From ff66523bb076a246c2fc159f0f76947bd6f84fc1 Mon Sep 17 00:00:00 2001
From: Julian Blake Kongslie
Date: Sat, 29 Oct 2022 12:55:08 -0700
Subject: Control register values should not be "unsigned int"

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

(limited to 'isa/decode.cpp')

diff --git a/isa/decode.cpp b/isa/decode.cpp
index 4af9a0d..9563327 100644
--- a/isa/decode.cpp
+++ b/isa/decode.cpp
@@ -140,6 +140,25 @@ instruction_context decode(unsigned int dfifb, unsigned int pc, unsigned int bit
                             break;
                     }
                     break;
+                case 003:
+                    // KEYBOARD
+                    switch (bits & 07) {
+                        case 1:
+                            // KSF skip if TTI flag is set
+                            inst.read_ctlreg = TT_BITS;
+                            inst.possibly_redirects = true;
+                            inst.ef = [](auto &ctx) {
+                                if (ctx.ctlval.value() & TTI_FLAG)
+                                    ctx.next_pc = (ctx.next_pc & ~07777) | ((ctx.next_pc + 1) & 07777);
+                            };
+                            break;
+                        default:
+                            inst.ef = [bits](auto &ctx) {
+                                std::cerr << "unimplemented IOT KB suboperation " << (bits & 07) << "\n";
+                                assert(false);
+                            };
+                    }
+                    break;
                 case 004:
                     // TELETYPE TELEPRINTER/PUNCH
                     switch (bits & 07) {
-- 
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