI_C6
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);
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type CACHE_MODES is (CACHE_IDLE, CACHE_INSTR, CACHE_OPER1, CACHE_OPER2,
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CACHE_PREFETCH );
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type PC_MODES is ( PC_INCR, PC_LOAD );
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type PC_CTRL_TYPE is record
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Oper : PC_MODES;
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Offset : DATA_TYPE;
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end record;
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-- These are fixed constant offsets to the program counter logic, which is
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-- always either incrementing or loading.
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constant PC_NEXT : DATA_TYPE := x"03";
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constant PC_IDLE : DATA_TYPE := x"02";
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constant PC_REV1 : DATA_TYPE := x"01";
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constant PC_REV2 : DATA_TYPE := x"00";
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constant PC_REV3 : DATA_TYPE := x"FF";
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type SP_MODES is ( SP_IDLE, SP_CLR, SP_SET, SP_POP, SP_PUSH );
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type SP_CTRL_TYPE is record
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Oper : SP_MODES;
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end record;
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type DP_MODES is ( DATA_BUS_IDLE, DATA_RD_MEM,
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DATA_WR_REG, DATA_WR_FLAG,
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DATA_WR_PC_L, DATA_WR_PC_H );
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type DATA_CTRL_TYPE is record
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Src : DP_MODES;
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Reg : SUBOP_TYPE;
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end record;
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type INT_CTRL_TYPE is record
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Mask_Set : std_logic;
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Soft_Ints : INTERRUPT_BUNDLE;
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Incr_ISR : std_logic;
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end record;
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-- Most of the ALU instructions are the same as their Opcode equivalents,
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-- with exceptions for IDLE, UPP2, RFLG, RSP, and GMSK, which perform
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-- internal operations not otherwise exposed by the instruction set.
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constant ALU_INC : OPCODE_TYPE := "00000"; -- x"00"
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constant ALU_ADC : OPCODE_TYPE := "00001"; -- x"01"
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constant ALU_TX0 : OPCODE_TYPE := "00010"; -- x"02"
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constant ALU_OR : OPCODE_TYPE := "00011"; -- x"03"
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constant ALU_AND : OPCODE_TYPE := "00100"; -- x"04"
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constant ALU_XOR : OPCODE_TYPE := "00101"; -- x"05"
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constant ALU_ROL : OPCODE_TYPE := "00110"; -- x"06"
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constant ALU_ROR : OPCODE_TYPE := "00111"; -- x"07"
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constant ALU_DEC : OPCODE_TYPE := "01000"; -- x"08"
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constant ALU_SBC : OPCODE_TYPE := "01001"; -- x"09"
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constant ALU_ADD : OPCODE_TYPE := "01010"; -- x"0A"
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constant ALU_STP : OPCODE_TYPE := "01011"; -- x"0B"
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constant ALU_BTT : OPCODE_TYPE := "01100"; -- x"0C"
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constant ALU_CLP : OPCODE_TYPE := "01101"; -- x"0D"
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constant ALU_T0X : OPCODE_TYPE := "01110"; -- x"0E"
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constant ALU_CMP : OPCODE_TYPE := "01111"; -- x"0F"
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constant ALU_POP : OPCODE_TYPE := "10001"; -- x"11"
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constant ALU_MUL : OPCODE_TYPE := "10110"; -- x"16"
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constant ALU_UPP : OPCODE_TYPE := "11000"; -- x"18"
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constant ALU_LDI : OPCODE_TYPE := "11100"; -- x"1C"
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constant ALU_IDLE : OPCODE_TYPE := "10000"; -- x"10"
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constant ALU_UPP2 : OPCODE_TYPE := "10010"; -- x"12"
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constant ALU_RFLG : OPCODE_TYPE := "10011"; -- x"13"
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constant ALU_RSP : OPCODE_TYPE := "10111"; -- x"17"
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constant ALU_GMSK : OPCODE_TYPE := "11111"; -- x"1F"
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-- These should match the assembler's definitions for the flags
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constant PSR_Z : integer := 0;
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constant PSR_C : integer := 1;
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constant PSR_N : integer := 2;
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constant PSR_I : integer := 3;
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constant PSR_GP4 : integer := 4;
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constant PSR_GP5 : integer := 5;
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constant PSR_GP6 : integer := 6;
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constant PSR_GP7 : integer := 7;
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type ALU_CTRL_TYPE is record
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Oper : OPCODE_TYPE;
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Reg : SUBOP_TYPE;
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end record;
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constant ACCUM : SUBOP_TYPE := "000";
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type REGFILE_TYPE is array (0 to 7) of DATA_TYPE;
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subtype FLAG_TYPE is DATA_TYPE;
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end package;
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end package;
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package body Open8_pkg is
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package body Open8_pkg is
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-- The ceil_log2 function returns the minimum register width required to
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-- The ceil_log2 function returns the minimum register width required to
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