1 """Power ISA Decoder second stage
3 based on Anton Blanchard microwatt decode2.vhdl
5 Note: OP_TRAP is used for exceptions and interrupts (micro-code style) by
6 over-riding the internal opcode when an exception is needed.
9 from nmigen
import Module
, Elaboratable
, Signal
, Mux
, Const
, Cat
, Repl
, Record
10 from nmigen
.cli
import rtlil
11 from soc
.regfile
.regfiles
import XERRegs
13 from nmutil
.picker
import PriorityPicker
14 from nmutil
.iocontrol
import RecordObject
15 from nmutil
.extend
import exts
17 from soc
.decoder
.power_regspec_map
import regspec_decode_read
18 from soc
.decoder
.power_regspec_map
import regspec_decode_write
19 from soc
.decoder
.power_decoder
import create_pdecode
20 from soc
.decoder
.power_enums
import (MicrOp
, CryIn
, Function
,
22 LdstLen
, In1Sel
, In2Sel
, In3Sel
,
23 OutSel
, SPR
, RC
, LDSTMode
)
24 from soc
.decoder
.decode2execute1
import Decode2ToExecute1Type
, Data
25 from soc
.consts
import MSR
27 from soc
.regfile
.regfiles
import FastRegs
28 from soc
.consts
import TT
29 from soc
.config
.state
import CoreState
30 from soc
.regfile
.util
import spr_to_fast
33 def decode_spr_num(spr
):
34 return Cat(spr
[5:10], spr
[0:5])
37 def instr_is_priv(m
, op
, insn
):
38 """determines if the instruction is privileged or not
41 is_priv_insn
= Signal(reset_less
=True)
43 with m
.Case(MicrOp
.OP_ATTN
, MicrOp
.OP_MFMSR
, MicrOp
.OP_MTMSRD
,
44 MicrOp
.OP_MTMSR
, MicrOp
.OP_RFID
):
45 comb
+= is_priv_insn
.eq(1)
47 #with m.Case(MicrOp.OP_TLBIE) : comb += is_priv_insn.eq(1)
48 with m
.Case(MicrOp
.OP_MFSPR
, MicrOp
.OP_MTSPR
):
49 with m
.If(insn
[20]): # field XFX.spr[-1] i think
50 comb
+= is_priv_insn
.eq(1)
54 class SPRMap(Elaboratable
):
55 """SPRMap: maps POWER9 SPR numbers to internal enum values, fast and slow
59 self
.spr_i
= Signal(10, reset_less
=True)
60 self
.spr_o
= Data(SPR
, name
="spr_o")
61 self
.fast_o
= Data(3, name
="fast_o")
63 def elaborate(self
, platform
):
65 with m
.Switch(self
.spr_i
):
66 for i
, x
in enumerate(SPR
):
68 m
.d
.comb
+= self
.spr_o
.data
.eq(i
)
69 m
.d
.comb
+= self
.spr_o
.ok
.eq(1)
70 for x
, v
in spr_to_fast
.items():
72 m
.d
.comb
+= self
.fast_o
.data
.eq(v
)
73 m
.d
.comb
+= self
.fast_o
.ok
.eq(1)
77 class DecodeA(Elaboratable
):
78 """DecodeA from instruction
80 decodes register RA, implicit and explicit CSRs
83 def __init__(self
, dec
):
85 self
.sel_in
= Signal(In1Sel
, reset_less
=True)
86 self
.insn_in
= Signal(32, reset_less
=True)
87 self
.reg_out
= Data(5, name
="reg_a")
88 self
.spr_out
= Data(SPR
, "spr_a")
89 self
.fast_out
= Data(3, "fast_a")
91 def elaborate(self
, platform
):
94 m
.submodules
.sprmap
= sprmap
= SPRMap()
96 # select Register A field
97 ra
= Signal(5, reset_less
=True)
98 comb
+= ra
.eq(self
.dec
.RA
)
99 with m
.If((self
.sel_in
== In1Sel
.RA
) |
100 ((self
.sel_in
== In1Sel
.RA_OR_ZERO
) &
101 (ra
!= Const(0, 5)))):
102 comb
+= self
.reg_out
.data
.eq(ra
)
103 comb
+= self
.reg_out
.ok
.eq(1)
105 # some Logic/ALU ops have RS as the 3rd arg, but no "RA".
106 with m
.If(self
.sel_in
== In1Sel
.RS
):
107 comb
+= self
.reg_out
.data
.eq(self
.dec
.RS
)
108 comb
+= self
.reg_out
.ok
.eq(1)
110 # decode Fast-SPR based on instruction type
112 with m
.Switch(op
.internal_op
):
114 # BC or BCREG: implicit register (CTR) NOTE: same in DecodeOut
115 with m
.Case(MicrOp
.OP_BC
):
116 with m
.If(~self
.dec
.BO
[2]): # 3.0B p38 BO2=0, use CTR reg
118 comb
+= self
.fast_out
.data
.eq(FastRegs
.CTR
)
119 comb
+= self
.fast_out
.ok
.eq(1)
120 with m
.Case(MicrOp
.OP_BCREG
):
121 xo9
= self
.dec
.FormXL
.XO
[9] # 3.0B p38 top bit of XO
122 xo5
= self
.dec
.FormXL
.XO
[5] # 3.0B p38
123 with m
.If(xo9
& ~xo5
):
125 comb
+= self
.fast_out
.data
.eq(FastRegs
.CTR
)
126 comb
+= self
.fast_out
.ok
.eq(1)
128 # MFSPR move from SPRs
129 with m
.Case(MicrOp
.OP_MFSPR
):
130 spr
= Signal(10, reset_less
=True)
131 comb
+= spr
.eq(decode_spr_num(self
.dec
.SPR
)) # from XFX
132 comb
+= sprmap
.spr_i
.eq(spr
)
133 comb
+= self
.spr_out
.eq(sprmap
.spr_o
)
134 comb
+= self
.fast_out
.eq(sprmap
.fast_o
)
139 class DecodeAImm(Elaboratable
):
140 """DecodeA immediate from instruction
142 decodes register RA, whether immediate-zero, implicit and
146 def __init__(self
, dec
):
148 self
.sel_in
= Signal(In1Sel
, reset_less
=True)
149 self
.immz_out
= Signal(reset_less
=True)
151 def elaborate(self
, platform
):
155 # zero immediate requested
156 ra
= Signal(5, reset_less
=True)
157 comb
+= ra
.eq(self
.dec
.RA
)
158 with m
.If((self
.sel_in
== In1Sel
.RA_OR_ZERO
) & (ra
== Const(0, 5))):
159 comb
+= self
.immz_out
.eq(1)
164 class DecodeB(Elaboratable
):
165 """DecodeB from instruction
167 decodes register RB, different forms of immediate (signed, unsigned),
168 and implicit SPRs. register B is basically "lane 2" into the CompUnits.
169 by industry-standard convention, "lane 2" is where fully-decoded
170 immediates are muxed in.
173 def __init__(self
, dec
):
175 self
.sel_in
= Signal(In2Sel
, reset_less
=True)
176 self
.insn_in
= Signal(32, reset_less
=True)
177 self
.reg_out
= Data(5, "reg_b")
178 self
.fast_out
= Data(3, "fast_b")
180 def elaborate(self
, platform
):
184 # select Register B field
185 with m
.Switch(self
.sel_in
):
186 with m
.Case(In2Sel
.RB
):
187 comb
+= self
.reg_out
.data
.eq(self
.dec
.RB
)
188 comb
+= self
.reg_out
.ok
.eq(1)
189 with m
.Case(In2Sel
.RS
):
190 # for M-Form shiftrot
191 comb
+= self
.reg_out
.data
.eq(self
.dec
.RS
)
192 comb
+= self
.reg_out
.ok
.eq(1)
194 # decode SPR2 based on instruction type
196 # BCREG implicitly uses LR or TAR for 2nd reg
197 # CTR however is already in fast_spr1 *not* 2.
198 with m
.If(op
.internal_op
== MicrOp
.OP_BCREG
):
199 xo9
= self
.dec
.FormXL
.XO
[9] # 3.0B p38 top bit of XO
200 xo5
= self
.dec
.FormXL
.XO
[5] # 3.0B p38
202 comb
+= self
.fast_out
.data
.eq(FastRegs
.LR
)
203 comb
+= self
.fast_out
.ok
.eq(1)
205 comb
+= self
.fast_out
.data
.eq(FastRegs
.TAR
)
206 comb
+= self
.fast_out
.ok
.eq(1)
211 class DecodeBImm(Elaboratable
):
212 """DecodeB immediate from instruction
214 def __init__(self
, dec
):
216 self
.sel_in
= Signal(In2Sel
, reset_less
=True)
217 self
.imm_out
= Data(64, "imm_b")
219 def elaborate(self
, platform
):
223 # select Register B Immediate
224 with m
.Switch(self
.sel_in
):
225 with m
.Case(In2Sel
.CONST_UI
): # unsigned
226 comb
+= self
.imm_out
.data
.eq(self
.dec
.UI
)
227 comb
+= self
.imm_out
.ok
.eq(1)
228 with m
.Case(In2Sel
.CONST_SI
): # sign-extended 16-bit
229 si
= Signal(16, reset_less
=True)
230 comb
+= si
.eq(self
.dec
.SI
)
231 comb
+= self
.imm_out
.data
.eq(exts(si
, 16, 64))
232 comb
+= self
.imm_out
.ok
.eq(1)
233 with m
.Case(In2Sel
.CONST_SI_HI
): # sign-extended 16+16=32 bit
234 si_hi
= Signal(32, reset_less
=True)
235 comb
+= si_hi
.eq(self
.dec
.SI
<< 16)
236 comb
+= self
.imm_out
.data
.eq(exts(si_hi
, 32, 64))
237 comb
+= self
.imm_out
.ok
.eq(1)
238 with m
.Case(In2Sel
.CONST_UI_HI
): # unsigned
239 ui
= Signal(16, reset_less
=True)
240 comb
+= ui
.eq(self
.dec
.UI
)
241 comb
+= self
.imm_out
.data
.eq(ui
<< 16)
242 comb
+= self
.imm_out
.ok
.eq(1)
243 with m
.Case(In2Sel
.CONST_LI
): # sign-extend 24+2=26 bit
244 li
= Signal(26, reset_less
=True)
245 comb
+= li
.eq(self
.dec
.LI
<< 2)
246 comb
+= self
.imm_out
.data
.eq(exts(li
, 26, 64))
247 comb
+= self
.imm_out
.ok
.eq(1)
248 with m
.Case(In2Sel
.CONST_BD
): # sign-extend (14+2)=16 bit
249 bd
= Signal(16, reset_less
=True)
250 comb
+= bd
.eq(self
.dec
.BD
<< 2)
251 comb
+= self
.imm_out
.data
.eq(exts(bd
, 16, 64))
252 comb
+= self
.imm_out
.ok
.eq(1)
253 with m
.Case(In2Sel
.CONST_DS
): # sign-extended (14+2=16) bit
254 ds
= Signal(16, reset_less
=True)
255 comb
+= ds
.eq(self
.dec
.DS
<< 2)
256 comb
+= self
.imm_out
.data
.eq(exts(ds
, 16, 64))
257 comb
+= self
.imm_out
.ok
.eq(1)
258 with m
.Case(In2Sel
.CONST_M1
): # signed (-1)
259 comb
+= self
.imm_out
.data
.eq(~
Const(0, 64)) # all 1s
260 comb
+= self
.imm_out
.ok
.eq(1)
261 with m
.Case(In2Sel
.CONST_SH
): # unsigned - for shift
262 comb
+= self
.imm_out
.data
.eq(self
.dec
.sh
)
263 comb
+= self
.imm_out
.ok
.eq(1)
264 with m
.Case(In2Sel
.CONST_SH32
): # unsigned - for shift
265 comb
+= self
.imm_out
.data
.eq(self
.dec
.SH32
)
266 comb
+= self
.imm_out
.ok
.eq(1)
271 class DecodeC(Elaboratable
):
272 """DecodeC from instruction
274 decodes register RC. this is "lane 3" into some CompUnits (not many)
277 def __init__(self
, dec
):
279 self
.sel_in
= Signal(In3Sel
, reset_less
=True)
280 self
.insn_in
= Signal(32, reset_less
=True)
281 self
.reg_out
= Data(5, "reg_c")
283 def elaborate(self
, platform
):
287 # select Register C field
288 with m
.Switch(self
.sel_in
):
289 with m
.Case(In3Sel
.RB
):
290 # for M-Form shiftrot
291 comb
+= self
.reg_out
.data
.eq(self
.dec
.RB
)
292 comb
+= self
.reg_out
.ok
.eq(1)
293 with m
.Case(In3Sel
.RS
):
294 comb
+= self
.reg_out
.data
.eq(self
.dec
.RS
)
295 comb
+= self
.reg_out
.ok
.eq(1)
300 class DecodeOut(Elaboratable
):
301 """DecodeOut from instruction
303 decodes output register RA, RT or SPR
306 def __init__(self
, dec
):
308 self
.sel_in
= Signal(OutSel
, reset_less
=True)
309 self
.insn_in
= Signal(32, reset_less
=True)
310 self
.reg_out
= Data(5, "reg_o")
311 self
.spr_out
= Data(SPR
, "spr_o")
312 self
.fast_out
= Data(3, "fast_o")
314 def elaborate(self
, platform
):
317 m
.submodules
.sprmap
= sprmap
= SPRMap()
320 # select Register out field
321 with m
.Switch(self
.sel_in
):
322 with m
.Case(OutSel
.RT
):
323 comb
+= self
.reg_out
.data
.eq(self
.dec
.RT
)
324 comb
+= self
.reg_out
.ok
.eq(1)
325 with m
.Case(OutSel
.RA
):
326 comb
+= self
.reg_out
.data
.eq(self
.dec
.RA
)
327 comb
+= self
.reg_out
.ok
.eq(1)
328 with m
.Case(OutSel
.SPR
):
329 spr
= Signal(10, reset_less
=True)
330 comb
+= spr
.eq(decode_spr_num(self
.dec
.SPR
)) # from XFX
331 # MFSPR move to SPRs - needs mapping
332 with m
.If(op
.internal_op
== MicrOp
.OP_MTSPR
):
333 comb
+= sprmap
.spr_i
.eq(spr
)
334 comb
+= self
.spr_out
.eq(sprmap
.spr_o
)
335 comb
+= self
.fast_out
.eq(sprmap
.fast_o
)
337 with m
.Switch(op
.internal_op
):
339 # BC or BCREG: implicit register (CTR) NOTE: same in DecodeA
340 with m
.Case(MicrOp
.OP_BC
, MicrOp
.OP_BCREG
):
341 with m
.If(~self
.dec
.BO
[2]): # 3.0B p38 BO2=0, use CTR reg
343 comb
+= self
.fast_out
.data
.eq(FastRegs
.CTR
)
344 comb
+= self
.fast_out
.ok
.eq(1)
346 # RFID 1st spr (fast)
347 with m
.Case(MicrOp
.OP_RFID
):
348 comb
+= self
.fast_out
.data
.eq(FastRegs
.SRR0
) # constant: SRR0
349 comb
+= self
.fast_out
.ok
.eq(1)
354 class DecodeOut2(Elaboratable
):
355 """DecodeOut2 from instruction
357 decodes output registers
360 def __init__(self
, dec
):
362 self
.sel_in
= Signal(OutSel
, reset_less
=True)
363 self
.lk
= Signal(reset_less
=True)
364 self
.insn_in
= Signal(32, reset_less
=True)
365 self
.reg_out
= Data(5, "reg_o")
366 self
.fast_out
= Data(3, "fast_o")
368 def elaborate(self
, platform
):
372 # update mode LD/ST uses read-reg A also as an output
373 with m
.If(self
.dec
.op
.upd
== LDSTMode
.update
):
374 comb
+= self
.reg_out
.eq(self
.dec
.RA
)
375 comb
+= self
.reg_out
.ok
.eq(1)
377 # B, BC or BCREG: potential implicit register (LR) output
378 # these give bl, bcl, bclrl, etc.
380 with m
.Switch(op
.internal_op
):
382 # BC* implicit register (LR)
383 with m
.Case(MicrOp
.OP_BC
, MicrOp
.OP_B
, MicrOp
.OP_BCREG
):
384 with m
.If(self
.lk
): # "link" mode
385 comb
+= self
.fast_out
.data
.eq(FastRegs
.LR
) # constant: LR
386 comb
+= self
.fast_out
.ok
.eq(1)
388 # RFID 2nd spr (fast)
389 with m
.Case(MicrOp
.OP_RFID
):
390 comb
+= self
.fast_out
.data
.eq(FastRegs
.SRR1
) # constant: SRR1
391 comb
+= self
.fast_out
.ok
.eq(1)
396 class DecodeRC(Elaboratable
):
397 """DecodeRc from instruction
399 decodes Record bit Rc
402 def __init__(self
, dec
):
404 self
.sel_in
= Signal(RC
, reset_less
=True)
405 self
.insn_in
= Signal(32, reset_less
=True)
406 self
.rc_out
= Data(1, "rc")
408 def elaborate(self
, platform
):
412 # select Record bit out field
413 with m
.Switch(self
.sel_in
):
415 comb
+= self
.rc_out
.data
.eq(self
.dec
.Rc
)
416 comb
+= self
.rc_out
.ok
.eq(1)
418 comb
+= self
.rc_out
.data
.eq(1)
419 comb
+= self
.rc_out
.ok
.eq(1)
420 with m
.Case(RC
.NONE
):
421 comb
+= self
.rc_out
.data
.eq(0)
422 comb
+= self
.rc_out
.ok
.eq(1)
427 class DecodeOE(Elaboratable
):
428 """DecodeOE from instruction
430 decodes OE field: uses RC decode detection which might not be good
432 -- For now, use "rc" in the decode table to decide whether oe exists.
433 -- This is not entirely correct architecturally: For mulhd and
434 -- mulhdu, the OE field is reserved. It remains to be seen what an
435 -- actual POWER9 does if we set it on those instructions, for now we
436 -- test that further down when assigning to the multiplier oe input.
439 def __init__(self
, dec
):
441 self
.sel_in
= Signal(RC
, reset_less
=True)
442 self
.insn_in
= Signal(32, reset_less
=True)
443 self
.oe_out
= Data(1, "oe")
445 def elaborate(self
, platform
):
450 with m
.Switch(op
.internal_op
):
452 # mulhw, mulhwu, mulhd, mulhdu - these *ignore* OE
454 # XXX ARGH! ignoring OE causes incompatibility with microwatt
455 # http://lists.libre-soc.org/pipermail/libre-soc-dev/2020-August/000302.html
456 with m
.Case(MicrOp
.OP_MUL_H64
, MicrOp
.OP_MUL_H32
,
457 MicrOp
.OP_EXTS
, MicrOp
.OP_CNTZ
,
458 MicrOp
.OP_SHL
, MicrOp
.OP_SHR
, MicrOp
.OP_RLC
,
459 MicrOp
.OP_LOAD
, MicrOp
.OP_STORE
,
460 MicrOp
.OP_RLCL
, MicrOp
.OP_RLCR
,
464 # all other ops decode OE field
466 # select OE bit out field
467 with m
.Switch(self
.sel_in
):
469 comb
+= self
.oe_out
.data
.eq(self
.dec
.OE
)
470 comb
+= self
.oe_out
.ok
.eq(1)
475 class DecodeCRIn(Elaboratable
):
476 """Decodes input CR from instruction
478 CR indices - insn fields - (not the data *in* the CR) require only 3
479 bits because they refer to CR0-CR7
482 def __init__(self
, dec
):
484 self
.sel_in
= Signal(CRInSel
, reset_less
=True)
485 self
.insn_in
= Signal(32, reset_less
=True)
486 self
.cr_bitfield
= Data(3, "cr_bitfield")
487 self
.cr_bitfield_b
= Data(3, "cr_bitfield_b")
488 self
.cr_bitfield_o
= Data(3, "cr_bitfield_o")
489 self
.whole_reg
= Data(8, "cr_fxm")
491 def elaborate(self
, platform
):
493 m
.submodules
.ppick
= ppick
= PriorityPicker(8, reverse_i
=True,
499 comb
+= self
.cr_bitfield
.ok
.eq(0)
500 comb
+= self
.cr_bitfield_b
.ok
.eq(0)
501 comb
+= self
.whole_reg
.ok
.eq(0)
502 with m
.Switch(self
.sel_in
):
503 with m
.Case(CRInSel
.NONE
):
504 pass # No bitfield activated
505 with m
.Case(CRInSel
.CR0
):
506 comb
+= self
.cr_bitfield
.data
.eq(0) # CR0 (MSB0 numbering)
507 comb
+= self
.cr_bitfield
.ok
.eq(1)
508 with m
.Case(CRInSel
.BI
):
509 comb
+= self
.cr_bitfield
.data
.eq(self
.dec
.BI
[2:5])
510 comb
+= self
.cr_bitfield
.ok
.eq(1)
511 with m
.Case(CRInSel
.BFA
):
512 comb
+= self
.cr_bitfield
.data
.eq(self
.dec
.FormX
.BFA
)
513 comb
+= self
.cr_bitfield
.ok
.eq(1)
514 with m
.Case(CRInSel
.BA_BB
):
515 comb
+= self
.cr_bitfield
.data
.eq(self
.dec
.BA
[2:5])
516 comb
+= self
.cr_bitfield
.ok
.eq(1)
517 comb
+= self
.cr_bitfield_b
.data
.eq(self
.dec
.BB
[2:5])
518 comb
+= self
.cr_bitfield_b
.ok
.eq(1)
519 comb
+= self
.cr_bitfield_o
.data
.eq(self
.dec
.BT
[2:5])
520 comb
+= self
.cr_bitfield_o
.ok
.eq(1)
521 with m
.Case(CRInSel
.BC
):
522 comb
+= self
.cr_bitfield
.data
.eq(self
.dec
.BC
[2:5])
523 comb
+= self
.cr_bitfield
.ok
.eq(1)
524 with m
.Case(CRInSel
.WHOLE_REG
):
525 comb
+= self
.whole_reg
.ok
.eq(1)
526 move_one
= Signal(reset_less
=True)
527 comb
+= move_one
.eq(self
.insn_in
[20]) # MSB0 bit 11
528 with m
.If((op
.internal_op
== MicrOp
.OP_MFCR
) & move_one
):
529 # must one-hot the FXM field
530 comb
+= ppick
.i
.eq(self
.dec
.FXM
)
531 comb
+= self
.whole_reg
.data
.eq(ppick
.o
)
533 # otherwise use all of it
534 comb
+= self
.whole_reg
.data
.eq(0xff)
539 class DecodeCROut(Elaboratable
):
540 """Decodes input CR from instruction
542 CR indices - insn fields - (not the data *in* the CR) require only 3
543 bits because they refer to CR0-CR7
546 def __init__(self
, dec
):
548 self
.rc_in
= Signal(reset_less
=True)
549 self
.sel_in
= Signal(CROutSel
, reset_less
=True)
550 self
.insn_in
= Signal(32, reset_less
=True)
551 self
.cr_bitfield
= Data(3, "cr_bitfield")
552 self
.whole_reg
= Data(8, "cr_fxm")
554 def elaborate(self
, platform
):
558 m
.submodules
.ppick
= ppick
= PriorityPicker(8, reverse_i
=True,
561 comb
+= self
.cr_bitfield
.ok
.eq(0)
562 comb
+= self
.whole_reg
.ok
.eq(0)
563 with m
.Switch(self
.sel_in
):
564 with m
.Case(CROutSel
.NONE
):
565 pass # No bitfield activated
566 with m
.Case(CROutSel
.CR0
):
567 comb
+= self
.cr_bitfield
.data
.eq(0) # CR0 (MSB0 numbering)
568 comb
+= self
.cr_bitfield
.ok
.eq(self
.rc_in
) # only when RC=1
569 with m
.Case(CROutSel
.BF
):
570 comb
+= self
.cr_bitfield
.data
.eq(self
.dec
.FormX
.BF
)
571 comb
+= self
.cr_bitfield
.ok
.eq(1)
572 with m
.Case(CROutSel
.BT
):
573 comb
+= self
.cr_bitfield
.data
.eq(self
.dec
.FormXL
.BT
[2:5])
574 comb
+= self
.cr_bitfield
.ok
.eq(1)
575 with m
.Case(CROutSel
.WHOLE_REG
):
576 comb
+= self
.whole_reg
.ok
.eq(1)
577 move_one
= Signal(reset_less
=True)
578 comb
+= move_one
.eq(self
.insn_in
[20])
579 with m
.If((op
.internal_op
== MicrOp
.OP_MTCRF
)):
581 # must one-hot the FXM field
582 comb
+= ppick
.i
.eq(self
.dec
.FXM
)
583 with m
.If(ppick
.en_o
):
584 comb
+= self
.whole_reg
.data
.eq(ppick
.o
)
586 comb
+= self
.whole_reg
.data
.eq(0b00000001) # CR7
588 comb
+= self
.whole_reg
.data
.eq(self
.dec
.FXM
)
590 # otherwise use all of it
591 comb
+= self
.whole_reg
.data
.eq(0xff)
596 class PowerDecodeSubset(Elaboratable
):
597 """PowerDecodeSubset: dynamic subset decoder
601 def __init__(self
, dec
, opkls
=None, fn_name
=None, col_subset
=None,
602 final
=False, state
=None):
607 self
.fn_name
= fn_name
608 self
.dec
= create_pdecode(name
=fn_name
, col_subset
=col_subset
,
609 row_subset
=self
.rowsubsetfn
)
613 self
.e
= Decode2ToExecute1Type(name
=self
.fn_name
, opkls
=self
.opkls
)
615 # state information needed by the Decoder
616 if state
is not None:
619 self
.state
= CoreState("dec2")
621 def rowsubsetfn(self
, opcode
, row
):
622 return row
['unit'] == self
.fn_name
625 return self
.dec
.ports() + self
.e
.ports()
627 def needs_field(self
, field
, op_field
):
632 return hasattr(do
, field
) and self
.op_get(op_field
) is not None
634 def do_copy(self
, field
, val
, final
=False):
635 if final
or self
.final
:
639 if hasattr(do
, field
) and val
is not None:
640 return getattr(do
, field
).eq(val
)
643 def op_get(self
, op_field
):
644 return getattr(self
.dec
.op
, op_field
, None)
646 def elaborate(self
, platform
):
650 e_out
, op
, do_out
= self
.e
, self
.dec
.op
, self
.e
.do
651 msr
, cia
= state
.msr
, state
.pc
653 # fill in for a normal instruction (not an exception)
654 # copy over if non-exception, non-privileged etc. is detected
658 if self
.fn_name
is None:
661 name
= self
.fn_name
+ "tmp"
662 self
.e_tmp
= e
= Decode2ToExecute1Type(name
=name
, opkls
=self
.opkls
)
665 # set up submodule decoders
666 m
.submodules
.dec
= self
.dec
667 m
.submodules
.dec_rc
= dec_rc
= DecodeRC(self
.dec
)
668 m
.submodules
.dec_oe
= dec_oe
= DecodeOE(self
.dec
)
669 m
.submodules
.dec_cr_in
= self
.dec_cr_in
= DecodeCRIn(self
.dec
)
670 m
.submodules
.dec_cr_out
= self
.dec_cr_out
= DecodeCROut(self
.dec
)
672 # copy instruction through...
674 dec_rc
.insn_in
, dec_oe
.insn_in
,
675 self
.dec_cr_in
.insn_in
, self
.dec_cr_out
.insn_in
]:
676 comb
+= i
.eq(self
.dec
.opcode_in
)
678 # ...and subdecoders' input fields
679 comb
+= dec_rc
.sel_in
.eq(op
.rc_sel
)
680 comb
+= dec_oe
.sel_in
.eq(op
.rc_sel
) # XXX should be OE sel
681 comb
+= self
.dec_cr_in
.sel_in
.eq(op
.cr_in
)
682 comb
+= self
.dec_cr_out
.sel_in
.eq(op
.cr_out
)
683 comb
+= self
.dec_cr_out
.rc_in
.eq(dec_rc
.rc_out
.data
)
686 comb
+= self
.do_copy("msr", msr
)
687 comb
+= self
.do_copy("cia", cia
)
689 # set up instruction, pick fn unit
690 # no op: defaults to OP_ILLEGAL
691 comb
+= self
.do_copy("insn_type", self
.op_get("internal_op"))
692 comb
+= self
.do_copy("fn_unit", self
.op_get("function_unit"))
695 if self
.needs_field("zero_a", "in1_sel"):
696 m
.submodules
.dec_ai
= dec_ai
= DecodeAImm(self
.dec
)
697 comb
+= dec_ai
.sel_in
.eq(op
.in1_sel
)
698 comb
+= self
.do_copy("zero_a", dec_ai
.immz_out
) # RA==0 detected
699 if self
.needs_field("imm_data", "in2_sel"):
700 m
.submodules
.dec_bi
= dec_bi
= DecodeBImm(self
.dec
)
701 comb
+= dec_bi
.sel_in
.eq(op
.in2_sel
)
702 comb
+= self
.do_copy("imm_data", dec_bi
.imm_out
) # imm in RB
705 comb
+= self
.do_copy("rc", dec_rc
.rc_out
)
706 comb
+= self
.do_copy("oe", dec_oe
.oe_out
)
709 comb
+= self
.do_copy("read_cr_whole", self
.dec_cr_in
.whole_reg
)
710 comb
+= self
.do_copy("write_cr_whole", self
.dec_cr_out
.whole_reg
)
711 comb
+= self
.do_copy("write_cr0", self
.dec_cr_out
.cr_bitfield
.ok
)
713 comb
+= self
.do_copy("input_cr", self
.op_get("cr_in")) # CR in
714 comb
+= self
.do_copy("output_cr", self
.op_get("cr_out")) # CR out
716 # decoded/selected instruction flags
717 comb
+= self
.do_copy("data_len", self
.op_get("ldst_len"))
718 comb
+= self
.do_copy("invert_in", self
.op_get("inv_a"))
719 comb
+= self
.do_copy("invert_out", self
.op_get("inv_out"))
720 comb
+= self
.do_copy("input_carry", self
.op_get("cry_in"))
721 comb
+= self
.do_copy("output_carry", self
.op_get("cry_out"))
722 comb
+= self
.do_copy("is_32bit", self
.op_get("is_32b"))
723 comb
+= self
.do_copy("is_signed", self
.op_get("sgn"))
724 lk
= self
.op_get("lk")
727 comb
+= self
.do_copy("lk", self
.dec
.LK
) # XXX TODO: accessor
729 comb
+= self
.do_copy("byte_reverse", self
.op_get("br"))
730 comb
+= self
.do_copy("sign_extend", self
.op_get("sgn_ext"))
731 comb
+= self
.do_copy("ldst_mode", self
.op_get("upd")) # LD/ST mode
736 class PowerDecode2(PowerDecodeSubset
):
737 """PowerDecode2: the main instruction decoder.
739 whilst PowerDecode is responsible for decoding the actual opcode, this
740 module encapsulates further specialist, sparse information and
741 expansion of fields that is inconvenient to have in the CSV files.
742 for example: the encoding of the immediates, which are detected
743 and expanded out to their full value from an annotated (enum)
746 implicit register usage is also set up, here. for example: OP_BC
747 requires implicitly reading CTR, OP_RFID requires implicitly writing
750 in addition, PowerDecoder2 is responsible for detecting whether
751 instructions are illegal (or privileged) or not, and instead of
752 just leaving at that, *replacing* the instruction to execute with
753 a suitable alternative (trap).
756 def elaborate(self
, platform
):
757 m
= super().elaborate(platform
)
760 e_out
, op
, do_out
= self
.e
, self
.dec
.op
, self
.e
.do
761 dec_spr
, msr
, cia
, ext_irq
= state
.dec
, state
.msr
, state
.pc
, state
.eint
765 # fill in for a normal instruction (not an exception)
766 # copy over if non-exception, non-privileged etc. is detected
768 # set up submodule decoders
769 m
.submodules
.dec_a
= dec_a
= DecodeA(self
.dec
)
770 m
.submodules
.dec_b
= dec_b
= DecodeB(self
.dec
)
771 m
.submodules
.dec_c
= dec_c
= DecodeC(self
.dec
)
772 m
.submodules
.dec_o
= dec_o
= DecodeOut(self
.dec
)
773 m
.submodules
.dec_o2
= dec_o2
= DecodeOut2(self
.dec
)
775 # copy instruction through...
776 for i
in [do
.insn
, dec_a
.insn_in
, dec_b
.insn_in
,
777 dec_c
.insn_in
, dec_o
.insn_in
, dec_o2
.insn_in
]:
778 comb
+= i
.eq(self
.dec
.opcode_in
)
780 # ...and subdecoders' input fields
781 comb
+= dec_a
.sel_in
.eq(op
.in1_sel
)
782 comb
+= dec_b
.sel_in
.eq(op
.in2_sel
)
783 comb
+= dec_c
.sel_in
.eq(op
.in3_sel
)
784 comb
+= dec_o
.sel_in
.eq(op
.out_sel
)
785 comb
+= dec_o2
.sel_in
.eq(op
.out_sel
)
786 if hasattr(do
, "lk"):
787 comb
+= dec_o2
.lk
.eq(do
.lk
)
789 # registers a, b, c and out and out2 (LD/ST EA)
790 comb
+= e
.read_reg1
.eq(dec_a
.reg_out
)
791 comb
+= e
.read_reg2
.eq(dec_b
.reg_out
)
792 comb
+= e
.read_reg3
.eq(dec_c
.reg_out
)
793 comb
+= e
.write_reg
.eq(dec_o
.reg_out
)
794 comb
+= e
.write_ea
.eq(dec_o2
.reg_out
)
797 comb
+= e
.read_spr1
.eq(dec_a
.spr_out
)
798 comb
+= e
.write_spr
.eq(dec_o
.spr_out
)
801 comb
+= e
.read_fast1
.eq(dec_a
.fast_out
)
802 comb
+= e
.read_fast2
.eq(dec_b
.fast_out
)
803 comb
+= e
.write_fast1
.eq(dec_o
.fast_out
)
804 comb
+= e
.write_fast2
.eq(dec_o2
.fast_out
)
806 # condition registers (CR)
807 comb
+= e
.read_cr1
.eq(self
.dec_cr_in
.cr_bitfield
)
808 comb
+= e
.read_cr2
.eq(self
.dec_cr_in
.cr_bitfield_b
)
809 comb
+= e
.read_cr3
.eq(self
.dec_cr_in
.cr_bitfield_o
)
810 comb
+= e
.write_cr
.eq(self
.dec_cr_out
.cr_bitfield
)
812 # sigh this is exactly the sort of thing for which the
813 # decoder is designed to not need. MTSPR, MFSPR and others need
814 # access to the XER bits. however setting e.oe is not appropriate
815 with m
.If(op
.internal_op
== MicrOp
.OP_MFSPR
):
816 comb
+= e
.xer_in
.eq(0b111) # SO, CA, OV
817 with m
.If(op
.internal_op
== MicrOp
.OP_CMP
):
818 comb
+= e
.xer_in
.eq(1<<XERRegs
.SO
) # SO
819 with m
.If(op
.internal_op
== MicrOp
.OP_MTSPR
):
820 comb
+= e
.xer_out
.eq(1)
822 # set the trapaddr to 0x700 for a td/tw/tdi/twi operation
823 with m
.If(op
.internal_op
== MicrOp
.OP_TRAP
):
824 # *DO NOT* call self.trap here. that would reset absolutely
825 # everything including destroying read of RA and RB.
826 comb
+= self
.do_copy("trapaddr", 0x70) # strip first nibble
829 # ok so the instruction's been decoded, blah blah, however
830 # now we need to determine if it's actually going to go ahead...
831 # *or* if in fact it's a privileged operation, whether there's
832 # an external interrupt, etc. etc. this is a simple priority
833 # if-elif-elif sequence. decrement takes highest priority,
834 # EINT next highest, privileged operation third.
836 # check if instruction is privileged
837 is_priv_insn
= instr_is_priv(m
, op
.internal_op
, e
.do
.insn
)
839 # different IRQ conditions
840 ext_irq_ok
= Signal()
841 dec_irq_ok
= Signal()
845 comb
+= ext_irq_ok
.eq(ext_irq
& msr
[MSR
.EE
]) # v3.0B p944 (MSR.EE)
846 comb
+= dec_irq_ok
.eq(dec_spr
[63] & msr
[MSR
.EE
]) # v3.0B 6.5.11 p1076
847 comb
+= priv_ok
.eq(is_priv_insn
& msr
[MSR
.PR
])
848 comb
+= illeg_ok
.eq(op
.internal_op
== MicrOp
.OP_ILLEGAL
)
850 # decrement counter (v3.0B p1099): TODO 32-bit version (MSR.LPCR)
851 with m
.If(dec_irq_ok
):
852 self
.trap(m
, TT
.DEC
, 0x900) # v3.0B 6.5 p1065
854 # external interrupt? only if MSR.EE set
855 with m
.Elif(ext_irq_ok
):
856 self
.trap(m
, TT
.EINT
, 0x500)
858 # privileged instruction trap
859 with m
.Elif(priv_ok
):
860 self
.trap(m
, TT
.PRIV
, 0x700)
862 # illegal instruction must redirect to trap. this is done by
863 # *overwriting* the decoded instruction and starting again.
864 # (note: the same goes for interrupts and for privileged operations,
865 # just with different trapaddr and traptype)
866 with m
.Elif(illeg_ok
):
867 # illegal instruction trap
868 self
.trap(m
, TT
.ILLEG
, 0x700)
870 # no exception, just copy things to the output
875 # follow-up after trap/irq to set up SRR0/1
877 # trap: (note e.insn_type so this includes OP_ILLEGAL) set up fast regs
878 # Note: OP_SC could actually be modified to just be a trap
879 with m
.If((do_out
.insn_type
== MicrOp
.OP_TRAP
) |
880 (do_out
.insn_type
== MicrOp
.OP_SC
)):
881 # TRAP write fast1 = SRR0
882 comb
+= e_out
.write_fast1
.data
.eq(FastRegs
.SRR0
) # constant: SRR0
883 comb
+= e_out
.write_fast1
.ok
.eq(1)
884 # TRAP write fast2 = SRR1
885 comb
+= e_out
.write_fast2
.data
.eq(FastRegs
.SRR1
) # constant: SRR1
886 comb
+= e_out
.write_fast2
.ok
.eq(1)
888 # RFID: needs to read SRR0/1
889 with m
.If(do_out
.insn_type
== MicrOp
.OP_RFID
):
890 # TRAP read fast1 = SRR0
891 comb
+= e_out
.read_fast1
.data
.eq(FastRegs
.SRR0
) # constant: SRR0
892 comb
+= e_out
.read_fast1
.ok
.eq(1)
893 # TRAP read fast2 = SRR1
894 comb
+= e_out
.read_fast2
.data
.eq(FastRegs
.SRR1
) # constant: SRR1
895 comb
+= e_out
.read_fast2
.ok
.eq(1)
899 def trap(self
, m
, traptype
, trapaddr
):
900 """trap: this basically "rewrites" the decoded instruction as a trap
903 op
, e
= self
.dec
.op
, self
.e
904 comb
+= e
.eq(0) # reset eeeeeverything
907 comb
+= self
.do_copy("insn", self
.dec
.opcode_in
, True)
908 comb
+= self
.do_copy("insn_type", MicrOp
.OP_TRAP
, True)
909 comb
+= self
.do_copy("fn_unit", Function
.TRAP
, True)
910 comb
+= self
.do_copy("trapaddr", trapaddr
>> 4, True) # bottom 4 bits
911 comb
+= self
.do_copy("traptype", traptype
, True) # request type
912 comb
+= self
.do_copy("msr", self
.state
.msr
, True) # copy of MSR "state"
913 comb
+= self
.do_copy("cia", self
.state
.pc
, True) # copy of PC "state"
916 def get_rdflags(e
, cu
):
918 for idx
in range(cu
.n_src
):
919 regfile
, regname
, _
= cu
.get_in_spec(idx
)
920 rdflag
, read
= regspec_decode_read(e
, regfile
, regname
)
922 print("rdflags", rdl
)
926 if __name__
== '__main__':
927 pdecode
= create_pdecode()
928 dec2
= PowerDecode2(pdecode
)
929 vl
= rtlil
.convert(dec2
, ports
=dec2
.ports() + pdecode
.ports())
930 with
open("dec2.il", "w") as f
: