initial commit

tridoraemu/uart.go

@@ -0,0 +1,59 @@
+// Copyright 2021-2024 Sebastian Lederer. See the file LICENSE.md for details
+package main
+import (
+//	"fmt"
+	"os"
+	"errors"
+	)
+
+type UART struct {
+	available bool
+	buf [] byte
+	consoleChan chan byte
+	cpu *CPU
+}
+
+func (u *UART) read(byteaddr word) (word, error) {
+	var result word = 0
+
+	if len(u.buf) > 0 {
+		result = word(u.buf[0])
+		result |= 512
+	} else {
+		select {
+		case inbyte, ok := <-u.consoleChan:
+			if ! ok {
+				return 0, errors.New("console channel error")
+			} else {
+				u.buf = make([]byte, 1)
+				u.buf[0] = inbyte
+				// fmt.Println("Read input:", inbyte)
+				idle(false)
+			}
+		default:
+			idle(true)
+		}
+	}
+
+	return result, nil
+}
+
+func (u *UART) write(value word, byteaddr word) (error) {
+	var err error = nil
+
+	idle(false)
+
+	if value & 512 != 0 {
+		u.buf = u.buf[1:]
+		// fmt.Println("rx_clear: len ", len(u.buf))
+	}
+
+	if value & 1024 != 0 {
+		buf := make([] byte, 1)
+		buf[0] = byte(value & 255)
+		_ , err = os.Stdout.Write(buf)
+	}
+
+	return err
+}
+