+ # one cycle later, msr read arrives. valid only once.
+ with m.If(~msr_read):
+ sync += msr_read.eq(1) # yeah don't read it again
+ sync += cur_state.msr.eq(self.state_r_msr.data_o)
+ with m.If(self.imem.f_busy_o): # zzz...
+ # busy: stay in wait-read
+ comb += self.imem.a_valid_i.eq(1)
+ comb += self.imem.f_valid_i.eq(1)
+ with m.Else():
+ # not busy: instruction fetched
+ f_instr_o = self.imem.f_instr_o
+ if f_instr_o.width == 32:
+ insn = f_instr_o
+ else:
+ insn = f_instr_o.word_select(cur_state.pc[2], 32)
+ # decode the SVP64 prefix, if any
+ comb += svp64.raw_opcode_in.eq(insn)
+ comb += svp64.bigendian.eq(self.core_bigendian_i)
+ # pass the decoded prefix (if any) to PowerDecoder2
+ sync += pdecode2.sv_rm.eq(svp64.svp64_rm)
+ # calculate the address of the following instruction
+ insn_size = Mux(svp64.is_svp64_mode, 8, 4)
+ sync += nia.eq(cur_state.pc + insn_size)
+ with m.If(~svp64.is_svp64_mode):
+ # with no prefix, store the instruction
+ # and hand it directly to the next FSM
+ sync += fetch_insn_o.eq(insn)
+ m.next = "INSN_READY"
+ with m.Else():
+ # fetch the rest of the instruction from memory
+ comb += self.imem.a_pc_i.eq(cur_state.pc + 4)
+ comb += self.imem.a_valid_i.eq(1)
+ comb += self.imem.f_valid_i.eq(1)
+ m.next = "INSN_READ2"
+
+ with m.State("INSN_READ2"):
+ with m.If(self.imem.f_busy_o): # zzz...
+ # busy: stay in wait-read
+ comb += self.imem.a_valid_i.eq(1)
+ comb += self.imem.f_valid_i.eq(1)
+ with m.Else():
+ # not busy: instruction fetched
+ f_instr_o = self.imem.f_instr_o
+ if f_instr_o.width == 32:
+ insn = f_instr_o
+ else:
+ insn = f_instr_o.word_select((cur_state.pc+4)[2], 32)
+ sync += fetch_insn_o.eq(insn)
+ m.next = "INSN_READY"
+
+ with m.State("INSN_READY"):
+ # hand over the instruction, to be decoded
+ comb += fetch_insn_valid_o.eq(1)
+ with m.If(fetch_insn_ready_i):
+ m.next = "IDLE"
+
+ # decode / issue / execute FSM
+ with m.FSM():
+
+ # go fetch the instruction at the current PC
+ # at this point, there is no instruction running, that
+ # could inadvertently update the PC.
+ with m.State("INSN_FETCH"):
+ comb += fetch_pc_valid_i.eq(1)
+ with m.If(fetch_pc_ready_o):
+ m.next = "INSN_WAIT"
+
+ # decode the instruction when it arrives
+ with m.State("INSN_WAIT"):
+ comb += fetch_insn_ready_i.eq(1)
+ with m.If(fetch_insn_valid_o):
+ # decode the instruction
+ # TODO, before issuing new instruction first
+ # check if it's SVP64. (svp64.is_svp64_mode set)
+ # if yes, record the svp64_rm, put that into
+ # pdecode2.sv_rm, then read another 32 bits (INSN_FETCH2?)
+ comb += dec_opcode_i.eq(fetch_insn_o) # actual opcode
+ sync += core.e.eq(pdecode2.e)
+ sync += core.state.eq(cur_state)
+ sync += core.raw_insn_i.eq(dec_opcode_i)
+ sync += core.bigendian_i.eq(self.core_bigendian_i)
+ sync += ilatch.eq(insn) # latch current insn
+ # also drop PC and MSR into decode "state"
+ m.next = "INSN_START" # move to "start"
+
+ # waiting for instruction bus (stays there until not busy)
+ with m.State("INSN_START"):
+ comb += core_ivalid_i.eq(1) # instruction is valid
+ comb += core_issue_i.eq(1) # and issued
+ sync += pc_changed.eq(0)
+
+ m.next = "INSN_ACTIVE" # move to "wait completion"