samples: usb: cdc_acm: Update CDC ACM echo sample

Update CDC ACM sample using ring buffer and fifo_fill / fifo_read
functions.

Signed-off-by: Andrei Emeltchenko <andrei.emeltchenko@intel.com>

samples/subsys/usb/cdc_acm/src/main.c

@@ -1,12 +1,12 @@
 /*
- * Copyright (c) 2016 Intel Corporation
+ * Copyright (c) 2019 Intel Corporation
  *
  * SPDX-License-Identifier: Apache-2.0
  */
 
 /**
  * @file
- * @brief Sample app for CDC ACM class driver
+ * @brief Sample echo app for CDC ACM class
  *
  * Sample app for USB CDC ACM class driver. The received data is echoed back
  * to the serial port.
@@ -17,108 +17,106 @@
 #include <device.h>
 #include <uart.h>
 #include <zephyr.h>
+#include <ring_buffer.h>
 
-static const char *banner1 = "Send characters to the UART device\r\n";
-static const char *banner2 = "Characters read:\r\n";
+#include <logging/log.h>
+LOG_MODULE_REGISTER(cdc_acm_echo, LOG_LEVEL_DBG);
 
-static volatile bool data_transmitted;
-static volatile bool data_arrived;
-static	char data_buf[64];
+#define RING_BUF_SIZE 1024
+u8_t ring_buffer[RING_BUF_SIZE];
+
+struct ring_buf ringbuf;
 
 static void interrupt_handler(struct device *dev)
 {
-	uart_irq_update(dev);
-
-	if (uart_irq_tx_ready(dev)) {
-		data_transmitted = true;
-	}
+	while (uart_irq_update(dev) && uart_irq_is_pending(dev)) {
+		if (uart_irq_rx_ready(dev)) {
+			int recv_len, rb_len;
+			u8_t buffer[64];
+			size_t len = MIN(ring_buf_space_get(&ringbuf),
+					 sizeof(buffer));
 
-	if (uart_irq_rx_ready(dev)) {
-		data_arrived = true;
-	}
-}
+			recv_len = uart_fifo_read(dev, buffer, len);
 
-static void write_data(struct device *dev, const char *buf, int len)
-{
-	uart_irq_tx_enable(dev);
+			rb_len = ring_buf_put(&ringbuf, buffer, recv_len);
+			if (rb_len < recv_len) {
+				LOG_ERR("Drop %u bytes", recv_len - rb_len);
+			}
 
-	while (len) {
-		int written;
+			LOG_DBG("tty fifo -> ringbuf %d bytes", rb_len);
 
-		data_transmitted = false;
-		written = uart_fifo_fill(dev, (const u8_t *)buf, len);
-		while (data_transmitted == false) {
-			k_yield();
+			uart_irq_tx_enable(dev);
 		}
 
-		len -= written;
-		buf += written;
-	}
+		if (uart_irq_tx_ready(dev)) {
+			u8_t buffer[64];
+			int rb_len, send_len;
 
-	uart_irq_tx_disable(dev);
-}
-
-static void read_and_echo_data(struct device *dev, int *bytes_read)
-{
-	while (data_arrived == false)
-		;
+			rb_len = ring_buf_get(&ringbuf, buffer, sizeof(buffer));
+			if (!rb_len) {
+				LOG_DBG("Ring buffer empty, disable TX IRQ");
+				uart_irq_tx_disable(dev);
+				continue;
+			}
 
-	data_arrived = false;
+			send_len = uart_fifo_fill(dev, buffer, rb_len);
+			if (send_len < rb_len) {
+				LOG_ERR("Drop %d bytes", rb_len - send_len);
+			}
 
-	/* Read all data and echo it back */
-	while ((*bytes_read = uart_fifo_read(dev,
-	    (u8_t *)data_buf, sizeof(data_buf)))) {
-		write_data(dev, data_buf, *bytes_read);
+			LOG_DBG("ringbuf -> tty fifo %d bytes", send_len);
+		}
 	}
 }
 
 void main(void)
 {
 	struct device *dev;
-	u32_t baudrate, bytes_read, dtr = 0U;
+	u32_t baudrate, dtr = 0U;
 	int ret;
 
 	dev = device_get_binding("CDC_ACM_0");
 	if (!dev) {
-		printf("CDC ACM device not found\n");
+		LOG_ERR("CDC ACM device not found");
 		return;
 	}
 
-	printf("Wait for DTR\n");
-	while (1) {
+	ring_buf_init(&ringbuf, sizeof(ring_buffer), ring_buffer);
+
+	LOG_DBG("Wait for DTR");
+
+	while (true) {
 		uart_line_ctrl_get(dev, LINE_CTRL_DTR, &dtr);
-		if (dtr)
+		if (dtr) {
 			break;
+		}
 	}
-	printf("DTR set, start test\n");
+
+	LOG_DBG("DTR set");
 
 	/* They are optional, we use them to test the interrupt endpoint */
 	ret = uart_line_ctrl_set(dev, LINE_CTRL_DCD, 1);
-	if (ret)
-		printf("Failed to set DCD, ret code %d\n", ret);
+	if (ret) {
+		LOG_WRN("Failed to set DCD, ret code %d", ret);
+	}
 
 	ret = uart_line_ctrl_set(dev, LINE_CTRL_DSR, 1);
-	if (ret)
-		printf("Failed to set DSR, ret code %d\n", ret);
+	if (ret) {
+		LOG_WRN("Failed to set DSR, ret code %d", ret);
+	}
 
 	/* Wait 1 sec for the host to do all settings */
 	k_busy_wait(1000000);
 
 	ret = uart_line_ctrl_get(dev, LINE_CTRL_BAUD_RATE, &baudrate);
-	if (ret)
-		printf("Failed to get baudrate, ret code %d\n", ret);
-	else
-		printf("Baudrate detected: %d\n", baudrate);
+	if (ret) {
+		LOG_WRN("Failed to get baudrate, ret code %d", ret);
+	} else {
+		LOG_INF("Baudrate detected: %d", baudrate);
+	}
 
 	uart_irq_callback_set(dev, interrupt_handler);
-	write_data(dev, banner1, strlen(banner1));
-	write_data(dev, banner2, strlen(banner2));
 
 	/* Enable rx interrupts */
 	uart_irq_rx_enable(dev);
-
-	/* Echo the received data */
-	while (1) {
-		read_and_echo_data(dev, (int *) &bytes_read);
-	}
 }