From da2682d49fc60e22bf8c3ea21947ace339967e68 Mon Sep 17 00:00:00 2001
From: Julian Blake Kongslie
Date: Sat, 5 Nov 2022 12:53:07 -0700
Subject: Implement RMF instruction

---
 isa/decode.cpp | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/isa/decode.cpp b/isa/decode.cpp
index 6ea3bb5..6ab90fd 100644
--- a/isa/decode.cpp
+++ b/isa/decode.cpp
@@ -6,13 +6,17 @@
 
 instruction_context decode(std::uint_fast32_t flags, unsigned int pc, unsigned int bits, bool interrupt)
 {
-    //bool gt = (flags >> 10) & 1;
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-variable"
+    bool ied = (flags >> 12) & 1;
+    bool gt = (flags >> 10) & 1;
     bool ir = (flags >> 9) & 1;
-    //bool ii = (flags >> 8) & 1;
+    bool ii = (flags >> 8) & 1;
     bool ie = (flags >> 7) & 1;
-    //bool u = (flags >> 6) & 1;
+    bool u = (flags >> 6) & 1;
     bool ifb = (flags >> 3) & 7;
     bool df = flags & 7;
+#pragma GCC diagnostic pop
 
     instruction_context inst;
     inst.next_pc = (pc & ~07777) | ((pc + 1) & 07777);
@@ -283,6 +287,15 @@ instruction_context decode(std::uint_fast32_t flags, unsigned int pc, unsigned i
                                     ctx.ctlval = (flags & ~FLAG_DF) | (field << FLAG_DF_SHIFT);
                                 };
                                 break;
+                            case 04:
+                                // RMF restore memory field
+                                inst.read_ctlreg = FLAGS_SAVED;
+                                inst.write_ctlreg = FLAGS;
+                                inst.ef = [flags](auto &ctx) {
+                                    ctx.ctlval.value() &= FLAG_DF | FLAG_IF | FLAG_USER_MODE;
+                                    ctx.ctlval.value() |= flags & ~(FLAG_DF | FLAG_IF | FLAG_USER_MODE);
+                                };
+                                break;
                             default:
                                 inst.ef = [bits, field](auto &ctx) {
                                     std::cerr << "unimplemented IOT MEMORY suboperation " << (bits & 07) << " upon field " << field << "\n";
-- 
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