From 86452af2d48e2d1883dbfd67316e371f2a593bfe Mon Sep 17 00:00:00 2001
From: Melodi <62381002+Melodi17@users.noreply.github.com>
Date: Mon, 4 Aug 2025 00:58:48 +1000
Subject: Initial commit

---
 Chip/Q1CpuAddressingModes.cs | 150 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 150 insertions(+)
 create mode 100644 Chip/Q1CpuAddressingModes.cs

(limited to 'Chip/Q1CpuAddressingModes.cs')

diff --git a/Chip/Q1CpuAddressingModes.cs b/Chip/Q1CpuAddressingModes.cs
new file mode 100644
index 0000000..0d664f7
--- /dev/null
+++ b/Chip/Q1CpuAddressingModes.cs
@@ -0,0 +1,150 @@
+namespace Q1Emu.Chip;
+
+using System;
+using System.Collections.Generic;
+
+public partial class Q1Cpu
+{
+    public u16 FetchData(u8 mode)
+    {
+        return mode switch
+        {
+            0x0 => this.AddressingMode_Implicit(),
+            0x1 => this.AddressingMode_Immediate(),
+            0x2 => this.AddressingMode_Direct(),
+            0x3 => this.AddressingMode_Indirect(),
+            0x4 => this.AddressingMode_Relative(),
+            0x5 => this.AddressingMode_Register(),
+            0x6 => this.AddressingMode_RegisterIndirect(),
+            0x7 => this.AddressingMode_RegisterIndirectOffset(),
+            _   => throw new InvalidOperationException($"Unknown addressing mode: {mode:X2}"),
+        };
+    }
+    
+    public void StoreData(u8 mode, u16 value)
+    {
+        Console.WriteLine($"StoreData: mode={mode:X8}, value={value:X16}");
+        if (mode != 0x05)
+        {
+            u16 address = this.FetchData(mode);
+            Console.WriteLine($"StoreData: address={address:X16}");
+            this.Bus.WriteWord(address, value);
+        }
+        else
+        {
+            u8 regIndex = this.Bus.Read(this.PC);
+            this.PC += 1;
+
+            this.StoreRegister(regIndex, value);
+        }
+    }
+    
+    public void TransformData(u8 mode, Func<u16, u16> transform)
+    {
+        if (mode != 0x05)
+        {
+            u16 address = this.FetchData(mode);
+            u16 value = this.Bus.ReadWord(address);
+            u16 transformedValue = transform(value);
+            this.Bus.WriteWord(address, transformedValue);
+        }
+        else
+        {
+            u8 regIndex = this.Bus.Read(this.PC);
+            this.PC += 1;
+
+            u16 value = this.FetchRegister(regIndex);
+            u16 transformedValue = transform(value);
+            this.StoreRegister(regIndex, transformedValue);
+        }
+    }
+
+    public u8 AddressingModeLength(u8 mode)
+    {
+        return mode switch
+        {
+            0x0 => 0, // Implicit
+            0x1 => 2, // Immediate
+            0x2 => 2, // Direct
+            0x3 => 2, // Indirect
+            0x4 => 2, // Relative
+            0x5 => 1, // Register
+            0x6 => 1, // Register indirect
+            0x7 => 3, // Register indirect with offset
+            _   => throw new InvalidOperationException($"Unknown addressing mode: {mode:X2}"),
+        };
+    }
+    
+    public u16 AddressingMode_Implicit()
+    {
+        return 0;
+    }
+
+
+    public u16 AddressingMode_Immediate()
+    {
+        u16 value = this.Bus.ReadWord(this.PC);
+        this.PC += 2;
+
+        return value;
+    }
+
+    public u16 AddressingMode_Direct()
+    {
+        u16 address = this.Bus.ReadWord(this.PC);
+        this.PC += 2;
+
+        u16 value = this.Bus.ReadWord(address);
+        return value;
+    }
+
+    public u16 AddressingMode_Indirect()
+    {
+        u16 address = this.Bus.ReadWord(this.PC);
+        this.PC += 2;
+
+        u16 indirectAddress = this.Bus.ReadWord(address);
+        u16 value = this.Bus.ReadWord(indirectAddress);
+        return value;
+    }
+
+    public u16 AddressingMode_Relative()
+    {
+        u16 offset = this.Bus.ReadWord(this.PC);
+        this.PC += 2;
+
+        u16 address = (u16) (this.PC + offset);
+        return address;
+    }
+
+    public u16 AddressingMode_Register()
+    {
+        u8 regIndex = this.Bus.Read(this.PC);
+        this.PC += 1;
+
+        return this.FetchRegister(regIndex);
+    }
+
+    public u16 AddressingMode_RegisterIndirect()
+    {
+        u8 regIndex = this.Bus.Read(this.PC);
+        this.PC += 1;
+
+        u16 address = this.FetchRegister(regIndex);
+        u16 value = this.Bus.ReadWord(address);
+        return value;
+    }
+
+    public u16 AddressingMode_RegisterIndirectOffset()
+    {
+        u8 regIndex = this.Bus.Read(this.PC);
+        this.PC += 1;
+
+        u16 offset = this.Bus.ReadWord(this.PC);
+        this.PC += 2;
+
+        u16 address = (u16) (this.FetchRegister(regIndex) + offset);
+        u16 value = this.Bus.ReadWord(address);
+        return value;
+    }
+}
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