/*
 * FreeRTOS Kernel V10.3.0
 * Copyright (C) 2020 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
 * the Software, and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 * http://www.FreeRTOS.org
 * http://aws.amazon.com/freertos
 *
 * 1 tab == 4 spaces!
 */

/*
 * A simple example that shows a stream buffer being used to pass data from an
 * interrupt to a task.
 *
 * There are two strings, pcStringToSend and pcStringToReceive, where
 * pcStringToReceive is a substring of pcStringToSend.  The interrupt sends
 * a few bytes of pcStringToSend to a stream buffer ever few times that it
 * executes.  A task reads the bytes from the stream buffer, looking for the
 * substring, and flagging an error if the received data is invalid.
 */

/* Standard includes. */
#include "stdio.h"
#include "string.h"

/* FreeRTOS includes. */
#include "FreeRTOS.h"
#include "task.h"
#include "stream_buffer.h"

/* Demo app includes. */
#include "StreamBufferInterrupt.h"

#define sbiSTREAM_BUFFER_LENGTH_BYTES ((size_t)100)
#define sbiSTREAM_BUFFER_TRIGGER_LEVEL_10 ((BaseType_t)10)

/*-----------------------------------------------------------*/

/* Implements the task that receives a stream of bytes from the interrupt. */
static void prvReceivingTask(void *pvParameters);

/*-----------------------------------------------------------*/

/* The stream buffer that is used to send data from an interrupt to the task. */
static StreamBufferHandle_t xStreamBuffer = NULL;

/* The string that is sent from the interrupt to the task four bytes at a
time.  Must be multiple of 4 bytes long as the ISR sends 4 bytes at a time*/
static const char *pcStringToSend = "_____Hello FreeRTOS_____";

/* The string to task is looking for, which must be a substring of
pcStringToSend. */
static const char *pcStringToReceive = "Hello FreeRTOS";

/* Set to pdFAIL if anything unexpected happens. */
static BaseType_t xDemoStatus = pdPASS;

/* Incremented each time pcStringToReceive is correctly received, provided no
errors have occurred.  Used so the check task can check this task is still
running as expected. */
static uint32_t ulCycleCount = 0;

/*-----------------------------------------------------------*/

void vStartStreamBufferInterruptDemo(void)
{
	/* Create the stream buffer that sends data from the interrupt to the
	task, and create the task. */
	xStreamBuffer =
		xStreamBufferCreate(/* The buffer length in bytes. */
				    sbiSTREAM_BUFFER_LENGTH_BYTES,
				    /* The stream buffer's trigger level. */
				    sbiSTREAM_BUFFER_TRIGGER_LEVEL_10);

	xTaskCreate(
		prvReceivingTask, /* The function that implements the task. */
		"StrIntRx", /* Human readable name for the task. */
		configMINIMAL_STACK_SIZE, /* Stack size (in words!). */
		NULL, /* Task parameter is not used. */
		tskIDLE_PRIORITY +
			2, /* The priority at which the task is created. */
		NULL); /* No use for the task handle. */
}
/*-----------------------------------------------------------*/

static void prvReceivingTask(void *pvParameters)
{
	char cRxBuffer[20];
	BaseType_t xNextByte = 0;

	/* Remove warning about unused parameters. */
	(void)pvParameters;

	/* Make sure the string will fit in the Rx buffer, including the NULL
	terminator. */
	configASSERT(sizeof(cRxBuffer) > strlen(pcStringToReceive));

	/* Make sure the stream buffer has been created. */
	configASSERT(xStreamBuffer != NULL);

	/* Start with the Rx buffer in a known state. */
	memset(cRxBuffer, 0x00, sizeof(cRxBuffer));

	for (;;) {
		/* Keep receiving characters until the end of the string is received.
		Note:  An infinite block time is used to simplify the example.  Infinite
		block times are not recommended in production code as they do not allow
		for error recovery. */
		xStreamBufferReceive(/* The stream buffer data is being received from. */
				     xStreamBuffer,
				     /* Where to place received data. */
				     (void *)&(cRxBuffer[xNextByte]),
				     /* The number of bytes to receive. */
				     sizeof(char),
				     /* The time to wait for the next data if the buffer
							  is empty. */
				     portMAX_DELAY);

		/* If xNextByte is 0 then this task is looking for the start of the
		string, which is 'H'. */
		if (xNextByte == 0) {
			if (cRxBuffer[xNextByte] == 'H') {
				/* The start of the string has been found.  Now receive
				characters until the end of the string is found. */
				xNextByte++;
			}
		} else {
			/* Receiving characters while looking for the end of the string,
			which is an 'S'. */
			if (cRxBuffer[xNextByte] == 'S') {
				/* The string has now been received.  Check its validity. */
				if (strcmp(cRxBuffer, pcStringToReceive) != 0) {
					xDemoStatus = pdFAIL;
				}

				/* Return to start looking for the beginning of the string
				again. */
				memset(cRxBuffer, 0x00, sizeof(cRxBuffer));
				xNextByte = 0;

				/* Increment the cycle count as an indication to the check task
				that this demo is still running. */
				if (xDemoStatus == pdPASS) {
					ulCycleCount++;
				}
			} else {
				/* Receive the next character the next time around, while
				continuing to look for the end of the string. */
				xNextByte++;

				configASSERT((size_t)xNextByte <
					     sizeof(cRxBuffer));
			}
		}
	}
}
/*-----------------------------------------------------------*/

void vBasicStreamBufferSendFromISR(void)
{
	static size_t xNextByteToSend = 0;
	const BaseType_t xCallsBetweenSends = 100, xBytesToSend = 4;
	static BaseType_t xCallCount = 0;

	/* Is it time to write to the stream buffer again? */
	xCallCount++;
	if (xCallCount > xCallsBetweenSends) {
		xCallCount = 0;

		/* Send the next four bytes to the stream buffer. */
		xStreamBufferSendFromISR(
			xStreamBuffer,
			(const void *)(pcStringToSend + xNextByteToSend),
			xBytesToSend, NULL);

		/* Send the next four bytes the next time around, wrapping to the start
		of the string if necessary. */
		xNextByteToSend += xBytesToSend;

		if (xNextByteToSend >= strlen(pcStringToSend)) {
			xNextByteToSend = 0;
		}
	}
}
/*-----------------------------------------------------------*/

BaseType_t xIsInterruptStreamBufferDemoStillRunning(void)
{
	uint32_t ulLastCycleCount = 0;

	/* Check the demo is still running. */
	if (ulLastCycleCount == ulCycleCount) {
		xDemoStatus = pdFAIL;
	} else {
		ulLastCycleCount = ulCycleCount;
	}

	return xDemoStatus;
}