From 7ce40467961158b4f58f2461c82958a81ba20bfa Mon Sep 17 00:00:00 2001
From: Daniele <daniele.verducci@gmail.com>
Date: Sun, 6 Feb 2022 20:30:49 +0100
Subject: [PATCH] Setting up PAT80 Emulator

---
 .gitmodules               |  3 +++
 pat80-emulator/.gitignore |  1 +
 pat80-emulator/Makefile   |  5 +++++
 pat80-emulator/README.md  |  9 +++++++++
 pat80-emulator/main.c     | 34 ++++++++++++++++++++++++++++++++++
 pat80-emulator/z80        |  1 +
 6 files changed, 53 insertions(+)
 create mode 100644 .gitmodules
 create mode 100644 pat80-emulator/.gitignore
 create mode 100644 pat80-emulator/Makefile
 create mode 100644 pat80-emulator/README.md
 create mode 100644 pat80-emulator/main.c
 create mode 160000 pat80-emulator/z80

diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..b28b723
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "pat80-emulator/z80"]
+	path = pat80-emulator/z80
+	url = git@github.com:algodesigner/z80.git
diff --git a/pat80-emulator/.gitignore b/pat80-emulator/.gitignore
new file mode 100644
index 0000000..5eb94e9
--- /dev/null
+++ b/pat80-emulator/.gitignore
@@ -0,0 +1 @@
+pat80emu
diff --git a/pat80-emulator/Makefile b/pat80-emulator/Makefile
new file mode 100644
index 0000000..c75bc5a
--- /dev/null
+++ b/pat80-emulator/Makefile
@@ -0,0 +1,5 @@
+build:
+	gcc -g -o pat80emu z80/console.c z80/z80.c main.c
+clean:
+	rm -rf main
+all: clean build
diff --git a/pat80-emulator/README.md b/pat80-emulator/README.md
new file mode 100644
index 0000000..c5f5489
--- /dev/null
+++ b/pat80-emulator/README.md
@@ -0,0 +1,9 @@
+# PAT80 Emulator
+Uses algodesigner's Z80 emulator (see submodule in z80 folder).
+Instances the Z80 object (representing the CPU) and:
+- intercepts all memory access and returns the corresponding rom value (read from rom file) if PC is in first 32k of memory (TODO)
+- intercepts all memory access and stops execution returning error if trying to write to first 32k of memory (TODO)
+
+## Usage
+Build with `make all`
+Run with `./pat80emu`
diff --git a/pat80-emulator/main.c b/pat80-emulator/main.c
new file mode 100644
index 0000000..6affdab
--- /dev/null
+++ b/pat80-emulator/main.c
@@ -0,0 +1,34 @@
+#include <stdio.h>
+#include "z80/z80.h"
+
+/*
+ * The intercept function is invoked on each and every CPU instruction. It
+ * quits the simulation when the PC register reaches address #0005 by changing
+ * the virtual CPU status.
+ */
+static void intercept(void *ctx)
+{
+    z80 *cpu = ctx;
+    if (PC == 5) {
+        puts("\nReached address: 5, terminating the simulation...");
+        cpu->status = 1;
+    }
+}
+
+int main(int argc, char *argv[])
+{
+    /*
+     * Instantiate the CPU, activate the debug mode, set the intercept
+     * function and run the virtual CPU until the termination criteria
+     * set by the intercept function, if any, are met.
+     */
+    z80 *cpu = z80_new();
+    cpu->debug = 1;
+
+    // TODO: Copy rom to first 32k CPU memory
+    _RamWrite(0x03, 0x76);  // As an example, here is how to set HALT at posizion 0x03. Use a loop to copy memory from a PAT80 OS rom file.
+
+    z80_set_intercept(cpu, cpu, intercept);
+    z80_run(cpu);
+    z80_destroy(cpu);
+}
diff --git a/pat80-emulator/z80 b/pat80-emulator/z80
new file mode 160000
index 0000000..80df33f
--- /dev/null
+++ b/pat80-emulator/z80
@@ -0,0 +1 @@
+Subproject commit 80df33fc873e8eb374c1fcb33458a1b7220d20db