From a1ad0a3e07b1d064d653c1a531d22310c34591ac Mon Sep 17 00:00:00 2001
From: Maxim Poliakovski <maximumspatium@googlemail.com>
Date: Sun, 10 Dec 2023 00:00:39 +0100
Subject: [PATCH] machineid: implement BoardRegister class.

---
 devices/common/hwcomponent.h |  2 ++
 devices/common/machineid.h   | 36 ++++++++++++++++++++++++++++++++++--
 2 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/devices/common/hwcomponent.h b/devices/common/hwcomponent.h
index 8d064bb..9315ca7 100644
--- a/devices/common/hwcomponent.h
+++ b/devices/common/hwcomponent.h
@@ -39,6 +39,8 @@ enum HWCompType : uint64_t {
     I2C_DEV     = 1ULL << 9,  // I2C device
     ADB_HOST    = 1ULL << 12, // ADB host
     ADB_DEV     = 1ULL << 13, // ADB device
+    IOBUS_HOST  = 1ULL << 14, // IOBus host
+    IOBUS_DEV   = 1ULL << 15, // IOBus device
     INT_CTRL    = 1ULL << 16, // interrupt controller
     SCSI_BUS    = 1ULL << 20, // SCSI bus
     SCSI_HOST   = 1ULL << 21, // SCSI host adapter
diff --git a/devices/common/machineid.h b/devices/common/machineid.h
index 36df9f4..aedbd19 100644
--- a/devices/common/machineid.h
+++ b/devices/common/machineid.h
@@ -1,6 +1,6 @@
 /*
 DingusPPC - The Experimental PowerPC Macintosh emulator
-Copyright (C) 2018-21 divingkatae and maximum
+Copyright (C) 2018-23 divingkatae and maximum
                       (theweirdo)     spatium
 
 (Contact divingkatae#1017 or powermax#2286 on Discord for more info)
@@ -24,8 +24,10 @@ along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 #include <devices/common/hwcomponent.h>
 #include <devices/common/mmiodevice.h>
+#include <devices/ioctrl/macio.h>
 
 #include <cinttypes>
+#include <string>
 
 /**
     @file Contains definitions for PowerMacintosh machine ID registers.
@@ -66,6 +68,36 @@ private:
     uint8_t id[4];
 };
 
+/**
+    TNT-style machines and derivatives provide two board registers
+    telling whether some particular piece of HW is installed or not.
+    Both board registers are attached to the IOBus of the I/O controller.
+    See machines/machinetnt.cpp for further details.
+ **/
+class BoardRegister : public HWComponent, public IobusDevice {
+public:
+    BoardRegister(std::string name, const uint16_t data) {
+        this->set_name(name);
+        supports_types(HWCompType::IOBUS_DEV);
+        this->data = data;
+    };
+    ~BoardRegister() = default;
+
+    uint16_t iodev_read(uint32_t address) {
+        return (!address) ? this->data : 0xFFFFU;
+    };
+
+    // appears read-only to guest
+    void iodev_write(uint32_t address, uint16_t value) {};
+
+    void update_bits(const uint16_t val, const uint16_t mask) {
+        this->data = (this->data & ~mask) | (val & mask);
+    };
+
+private:
+    uint16_t    data;
+};
+
 /**
     The machine ID for the Gossamer board is accesible at 0xFF000004 (phys).
     It contains a 16-bit value revealing machine's capabilities like bus speed,
@@ -92,4 +124,4 @@ private:
     uint16_t id;
 };
 
-#endif /* MACHINE_ID_H */
+#endif // MACHINE_ID_H