3 * Copyright 2018 Jacob Lifshay
5 * Permission is hereby granted, free of charge, to any person obtaining a copy
6 * of this software and associated documentation files (the "Software"), to deal
7 * in the Software without restriction, including without limitation the rights
8 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
9 * copies of the Software, and to permit persons to whom the Software is
10 * furnished to do so, subject to the following conditions:
12 * The above copyright notice and this permission notice shall be included in all
13 * copies or substantial portions of the Software.
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
18 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
31 from migen
.fhdl
import verilog
32 from migen
.fhdl
.structure
import _Operator
34 from riscvdefs
import *
37 class MemoryInterface
:
38 fetch_address
= Signal(32, name
="memory_interface_fetch_address") # XXX [2:]
39 fetch_data
= Signal(32, name
="memory_interface_fetch_data")
40 fetch_valid
= Signal(name
="memory_interface_fetch_valid")
41 rw_address
= Signal(32, name
="memory_interface_rw_address") # XXX [2:]
42 rw_byte_mask
= Signal(4, name
="memory_interface_rw_byte_mask")
43 rw_read_not_write
= Signal(name
="memory_interface_rw_read_not_write")
44 rw_active
= Signal(name
="memory_interface_rw_active")
45 rw_data_in
= Signal(32, name
="memory_interface_rw_data_in")
46 rw_data_out
= Signal(32, name
="memory_interface_rw_data_out")
47 rw_address_valid
= Signal(name
="memory_interface_rw_address_valid")
48 rw_wait
= Signal(name
="memory_interface_rw_wait")
52 funct7
= Signal(7, name
="decoder_funct7")
53 funct3
= Signal(3, name
="decoder_funct3")
54 rd
= Signal(5, name
="decoder_rd")
55 rs1
= Signal(5, name
="decoder_rs1")
56 rs2
= Signal(5, name
="decoder_rs2")
57 immediate
= Signal(32, name
="decoder_immediate")
58 opcode
= Signal(7, name
="decoder_opcode")
59 act
= Signal(decode_action
, name
="decoder_action")
62 def __init__(self
, comb
, sync
):
65 self
.mpie
= Signal(name
="mstatus_mpie")
66 self
.mie
= Signal(name
="mstatus_mie")
67 self
.mprv
= Signal(name
="mstatus_mprv")
68 self
.tsr
= Signal(name
="mstatus_tsr")
69 self
.tw
= Signal(name
="mstatus_tw")
70 self
.tvm
= Signal(name
="mstatus_tvm")
71 self
.mxr
= Signal(name
="mstatus_mxr")
72 self
._sum
= Signal(name
="mstatus_sum")
73 self
.xs
= Signal(name
="mstatus_xs")
74 self
.fs
= Signal(name
="mstatus_fs")
75 self
.mpp
= Signal(2, name
="mstatus_mpp")
76 self
.spp
= Signal(name
="mstatus_spp")
77 self
.spie
= Signal(name
="mstatus_spie")
78 self
.upie
= Signal(name
="mstatus_upie")
79 self
.sie
= Signal(name
="mstatus_sie")
80 self
.uie
= Signal(name
="mstatus_uie")
83 if n
in ['make', 'mpp', 'comb', 'sync'] or n
.startswith("_"):
85 self
.comb
+= getattr(self
, n
).eq(0x0)
86 self
.comb
+= self
.mpp
.eq(0b11)
88 self
.sync
+= self
.mie
.eq(0)
89 self
.sync
+= self
.mpie
.eq(0)
93 self
.uie
, self
.sie
, Constant(0), self
.mie
,
94 self
.upie
, self
.spie
, Constant(0), self
.mpie
,
95 self
.spp
, Constant(0, 2), self
.mpp
,
96 self
.fs
, self
.xs
, self
.mprv
, self
._sum
,
97 self
.mxr
, self
.tvm
, self
.tw
, self
.tsr
,
99 (self
.xs
== Constant(0b11, 2)) |
(self
.fs
== Constant(0b11, 2))
104 def __init__(self
, comb
, sync
):
107 self
.meie
= Signal(name
="mie_meie")
108 self
.mtie
= Signal(name
="mie_mtie")
109 self
.msie
= Signal(name
="mie_msie")
110 self
.ueie
= Signal(name
="mie_ueie")
111 self
.stie
= Signal(name
="mie_stie")
112 self
.utie
= Signal(name
="mie_utie")
113 self
.ssie
= Signal(name
="mie_ssie")
114 self
.usie
= Signal(name
="mie_usie")
117 if n
in ['make', 'comb', 'sync'] or n
.startswith("_"):
119 self
.comb
+= getattr(self
, n
).eq(0x0)
121 self
.sync
+= self
.meie
.eq(0)
122 self
.sync
+= self
.mtie
.eq(0)
123 self
.sync
+= self
.msie
.eq(0)
126 def __init__(self
, comb
, sync
):
129 self
.meip
= Signal(name
="mip_meip") # TODO: implement ext interrupts
130 self
.seip
= Signal(name
="mip_seip")
131 self
.ueip
= Signal(name
="mip_uiep")
132 self
.mtip
= Signal(name
="mip_mtip") # TODO: implement timer interrupts
133 self
.stip
= Signal(name
="mip_stip")
134 self
.msip
= Signal(name
="mip_stip")
135 self
.utip
= Signal(name
="mip_utip")
136 self
.ssip
= Signal(name
="mip_ssip")
137 self
.usip
= Signal(name
="mip_usip")
140 if n
in ['comb', 'sync'] or n
.startswith("_"):
142 self
.comb
+= getattr(self
, n
).eq(0x0)
146 def __init__(self
, comb
, sync
):
149 self
.mcause
= Signal(32)
150 self
.mepc
= Signal(32)
151 self
.mscratch
= Signal(32)
152 self
.sync
+= self
.mcause
.eq(0)
153 self
.sync
+= self
.mepc
.eq(0) # 32'hXXXXXXXX;
154 self
.sync
+= self
.mscratch
.eq(0) # 32'hXXXXXXXX;
158 def __init__(self
, comb
, sync
):
161 self
.misa
= Signal(32)
163 for l
in list(string
.ascii_lowercase
):
164 value
= 1 if l
== 'i' else 0
165 cl
.append(Constant(value
))
166 cl
.append(Constant(0, 4))
167 cl
.append(Constant(0b01, 2))
168 self
.comb
+= self
.misa
.eq(Cat(cl
))
172 def __init__(self
, comb
, sync
):
175 self
.action
= Signal(fetch_action
, name
="fetch_action")
176 self
.target_pc
= Signal(32, name
="fetch_target_pc")
177 self
.output_pc
= Signal(32, name
="fetch_output_pc")
178 self
.output_instruction
= Signal(32, name
="fetch_ouutput_instruction")
179 self
.output_state
= Signal(fetch_output_state
,name
="fetch_output_state")
181 def get_fetch_action(self
, dc
, load_store_misaligned
, mi
,
182 branch_taken
, misaligned_jump_target
,
185 c
["default"] = self
.action
.eq(FA
.default
) # XXX should be 32'XXXXXXXX?
186 c
[FOS
.empty
] = self
.action
.eq(FA
.default
)
187 c
[FOS
.trap
] = self
.action
.eq(FA
.ack_trap
)
189 # illegal instruction -> error trap
190 i
= If((dc
.act
& DA
.trap_illegal_instruction
) != 0,
191 self
.action
.eq(FA
.error_trap
)
194 # ecall / ebreak -> noerror trap
195 i
= i
.Elif((dc
.act
& DA
.trap_ecall_ebreak
) != 0,
196 self
.action
.eq(FA
.noerror_trap
))
198 # load/store: check alignment, check wait
199 i
= i
.Elif((dc
.act
& (DA
.load | DA
.store
)) != 0,
200 If((load_store_misaligned | ~mi
.rw_address_valid
),
201 self
.action
.eq(FA
.error_trap
) # misaligned or invalid addr
203 self
.action
.eq(FA
.wait
) # wait
205 self
.action
.eq(FA
.default
) # ok
210 i
= i
.Elif((dc
.act
& DA
.fence
) != 0,
211 self
.action
.eq(FA
.fence
))
213 # branch -> misaligned=error, otherwise jump
214 i
= i
.Elif((dc
.act
& DA
.branch
) != 0,
215 If(misaligned_jump_target
,
216 self
.action
.eq(FA
.error_trap
)
218 self
.action
.eq(FA
.jump
)
222 # jal/jalr -> misaligned=error, otherwise jump
223 i
= i
.Elif((dc
.act
& (DA
.jal | DA
.jalr
)) != 0,
224 If(misaligned_jump_target
,
225 self
.action
.eq(FA
.error_trap
)
227 self
.action
.eq(FA
.jump
)
231 # csr -> opvalid=ok, else error trap
232 i
= i
.Elif((dc
.act
& DA
.csr
) != 0,
234 self
.action
.eq(FA
.default
)
236 self
.action
.eq(FA
.error_trap
)
242 return Case(self
.output_state
, c
)
245 def __init__(self
, comb
, sync
, dc
, register_rs1
):
248 self
.number
= Signal(12, name
="csr_number")
249 self
.input_value
= Signal(32, name
="csr_input_value")
250 self
.reads
= Signal(name
="csr_reads")
251 self
.writes
= Signal(name
="csr_writes")
252 self
.op_is_valid
= Signal(name
="csr_op_is_valid")
254 self
.comb
+= self
.number
.eq(dc
.immediate
)
255 self
.comb
+= self
.input_value
.eq(Mux(dc
.funct3
[2],
258 self
.comb
+= self
.reads
.eq(dc
.funct3
[1] |
(dc
.rd
!= 0))
259 self
.comb
+= self
.writes
.eq(~dc
.funct3
[1] |
(dc
.rs1
!= 0))
261 self
.comb
+= self
.get_csr_op_is_valid()
263 def get_csr_op_is_valid(self
):
264 """ determines if a CSR is valid
268 for f
in [csr_ustatus
, csr_fflags
, csr_frm
, csr_fcsr
,
269 csr_uie
, csr_utvec
, csr_uscratch
, csr_uepc
,
270 csr_ucause
, csr_utval
, csr_uip
, csr_sstatus
,
271 csr_sedeleg
, csr_sideleg
, csr_sie
, csr_stvec
,
272 csr_scounteren
, csr_sscratch
, csr_sepc
, csr_scause
,
273 csr_stval
, csr_sip
, csr_satp
, csr_medeleg
,
274 csr_mideleg
, csr_dcsr
, csr_dpc
, csr_dscratch
]:
275 c
[f
] = self
.op_is_valid
.eq(0)
277 # not-writeable -> ok
278 for f
in [csr_cycle
, csr_time
, csr_instret
, csr_cycleh
,
279 csr_timeh
, csr_instreth
, csr_mvendorid
, csr_marchid
,
280 csr_mimpid
, csr_mhartid
]:
281 c
[f
] = self
.op_is_valid
.eq(~self
.writes
)
284 for f
in [csr_misa
, csr_mstatus
, csr_mie
, csr_mtvec
,
285 csr_mscratch
, csr_mepc
, csr_mcause
, csr_mip
]:
286 c
[f
] = self
.op_is_valid
.eq(1)
288 # not implemented / default
289 for f
in [csr_mcounteren
, csr_mtval
, csr_mcycle
, csr_minstret
,
290 csr_mcycleh
, csr_minstreth
, "default"]:
291 c
[f
] = self
.op_is_valid
.eq(0)
293 return Case(self
.number
, c
)
295 def evaluate_csr_funct3_op(self
, funct3
, previous_value
, written_value
):
296 c
= { "default": Constant(0, 32)}
297 for f
in [F3
.csrrw
, F3
.csrrwi
]: c
[f
] = written_value
298 for f
in [F3
.csrrs
, F3
.csrrsi
]: c
[f
] = written_value | previous_value
299 for f
in [F3
.csrrc
, F3
.csrrci
]: c
[f
] = ~written_value
& previous_value
300 return Case(funct3
, c
)
304 def __init__(self
, comb
):
307 self
.cycle_counter
= Signal(64); # TODO: implement cycle_counter
308 self
.time_counter
= Signal(64); # TODO: implement time_counter
309 self
.instret_counter
= Signal(64); # TODO: implement instret_counter
311 self
.mvendorid
= Signal(32)
312 self
.marchid
= Signal(32)
313 self
.mimpid
= Signal(32)
314 self
.mhartid
= Signal(32)
315 self
.comb
+= self
.mvendorid
.eq(Constant(0, 32))
316 self
.comb
+= self
.marchid
.eq(Constant(0, 32))
317 self
.comb
+= self
.mimpid
.eq(Constant(0, 32))
318 self
.comb
+= self
.mhartid
.eq(Constant(0, 32))
325 def get_ls_misaligned(self
, ls
, funct3
, load_store_address_low_2
):
326 """ returns whether a load/store is misaligned
328 return Case(funct3
[:2],
329 { F3
.sb
: ls
.eq(Constant(0)),
330 F3
.sh
: ls
.eq(load_store_address_low_2
[0] != 0),
331 F3
.sw
: ls
.eq(load_store_address_low_2
[0:2] != Constant(0, 2)),
332 "default": ls
.eq(Constant(1))
335 def get_lsbm(self
, dc
):
336 return Cat(Constant(1),
337 Mux((dc
.funct3
[1] | dc
.funct3
[0]),
338 Constant(1), Constant(0)),
340 Constant(0b11, 2), Constant(0, 2)))
342 # XXX this happens to get done by various self.sync actions
343 #def reset_to_initial(self, m, mstatus, mie, registers):
344 # return [m.mcause.eq(0),
347 def write_register(self
, register_number
, value
):
348 return If(register_number
!= 0,
349 self
.registers
[register_number
].eq(value
)
352 def handle_trap(self
, m
, ms
, ft
, dc
, load_store_misaligned
):
353 s
= [ms
.mpie
.eq(ms
.mie
),
355 m
.mepc
.eq(Mux(ft
.action
== FA
.noerror_trap
,
359 # fetch action ack trap
360 i
= If(ft
.action
== FA
.ack_trap
,
361 m
.mcause
.eq(cause_instruction_access_fault
)
365 i
= i
.Elif((dc
.act
& DA
.trap_ecall_ebreak
) != 0,
366 m
.mcause
.eq(Mux(dc
.immediate
[0],
367 cause_machine_environment_call
,
372 i
= i
.Elif((dc
.act
& DA
.load
) != 0,
373 If(load_store_misaligned
,
374 m
.mcause
.eq(cause_load_address_misaligned
)
376 m
.mcause
.eq(cause_load_access_fault
)
381 i
= i
.Elif((dc
.act
& DA
.store
) != 0,
382 If(load_store_misaligned
,
383 m
.mcause
.eq(cause_store_amo_address_misaligned
)
385 m
.mcause
.eq(cause_store_amo_access_fault
)
389 # jal/jalr -> misaligned=error, otherwise jump
390 i
= i
.Elif((dc
.act
& (DA
.jal | DA
.jalr | DA
.branch
)) != 0,
391 m
.mcause
.eq(cause_instruction_address_misaligned
)
394 # defaults to illegal instruction
395 i
= i
.Else(m
.mcause
.eq(cause_illegal_instruction
))
400 def main_block(self
, minfo
, csr
, mi
, m
, mstatus
, ft
, dc
,
401 load_store_misaligned
,
402 loaded_value
, alu_result
,
406 c
[FOS
.trap
] = self
.handle_trap(m
, mstatus
, ft
, dc
,
407 load_store_misaligned
)
408 c
[FOS
.valid
] = self
.handle_valid(minfo
, csr
, mi
, m
, mstatus
, ft
, dc
,
409 load_store_misaligned
,
413 return Case(ft
.output_state
, c
)
415 def handle_valid(self
, minfo
, csr
, mi
, m
, mstatus
, ft
, dc
,
416 load_store_misaligned
,
417 loaded_value
, alu_result
,
419 # fetch action ack trap
420 i
= If((ft
.action
== FA
.ack_trap
) |
(ft
.action
== FA
.noerror_trap
),
421 self
.handle_trap(m
, mstatus
, ft
, dc
,
422 load_store_misaligned
)
426 i
= i
.Elif((dc
.act
& DA
.load
) != 0,
428 self
.write_register(dc
.rd
, loaded_value
)
433 i
= i
.Elif((dc
.act
& DA
.op_op_imm
) != 0,
434 self
.write_register(dc
.rd
, alu_result
)
438 i
= i
.Elif((dc
.act
& DA
.lui_auipc
) != 0,
439 self
.write_register(dc
.rd
, lui_auipc_result
)
443 i
= i
.Elif((dc
.act
& (DA
.jal | DA
.jalr
)) != 0,
444 self
.write_register(dc
.rd
, ft
.output_pc
+ 4)
447 i
= i
.Elif((dc
.act
& DA
.csr
) != 0,
448 self
.handle_csr(minfo
, mstatus
, dc
, csr
)
451 # fence, store, branch
452 i
= i
.Elif((dc
.act
& (DA
.fence | DA
.fence_i |
453 DA
.store | DA
.branch
)) != 0,
459 def handle_csr(self
, minfo
, mstatus
, dc
, csr
):
460 csr_output_value
= Signal()
461 csr_written_value
= Signal()
464 return Case(csr
.number
, c
)
467 reg [31:0] csr_output_value;
468 reg [31:0] csr_written_value;
469 csr_output_value = 32'hXXXXXXXX;
470 csr_written_value = 32'hXXXXXXXX;
473 csr_output_value = cycle_counter[31:0];
476 csr_output_value = time_counter[31:0];
479 csr_output_value = instret_counter[31:0];
482 csr_output_value = cycle_counter[63:32];
485 csr_output_value = time_counter[63:32];
488 csr_output_value = instret_counter[63:32];
490 `csr_mvendorid: begin
491 csr_output_value = mvendorid;
494 csr_output_value = marchid;
497 csr_output_value = mimpid;
500 csr_output_value = mhartid;
503 csr_output_value = misa;
506 csr_output_value = make_mstatus(mstatus_tsr,
522 csr_written_value = evaluate_csr_funct3_operation(decoder_funct3, csr_output_value, csr_input_value);
524 mstatus_mpie = csr_written_value[7];
525 mstatus_mie = csr_written_value[3];
529 csr_output_value = 0;
530 csr_output_value[11] = mie_meie;
531 csr_output_value[9] = mie_seie;
532 csr_output_value[8] = mie_ueie;
533 csr_output_value[7] = mie_mtie;
534 csr_output_value[5] = mie_stie;
535 csr_output_value[4] = mie_utie;
536 csr_output_value[3] = mie_msie;
537 csr_output_value[1] = mie_ssie;
538 csr_output_value[0] = mie_usie;
539 csr_written_value = evaluate_csr_funct3_operation(decoder_funct3, csr_output_value, csr_input_value);
541 mie_meie = csr_written_value[11];
542 mie_mtie = csr_written_value[7];
543 mie_msie = csr_written_value[3];
547 csr_output_value = mtvec;
550 csr_output_value = mscratch;
551 csr_written_value = evaluate_csr_funct3_operation(decoder_funct3, csr_output_value, csr_input_value);
553 mscratch = csr_written_value;
556 csr_output_value = mepc;
557 csr_written_value = evaluate_csr_funct3_operation(decoder_funct3, csr_output_value, csr_input_value);
559 mepc = csr_written_value;
562 csr_output_value = mcause;
563 csr_written_value = evaluate_csr_funct3_operation(decoder_funct3, csr_output_value, csr_input_value);
565 mcause = csr_written_value;
568 csr_output_value = 0;
569 csr_output_value[11] = mip_meip;
570 csr_output_value[9] = mip_seip;
571 csr_output_value[8] = mip_ueip;
572 csr_output_value[7] = mip_mtip;
573 csr_output_value[5] = mip_stip;
574 csr_output_value[4] = mip_utip;
575 csr_output_value[3] = mip_msip;
576 csr_output_value[1] = mip_ssip;
577 csr_output_value[0] = mip_usip;
581 write_register(decoder_rd, csr_output_value);
588 self
.clk
= ClockSignal()
589 self
.reset
= ResetSignal()
590 self
.tty_write
= Signal()
591 self
.tty_write_data
= Signal(8)
592 self
.tty_write_busy
= Signal()
593 self
.switch_2
= Signal()
594 self
.switch_3
= Signal()
595 self
.led_1
= Signal()
596 self
.led_3
= Signal()
598 ram_size
= Constant(0x8000)
599 ram_start
= Constant(0x10000, 32)
600 reset_vector
= Signal(32)
603 reset_vector
.eq(ram_start
)
604 mtvec
.eq(ram_start
+ 0x40)
608 r
= Signal(32, name
="register%d" % i
)
610 self
.sync
+= r
.eq(Constant(0, 32))
611 self
.registers
= Array(l
)
613 mi
= MemoryInterface()
615 mii
= Instance("cpu_memory_interface", name
="memory_instance",
616 p_ram_size
= ram_size
,
617 p_ram_start
= ram_start
,
620 i_fetch_address
= mi
.fetch_address
,
621 o_fetch_data
= mi
.fetch_data
,
622 o_fetch_valid
= mi
.fetch_valid
,
623 i_rw_address
= mi
.rw_address
,
624 i_rw_byte_mask
= mi
.rw_byte_mask
,
625 i_rw_read_not_write
= mi
.rw_read_not_write
,
626 i_rw_active
= mi
.rw_active
,
627 i_rw_data_in
= mi
.rw_data_in
,
628 o_rw_data_out
= mi
.rw_data_out
,
629 o_rw_address_valid
= mi
.rw_address_valid
,
630 o_rw_wait
= mi
.rw_wait
,
631 o_tty_write
= self
.tty_write
,
632 o_tty_write_data
= self
.tty_write_data
,
633 i_tty_write_busy
= self
.tty_write_busy
,
634 i_switch_2
= self
.switch_2
,
635 i_switch_3
= self
.switch_3
,
636 o_led_1
= self
.led_1
,
641 ft
= Fetch(self
.comb
, self
.sync
)
643 fs
= Instance("CPUFetchStage", name
="fetch_stage",
646 o_memory_interface_fetch_address
= mi
.fetch_address
,
647 i_memory_interface_fetch_data
= mi
.fetch_data
,
648 i_memory_interface_fetch_valid
= mi
.fetch_valid
,
649 i_fetch_action
= ft
.action
,
650 i_target_pc
= ft
.target_pc
,
651 o_output_pc
= ft
.output_pc
,
652 o_output_instruction
= ft
.output_instruction
,
653 o_output_state
= ft
.output_state
,
654 i_reset_vector
= reset_vector
,
661 cd
= Instance("CPUDecoder", name
="decoder",
662 i_instruction
= ft
.output_instruction
,
663 o_funct7
= dc
.funct7
,
664 o_funct3
= dc
.funct3
,
668 o_immediate
= dc
.immediate
,
669 o_opcode
= dc
.opcode
,
670 o_decode_action
= dc
.act
674 register_rs1
= Signal(32)
675 register_rs2
= Signal(32)
676 self
.comb
+= If(dc
.rs1
== 0,
679 register_rs1
.eq(self
.registers
[dc
.rs1
-1]))
680 self
.comb
+= If(dc
.rs2
== 0,
683 register_rs2
.eq(self
.registers
[dc
.rs2
-1]))
685 load_store_address
= Signal(32)
686 load_store_address_low_2
= Signal(2)
688 self
.comb
+= load_store_address
.eq(dc
.immediate
+ register_rs1
)
689 self
.comb
+= load_store_address_low_2
.eq(
690 dc
.immediate
[:2] + register_rs1
[:2])
692 load_store_misaligned
= Signal()
694 lsa
= self
.get_ls_misaligned(load_store_misaligned
, dc
.funct3
,
695 load_store_address_low_2
)
698 # XXX rwaddr not 31:2 any more
699 self
.comb
+= mi
.rw_address
.eq(load_store_address
[2:])
701 unshifted_load_store_byte_mask
= Signal(4)
703 self
.comb
+= unshifted_load_store_byte_mask
.eq(self
.get_lsbm(dc
))
705 # XXX yuck. this will cause migen simulation to fail
706 # (however conversion to verilog works)
707 self
.comb
+= mi
.rw_byte_mask
.eq(
708 _Operator("<<", [unshifted_load_store_byte_mask
,
709 load_store_address_low_2
]))
712 b3
= Mux(load_store_address_low_2
[1],
713 Mux(load_store_address_low_2
[0], register_rs2
[0:8],
715 Mux(load_store_address_low_2
[0], register_rs2
[16:24],
716 register_rs2
[24:32]))
717 b2
= Mux(load_store_address_low_2
[1], register_rs2
[0:8],
719 b1
= Mux(load_store_address_low_2
[0], register_rs2
[0:8],
721 b0
= register_rs2
[0:8]
723 self
.comb
+= mi
.rw_data_in
.eq(Cat(b0
, b1
, b2
, b3
))
726 unmasked_loaded_value
= Signal(32)
728 b0
= Mux(load_store_address_low_2
[1],
729 Mux(load_store_address_low_2
[0], mi
.rw_data_out
[24:32],
730 mi
.rw_data_out
[16:24]),
731 Mux(load_store_address_low_2
[0], mi
.rw_data_out
[15:8],
732 mi
.rw_data_out
[0:8]))
733 b1
= Mux(load_store_address_low_2
[1], mi
.rw_data_out
[24:31],
734 mi
.rw_data_out
[8:16])
735 b23
= mi
.rw_data_out
[16:32]
737 self
.comb
+= unmasked_loaded_value
.eq(Cat(b0
, b1
, b23
))
740 loaded_value
= Signal(32)
742 b0
= unmasked_loaded_value
[0:8]
743 b1
= Mux(dc
.funct3
[0:2] == 0,
744 Replicate(~dc
.funct3
[2] & unmasked_loaded_value
[7], 8),
745 unmasked_loaded_value
[8:16])
746 b2
= Mux(dc
.funct3
[1] == 0,
747 Replicate(~dc
.funct3
[2] &
748 Mux(dc
.funct3
[0], unmasked_loaded_value
[15],
749 unmasked_loaded_value
[7]),
751 unmasked_loaded_value
[16:32])
753 self
.comb
+= loaded_value
.eq(Cat(b0
, b1
, b2
))
755 self
.comb
+= mi
.rw_active
.eq(~self
.reset
756 & (ft
.output_state
== FOS
.valid
)
757 & ~load_store_misaligned
758 & ((dc
.act
& (DA
.load | DA
.store
)) != 0))
760 self
.comb
+= mi
.rw_read_not_write
.eq(~dc
.opcode
[5])
765 alu_result
= Signal(32)
767 self
.comb
+= alu_a
.eq(register_rs1
)
768 self
.comb
+= alu_b
.eq(Mux(dc
.opcode
[5],
772 ali
= Instance("cpu_alu", name
="alu",
773 i_funct7
= dc
.funct7
,
774 i_funct3
= dc
.funct3
,
775 i_opcode
= dc
.opcode
,
778 o_result
= alu_result
782 lui_auipc_result
= Signal(32)
783 self
.comb
+= lui_auipc_result
.eq(Mux(dc
.opcode
[5],
785 dc
.immediate
+ ft
.output_pc
))
787 self
.comb
+= ft
.target_pc
.eq(Cat(0,
788 Mux(dc
.opcode
!= OP
.jalr
,
790 register_rs1
[1:32] + dc
.immediate
[1:32])))
792 misaligned_jump_target
= Signal()
793 self
.comb
+= misaligned_jump_target
.eq(ft
.target_pc
[1])
795 branch_arg_a
= Signal(32)
796 branch_arg_b
= Signal(32)
797 self
.comb
+= branch_arg_a
.eq(Cat( register_rs1
[0:31],
798 register_rs1
[31] ^ ~dc
.funct3
[1]))
799 self
.comb
+= branch_arg_b
.eq(Cat( register_rs2
[0:31],
800 register_rs2
[31] ^ ~dc
.funct3
[1]))
802 branch_taken
= Signal()
803 self
.comb
+= branch_taken
.eq(dc
.funct3
[0] ^
805 branch_arg_a
< branch_arg_b
,
806 branch_arg_a
== branch_arg_b
))
808 m
= M(self
.comb
, self
.sync
)
809 mstatus
= MStatus(self
.comb
, self
.sync
)
810 mie
= MIE(self
.comb
, self
.sync
)
811 misa
= Misa(self
.comb
, self
.sync
)
812 mip
= MIP(self
.comb
, self
.sync
)
815 csr
= CSR(self
.comb
, self
.sync
, dc
, register_rs1
)
817 self
.comb
+= ft
.get_fetch_action(dc
, load_store_misaligned
, mi
,
818 branch_taken
, misaligned_jump_target
,
821 minfo
= MInfo(self
.comb
)
823 self
.sync
+= If(~self
.reset
,
824 self
.main_block(minfo
, csr
, mi
, m
, mstatus
, ft
, dc
,
825 load_store_misaligned
,
831 if __name__
== "__main__":
833 print(verilog
.convert(example
,
836 example
.tty_write_data
,
837 example
.tty_write_busy
,
846 always @(posedge clk) begin:main_block
851 case(fetch_output_state)
852 `fetch_output_state_empty: begin
854 `fetch_output_state_trap: begin
857 `fetch_output_state_valid: begin:valid
858 if((fetch_action == `fetch_action_error_trap) | (fetch_action == `fetch_action_noerror_trap)) begin
861 else if((decode_action & `decode_action_load) != 0) begin
862 if(~memory_interface_rw_wait)
863 write_register(decoder_rd, loaded_value);
865 else if((decode_action & `decode_action_op_op_imm) != 0) begin
866 write_register(decoder_rd, alu_result);
868 else if((decode_action & `decode_action_lui_auipc) != 0) begin
869 write_register(decoder_rd, lui_auipc_result);
871 else if((decode_action & (`decode_action_jal | `decode_action_jalr)) != 0) begin
872 write_register(decoder_rd, fetch_output_pc + 4);
874 else if((decode_action & `decode_action_csr) != 0) begin:csr
875 reg [31:0] csr_output_value;
876 reg [31:0] csr_written_value;
877 csr_output_value = 32'hXXXXXXXX;
878 csr_written_value = 32'hXXXXXXXX;
881 csr_output_value = cycle_counter[31:0];
884 csr_output_value = time_counter[31:0];
887 csr_output_value = instret_counter[31:0];
890 csr_output_value = cycle_counter[63:32];
893 csr_output_value = time_counter[63:32];
896 csr_output_value = instret_counter[63:32];
898 `csr_mvendorid: begin
899 csr_output_value = mvendorid;
902 csr_output_value = marchid;
905 csr_output_value = mimpid;
908 csr_output_value = mhartid;
911 csr_output_value = misa;
914 csr_output_value = make_mstatus(mstatus_tsr,
930 csr_written_value = evaluate_csr_funct3_operation(decoder_funct3, csr_output_value, csr_input_value);
932 mstatus_mpie = csr_written_value[7];
933 mstatus_mie = csr_written_value[3];
937 csr_output_value = 0;
938 csr_output_value[11] = mie_meie;
939 csr_output_value[9] = mie_seie;
940 csr_output_value[8] = mie_ueie;
941 csr_output_value[7] = mie_mtie;
942 csr_output_value[5] = mie_stie;
943 csr_output_value[4] = mie_utie;
944 csr_output_value[3] = mie_msie;
945 csr_output_value[1] = mie_ssie;
946 csr_output_value[0] = mie_usie;
947 csr_written_value = evaluate_csr_funct3_operation(decoder_funct3, csr_output_value, csr_input_value);
949 mie_meie = csr_written_value[11];
950 mie_mtie = csr_written_value[7];
951 mie_msie = csr_written_value[3];
955 csr_output_value = mtvec;
958 csr_output_value = mscratch;
959 csr_written_value = evaluate_csr_funct3_operation(decoder_funct3, csr_output_value, csr_input_value);
961 mscratch = csr_written_value;
964 csr_output_value = mepc;
965 csr_written_value = evaluate_csr_funct3_operation(decoder_funct3, csr_output_value, csr_input_value);
967 mepc = csr_written_value;
970 csr_output_value = mcause;
971 csr_written_value = evaluate_csr_funct3_operation(decoder_funct3, csr_output_value, csr_input_value);
973 mcause = csr_written_value;
976 csr_output_value = 0;
977 csr_output_value[11] = mip_meip;
978 csr_output_value[9] = mip_seip;
979 csr_output_value[8] = mip_ueip;
980 csr_output_value[7] = mip_mtip;
981 csr_output_value[5] = mip_stip;
982 csr_output_value[4] = mip_utip;
983 csr_output_value[3] = mip_msip;
984 csr_output_value[1] = mip_ssip;
985 csr_output_value[0] = mip_usip;
989 write_register(decoder_rd, csr_output_value);
991 else if((decode_action & (`decode_action_fence | `decode_action_fence_i | `decode_action_store | `decode_action_branch)) != 0) begin