Add serial_uart.c and use it for PC98

protocol/serial_uart.c

@@ -0,0 +1,93 @@
+/*
+Copyright 2013 Jun WAKO <wakojun@gmail.com>
+
+This software is licensed with a Modified BSD License.
+All of this is supposed to be Free Software, Open Source, DFSG-free,
+GPL-compatible, and OK to use in both free and proprietary applications.
+Additions and corrections to this file are welcome.
+
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+* Redistributions of source code must retain the above copyright
+  notice, this list of conditions and the following disclaimer.
+
+* Redistributions in binary form must reproduce the above copyright
+  notice, this list of conditions and the following disclaimer in
+  the documentation and/or other materials provided with the
+  distribution.
+
+* Neither the name of the copyright holders nor the names of
+  contributors may be used to endorse or promote products derived
+  from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGE.
+*/
+
+#include <stdbool.h>
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include "serial.h"
+
+
+void serial_init(void)
+{
+    SERIAL_UART_INIT();
+}
+
+// RX ring buffer
+#define RBUF_SIZE   8
+static uint8_t rbuf[RBUF_SIZE];
+static uint8_t rbuf_head = 0;
+static uint8_t rbuf_tail = 0;
+
+uint8_t serial_recv(void)
+{
+    uint8_t data = 0;
+    if (rbuf_head == rbuf_tail) {
+        return 0;
+    }
+
+    data = rbuf[rbuf_tail];
+    rbuf_tail = (rbuf_tail + 1) % RBUF_SIZE;
+    return data;
+}
+
+int16_t serial_recv2(void)
+{
+    uint8_t data = 0;
+    if (rbuf_head == rbuf_tail) {
+        return -1;
+    }
+
+    data = rbuf[rbuf_tail];
+    rbuf_tail = (rbuf_tail + 1) % RBUF_SIZE;
+    return data;
+}
+
+void serial_send(uint8_t data)
+{
+    while (!SERIAL_UART_TXD_READY) ;
+    SERIAL_UART_DATA = data;
+}
+
+// USART RX complete interrupt
+ISR(SERIAL_UART_RXD_VECT)
+{
+    uint8_t next = (rbuf_head + 1) % RBUF_SIZE;
+    if (next != rbuf_tail) {
+        rbuf[rbuf_head] = SERIAL_UART_DATA;
+        rbuf_head = next;
+    }
+}