From ec5b362c3cda195178697192ba5a31643e5c358d Mon Sep 17 00:00:00 2001
From: Julian Blake Kongslie
Date: Mon, 31 Oct 2022 21:23:09 -0700
Subject: Fix FLAGS bit handling by IO model

---
 io/model.cpp | 8 ++++----
 isa/isa.h    | 2 +-
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/io/model.cpp b/io/model.cpp
index fb9f62b..79bc511 100644
--- a/io/model.cpp
+++ b/io/model.cpp
@@ -33,16 +33,16 @@ bool iomodel::interact(std::array<std::uint_fast32_t, NUM_CTLREGS> &ctlregs) {
     if (interrupt)
         ctlregs[FLAGS] |= FLAG_INT_REQUEST;
     else
-        ctlregs[FLAGS] &= !FLAG_INT_REQUEST;
+        ctlregs[FLAGS] &= ~FLAG_INT_REQUEST;
     interrupt = interrupt && (ctlregs[FLAGS] & FLAG_INT_ENABLE);
 
+    if (ctlregs[FLAGS] & FLAG_INT_ENABLE_DELAY)
+        ctlregs[FLAGS] |= FLAG_INT_ENABLE;
+
     if (interrupt) {
         ctlregs[FLAGS_SAVED] = ctlregs[FLAGS];
         ctlregs[FLAGS] = 0;
         ctlregs[HALTED] = 0;
-    } else {
-        if (ctlregs[FLAGS] & FLAG_INT_ENABLE_DELAY)
-            ctlregs[FLAGS] |= FLAG_INT_ENABLE;
     }
 
     return interrupt;
diff --git a/isa/isa.h b/isa/isa.h
index 71f852e..8156c08 100644
--- a/isa/isa.h
+++ b/isa/isa.h
@@ -36,7 +36,7 @@ static constexpr std::uint_fast32_t FLAG_INT_ENABLE = 1 << 7;
 static constexpr std::uint_fast32_t FLAG_INT_INHIBIT = 1 << 8;
 static constexpr std::uint_fast32_t FLAG_INT_REQUEST = 1 << 9;
 static constexpr std::uint_fast32_t FLAG_GREATER_THAN = 1 << 10;
-static constexpr std::uint_fast32_t FLAG_INT_ENABLE_DELAY = 1 << 12;
+static constexpr std::uint_fast32_t FLAG_INT_ENABLE_DELAY = 1 << 12;    // n.b. this is not a "visible" flag
 
 // TT_BITS
 static constexpr std::uint_fast32_t TTI_FLAG = 1 << 0;
-- 
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