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predecode: Add some more comments

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Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
pull/445/head
Paul Mackerras 2 months ago
parent 0f8c4afc52
commit 8bfce4890b
1 changed files with 47 additions and 46 deletions
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93
predecode.vhdl
Unescape Escape View File

@ -29,16 +29,17 @@ architecture behaviour of predecoder is

type predecoder_rom_t is array(0 to 2047) of insn_code;

-- indexed by instruction bits 31..26 and 4..0
constant major_predecode_rom : predecoder_rom_t := (
2#001100_00000# to 2#001100_11111# => INSN_addic,
2#001101_00000# to 2#001101_11111# => INSN_addic_dot,
2#001110_00000# to 2#001110_11111# => INSN_addi,
2#001111_00000# to 2#001111_11111# => INSN_addis,
2#010011_00100# to 2#010011_00101# => INSN_addpcis,
2#011100_00000# to 2#011100_11111# => INSN_andi_dot,
2#011101_00000# to 2#011101_11111# => INSN_andis_dot,
2#000000_00000# => INSN_attn,
2#010010_00000# to 2#010010_00001# => INSN_brel,
2#001100_00000# to 2#001100_11111# => INSN_addic, -- 12
2#001101_00000# to 2#001101_11111# => INSN_addic_dot, -- 13
2#001110_00000# to 2#001110_11111# => INSN_addi, -- 14
2#001111_00000# to 2#001111_11111# => INSN_addis, -- 15
2#010011_00100# to 2#010011_00101# => INSN_addpcis, -- 19
2#011100_00000# to 2#011100_11111# => INSN_andi_dot, -- 28
2#011101_00000# to 2#011101_11111# => INSN_andis_dot, -- 29
2#000000_00000# => INSN_attn, -- 0
2#010010_00000# to 2#010010_00001# => INSN_brel, -- 18
2#010010_00010# to 2#010010_00011# => INSN_babs,
2#010010_00100# to 2#010010_00101# => INSN_brel,
2#010010_00110# to 2#010010_00111# => INSN_babs,
@ -54,7 +55,7 @@ architecture behaviour of predecoder is
2#010010_11010# to 2#010010_11011# => INSN_babs,
2#010010_11100# to 2#010010_11101# => INSN_brel,
2#010010_11110# to 2#010010_11111# => INSN_babs,
2#010000_00000# to 2#010000_00001# => INSN_bcrel,
2#010000_00000# to 2#010000_00001# => INSN_bcrel, -- 16
2#010000_00010# to 2#010000_00011# => INSN_bcabs,
2#010000_00100# to 2#010000_00101# => INSN_bcrel,
2#010000_00110# to 2#010000_00111# => INSN_bcabs,
@ -70,42 +71,42 @@ architecture behaviour of predecoder is
2#010000_11010# to 2#010000_11011# => INSN_bcabs,
2#010000_11100# to 2#010000_11101# => INSN_bcrel,
2#010000_11110# to 2#010000_11111# => INSN_bcabs,
2#001011_00000# to 2#001011_11111# => INSN_cmpi,
2#001010_00000# to 2#001010_11111# => INSN_cmpli,
2#100010_00000# to 2#100010_11111# => INSN_lbz,
2#100011_00000# to 2#100011_11111# => INSN_lbzu,
2#110010_00000# to 2#110010_11111# => INSN_lfd,
2#110011_00000# to 2#110011_11111# => INSN_lfdu,
2#110000_00000# to 2#110000_11111# => INSN_lfs,
2#110001_00000# to 2#110001_11111# => INSN_lfsu,
2#101010_00000# to 2#101010_11111# => INSN_lha,
2#101011_00000# to 2#101011_11111# => INSN_lhau,
2#101000_00000# to 2#101000_11111# => INSN_lhz,
2#101001_00000# to 2#101001_11111# => INSN_lhzu,
2#100000_00000# to 2#100000_11111# => INSN_lwz,
2#100001_00000# to 2#100001_11111# => INSN_lwzu,
2#000111_00000# to 2#000111_11111# => INSN_mulli,
2#011000_00000# to 2#011000_11111# => INSN_ori,
2#011001_00000# to 2#011001_11111# => INSN_oris,
2#010100_00000# to 2#010100_11111# => INSN_rlwimi,
2#010101_00000# to 2#010101_11111# => INSN_rlwinm,
2#010111_00000# to 2#010111_11111# => INSN_rlwnm,
2#010001_00000# to 2#010001_11111# => INSN_sc,
2#100110_00000# to 2#100110_11111# => INSN_stb,
2#100111_00000# to 2#100111_11111# => INSN_stbu,
2#110110_00000# to 2#110110_11111# => INSN_stfd,
2#110111_00000# to 2#110111_11111# => INSN_stfdu,
2#110100_00000# to 2#110100_11111# => INSN_stfs,
2#110101_00000# to 2#110101_11111# => INSN_stfsu,
2#101100_00000# to 2#101100_11111# => INSN_sth,
2#101101_00000# to 2#101101_11111# => INSN_sthu,
2#100100_00000# to 2#100100_11111# => INSN_stw,
2#100101_00000# to 2#100101_11111# => INSN_stwu,
2#001000_00000# to 2#001000_11111# => INSN_subfic,
2#000010_00000# to 2#000010_11111# => INSN_tdi,
2#000011_00000# to 2#000011_11111# => INSN_twi,
2#011010_00000# to 2#011010_11111# => INSN_xori,
2#011011_00000# to 2#011011_11111# => INSN_xoris,
2#001011_00000# to 2#001011_11111# => INSN_cmpi, -- 11
2#001010_00000# to 2#001010_11111# => INSN_cmpli, -- 10
2#100010_00000# to 2#100010_11111# => INSN_lbz, -- 34
2#100011_00000# to 2#100011_11111# => INSN_lbzu, -- 35
2#110010_00000# to 2#110010_11111# => INSN_lfd, -- 50
2#110011_00000# to 2#110011_11111# => INSN_lfdu, -- 51
2#110000_00000# to 2#110000_11111# => INSN_lfs, -- 56
2#110001_00000# to 2#110001_11111# => INSN_lfsu, -- 57
2#101010_00000# to 2#101010_11111# => INSN_lha, -- 42
2#101011_00000# to 2#101011_11111# => INSN_lhau, -- 43
2#101000_00000# to 2#101000_11111# => INSN_lhz, -- 40
2#101001_00000# to 2#101001_11111# => INSN_lhzu, -- 41
2#100000_00000# to 2#100000_11111# => INSN_lwz, -- 32
2#100001_00000# to 2#100001_11111# => INSN_lwzu, -- 33
2#000111_00000# to 2#000111_11111# => INSN_mulli, -- 7
2#011000_00000# to 2#011000_11111# => INSN_ori, -- 24
2#011001_00000# to 2#011001_11111# => INSN_oris, -- 25
2#010100_00000# to 2#010100_11111# => INSN_rlwimi, -- 20
2#010101_00000# to 2#010101_11111# => INSN_rlwinm, -- 21
2#010111_00000# to 2#010111_11111# => INSN_rlwnm, -- 23
2#010001_00000# to 2#010001_11111# => INSN_sc, -- 17
2#100110_00000# to 2#100110_11111# => INSN_stb, -- 38
2#100111_00000# to 2#100111_11111# => INSN_stbu, -- 39
2#110110_00000# to 2#110110_11111# => INSN_stfd, -- 54
2#110111_00000# to 2#110111_11111# => INSN_stfdu, -- 55
2#110100_00000# to 2#110100_11111# => INSN_stfs, -- 52
2#110101_00000# to 2#110101_11111# => INSN_stfsu, -- 53
2#101100_00000# to 2#101100_11111# => INSN_sth, -- 44
2#101101_00000# to 2#101101_11111# => INSN_sthu, -- 45
2#100100_00000# to 2#100100_11111# => INSN_stw, -- 36
2#100101_00000# to 2#100101_11111# => INSN_stwu, -- 37
2#001000_00000# to 2#001000_11111# => INSN_subfic, -- 8
2#000010_00000# to 2#000010_11111# => INSN_tdi, -- 2
2#000011_00000# to 2#000011_11111# => INSN_twi, -- 3
2#011010_00000# to 2#011010_11111# => INSN_xori, -- 26
2#011011_00000# to 2#011011_11111# => INSN_xoris, -- 27
-- major opcode 4
2#000100_10000# => INSN_maddhd,
2#000100_10001# => INSN_maddhdu,

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