From 37e4b219d4f65441085f1856497cf5a7279f7d1a Mon Sep 17 00:00:00 2001
From: Godzil <godzil@godzil.net>
Date: Mon, 27 Jun 2022 17:04:55 +0100
Subject: [PATCH] Add a skeleton for the interrupt controller

---
 source/includes/interrupt_controller.h    |  32 +++++++
 source/peripherals/interrupt_controller.c | 103 ++++++++++++++++++++++
 2 files changed, 135 insertions(+)
 create mode 100644 source/includes/interrupt_controller.h
 create mode 100644 source/peripherals/interrupt_controller.c

diff --git a/source/includes/interrupt_controller.h b/source/includes/interrupt_controller.h
new file mode 100644
index 0000000..f038cb5
--- /dev/null
+++ b/source/includes/interrupt_controller.h
@@ -0,0 +1,32 @@
+/*******************************************************************************
+ * NewOswan
+ * interrupt_controller.h:
+ *
+ * Created by mlt on 14/03/2022.
+ * Copyright (c) 2022 986-Studio. All rights reserved.
+ *
+ ******************************************************************************/
+
+#ifndef __INTERRUPT_CONTROLLER_H__
+#define __INTERRUPT_CONTROLLER_H__
+
+#include <device.h>
+
+typedef enum hw_interrupt_type_t
+{
+    /* They are in the same order as the hardware */
+    HWI_SERIAL_TX = 0,
+    HWI_KEY,
+    HWI_CART,
+    HWI_SERIAL_RX,
+    HWI_LINE_COMPARE,
+    HWI_VBLANK_TIMER,
+    HWI_VBLANK,
+    HWI_HBLANK_TIMER,
+} hw_interrupt_type_t;
+
+extern device_t InterruptController;
+
+void trigger_interrupt(hw_interrupt_type_t type);
+
+#endif /* __INTERRUPT_CONTROLLER_H__ */
diff --git a/source/peripherals/interrupt_controller.c b/source/peripherals/interrupt_controller.c
new file mode 100644
index 0000000..da57d4d
--- /dev/null
+++ b/source/peripherals/interrupt_controller.c
@@ -0,0 +1,103 @@
+/*******************************************************************************
+ * NewOswan
+ * interrupt_controller.c:
+ *
+ * Created by mlt on 14/03/2022.
+ * Copyright (c) 2022 986-Studio. All rights reserved.
+ *
+ ******************************************************************************/
+
+#include <stdio.h>
+#include <stdint.h>
+
+#include <device.h>
+#include <io.h>
+#include <interrupt_controller.h>
+
+/* device internal parameters */
+typedef struct ic_params_t
+{
+    uint8_t address_base;
+    uint8_t int_enable_mask;
+    uint8_t int_status;
+} ic_params_t;
+
+static ic_params_t interrupt_controller;
+
+static uint8_t IC_IO_read(void *pdata, uint8_t port)
+{
+    ic_params_t *params = (ic_params_t *)pdata;
+
+    switch(port)
+    {
+    case 0xB0: return params->address_base;
+    case 0xB2: return params->int_enable_mask;
+    case 0xB4: return params->int_status;
+    }
+
+    return 0x00;
+}
+
+static void IC_IO_write(void *pdata, uint8_t port, uint8_t value)
+{
+    ic_params_t *params = (ic_params_t *)pdata;
+
+    switch(port)
+    {
+    case 0xB0: params->address_base = value; break;
+    case 0xB2: params->int_enable_mask = value; break;
+    }
+}
+
+static void IC_IO_write_ack(void *pdata, uint8_t port, uint8_t value)
+{
+    ic_params_t *params = (ic_params_t *)pdata;
+
+    // De-assert CPU interrupt accordingly to the mask in value
+}
+
+
+static void IC_init(void *params)
+{
+    UNUSED_PARAMETER(params);
+
+    register_io_hook(0xB0, IC_IO_read, IC_IO_write, &interrupt_controller);
+    register_io_hook(0xB2, IC_IO_read, IC_IO_write, &interrupt_controller);
+    register_io_hook(0xB4, IC_IO_read, NULL, &interrupt_controller);
+    register_io_hook(0xB6, NULL, IC_IO_write_ack, &interrupt_controller);
+}
+
+static void IC_reset()
+{
+    interrupt_controller.int_enable_mask = 0;
+    interrupt_controller.address_base = 0;
+}
+
+static void IC_free()
+{
+
+}
+
+device_t InterruptController =
+{
+        .init = IC_init,
+        .reset = IC_reset,
+        .free = IC_free,
+        .deviceType = DT_INTERRUPT_CONTROLLER,
+};
+
+/* Exported functions */
+void trigger_interrupt(hw_interrupt_type_t type)
+{
+    uint16_t int_vector = interrupt_controller.address_base & 0xF8 + (uint8_t)type;
+
+    /* Check that the INT is enabled */
+    if ((interrupt_controller.int_enable_mask >> type) & 0x1)
+    {
+        /* TODO: Do we have to enable that even if the int is not enabled? */
+        interrupt_controller.int_status |= (1 << type);
+
+        // Fire the NEC interrupt
+
+    }
+}
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