From 753e445b4be0726ef30dd4fec401c50cca9f0f25 Mon Sep 17 00:00:00 2001
From: Maxim Poliakovski <maximumspatium@googlemail.com>
Date: Sat, 14 Mar 2020 21:38:18 +0100
Subject: [PATCH] Initial I2C bus implementation.

---
 devices/i2c.h       | 78 +++++++++++++++++++++++++++++++++++++++++++++
 devices/viacuda.cpp |  2 +-
 devices/viacuda.h   |  3 +-
 3 files changed, 81 insertions(+), 2 deletions(-)
 create mode 100644 devices/i2c.h

diff --git a/devices/i2c.h b/devices/i2c.h
new file mode 100644
index 0000000..b01816f
--- /dev/null
+++ b/devices/i2c.h
@@ -0,0 +1,78 @@
+/*
+DingusPPC - The Experimental PowerPC Macintosh emulator
+Copyright (C) 2018-20 divingkatae and maximum
+                      (theweirdo)     spatium
+
+(Contact divingkatae#1017 or powermax#2286 on Discord for more info)
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+/** @file I2C bus emulation.
+
+    Author: Max Poliakovski
+ */
+
+#ifndef I2C_H
+#define I2C_H
+
+#include <vector>
+
+/** Base class for I2C devices */
+class I2CDevice {
+public:
+    virtual void start_transaction() = 0;
+    virtual bool send_byte(uint8_t data) = 0;
+    virtual bool receive_byte(uint8_t *p_data) = 0;
+};
+
+/** Base class for I2C hosts */
+class I2CBus {
+public:
+    I2CBus()  { this->dev_list.clear(); };
+    ~I2CBus() { this->dev_list.clear(); };
+
+    virtual bool register_device(uint8_t dev_addr, I2CDevice *dev_obj) {
+        if (!this->dev_list[dev_addr]) {
+            return false; /* device address already taken */
+        }
+        this->dev_list[dev_addr] = dev_obj;
+        return true;
+    };
+
+    virtual void start_transaction(uint8_t dev_addr) {
+        if (this->dev_list[dev_addr]) {
+            this->dev_list[dev_addr]->start_transaction();
+        }
+    };
+
+    virtual bool send_byte(uint8_t dev_addr, uint8_t data) {
+        if (!this->dev_list[dev_addr]) {
+            return false; /* no device -> no acknowledge */
+        }
+        return this->dev_list[dev_addr]->send_byte(data);
+    };
+
+    virtual bool receive_byte(uint8_t dev_addr, uint8_t *p_data) {
+        if (!this->dev_list[dev_addr]) {
+            return false; /* no device -> no acknowledge */
+        }
+        return this->dev_list[dev_addr]->receive_byte(p_data);
+    };
+
+protected:
+    std::vector<I2CDevice *> dev_list; /* list of registered I2C devices */
+};
+
+#endif /* I2C_H */
diff --git a/devices/viacuda.cpp b/devices/viacuda.cpp
index c3d5ac9..bd5c2ef 100644
--- a/devices/viacuda.cpp
+++ b/devices/viacuda.cpp
@@ -129,7 +129,7 @@ void ViaCuda::write(int reg, uint8_t value)
 
 void ViaCuda::print_enabled_ints()
 {
-    static char *via_int_src[] = { "CA2", "CA1", "SR", "CB2", "CB1", "T2", "T1" };
+    const char *via_int_src[] = { "CA2", "CA1", "SR", "CB2", "CB1", "T2", "T1" };
 
     for (int i = 0; i < 7; i++) {
         if (this->via_regs[VIA_IER] & (1 << i))
diff --git a/devices/viacuda.h b/devices/viacuda.h
index 2fb9262..c1eaf34 100644
--- a/devices/viacuda.h
+++ b/devices/viacuda.h
@@ -47,6 +47,7 @@ along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 #include "hwcomponent.h"
 #include "nvram.h"
+#include "i2c.h"
 
 /** VIA register offsets. */
 enum {
@@ -100,7 +101,7 @@ enum {
 };
 
 
-class ViaCuda : public HWComponent
+class ViaCuda : public HWComponent, public I2CBus
 {
 public:
     ViaCuda();