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589 lines
26 KiB
VHDL
589 lines
26 KiB
VHDL
-- Instruction pre-decoder for microwatt
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-- One cycle latency. Does 'WIDTH' instructions in parallel.
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library ieee;
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use ieee.std_logic_1164.all;
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use ieee.numeric_std.all;
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library work;
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use work.common.all;
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use work.decode_types.all;
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use work.insn_helpers.all;
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entity predecoder is
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generic (
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HAS_FPU : boolean := true;
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WIDTH : natural := 2;
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ICODE_LEN : natural := 10;
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IMAGE_LEN : natural := 26
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);
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port (
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clk : in std_ulogic;
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valid_in : in std_ulogic;
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insns_in : in std_ulogic_vector(WIDTH * 32 - 1 downto 0);
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icodes_out : out std_ulogic_vector(WIDTH * (ICODE_LEN + IMAGE_LEN) - 1 downto 0)
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);
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end entity predecoder;
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architecture behaviour of predecoder is
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type predecoder_rom_t is array(0 to 2047) of insn_code;
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constant major_predecode_rom : predecoder_rom_t := (
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2#001100_00000# to 2#001100_11111# => INSN_addic,
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2#001101_00000# to 2#001101_11111# => INSN_addic_dot,
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2#001110_00000# to 2#001110_11111# => INSN_addi,
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2#001111_00000# to 2#001111_11111# => INSN_addis,
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2#010011_00100# to 2#010011_00101# => INSN_addpcis,
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2#011100_00000# to 2#011100_11111# => INSN_andi_dot,
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2#011101_00000# to 2#011101_11111# => INSN_andis_dot,
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2#000000_00000# => INSN_attn,
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2#010010_00000# to 2#010010_11111# => INSN_b,
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2#010000_00000# to 2#010000_11111# => INSN_bc,
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2#001011_00000# to 2#001011_11111# => INSN_cmpi,
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2#001010_00000# to 2#001010_11111# => INSN_cmpli,
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2#100010_00000# to 2#100010_11111# => INSN_lbz,
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2#100011_00000# to 2#100011_11111# => INSN_lbzu,
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2#110010_00000# to 2#110010_11111# => INSN_lfd,
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2#110011_00000# to 2#110011_11111# => INSN_lfdu,
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2#110000_00000# to 2#110000_11111# => INSN_lfs,
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2#110001_00000# to 2#110001_11111# => INSN_lfsu,
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2#101010_00000# to 2#101010_11111# => INSN_lha,
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2#101011_00000# to 2#101011_11111# => INSN_lhau,
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2#101000_00000# to 2#101000_11111# => INSN_lhz,
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2#101001_00000# to 2#101001_11111# => INSN_lhzu,
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2#100000_00000# to 2#100000_11111# => INSN_lwz,
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2#100001_00000# to 2#100001_11111# => INSN_lwzu,
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2#000111_00000# to 2#000111_11111# => INSN_mulli,
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2#011000_00000# to 2#011000_11111# => INSN_ori,
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2#011001_00000# to 2#011001_11111# => INSN_oris,
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2#010100_00000# to 2#010100_11111# => INSN_rlwimi,
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2#010101_00000# to 2#010101_11111# => INSN_rlwinm,
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2#010111_00000# to 2#010111_11111# => INSN_rlwnm,
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2#010001_00000# to 2#010001_11111# => INSN_sc,
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2#100110_00000# to 2#100110_11111# => INSN_stb,
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2#100111_00000# to 2#100111_11111# => INSN_stbu,
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2#110110_00000# to 2#110110_11111# => INSN_stfd,
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2#110111_00000# to 2#110111_11111# => INSN_stfdu,
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2#110100_00000# to 2#110100_11111# => INSN_stfs,
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2#110101_00000# to 2#110101_11111# => INSN_stfsu,
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2#101100_00000# to 2#101100_11111# => INSN_sth,
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2#101101_00000# to 2#101101_11111# => INSN_sthu,
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2#100100_00000# to 2#100100_11111# => INSN_stw,
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2#100101_00000# to 2#100101_11111# => INSN_stwu,
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2#001000_00000# to 2#001000_11111# => INSN_subfic,
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2#000010_00000# to 2#000010_11111# => INSN_tdi,
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2#000011_00000# to 2#000011_11111# => INSN_twi,
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2#011010_00000# to 2#011010_11111# => INSN_xori,
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2#011011_00000# to 2#011011_11111# => INSN_xoris,
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-- major opcode 4
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2#000100_10000# => INSN_maddhd,
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2#000100_10001# => INSN_maddhdu,
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2#000100_10011# => INSN_maddld,
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-- major opcode 30
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2#011110_01000# to 2#011110_01001# => INSN_rldic,
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2#011110_01010# to 2#011110_01011# => INSN_rldic,
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2#011110_00000# to 2#011110_00001# => INSN_rldicl,
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2#011110_00010# to 2#011110_00011# => INSN_rldicl,
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2#011110_00100# to 2#011110_00101# => INSN_rldicr,
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2#011110_00110# to 2#011110_00111# => INSN_rldicr,
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2#011110_01100# to 2#011110_01101# => INSN_rldimi,
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2#011110_01110# to 2#011110_01111# => INSN_rldimi,
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2#011110_10000# to 2#011110_10001# => INSN_rldcl,
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2#011110_10010# to 2#011110_10011# => INSN_rldcr,
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-- major opcode 58
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2#111010_00000# => INSN_ld,
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2#111010_00001# => INSN_ldu,
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2#111010_00010# => INSN_lwa,
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2#111010_00100# => INSN_ld,
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2#111010_00101# => INSN_ldu,
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2#111010_00110# => INSN_lwa,
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2#111010_01000# => INSN_ld,
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2#111010_01001# => INSN_ldu,
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2#111010_01010# => INSN_lwa,
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2#111010_01100# => INSN_ld,
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2#111010_01101# => INSN_ldu,
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2#111010_01110# => INSN_lwa,
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2#111010_10000# => INSN_ld,
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2#111010_10001# => INSN_ldu,
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2#111010_10010# => INSN_lwa,
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2#111010_10100# => INSN_ld,
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2#111010_10101# => INSN_ldu,
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2#111010_10110# => INSN_lwa,
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2#111010_11000# => INSN_ld,
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2#111010_11001# => INSN_ldu,
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2#111010_11010# => INSN_lwa,
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2#111010_11100# => INSN_ld,
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2#111010_11101# => INSN_ldu,
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2#111010_11110# => INSN_lwa,
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-- major opcode 59
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2#111011_00100# to 2#111011_00101# => INSN_fdivs,
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2#111011_01000# to 2#111011_01001# => INSN_fsubs,
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2#111011_01010# to 2#111011_01011# => INSN_fadds,
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2#111011_01100# to 2#111011_01101# => INSN_fsqrts,
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2#111011_10000# to 2#111011_10001# => INSN_fres,
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2#111011_10010# to 2#111011_10011# => INSN_fmuls,
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2#111011_10100# to 2#111011_10101# => INSN_frsqrtes,
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2#111011_11000# to 2#111011_11001# => INSN_fmsubs,
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2#111011_11010# to 2#111011_11011# => INSN_fmadds,
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2#111011_11100# to 2#111011_11101# => INSN_fnmsubs,
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2#111011_11110# to 2#111011_11111# => INSN_fnmadds,
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-- major opcode 62
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2#111110_00000# => INSN_std,
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2#111110_00001# => INSN_stdu,
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2#111110_00100# => INSN_std,
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2#111110_00101# => INSN_stdu,
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2#111110_01000# => INSN_std,
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2#111110_01001# => INSN_stdu,
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2#111110_01100# => INSN_std,
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2#111110_01101# => INSN_stdu,
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2#111110_10000# => INSN_std,
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2#111110_10001# => INSN_stdu,
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2#111110_10100# => INSN_std,
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2#111110_10101# => INSN_stdu,
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2#111110_11000# => INSN_std,
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2#111110_11001# => INSN_stdu,
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2#111110_11100# => INSN_std,
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2#111110_11101# => INSN_stdu,
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-- major opcode 63
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2#111111_00100# to 2#111111_00101# => INSN_fdiv,
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2#111111_01000# to 2#111111_01001# => INSN_fsub,
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2#111111_01010# to 2#111111_01011# => INSN_fadd,
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2#111111_01100# to 2#111111_01101# => INSN_fsqrt,
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2#111111_01110# to 2#111111_01111# => INSN_fsel,
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2#111111_10000# to 2#111111_10001# => INSN_fre,
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2#111111_10010# to 2#111111_10011# => INSN_fmul,
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2#111111_10100# to 2#111111_10101# => INSN_frsqrte,
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2#111111_11000# to 2#111111_11001# => INSN_fmsub,
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2#111111_11010# to 2#111111_11011# => INSN_fmadd,
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2#111111_11100# to 2#111111_11101# => INSN_fnmsub,
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2#111111_11110# to 2#111111_11111# => INSN_fnmadd,
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others => INSN_illegal
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);
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constant row_predecode_rom : predecoder_rom_t := (
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-- Major opcode 31
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-- Address bits are 0, insn(10:1)
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2#0_01000_01010# => INSN_add,
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2#0_11000_01010# => INSN_add, -- addo
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2#0_00000_01010# => INSN_addc,
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2#0_10000_01010# => INSN_addc, -- addco
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2#0_00100_01010# => INSN_adde,
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2#0_10100_01010# => INSN_adde, -- addeo
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2#0_00101_01010# => INSN_addex,
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2#0_00010_01010# => INSN_addg6s,
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2#0_00111_01010# => INSN_addme,
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2#0_10111_01010# => INSN_addme, -- addmeo
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2#0_00110_01010# => INSN_addze,
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2#0_10110_01010# => INSN_addze, -- addzeo
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2#0_00000_11100# => INSN_and,
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2#0_00001_11100# => INSN_andc,
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2#0_00111_11100# => INSN_bperm,
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2#0_01001_11010# => INSN_cbcdtd,
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2#0_01000_11010# => INSN_cdtbcd,
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2#0_00000_00000# => INSN_cmp,
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2#0_01111_11100# => INSN_cmpb,
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2#0_00111_00000# => INSN_cmpeqb,
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2#0_00001_00000# => INSN_cmpl,
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2#0_00110_00000# => INSN_cmprb,
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2#0_00001_11010# => INSN_cntlzd,
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2#0_00000_11010# => INSN_cntlzw,
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2#0_10001_11010# => INSN_cnttzd,
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2#0_10000_11010# => INSN_cnttzw,
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2#0_10111_10011# => INSN_darn,
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2#0_00010_10110# => INSN_dcbf,
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2#0_00001_10110# => INSN_dcbst,
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2#0_01000_10110# => INSN_dcbt,
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2#0_00111_10110# => INSN_dcbtst,
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2#0_11111_10110# => INSN_dcbz,
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2#0_01100_01001# => INSN_divdeu,
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2#0_11100_01001# => INSN_divdeu, -- divdeuo
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2#0_01100_01011# => INSN_divweu,
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2#0_11100_01011# => INSN_divweu, -- divweuo
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2#0_01101_01001# => INSN_divde,
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2#0_11101_01001# => INSN_divde, -- divdeo
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2#0_01101_01011# => INSN_divwe,
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2#0_11101_01011# => INSN_divwe, -- divweo
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2#0_01110_01001# => INSN_divdu,
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2#0_11110_01001# => INSN_divdu, -- divduo
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2#0_01110_01011# => INSN_divwu,
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2#0_11110_01011# => INSN_divwu, -- divwuo
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2#0_01111_01001# => INSN_divd,
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2#0_11111_01001# => INSN_divd, -- divdo
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2#0_01111_01011# => INSN_divw,
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2#0_11111_01011# => INSN_divw, -- divwo
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2#0_11001_10110# => INSN_nop, -- dss
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2#0_01010_10110# => INSN_nop, -- dst
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2#0_01011_10110# => INSN_nop, -- dstst
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2#0_11010_10110# => INSN_eieio,
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2#0_01000_11100# => INSN_eqv,
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2#0_11101_11010# => INSN_extsb,
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2#0_11100_11010# => INSN_extsh,
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2#0_11110_11010# => INSN_extsw,
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2#0_11011_11010# => INSN_extswsli,
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2#0_11011_11011# => INSN_extswsli,
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2#0_11110_10110# => INSN_icbi,
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2#0_00000_10110# => INSN_icbt,
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2#0_00000_01111# => INSN_isel,
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2#0_00001_01111# => INSN_isel,
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2#0_00010_01111# => INSN_isel,
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2#0_00011_01111# => INSN_isel,
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2#0_00100_01111# => INSN_isel,
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2#0_00101_01111# => INSN_isel,
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2#0_00110_01111# => INSN_isel,
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2#0_00111_01111# => INSN_isel,
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2#0_01000_01111# => INSN_isel,
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2#0_01001_01111# => INSN_isel,
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2#0_01010_01111# => INSN_isel,
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2#0_01011_01111# => INSN_isel,
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2#0_01100_01111# => INSN_isel,
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2#0_01101_01111# => INSN_isel,
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2#0_01110_01111# => INSN_isel,
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2#0_01111_01111# => INSN_isel,
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2#0_10000_01111# => INSN_isel,
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2#0_10001_01111# => INSN_isel,
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2#0_10010_01111# => INSN_isel,
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2#0_10011_01111# => INSN_isel,
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2#0_10100_01111# => INSN_isel,
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2#0_10101_01111# => INSN_isel,
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2#0_10110_01111# => INSN_isel,
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2#0_10111_01111# => INSN_isel,
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2#0_11000_01111# => INSN_isel,
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2#0_11001_01111# => INSN_isel,
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2#0_11010_01111# => INSN_isel,
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2#0_11011_01111# => INSN_isel,
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2#0_11100_01111# => INSN_isel,
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2#0_11101_01111# => INSN_isel,
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2#0_11110_01111# => INSN_isel,
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2#0_11111_01111# => INSN_isel,
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2#0_00001_10100# => INSN_lbarx,
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2#0_11010_10101# => INSN_lbzcix,
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2#0_00011_10111# => INSN_lbzux,
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2#0_00010_10111# => INSN_lbzx,
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2#0_00010_10100# => INSN_ldarx,
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2#0_10000_10100# => INSN_ldbrx,
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2#0_11011_10101# => INSN_ldcix,
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2#0_00001_10101# => INSN_ldux,
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2#0_00000_10101# => INSN_ldx,
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2#0_10010_10111# => INSN_lfdx,
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2#0_10011_10111# => INSN_lfdux,
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2#0_11010_10111# => INSN_lfiwax,
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2#0_11011_10111# => INSN_lfiwzx,
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2#0_10000_10111# => INSN_lfsx,
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2#0_10001_10111# => INSN_lfsux,
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2#0_00011_10100# => INSN_lharx,
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2#0_01011_10111# => INSN_lhaux,
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2#0_01010_10111# => INSN_lhax,
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2#0_11000_10110# => INSN_lhbrx,
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2#0_11001_10101# => INSN_lhzcix,
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2#0_01001_10111# => INSN_lhzux,
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2#0_01000_10111# => INSN_lhzx,
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2#0_00000_10100# => INSN_lwarx,
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2#0_01011_10101# => INSN_lwaux,
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2#0_01010_10101# => INSN_lwax,
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2#0_10000_10110# => INSN_lwbrx,
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2#0_11000_10101# => INSN_lwzcix,
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2#0_00001_10111# => INSN_lwzux,
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2#0_00000_10111# => INSN_lwzx,
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2#0_10010_00000# => INSN_mcrxrx,
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2#0_00000_10011# => INSN_mfcr,
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2#0_00010_10011# => INSN_mfmsr,
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2#0_01010_10011# => INSN_mfspr,
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2#0_01000_01001# => INSN_modud,
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2#0_01000_01011# => INSN_moduw,
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2#0_11000_01001# => INSN_modsd,
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2#0_11000_01011# => INSN_modsw,
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2#0_00100_10000# => INSN_mtcrf,
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2#0_00100_10010# => INSN_mtmsr,
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2#0_00101_10010# => INSN_mtmsrd,
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2#0_01110_10011# => INSN_mtspr,
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2#0_00010_01001# => INSN_mulhd,
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2#0_00000_01001# => INSN_mulhdu,
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2#0_00010_01011# => INSN_mulhw,
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2#0_00000_01011# => INSN_mulhwu,
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-- next 4 have reserved bit set
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2#0_10010_01001# => INSN_mulhd,
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2#0_10000_01001# => INSN_mulhdu,
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2#0_10010_01011# => INSN_mulhw,
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2#0_10000_01011# => INSN_mulhwu,
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2#0_00111_01001# => INSN_mulld,
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2#0_10111_01001# => INSN_mulld, -- mulldo
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2#0_00111_01011# => INSN_mullw,
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2#0_10111_01011# => INSN_mullw, -- mullwo
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2#0_01110_11100# => INSN_nand,
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2#0_00011_01000# => INSN_neg,
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2#0_10011_01000# => INSN_neg, -- nego
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-- next 8 are reserved no-op instructions
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2#0_10000_10010# => INSN_nop,
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2#0_10001_10010# => INSN_nop,
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2#0_10010_10010# => INSN_nop,
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2#0_10011_10010# => INSN_nop,
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2#0_10100_10010# => INSN_nop,
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2#0_10101_10010# => INSN_nop,
|
|
2#0_10110_10010# => INSN_nop,
|
|
2#0_10111_10010# => INSN_nop,
|
|
2#0_00011_11100# => INSN_nor,
|
|
2#0_01101_11100# => INSN_or,
|
|
2#0_01100_11100# => INSN_orc,
|
|
2#0_00011_11010# => INSN_popcntb,
|
|
2#0_01111_11010# => INSN_popcntd,
|
|
2#0_01011_11010# => INSN_popcntw,
|
|
2#0_00101_11010# => INSN_prtyd,
|
|
2#0_00100_11010# => INSN_prtyw,
|
|
2#0_00100_00000# => INSN_setb,
|
|
2#0_01111_10010# => INSN_slbia,
|
|
2#0_00000_11011# => INSN_sld,
|
|
2#0_00000_11000# => INSN_slw,
|
|
2#0_11000_11010# => INSN_srad,
|
|
2#0_11001_11010# => INSN_sradi,
|
|
2#0_11001_11011# => INSN_sradi,
|
|
2#0_11000_11000# => INSN_sraw,
|
|
2#0_11001_11000# => INSN_srawi,
|
|
2#0_10000_11011# => INSN_srd,
|
|
2#0_10000_11000# => INSN_srw,
|
|
2#0_11110_10101# => INSN_stbcix,
|
|
2#0_10101_10110# => INSN_stbcx,
|
|
2#0_00111_10111# => INSN_stbux,
|
|
2#0_00110_10111# => INSN_stbx,
|
|
2#0_10100_10100# => INSN_stdbrx,
|
|
2#0_11111_10101# => INSN_stdcix,
|
|
2#0_00110_10110# => INSN_stdcx,
|
|
2#0_00101_10101# => INSN_stdux,
|
|
2#0_00100_10101# => INSN_stdx,
|
|
2#0_10110_10111# => INSN_stfdx,
|
|
2#0_10111_10111# => INSN_stfdux,
|
|
2#0_11110_10111# => INSN_stfiwx,
|
|
2#0_10100_10111# => INSN_stfsx,
|
|
2#0_10101_10111# => INSN_stfsux,
|
|
2#0_11100_10110# => INSN_sthbrx,
|
|
2#0_11101_10101# => INSN_sthcix,
|
|
2#0_10110_10110# => INSN_sthcx,
|
|
2#0_01101_10111# => INSN_sthux,
|
|
2#0_01100_10111# => INSN_sthx,
|
|
2#0_10100_10110# => INSN_stwbrx,
|
|
2#0_11100_10101# => INSN_stwcix,
|
|
2#0_00100_10110# => INSN_stwcx,
|
|
2#0_00101_10111# => INSN_stwux,
|
|
2#0_00100_10111# => INSN_stwx,
|
|
2#0_00001_01000# => INSN_subf,
|
|
2#0_10001_01000# => INSN_subf, -- subfo
|
|
2#0_00000_01000# => INSN_subfc,
|
|
2#0_10000_01000# => INSN_subfc, -- subfco
|
|
2#0_00100_01000# => INSN_subfe,
|
|
2#0_10100_01000# => INSN_subfe, -- subfeo
|
|
2#0_00111_01000# => INSN_subfme,
|
|
2#0_10111_01000# => INSN_subfme, -- subfmeo
|
|
2#0_00110_01000# => INSN_subfze,
|
|
2#0_10110_01000# => INSN_subfze, -- subfzeo
|
|
2#0_10010_10110# => INSN_sync,
|
|
2#0_00010_00100# => INSN_td,
|
|
2#0_00000_00100# => INSN_tw,
|
|
2#0_01001_10010# => INSN_tlbie,
|
|
2#0_01000_10010# => INSN_tlbiel,
|
|
2#0_10001_10110# => INSN_tlbsync,
|
|
2#0_00000_11110# => INSN_wait,
|
|
2#0_01001_11100# => INSN_xor,
|
|
|
|
-- Major opcode 19
|
|
-- Columns with insn(4) = '1' are all illegal and not mapped here; to
|
|
-- fit into 2048 entries, the columns are remapped so that 16-24 are
|
|
-- stored here as 8-15; in other words the address bits are
|
|
-- 1, insn(10..6), 1, insn(5), insn(3..1)
|
|
2#1_10000_11000# => INSN_bcctr,
|
|
2#1_00000_11000# => INSN_bclr,
|
|
2#1_10001_11000# => INSN_bctar,
|
|
2#1_01000_10001# => INSN_crand,
|
|
2#1_00100_10001# => INSN_crandc,
|
|
2#1_01001_10001# => INSN_creqv,
|
|
2#1_00111_10001# => INSN_crnand,
|
|
2#1_00001_10001# => INSN_crnor,
|
|
2#1_01110_10001# => INSN_cror,
|
|
2#1_01101_10001# => INSN_crorc,
|
|
2#1_00110_10001# => INSN_crxor,
|
|
2#1_00100_11110# => INSN_isync,
|
|
2#1_00000_10000# => INSN_mcrf,
|
|
2#1_00000_11010# => INSN_rfid,
|
|
|
|
-- Major opcode 59
|
|
-- Only column 14 is valid here; columns 16-31 are handled in the major table
|
|
-- Column 14 is mapped to column 6 of the space which is
|
|
-- mostly used for opcode 19.
|
|
2#1_11010_10110# => INSN_fcfids,
|
|
2#1_11110_10110# => INSN_fcfidus,
|
|
|
|
-- Major opcode 63
|
|
-- Columns 0-15 are mapped here; columns 16-31 are in the major table.
|
|
-- Address bits are 1, insn(10:6), 0, insn(4:1)
|
|
2#1_00000_00000# => INSN_fcmpu,
|
|
2#1_00001_00000# => INSN_fcmpo,
|
|
2#1_00010_00000# => INSN_mcrfs,
|
|
2#1_00100_00000# => INSN_ftdiv,
|
|
2#1_00101_00000# => INSN_ftsqrt,
|
|
2#1_00001_00110# => INSN_mtfsb,
|
|
2#1_00010_00110# => INSN_mtfsb,
|
|
2#1_00100_00110# => INSN_mtfsfi,
|
|
2#1_11010_00110# => INSN_fmrgow,
|
|
2#1_11110_00110# => INSN_fmrgew,
|
|
2#1_10010_00111# => INSN_mffs,
|
|
2#1_10110_00111# => INSN_mtfsf,
|
|
2#1_00000_01000# => INSN_fcpsgn,
|
|
2#1_00001_01000# => INSN_fneg,
|
|
2#1_00010_01000# => INSN_fmr,
|
|
2#1_00100_01000# => INSN_fnabs,
|
|
2#1_01000_01000# => INSN_fabs,
|
|
2#1_01100_01000# => INSN_frin,
|
|
2#1_01101_01000# => INSN_friz,
|
|
2#1_01110_01000# => INSN_frip,
|
|
2#1_01111_01000# => INSN_frim,
|
|
2#1_00000_01100# => INSN_frsp,
|
|
2#1_00000_01110# => INSN_fctiw,
|
|
2#1_00100_01110# => INSN_fctiwu,
|
|
2#1_11001_01110# => INSN_fctid,
|
|
2#1_11010_01110# => INSN_fcfid,
|
|
2#1_11101_01110# => INSN_fctidu,
|
|
2#1_11110_01110# => INSN_fcfidu,
|
|
2#1_00000_01111# => INSN_fctiwz,
|
|
2#1_00100_01111# => INSN_fctiwuz,
|
|
2#1_11001_01111# => INSN_fctidz,
|
|
2#1_11101_01111# => INSN_fctiduz,
|
|
|
|
others => INSN_illegal
|
|
);
|
|
|
|
constant IOUT_LEN : natural := ICODE_LEN + IMAGE_LEN;
|
|
|
|
type predec_t is record
|
|
image : std_ulogic_vector(31 downto 0);
|
|
maj_predecode : unsigned(ICODE_LEN - 1 downto 0);
|
|
row_predecode : unsigned(ICODE_LEN - 1 downto 0);
|
|
end record;
|
|
|
|
subtype index_t is integer range 0 to WIDTH-1;
|
|
type predec_array is array(index_t) of predec_t;
|
|
|
|
signal pred : predec_array;
|
|
signal valid : std_ulogic;
|
|
|
|
begin
|
|
predecode_0: process(clk)
|
|
variable majaddr : std_ulogic_vector(10 downto 0);
|
|
variable rowaddr : std_ulogic_vector(10 downto 0);
|
|
variable iword : std_ulogic_vector(31 downto 0);
|
|
variable majcode : insn_code;
|
|
variable rowcode : insn_code;
|
|
begin
|
|
if rising_edge(clk) then
|
|
valid <= valid_in;
|
|
for i in index_t loop
|
|
iword := insns_in(i * 32 + 31 downto i * 32);
|
|
pred(i).image <= iword;
|
|
|
|
if is_X(iword) then
|
|
pred(i).maj_predecode <= (others => 'X');
|
|
pred(i).row_predecode <= (others => 'X');
|
|
else
|
|
majaddr := iword(31 downto 26) & iword(4 downto 0);
|
|
|
|
-- row_predecode_rom is used for op 19, 31, 59, 63
|
|
-- addr bit 10 is 0 for op 31, 1 for 19, 59, 63
|
|
rowaddr(10) := iword(31) or not iword(29);
|
|
rowaddr(9 downto 5) := iword(10 downto 6);
|
|
if iword(28) = '0' then
|
|
-- op 19 and op 59
|
|
rowaddr(4 downto 3) := '1' & iword(5);
|
|
else
|
|
-- op 31 and 63; for 63 we only use this when iword(5) = '0'
|
|
rowaddr(4 downto 3) := iword(5 downto 4);
|
|
end if;
|
|
rowaddr(2 downto 0) := iword(3 downto 1);
|
|
|
|
majcode := major_predecode_rom(to_integer(unsigned(majaddr)));
|
|
pred(i).maj_predecode <= to_unsigned(insn_code'pos(majcode), ICODE_LEN);
|
|
rowcode := row_predecode_rom(to_integer(unsigned(rowaddr)));
|
|
pred(i).row_predecode <= to_unsigned(insn_code'pos(rowcode), ICODE_LEN);
|
|
end if;
|
|
end loop;
|
|
end if;
|
|
end process;
|
|
|
|
predecode_1: process(all)
|
|
variable iword : std_ulogic_vector(31 downto 0);
|
|
variable use_row : std_ulogic;
|
|
variable illegal : std_ulogic;
|
|
variable ici : std_ulogic_vector(IOUT_LEN - 1 downto 0);
|
|
variable icode : unsigned(ICODE_LEN - 1 downto 0);
|
|
begin
|
|
for i in index_t loop
|
|
iword := pred(i).image;
|
|
icode := pred(i).maj_predecode;
|
|
use_row := '0';
|
|
illegal := '0';
|
|
|
|
case iword(31 downto 26) is
|
|
when "000100" => -- 4
|
|
-- major opcode 4, mostly VMX/VSX stuff but also some integer ops (madd*)
|
|
illegal := not iword(5);
|
|
|
|
when "010011" => -- 19
|
|
-- Columns 8-15 and 24-31 don't have any valid instructions
|
|
-- (where insn(5..1) is the column number).
|
|
-- addpcis (column 2) is in the major table
|
|
-- Other valid columns are mapped to columns in the second
|
|
-- half of the row table: columns 0-1 are mapped to 16-17
|
|
-- and 16-23 are mapped to 24-31.
|
|
illegal := iword(4);
|
|
use_row := iword(5) or (not iword(3) and not iword(2));
|
|
|
|
when "011000" => -- 24
|
|
-- ori, special-case the standard NOP
|
|
if std_match(iword, "01100000000000000000000000000000") then
|
|
icode := to_unsigned(insn_code'pos(INSN_nop), ICODE_LEN);
|
|
end if;
|
|
|
|
when "011111" => -- 31
|
|
-- major opcode 31, lots of things
|
|
-- Use the first half of the row table for all columns
|
|
use_row := '1';
|
|
|
|
when "111011" => -- 59
|
|
-- floating point operations, mostly single-precision
|
|
-- Columns 0-11 are illegal; columns 12-15 are mapped
|
|
-- to columns 20-23 in the second half of the row table,
|
|
-- and columns 16-31 are in the major table.
|
|
illegal := not iword(5) and (not iword(4) or not iword(3));
|
|
use_row := not iword(5);
|
|
|
|
when "111111" => -- 63
|
|
-- floating point operations, general and double-precision
|
|
-- Use columns 0-15 of the second half of the row table
|
|
-- for columns 0-15, and the major table for columns 16-31.
|
|
use_row := not iword(5);
|
|
|
|
when others =>
|
|
end case;
|
|
if use_row = '1' then
|
|
icode := pred(i).row_predecode;
|
|
end if;
|
|
|
|
-- Mark FP instructions as illegal if we don't have an FPU
|
|
if not HAS_FPU and not is_X(icode) and
|
|
to_integer(icode) >= insn_code'pos(INSN_first_frs) then
|
|
illegal := '1';
|
|
end if;
|
|
|
|
ici(31 downto 0) := iword;
|
|
ici(IOUT_LEN - 1 downto 32) := (others => '0');
|
|
if valid = '0' or illegal = '1' or is_X(icode) or
|
|
icode = to_unsigned(insn_code'pos(INSN_illegal), ICODE_LEN) then
|
|
-- Since an insn_code currently fits in 9 bits, use just
|
|
-- the most significant bit of ici to indicate illegal insns.
|
|
ici(IOUT_LEN - 1) := '1';
|
|
else
|
|
ici(IOUT_LEN - 1 downto IMAGE_LEN) := std_ulogic_vector(icode);
|
|
end if;
|
|
icodes_out(i * IOUT_LEN + IOUT_LEN - 1 downto i * IOUT_LEN) <= ici;
|
|
end loop;
|
|
end process;
|
|
|
|
end architecture behaviour;
|