From 8a7cc67b32a9a845d5c10ecb9ed6ffb261184ae8 Mon Sep 17 00:00:00 2001
From: Terence Boldt <terence@boldt.ca>
Date: Thu, 10 Dec 2020 04:58:53 +0000
Subject: [PATCH] Add Raspberry Pi driver code

---
 RaspberryPi/Driver.go | 196 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 196 insertions(+)
 create mode 100644 RaspberryPi/Driver.go

diff --git a/RaspberryPi/Driver.go b/RaspberryPi/Driver.go
new file mode 100644
index 0000000..4401c30
--- /dev/null
+++ b/RaspberryPi/Driver.go
@@ -0,0 +1,196 @@
+package main
+
+import (
+	//"time"
+	"periph.io/x/periph/conn/gpio"
+	"periph.io/x/periph/conn/gpio/gpioreg"
+	"periph.io/x/periph/host"
+	"fmt"
+	"os"
+)
+
+var out_write gpio.PinIO
+var out_read gpio.PinIO
+var out_commandWrite gpio.PinIO
+var out_commandRead gpio.PinIO
+var out_bit3 gpio.PinIO
+var out_bit2 gpio.PinIO
+var out_bit1 gpio.PinIO
+var out_bit0 gpio.PinIO
+var in_write gpio.PinIO
+var in_read gpio.PinIO
+var in_commandWrite gpio.PinIO
+var in_commandRead gpio.PinIO
+var in_bit3 gpio.PinIO
+var in_bit2 gpio.PinIO
+var in_bit1 gpio.PinIO
+var in_bit0 gpio.PinIO
+
+func readNibble() byte {
+	// let the Apple II know we are ready to read
+	fmt.Printf("let the Apple II know we are ready to read\n")
+	out_read.Out(gpio.Low)
+
+	// wait for the Apple II to write
+	fmt.Printf("wait for the Apple II to write\n")
+	for in_write.Read() == gpio.High {
+		in_write.WaitForEdge(-1)
+	}
+
+	// get a nibble of data
+	fmt.Printf("get a nibble of data\n")
+	var nibble byte
+	nibble = 0
+	bit3 := in_bit3.Read()
+	bit2 := in_bit2.Read()
+	bit1 := in_bit1.Read()
+	bit0 := in_bit0.Read()
+
+	if bit3 == gpio.High {
+		nibble += 8
+	}
+	if bit2 == gpio.High {
+		nibble += 4
+	}
+	if bit1 == gpio.High {
+		nibble += 2
+	}
+	if bit0 == gpio.High {
+		nibble += 1
+	}
+
+	// let the Apple II know we are done reading
+	fmt.Printf("let the Apple II know we are done reading\n")
+	out_read.Out(gpio.High)
+
+	// wait for the Apple II to finish writing
+	fmt.Printf("wait for the Apple II to finish writing\n")
+	for in_write.Read() == gpio.Low {
+		in_write.WaitForEdge(-1)
+	}
+
+	return nibble
+}
+
+func readByte() byte {
+	data := byte(0)
+	data = readNibble() << byte(4)
+	data += readNibble()
+	return data
+}
+
+func writeNibble(data byte) {
+	// wait for the Apple II to be ready to read
+	fmt.Printf("wait for the Apple II to be ready to read\n")
+	for in_read.Read() == gpio.High {
+		in_read.WaitForEdge(-1)
+	}
+
+	bit3 := gpio.Low
+	bit2 := gpio.Low
+	bit1 := gpio.Low
+	bit0 := gpio.Low
+	if ((data & 8) >> 3) == 1 {
+		bit3 = gpio.High
+	}
+	out_bit3.Out(bit3)
+
+	if ((data & 4) >> 2) == 1 {
+		bit2 = gpio.High
+	}
+	out_bit2.Out(bit2)
+
+	if ((data & 2) >> 1) == 1 {
+		bit1 = gpio.High
+	}
+	out_bit1.Out(bit1)
+
+	if (data & 1) == 1 {
+		bit0 = gpio.High
+	}
+	out_bit0.Out(bit0)
+
+	// let Apple II know we're writing
+	fmt.Printf("let Apple II know we're writing\n")
+	out_write.Out(gpio.Low)
+
+
+	// wait for the Apple II to finsih reading
+	fmt.Printf("wait for the Apple II to finsih reading\n")
+	for in_read.Read() == gpio.Low {
+		in_write.WaitForEdge(-1)
+	}
+
+	// let the Apple II know we are done writing
+	fmt.Printf("let the Apple II know we are done writing\n")
+	out_read.Out(gpio.High)
+}
+
+func writeByte(data byte) {
+	writeNibble(data >> 4)
+	writeNibble(data & 15)
+}
+
+func readBlock(buffer []byte) {
+	for i := 0; i < 512; i++ {
+		writeByte(buffer[i])
+	}
+}
+
+func writeBlock() {
+}
+
+func main() {
+	host.Init()
+
+	out_write = gpioreg.ByName("GPIO5")
+	out_read = gpioreg.ByName("GPIO11")
+	out_commandWrite = gpioreg.ByName("GPIO9")
+	out_commandRead = gpioreg.ByName("GPIO10")
+	out_bit3 = gpioreg.ByName("GPIO22")
+	out_bit2 = gpioreg.ByName("GPIO27")
+	out_bit1 = gpioreg.ByName("GPIO17")
+	out_bit0 = gpioreg.ByName("GPIO4")
+	in_write = gpioreg.ByName("GPIO12")
+	in_read = gpioreg.ByName("GPIO16")
+	in_commandWrite = gpioreg.ByName("GPIO20")
+	in_commandRead = gpioreg.ByName("GPIO21")
+	in_bit3 = gpioreg.ByName("GPIO26")
+	in_bit2 = gpioreg.ByName("GPIO19")
+	in_bit1 = gpioreg.ByName("GPIO13")
+	in_bit0 = gpioreg.ByName("GPIO6")
+
+	fmt.Printf("Starting Apple II RPi...\n")
+	fileName := "Total Replay v4.0-beta.1.hdv"
+	file, err := os.OpenFile(fileName, os.O_RDWR, 0755)
+	if err != nil {
+	//log.Fatal(err)
+	}
+	//if err := f.Close(); err != nil {
+	//log.Fatal(err)
+	//}
+
+	for in_write.Read() == gpio.Low {
+		in_write.WaitForEdge(-1)
+	}
+
+	for {
+		command := readByte();
+		if (command == 1) {
+			blockLow := readByte();
+			blockHigh := readByte();
+
+
+			var block int64
+			block = int64(blockHigh) * 256 + int64(blockLow)
+
+			fmt.Printf("Read block %d\n", block)
+
+			buffer := make([]byte, 512)
+
+			file.ReadAt(buffer, int64(block) * 512)
+			readBlock(buffer)
+		}
+	}
+}
+