From a59407a215d6112c2e20b1a746b33742209e5f87 Mon Sep 17 00:00:00 2001
From: Julian Blake Kongslie
Date: Sun, 16 Oct 2022 16:24:49 -0700
Subject: Support for log-based event model

---
 isa/decode.cpp | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

(limited to 'isa/decode.cpp')

diff --git a/isa/decode.cpp b/isa/decode.cpp
index 1979982..d24632b 100644
--- a/isa/decode.cpp
+++ b/isa/decode.cpp
@@ -2,15 +2,21 @@
 
 #include "isa/isa.h"
 
-instruction_context decode(unsigned int dfifb, unsigned int pc, unsigned int bits)
+instruction_context decode(unsigned int dfifb, unsigned int pc, unsigned int bits, bool interrupt)
 {
-    instruction_context inst;
-
     auto df = dfifb >> 3;
     auto ifb = dfifb & 00007;
 
+    instruction_context inst;
     inst.next_pc = (pc & ~07777) | ((pc + 1) & 07777);
 
+    if (interrupt) {
+        bits = 04000;
+        assert(df == 0);
+        assert(ifb == 0);
+        inst.next_pc = pc;
+    }
+
     switch (bits >> 9) {
         case 0: // AND
             inst.need_exec_load = true;
@@ -121,6 +127,8 @@ instruction_context decode(unsigned int dfifb, unsigned int pc, unsigned int bit
                 inst.need_read_acc = sma || sza;
                 inst.need_read_link = snl;
                 inst.need_write_acc = cla;
+                if (hlt)
+                    inst.write_ctlreg = HALTED;
                 inst.possibly_redirects = true;
                 inst.ef = [cla, sma, sza, snl, osr, hlt](auto &ctx) {
                     bool skip = false;
@@ -129,7 +137,7 @@ instruction_context decode(unsigned int dfifb, unsigned int pc, unsigned int bit
                     if (snl && ctx.link.value()) skip = true;
                     if (cla) ctx.acc = 0;
                     assert(!osr);
-                    if (hlt) ctx.halt = true;
+                    if (hlt) ctx.ctlval = 1;
                     if (skip)
                         ctx.next_pc = (ctx.next_pc & 070000) | ((ctx.next_pc + 1) & 007777);
                 };
@@ -143,6 +151,8 @@ instruction_context decode(unsigned int dfifb, unsigned int pc, unsigned int bit
                 inst.need_read_acc = spa || sna;
                 inst.need_read_link = szl;
                 inst.need_write_acc = cla;
+                if (hlt)
+                    inst.write_ctlreg = HALTED;
                 inst.possibly_redirects = true;
                 inst.ef = [cla, spa, sna, szl, osr, hlt](auto &ctx) {
                     bool skip = true;
@@ -151,7 +161,7 @@ instruction_context decode(unsigned int dfifb, unsigned int pc, unsigned int bit
                     if (szl && ctx.link.value()) skip = false;
                     if (cla) ctx.acc = 0;
                     assert(!osr);
-                    if (hlt) ctx.halt = true;
+                    if (hlt) ctx.ctlval = 1;
                     if (skip)
                         ctx.next_pc = (ctx.next_pc & 070000) | ((ctx.next_pc + 1) & 007777);
                 };
-- 
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