/*
 * FreeRTOS Common V1.2.0
 * 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://aws.amazon.com/freertos
 * http://www.FreeRTOS.org
 */

/**
 * @file iot_static_memory_common.c
 * @brief Implementation of common static memory functions in iot_static_memory.h
 */

/* The config header is always included first. */
#include "iot_config.h"

/* This file should only be compiled if dynamic memory allocation is forbidden. */
#if IOT_STATIC_MEMORY_ONLY == 1

/* Standard includes. */
    #include <stdbool.h>
    #include <stddef.h>
    #include <stdint.h>
    #include <string.h>

/* Platform layer includes. */
    #include "platform/iot_threads.h"

/* Static memory include. */
    #include "private/iot_static_memory.h"

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

/**
 * @cond DOXYGEN_IGNORE
 * Doxygen should ignore this section.
 *
 * Provide default values for undefined configuration constants.
 */
    #ifndef IOT_MESSAGE_BUFFERS
        #define IOT_MESSAGE_BUFFERS        ( 8 )
    #endif
    #ifndef IOT_MESSAGE_BUFFER_SIZE
        #define IOT_MESSAGE_BUFFER_SIZE    ( 1024 )
    #endif
/** @endcond */

/* Validate static memory configuration settings. */
    #if IOT_MESSAGE_BUFFERS <= 0
        #error "IOT_MESSAGE_BUFFERS cannot be 0 or negative."
    #endif
    #if IOT_MESSAGE_BUFFER_SIZE <= 0
        #error "IOT_MESSAGE_BUFFER_SIZE cannot be 0 or negative."
    #endif

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

/**
 * @brief Guards access to critical sections.
 */
    static IotMutex_t _mutex;

/*
 * Static memory buffers and flags, allocated and zeroed at compile-time.
 */
    static bool _pInUseMessageBuffers[ IOT_MESSAGE_BUFFERS ] = { 0 };                           /**< @brief Message buffer in-use flags. */
    static char _pMessageBuffers[ IOT_MESSAGE_BUFFERS ][ IOT_MESSAGE_BUFFER_SIZE ] = { { 0 } }; /**< @brief Message buffers. */

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

    int32_t IotStaticMemory_FindFree( bool * pInUse,
                                      size_t limit )
    {
        size_t i = 0;
        int32_t freeIndex = -1;

        /* Perform the search for a free buffer in a critical section. */
        IotMutex_Lock( &( _mutex ) );

        for( i = 0; i < limit; i++ )
        {
            if( pInUse[ i ] == false )
            {
                /* If a free buffer is found, mark it "in-use" and return its index. */
                pInUse[ i ] = true;
                freeIndex = ( int32_t ) i;
                break;
            }
        }

        /* Exit the critical section. */
        IotMutex_Unlock( &( _mutex ) );

        return freeIndex;
    }

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

    void IotStaticMemory_ReturnInUse( void * ptr,
                                      void * pPool,
                                      bool * pInUse,
                                      size_t limit,
                                      size_t elementSize )
    {
        size_t i = 0;
        uint8_t * element = NULL;

        /* Clear ptr. */
        ( void ) memset( ptr, 0x00, elementSize );

        /* Perform a search for ptr to make sure it's part of pPool. This search
         * is done in a critical section. */
        IotMutex_Lock( &( _mutex ) );

        for( i = 0; i < limit; i++ )
        {
            /* Calculate address of the i-th element in pPool. */
            element = ( ( uint8_t * ) pPool ) + elementSize * i;

            /* Check for a match. */
            if( ( ( void * ) element == ptr ) &&
                ( pInUse[ i ] == true ) )
            {
                pInUse[ i ] = false;
                break;
            }
        }

        /* Exit the critical section. */
        IotMutex_Unlock( &( _mutex ) );
    }

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

    bool IotStaticMemory_Init( void )
    {
        return IotMutex_Create( &( _mutex ), false );
    }

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

    void IotStaticMemory_Cleanup( void )
    {
        IotMutex_Destroy( &( _mutex ) );
    }

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

    size_t Iot_MessageBufferSize( void )
    {
        return ( size_t ) IOT_MESSAGE_BUFFER_SIZE;
    }

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

    void * Iot_MallocMessageBuffer( size_t size )
    {
        int32_t freeIndex = -1;
        void * pNewBuffer = NULL;

        /* Check that size is within the fixed message buffer size. */
        if( size <= IOT_MESSAGE_BUFFER_SIZE )
        {
            /* Get the index of a free message buffer. */
            freeIndex = IotStaticMemory_FindFree( _pInUseMessageBuffers,
                                                  IOT_MESSAGE_BUFFERS );

            if( freeIndex != -1 )
            {
                pNewBuffer = &( _pMessageBuffers[ freeIndex ][ 0 ] );
            }
        }

        return pNewBuffer;
    }

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

    void Iot_FreeMessageBuffer( void * ptr )
    {
        /* Return the in-use message buffer. */
        IotStaticMemory_ReturnInUse( ptr,
                                     _pMessageBuffers,
                                     _pInUseMessageBuffers,
                                     IOT_MESSAGE_BUFFERS,
                                     IOT_MESSAGE_BUFFER_SIZE );
    }

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

#endif /* if IOT_STATIC_MEMORY_ONLY == 1 */