From 9f4aa97822adc791f700670ef0fc7636849563b7 Mon Sep 17 00:00:00 2001
From: Julian Blake Kongslie
Date: Sat, 29 Oct 2022 18:18:26 -0700
Subject: Understanding interrupt handling within SIMH (see echo_int.pal)

Add list of Bugs

Add event log file parser

More changes associated with widening the ctlregs (FIXME add a typedef)

Add some keyboard instructions
---
 io/event.h   |  2 +-
 io/model.cpp | 44 +++++++++++++++++++++++++++++++++++++++++---
 io/model.h   |  4 ++++
 3 files changed, 46 insertions(+), 4 deletions(-)

(limited to 'io')

diff --git a/io/event.h b/io/event.h
index 2da3323..e17c333 100644
--- a/io/event.h
+++ b/io/event.h
@@ -9,7 +9,7 @@ struct event {
     ctlreg reg;
     std::uint_fast32_t mask;
     std::uint_fast32_t value;
-    event(ctlreg reg, std::uint_fast32_t value, std::uint_fast32_t mask=~0)
+    event(ctlreg reg, std::uint_fast32_t value, std::uint_fast32_t mask=~(std::uint_fast32_t)0)
         : reg(reg)
         , mask(mask)
         , value(value)
diff --git a/io/model.cpp b/io/model.cpp
index 4b37be4..e9caba0 100644
--- a/io/model.cpp
+++ b/io/model.cpp
@@ -1,4 +1,5 @@
 #include <array>
+#include <cassert>
 #include <cstdint>
 #include <iostream>
 #include <utility>
@@ -17,8 +18,7 @@ bool iomodel::interact(std::array<std::uint_fast32_t, NUM_CTLREGS> &ctlregs) {
     ++time;
 
     if (ctlregs[TT_BITS] & TTO_TX) {
-        // PDP-8 doesn't really have support for 8-bit output, this is Jules' contribution
-        std::cout << (char)(((ctlregs[TT_BITS] & TTO_DATA) >> TTO_DATA_SHIFT) ^ 0x80) << std::flush;
+        std::cout << (char)(((ctlregs[TT_BITS] & TTO_DATA) >> TTO_DATA_SHIFT) & 0x7f) << std::flush;
         ctlregs[TT_BITS] &= ~TTO_TX & ~TTO_DATA;
         log.emplace(time + TT_OUTPUT_DELAY, event(TT_BITS, TTO_FLAG, 0));
     }
@@ -46,4 +46,42 @@ bool iomodel::interact(std::array<std::uint_fast32_t, NUM_CTLREGS> &ctlregs) {
     }
 
     return interrupt;
-};
+}
+
+void iomodel::load_evt(std::istream &fh) {
+    // File format:
+    //  +time                   advances time by relative increment
+    //  regname=value/mask      adds event that sets regname = (regname & ~mask) | value
+    //  regname=value           adds event that sets regname = value
+    // FIXME: add assertions
+    // FIXME: add DMA
+    for (std::string line; std::getline(fh, line); ) {
+        if (line.size() == 0)
+            continue;
+        if (line[0] == '+') {
+            char *end = nullptr;
+            auto step = std::strtoull(line.c_str(), &end, 0);
+            assert(end && *end == '\0');
+            load_time += step;
+        } else {
+            auto eqpos = line.find('=');
+            assert(eqpos != std::string::npos);
+            auto regname = line.substr(0, eqpos);
+            ctlreg reg = ctlreg_map.at(regname);
+            std::uint_fast32_t value, mask;
+            auto slashpos = line.find('/', eqpos);
+            auto valuestr = line.substr(eqpos + 1, slashpos - (eqpos + 1));
+            char *end = nullptr;
+            value = std::strtoull(valuestr.c_str(), &end, 0);
+            assert(end && *end == '\0');
+            if (slashpos == std::string::npos) {
+                mask = ~(std::uint_fast32_t)0;
+            } else {
+                auto maskstr = line.substr(slashpos + 1);
+                mask = std::strtoull(maskstr.c_str(), &end, 0);
+                assert(end && *end == '\0');
+            }
+            log.emplace(load_time, event(reg, value, mask));
+        }
+    }
+}
diff --git a/io/model.h b/io/model.h
index 8758a43..2826170 100644
--- a/io/model.h
+++ b/io/model.h
@@ -13,6 +13,10 @@ struct iomodel {
     event_log log;
     std::uint64_t time = 0;
     bool interact(std::array<std::uint_fast32_t, NUM_CTLREGS> &ctlregs);
+    bool done() {
+        return log.lower_bound(time) == log.end();
+    }
 
+    std::uint64_t load_time = 0;
     void load_evt(std::istream &fh);
 };
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