Apple2-IO-RPi/RaspberryPi/apple2driver/a2io/gpio.go
2021-10-31 14:35:55 -04:00

302 lines
6.3 KiB
Go

// Copyright Terence J. Boldt (c)2020-2021
// Use of this source code is governed by an MIT
// license that can be found in the LICENSE file.
// This file is used for communicating with the Apple II data bus via the
// GPIO ports on the Raspberry Pi
package a2io
import (
"bytes"
"errors"
"fmt"
"time"
"periph.io/x/periph/conn/gpio"
"periph.io/x/periph/conn/gpio/gpioreg"
"periph.io/x/periph/host"
)
var edgeTimeout time.Duration
var out_write gpio.PinIO
var out_read gpio.PinIO
var out_reserved2 gpio.PinIO
var out_reserved1 gpio.PinIO
var out_bit7 gpio.PinIO
var out_bit6 gpio.PinIO
var out_bit5 gpio.PinIO
var out_bit4 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_reserved2 gpio.PinIO
var in_reserved1 gpio.PinIO
var in_bit7 gpio.PinIO
var in_bit6 gpio.PinIO
var in_bit5 gpio.PinIO
var in_bit4 gpio.PinIO
var in_bit3 gpio.PinIO
var in_bit2 gpio.PinIO
var in_bit1 gpio.PinIO
var in_bit0 gpio.PinIO
type A2Gpio struct {
}
func (a2 A2Gpio) Init() {
host.Init()
out_write = gpioreg.ByName("GPIO24")
out_read = gpioreg.ByName("GPIO25")
out_reserved2 = gpioreg.ByName("GPIO7") //note GPIO7 and CPIO8 require extra effort to use
out_reserved1 = gpioreg.ByName("GPIO8")
out_bit7 = gpioreg.ByName("GPIO5")
out_bit6 = gpioreg.ByName("GPIO11")
out_bit5 = gpioreg.ByName("GPIO9")
out_bit4 = 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("GPIO23")
in_read = gpioreg.ByName("GPIO18")
in_reserved2 = gpioreg.ByName("GPIO14")
in_reserved1 = gpioreg.ByName("GPIO15")
in_bit7 = gpioreg.ByName("GPIO12")
in_bit6 = gpioreg.ByName("GPIO16")
in_bit5 = gpioreg.ByName("GPIO20")
in_bit4 = gpioreg.ByName("GPIO21")
in_bit3 = gpioreg.ByName("GPIO26")
in_bit2 = gpioreg.ByName("GPIO19")
in_bit1 = gpioreg.ByName("GPIO13")
in_bit0 = gpioreg.ByName("GPIO6")
in_write.In(gpio.PullDown, gpio.BothEdges)
in_read.In(gpio.PullDown, gpio.BothEdges)
out_reserved1.Out(gpio.High)
out_reserved2.Out(gpio.High)
out_read.Out(gpio.High)
out_write.Out(gpio.High)
out_bit7.Out(gpio.Low)
out_bit6.Out(gpio.Low)
out_bit5.Out(gpio.Low)
out_bit4.Out(gpio.Low)
out_bit3.Out(gpio.Low)
out_bit2.Out(gpio.Low)
out_bit1.Out(gpio.Low)
out_bit0.Out(gpio.Low)
edgeTimeout = time.Second
}
func (a2 A2Gpio) ReadString() (string, error) {
var inBytes bytes.Buffer
for {
inByte, err := a2.ReadByte()
if err != nil {
return "", err
}
if inByte == 0 {
break
}
inBytes.WriteByte(inByte)
}
return string(inBytes.Bytes()), nil
}
func (a2 A2Gpio) WriteString(outString string) error {
for _, character := range outString {
err := a2.WriteByte(byte(character) | 128)
if err != nil {
fmt.Printf("Failed to write string\n")
return err
}
}
a2.WriteByte(0)
return nil
}
func (a2 A2Gpio) ReadByte() (byte, error) {
// let the Apple II know we are ready to read
out_read.Out(gpio.Low)
// wait for the Apple II to write
for in_write.Read() == gpio.High {
if !in_write.WaitForEdge(edgeTimeout) {
out_read.Out(gpio.High)
return 0, errors.New("Timed out reading byte -- write stuck high\n")
}
}
// get a nibble of data
var data byte
data = 0
bit7 := in_bit7.Read()
bit6 := in_bit6.Read()
bit5 := in_bit5.Read()
bit4 := in_bit4.Read()
bit3 := in_bit3.Read()
bit2 := in_bit2.Read()
bit1 := in_bit1.Read()
bit0 := in_bit0.Read()
if bit7 == gpio.High {
data += 128
}
if bit6 == gpio.High {
data += 64
}
if bit5 == gpio.High {
data += 32
}
if bit4 == gpio.High {
data += 16
}
if bit3 == gpio.High {
data += 8
}
if bit2 == gpio.High {
data += 4
}
if bit1 == gpio.High {
data += 2
}
if bit0 == gpio.High {
data += 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 {
if !in_write.WaitForEdge(edgeTimeout) {
return 0, errors.New("Timed out reading byte -- write stuck low")
}
}
return data, nil
}
func (a2 A2Gpio) WriteByte(data byte) error {
// check if the Apple II wants to send a byte to us first
if in_write.Read() == gpio.Low {
out_write.Out(gpio.High)
return errors.New("Can't write byte while byte is incoming")
}
// wait for the Apple II to be ready to read
for in_read.Read() == gpio.High {
if !in_read.WaitForEdge(edgeTimeout) {
out_write.Out(gpio.High)
return errors.New("Timed out writing byte -- read stuck high")
}
}
bit7 := gpio.Low
bit6 := gpio.Low
bit5 := gpio.Low
bit4 := gpio.Low
bit3 := gpio.Low
bit2 := gpio.Low
bit1 := gpio.Low
bit0 := gpio.Low
if ((data & 128) >> 7) == 1 {
bit7 = gpio.High
}
out_bit7.Out(bit7)
if ((data & 64) >> 6) == 1 {
bit6 = gpio.High
}
out_bit6.Out(bit6)
if ((data & 32) >> 5) == 1 {
bit5 = gpio.High
}
out_bit5.Out(bit5)
if ((data & 16) >> 4) == 1 {
bit4 = gpio.High
}
out_bit4.Out(bit4)
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
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 {
if !in_read.WaitForEdge(edgeTimeout) {
out_write.Out(gpio.High)
return errors.New("Timed out writing byte -- read stuck low")
}
}
// let the Apple II know we are done writing
out_write.Out(gpio.High)
return nil
}
func (a2 A2Gpio) WriteBlock(buffer []byte) error {
for i := 0; i < 512; i++ {
err := a2.WriteByte(buffer[i])
if err != nil {
return err
}
}
return nil
}
func (a2 A2Gpio) ReadBlock(buffer []byte) error {
var err error
for i := 0; i < 512; i++ {
buffer[i], err = a2.ReadByte()
if err != nil {
return err
}
}
return nil
}
func (a2 A2Gpio) WriteBuffer(buffer []byte) error {
bufferSize := len(buffer)
for i := 0; i < bufferSize; i++ {
err := a2.WriteByte(buffer[i])
if err != nil {
return err
}
}
return nil
}