From: Paul Mackerras Date: Thu, 4 Aug 2022 05:25:06 +0000 (+1000) Subject: predecode: Add more comments to row_predecode_rom and insn_code values X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=58e799b3504090451d5ffb32352d665ec187a0b8;p=microwatt.git predecode: Add more comments to row_predecode_rom and insn_code values This adds comments to row_predecode_rom to aid understanding how the columns in the second half of the table are allocated to different primary opcodes, and to the insn_code values to assist in locating the code with a given numeric value. No code change. Signed-off-by: Paul Mackerras --- diff --git a/decode_types.vhdl b/decode_types.vhdl index 9f19530..7ceb2ae 100644 --- a/decode_types.vhdl +++ b/decode_types.vhdl @@ -32,7 +32,7 @@ package decode_types is -- comparisons of the insn_code for the instruction with a few constants. type insn_code is ( -- The following instructions don't have an RB operand or access FPRs - INSN_illegal, + INSN_illegal, -- 0 INSN_fetch_fail, INSN_addi, INSN_addic, @@ -42,7 +42,7 @@ package decode_types is INSN_addpcis, INSN_addze, INSN_andi_dot, - INSN_andis_dot, + INSN_andis_dot, -- 10 INSN_attn, INSN_b, INSN_bc, @@ -52,7 +52,7 @@ package decode_types is INSN_cbcdtd, INSN_cdtbcd, INSN_cmpi, - INSN_cmpli, + INSN_cmpli, -- 20 INSN_cntlzw, INSN_cntlzd, INSN_cnttzw, @@ -62,7 +62,7 @@ package decode_types is INSN_creqv, INSN_crnand, INSN_crnor, - INSN_cror, + INSN_cror, -- 30 INSN_crorc, INSN_crxor, INSN_darn, @@ -72,7 +72,7 @@ package decode_types is INSN_extsw, INSN_extswsli, INSN_isync, - INSN_lbz, + INSN_lbz, -- 40 INSN_lbzu, INSN_ld, INSN_ldu, @@ -82,7 +82,7 @@ package decode_types is INSN_lhzu, INSN_lwa, INSN_lwz, - INSN_lwzu, + INSN_lwzu, -- 50 INSN_mcrf, INSN_mcrfs, INSN_mcrxrx, @@ -92,7 +92,7 @@ package decode_types is INSN_mtcrf, INSN_mtfsb, INSN_mtfsfi, - INSN_mtmsr, + INSN_mtmsr, -- 60 INSN_mtmsrd, INSN_mtspr, INSN_mulli, @@ -102,7 +102,7 @@ package decode_types is INSN_oris, INSN_popcntb, INSN_popcntw, - INSN_popcntd, + INSN_popcntd, -- 70 INSN_prtyw, INSN_prtyd, INSN_rfid, @@ -112,7 +112,7 @@ package decode_types is INSN_rldimi, INSN_rlwimi, INSN_rlwinm, - INSN_sc, + INSN_sc, -- 80 INSN_setb, INSN_slbia, INSN_sradi, @@ -122,7 +122,7 @@ package decode_types is INSN_std, INSN_stdu, INSN_sth, - INSN_sthu, + INSN_sthu, -- 90 INSN_stw, INSN_stwu, INSN_subfic, @@ -132,7 +132,7 @@ package decode_types is INSN_tdi, INSN_tlbsync, INSN_twi, - INSN_wait, + INSN_wait, -- 100 INSN_xori, INSN_xoris, @@ -150,7 +150,7 @@ package decode_types is INSN_and, INSN_andc, INSN_bperm, - INSN_cmp, + INSN_cmp, -- 120 INSN_cmpb, INSN_cmpeqb, INSN_cmpl, @@ -160,7 +160,7 @@ package decode_types is INSN_dcbt, INSN_dcbtst, INSN_dcbz, - INSN_divd, + INSN_divd, -- 130 INSN_divdu, INSN_divde, INSN_divdeu, @@ -170,7 +170,7 @@ package decode_types is INSN_divweu, INSN_eqv, INSN_icbi, - INSN_icbt, + INSN_icbt, -- 140 INSN_isel, INSN_lbarx, INSN_lbzcix, @@ -180,7 +180,7 @@ package decode_types is INSN_ldbrx, INSN_ldcix, INSN_ldx, - INSN_ldux, + INSN_ldux, -- 150 INSN_lharx, INSN_lhax, INSN_lhaux, @@ -190,7 +190,7 @@ package decode_types is INSN_lhzux, INSN_lwarx, INSN_lwax, - INSN_lwaux, + INSN_lwaux, -- 160 INSN_lwbrx, INSN_lwzcix, INSN_lwzx, @@ -200,7 +200,7 @@ package decode_types is INSN_moduw, INSN_modud, INSN_mulhw, - INSN_mulhwu, + INSN_mulhwu, -- 170 INSN_mulhd, INSN_mulhdu, INSN_mullw, @@ -210,7 +210,7 @@ package decode_types is INSN_or, INSN_orc, INSN_rldcl, - INSN_rldcr, + INSN_rldcr, -- 180 INSN_rlwnm, INSN_slw, INSN_sld, @@ -220,7 +220,7 @@ package decode_types is INSN_srd, INSN_stbcix, INSN_stbcx, - INSN_stbx, + INSN_stbx, -- 190 INSN_stbux, INSN_stdbrx, INSN_stdcix, @@ -230,7 +230,7 @@ package decode_types is INSN_sthbrx, INSN_sthcix, INSN_sthcx, - INSN_sthx, + INSN_sthx, -- 200 INSN_sthux, INSN_stwbrx, INSN_stwcix, @@ -240,7 +240,7 @@ package decode_types is INSN_subf, INSN_subfc, INSN_subfe, - INSN_td, + INSN_td, -- 210 INSN_tlbie, INSN_tlbiel, INSN_tw, @@ -272,7 +272,7 @@ package decode_types is INSN_stfdu, INSN_stfs, INSN_stfsu, - INSN_stfdux, + INSN_stfdux, -- 260 INSN_stfdx, INSN_stfiwx, INSN_stfsux, @@ -284,7 +284,7 @@ package decode_types is INSN_lfs, INSN_lfsu, INSN_lfdx, - INSN_lfdux, + INSN_lfdux, -- 270 INSN_lfiwax, INSN_lfiwzx, INSN_lfsx, @@ -296,7 +296,7 @@ package decode_types is INSN_fadd, INSN_fadds, INSN_fcfid, - INSN_fcfids, + INSN_fcfids, -- 280 INSN_fcfidu, INSN_fcfidus, INSN_fcmpo, @@ -306,7 +306,7 @@ package decode_types is INSN_fctidz, INSN_fctidu, INSN_fctiduz, - INSN_fctiw, + INSN_fctiw, -- 290 INSN_fctiwz, INSN_fctiwu, INSN_fctiwuz, @@ -316,7 +316,7 @@ package decode_types is INSN_fmrgew, INSN_fmrgow, INSN_fnabs, - INSN_fneg, + INSN_fneg, -- 300 INSN_fre, INSN_fres, INSN_frim, @@ -326,7 +326,7 @@ package decode_types is INSN_frsp, INSN_frsqrte, INSN_frsqrtes, - INSN_fsqrt, + INSN_fsqrt, -- 310 INSN_fsqrts, INSN_fsub, INSN_fsubs, @@ -339,7 +339,7 @@ package decode_types is INSN_318, INSN_319, -- The following instructions access FRA, FRB (possibly) and FRC operands - INSN_fmul, + INSN_fmul, -- 320 INSN_fmuls, INSN_fmadd, INSN_fmadds, @@ -349,7 +349,7 @@ package decode_types is INSN_fnmadds, INSN_fnmsub, INSN_fnmsubs, - INSN_fsel + INSN_fsel -- 330 ); constant INSN_first_rb : insn_code := INSN_add; diff --git a/predecode.vhdl b/predecode.vhdl index 3bbd224..7e1149b 100644 --- a/predecode.vhdl +++ b/predecode.vhdl @@ -389,6 +389,8 @@ architecture behaviour of predecoder is -- 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) + -- Columns 16-17 here are opcode 19 columns 0-1 + -- Columns 24-31 here are opcode 19 columns 16-23 2#1_10000_11000# => INSN_bcctr, 2#1_00000_11000# => INSN_bclr, 2#1_10001_11000# => INSN_bctar, @@ -405,15 +407,17 @@ architecture behaviour of predecoder is 2#1_00000_11010# => INSN_rfid, -- Major opcode 59 + -- Address bits are 1, insn(10..6), 1, 0, insn(3..1) -- 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. + -- Column 14 is mapped to column 22. + -- Columns 20-23 here are opcode 59 columns 12-15 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) + -- Columns 0-15 here are opcode 63 columns 0-15 2#1_00000_00000# => INSN_fcmpu, 2#1_00001_00000# => INSN_fcmpo, 2#1_00010_00000# => INSN_mcrfs,