From 516352a6c0904b1c2dd62bd0a5a5efce1e678710 Mon Sep 17 00:00:00 2001
From: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Date: Fri, 26 Feb 2021 13:40:22 +0000
Subject: [PATCH] moving new_svstate and update_svstate into issue FSM
 TestIssuer

---
 src/soc/simple/issuer.py | 22 +++++++++++++---------
 1 file changed, 13 insertions(+), 9 deletions(-)

diff --git a/src/soc/simple/issuer.py b/src/soc/simple/issuer.py
index 6d1bcf7d..5998feed 100644
--- a/src/soc/simple/issuer.py
+++ b/src/soc/simple/issuer.py
@@ -286,6 +286,11 @@ class TestIssuerInternal(Elaboratable):
         # temporaries
         dec_opcode_i = pdecode2.dec.raw_opcode_in # raw opcode
 
+        # for updating svstate (things like srcstep etc.)
+        update_svstate = Signal() # set this (below) if updating
+        new_svstate = SVSTATERec("new_svstate")
+        comb += new_svstate.eq(cur_state.svstate)
+
         with m.FSM(name="issue_fsm"):
 
             # go fetch the instruction at the current PC
@@ -319,7 +324,8 @@ class TestIssuerInternal(Elaboratable):
             with m.State("EXECUTE_WAIT"):
                 comb += exec_pc_ready_i.eq(1)
                 with m.If(exec_pc_valid_o):
-                    # TODO: update SRCSTEP here
+                    # TODO: update SRCSTEP here (in new_svstate)
+                    #       and set update_svstate to True.
                     # TODO: loop into INSN_EXECUTE if it's a vector instruction
                     #       and SRCSTEP != VL-1 and PowerDecoder.no_out_vec
                     #       is True
@@ -327,6 +333,12 @@ class TestIssuerInternal(Elaboratable):
                     #       go back to INSN_FETCH.
                     m.next = "INSN_FETCH"
 
+        # check if svstate needs updating: if so, write it to State Regfile
+        with m.If(update_svstate):
+            comb += self.state_w_sv.wen.eq(1<<StateRegs.SVSTATE)
+            comb += self.state_w_sv.data_i.eq(new_svstate)
+            sync += cur_state.svstate.eq(new_svstate) # for next clock
+
     def execute_fsm(self, m, core, insn_done, pc_changed, sv_changed,
                     exec_insn_valid_i, exec_insn_ready_o,
                     exec_pc_valid_o, exec_pc_ready_i):
@@ -532,14 +544,6 @@ class TestIssuerInternal(Elaboratable):
                          exec_insn_valid_i, exec_insn_ready_o,
                          exec_pc_ready_i, exec_pc_valid_o)
 
-        # for updating svstate (things like srcstep etc.)
-        update_svstate = Signal() # TODO: move this somewhere above
-        new_svstate = SVSTATERec("new_svstate") # and move this as well
-        # check if svstate needs updating: if so, write it to State Regfile
-        with m.If(update_svstate):
-            comb += self.state_w_sv.wen.eq(1<<StateRegs.SVSTATE)
-            comb += self.state_w_sv.data_i.eq(new_svstate)
-
         # this bit doesn't have to be in the FSM: connect up to read
         # regfiles on demand from DMI
         with m.If(d_reg.req): # request for regfile access being made
-- 
2.30.2