Porting guide

High level of ESP-AT library is platform independent, written in ANSI C99, however there is an important part where middleware needs to communicate with target ESP device and it must work under different optional operating systems selected by final customer.

Porting consists of:

  • Implementation of low-level part, for actual communication between host device and ESP device

  • Implementation of system functions, link between target operating system and middleware functions

  • Assignment of memory for allocation manager

Implement low-level driver

To successfully prepare all parts of low-level driver, application must take care of:

  • Implementing lwesp_ll_init() and lwesp_ll_deinit() callback functions

  • Implement and assign send data and optional hardware reset function callbacks

  • Assign memory for allocation manager when using default allocator or use custom allocator

  • Process received data from ESP device and send it to input module for further processing

Tip

Port examples are available for STM32 and WIN32 architectures. Both actual working and up-to-date implementations are available within the library.

Note

Check Input module for more information about direct & indirect input processing.

Implement system functions

System functions are bridge between operating system calls and ESP middleware. ESP library relies on stable operating system features and its implementation and does not require any special features which do not normally come with operating systems.

Operating system must support:

  • Thread management functions

  • Mutex management functions

  • Binary semaphores only, no need for counting semaphores

  • Message queue management functions

Warning

If any of the features are not available within targeted operating system, customer needs to resolve it with care. As an example, message queue is not available in WIN32 OS API therefore custom message queue has been implemented using binary semaphores

Application needs to implement all system call functions, starting with lwesp_sys_. It must also prepare header file for standard types in order to support OS types within ESP middleware.

An example code is provided latter section of this page for WIN32 and STM32.

Steps to follow

  • Copy lwesp/src/system/lwesp_sys_template.c to the same folder and rename it to application port, eg. lwesp_sys_win32.c

  • Open newly created file and implement all system functions

  • Copy folder lwesp/src/include/system/port/template/* to the same folder and rename folder name to application port, eg. cmsis_os

  • Open lwesp_sys_port.h file from newly created folder and implement all typedefs and macros for specific target

  • Add source file to compiler sources and add path to header file to include paths in compiler options

Note

Check System functions for function prototypes.

Example: Low-level driver for WIN32

Example code for low-level porting on WIN32 platform. It uses native Windows features to open COM port and read/write from/to it.

Notes:

  • It uses separate thread for received data processing. It uses lwesp_input_process() or lwesp_input() functions, based on application configuration of LWESP_CFG_INPUT_USE_PROCESS parameter.

    • When LWESP_CFG_INPUT_USE_PROCESS is disabled, dedicated receive buffer is created by ESP-AT library and lwesp_input() function just writes data to it and does not process received characters immediately. This is handled by Processing thread at later stage instead.

    • When LWESP_CFG_INPUT_USE_PROCESS is enabled, lwesp_input_process() is used, which directly processes input data and sends potential callback/event functions to application layer.

  • Memory manager has been assigned to 1 region of LWESP_MEM_SIZE size

  • It sets send and reset callback functions for ESP-AT library

Actual implementation of low-level driver for WIN32
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/**
 * \file            lwesp_ll_win32.c
 * \brief           Low-level communication with ESP device for WIN32
 */

/*
 * Copyright (c) 2020 Tilen MAJERLE
 *
 * 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.
 *
 * This file is part of LwESP - Lightweight ESP-AT parser library.
 *
 * Author:          Tilen MAJERLE <tilen@majerle.eu>
 * Version:         $_version_$
 */
#include "system/lwesp_ll.h"
#include "lwesp/lwesp.h"
#include "lwesp/lwesp_mem.h"
#include "lwesp/lwesp_input.h"

#if !__DOXYGEN__

volatile uint8_t lwesp_ll_win32_driver_ignore_data;
static uint8_t initialized = 0;
static HANDLE thread_handle;
static volatile HANDLE com_port;                /*!< COM port handle */
static uint8_t data_buffer[0x1000];             /*!< Received data array */

static void uart_thread(void* param);

/**
 * \brief           Send data to ESP device, function called from ESP stack when we have data to send
 */
static size_t
send_data(const void* data, size_t len) {
    DWORD written;
    if (com_port != NULL) {
#if !LWESP_CFG_AT_ECHO
        const uint8_t* d = data;
        HANDLE hConsole;

        hConsole = GetStdHandle(STD_OUTPUT_HANDLE);
        SetConsoleTextAttribute(hConsole, FOREGROUND_RED);
        for (DWORD i = 0; i < len; ++i) {
            printf("%c", d[i]);
        }
        SetConsoleTextAttribute(hConsole, FOREGROUND_RED | FOREGROUND_GREEN | FOREGROUND_BLUE);
#endif /* !LWESP_CFG_AT_ECHO */

        WriteFile(com_port, data, len, &written, NULL);
        FlushFileBuffers(com_port);
        return written;
    }
    return 0;
}

/**
 * \brief           Configure UART (USB to UART)
 */
static void
configure_uart(uint32_t baudrate) {
    DCB dcb = { 0 };
    dcb.DCBlength = sizeof(dcb);

    /*
     * On first call,
     * create virtual file on selected COM port and open it
     * as generic read and write
     */
    if (!initialized) {
        com_port = CreateFile(L"\\\\.\\COM4",
                              GENERIC_READ | GENERIC_WRITE,
                              0,
                              0,
                              OPEN_EXISTING,
                              0,
                              NULL
                             );
    }

    /* Configure COM port parameters */
    if (GetCommState(com_port, &dcb)) {
        COMMTIMEOUTS timeouts;

        dcb.BaudRate = baudrate;
        dcb.ByteSize = 8;
        dcb.Parity = NOPARITY;
        dcb.StopBits = ONESTOPBIT;

        if (!SetCommState(com_port, &dcb)) {
            printf("Cannot set COM PORT info\r\n");
        }
        if (GetCommTimeouts(com_port, &timeouts)) {
            /* Set timeout to return immediately from ReadFile function */
            timeouts.ReadIntervalTimeout = MAXDWORD;
            timeouts.ReadTotalTimeoutConstant = 0;
            timeouts.ReadTotalTimeoutMultiplier = 0;
            if (!SetCommTimeouts(com_port, &timeouts)) {
                printf("Cannot set COM PORT timeouts\r\n");
            }
            GetCommTimeouts(com_port, &timeouts);
        } else {
            printf("Cannot get COM PORT timeouts\r\n");
        }
    } else {
        printf("Cannot get COM PORT info\r\n");
    }

    /* On first function call, create a thread to read data from COM port */
    if (!initialized) {
        lwesp_sys_thread_create(&thread_handle, "lwesp_ll_thread", uart_thread, NULL, 0, 0);
    }
}

/**
 * \brief           UART thread
 */
static void
uart_thread(void* param) {
    DWORD bytes_read;
    lwesp_sys_sem_t sem;
    FILE* file = NULL;

    lwesp_sys_sem_create(&sem, 0);              /* Create semaphore for delay functions */

    while (com_port == NULL) {
        lwesp_sys_sem_wait(&sem, 1);            /* Add some delay with yield */
    }

    fopen_s(&file, "log_file.txt", "w+");       /* Open debug file in write mode */
    while (1) {
        /*
         * Try to read data from COM port
         * and send it to upper layer for processing
         */
        do {
            ReadFile(com_port, data_buffer, sizeof(data_buffer), &bytes_read, NULL);
            if (bytes_read > 0) {
                HANDLE hConsole;
                hConsole = GetStdHandle(STD_OUTPUT_HANDLE);
                SetConsoleTextAttribute(hConsole, FOREGROUND_GREEN);
                for (DWORD i = 0; i < bytes_read; ++i) {
                    printf("%c", data_buffer[i]);
                }
                SetConsoleTextAttribute(hConsole, FOREGROUND_RED | FOREGROUND_GREEN | FOREGROUND_BLUE);

                if (lwesp_ll_win32_driver_ignore_data) {
                    printf("IGNORING..\r\n");
                    continue;
                }

                /* Send received data to input processing module */
#if LWESP_CFG_INPUT_USE_PROCESS
                lwesp_input_process(data_buffer, (size_t)bytes_read);
#else /* LWESP_CFG_INPUT_USE_PROCESS */
                lwesp_input(data_buffer, (size_t)bytes_read);
#endif /* !LWESP_CFG_INPUT_USE_PROCESS */

                /* Write received data to output debug file */
                if (file != NULL) {
                    fwrite(data_buffer, 1, bytes_read, file);
                    fflush(file);
                }
            }
        } while (bytes_read == (DWORD)sizeof(data_buffer));

        /* Implement delay to allow other tasks processing */
        lwesp_sys_sem_wait(&sem, 1);
    }
}

/**
 * \brief           Reset device GPIO management
 */
static uint8_t
reset_device(uint8_t state) {
    return 0;                                   /* Hardware reset was not successful */
}

/**
 * \brief           Callback function called from initialization process
 */
lwespr_t
lwesp_ll_init(lwesp_ll_t* ll) {
#if !LWESP_CFG_MEM_CUSTOM
    /* Step 1: Configure memory for dynamic allocations */
    static uint8_t memory[0x10000];             /* Create memory for dynamic allocations with specific size */

    /*
     * Create memory region(s) of memory.
     * If device has internal/external memory available,
     * multiple memories may be used
     */
    lwesp_mem_region_t mem_regions[] = {
        { memory, sizeof(memory) }
    };
    if (!initialized) {
        lwesp_mem_assignmemory(mem_regions, LWESP_ARRAYSIZE(mem_regions));  /* Assign memory for allocations to ESP library */
    }
#endif /* !LWESP_CFG_MEM_CUSTOM */

    /* Step 2: Set AT port send function to use when we have data to transmit */
    if (!initialized) {
        ll->send_fn = send_data;                /* Set callback function to send data */
        ll->reset_fn = reset_device;
    }

    /* Step 3: Configure AT port to be able to send/receive data to/from ESP device */
    configure_uart(ll->uart.baudrate);          /* Initialize UART for communication */
    initialized = 1;
    return lwespOK;
}

/**
 * \brief           Callback function to de-init low-level communication part
 */
lwespr_t
lwesp_ll_deinit(lwesp_ll_t* ll) {
    if (thread_handle != NULL) {
        lwesp_sys_thread_terminate(&thread_handle);
        thread_handle = NULL;
    }
    initialized = 0;                            /* Clear initialized flag */
    return lwespOK;
}

#endif /* !__DOXYGEN__ */

Example: Low-level driver for STM32

Example code for low-level porting on STM32 platform. It uses CMSIS-OS based application layer functions for implementing threads & other OS dependent features.

Notes:

  • It uses separate thread for received data processing. It uses lwesp_input_process() function to directly process received data without using intermediate receive buffer

  • Memory manager has been assigned to 1 region of LWESP_MEM_SIZE size

  • It sets send and reset callback functions for ESP-AT library

Actual implementation of low-level driver for STM32
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/**
 * \file            lwesp_ll_stm32.c
 * \brief           Generic STM32 driver, included in various STM32 driver variants
 */

/*
 * Copyright (c) 2020 Tilen MAJERLE
 *
 * 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.
 *
 * This file is part of LwESP - Lightweight ESP-AT parser library.
 *
 * Author:          Tilen MAJERLE <tilen@majerle.eu>
 * Version:         $_version_$
 */

/*
 * How it works
 *
 * On first call to \ref lwesp_ll_init, new thread is created and processed in usart_ll_thread function.
 * USART is configured in RX DMA mode and any incoming bytes are processed inside thread function.
 * DMA and USART implement interrupt handlers to notify main thread about new data ready to send to upper layer.
 *
 * More about UART + RX DMA: https://github.com/MaJerle/stm32-usart-dma-rx-tx
 *
 * \ref LWESP_CFG_INPUT_USE_PROCESS must be enabled in `lwesp_config.h` to use this driver.
 */
#include "lwesp/lwesp.h"
#include "lwesp/lwesp_mem.h"
#include "lwesp/lwesp_input.h"
#include "system/lwesp_ll.h"

#if !__DOXYGEN__

#if !LWESP_CFG_INPUT_USE_PROCESS
#error "LWESP_CFG_INPUT_USE_PROCESS must be enabled in `lwesp_config.h` to use this driver."
#endif /* LWESP_CFG_INPUT_USE_PROCESS */

#if !defined(LWESP_USART_DMA_RX_BUFF_SIZE)
#define LWESP_USART_DMA_RX_BUFF_SIZE      0x1000
#endif /* !defined(LWESP_USART_DMA_RX_BUFF_SIZE) */

#if !defined(LWESP_MEM_SIZE)
#define LWESP_MEM_SIZE                    0x1000
#endif /* !defined(LWESP_MEM_SIZE) */

#if !defined(LWESP_USART_RDR_NAME)
#define LWESP_USART_RDR_NAME              RDR
#endif /* !defined(LWESP_USART_RDR_NAME) */

/* USART memory */
static uint8_t      usart_mem[LWESP_USART_DMA_RX_BUFF_SIZE];
static uint8_t      is_running, initialized;
static size_t       old_pos;

/* USART thread */
static void usart_ll_thread(void* arg);
static osThreadId_t usart_ll_thread_id;

/* Message queue */
static osMessageQueueId_t usart_ll_mbox_id;

/**
 * \brief           USART data processing
 */
static void
usart_ll_thread(void* arg) {
    size_t pos;

    LWESP_UNUSED(arg);

    while (1) {
        void* d;
        /* Wait for the event message from DMA or USART */
        osMessageQueueGet(usart_ll_mbox_id, &d, NULL, osWaitForever);

        /* Read data */
#if defined(LWESP_USART_DMA_RX_STREAM)
        pos = sizeof(usart_mem) - LL_DMA_GetDataLength(LWESP_USART_DMA, LWESP_USART_DMA_RX_STREAM);
#else
        pos = sizeof(usart_mem) - LL_DMA_GetDataLength(LWESP_USART_DMA, LWESP_USART_DMA_RX_CH);
#endif /* defined(LWESP_USART_DMA_RX_STREAM) */
        if (pos != old_pos && is_running) {
            if (pos > old_pos) {
                lwesp_input_process(&usart_mem[old_pos], pos - old_pos);
            } else {
                lwesp_input_process(&usart_mem[old_pos], sizeof(usart_mem) - old_pos);
                if (pos > 0) {
                    lwesp_input_process(&usart_mem[0], pos);
                }
            }
            old_pos = pos;
            if (old_pos == sizeof(usart_mem)) {
                old_pos = 0;
            }
        }
    }
}

/**
 * \brief           Configure UART using DMA for receive in double buffer mode and IDLE line detection
 */
static void
configure_uart(uint32_t baudrate) {
    static LL_USART_InitTypeDef usart_init;
    static LL_DMA_InitTypeDef dma_init;
    LL_GPIO_InitTypeDef gpio_init;

    if (!initialized) {
        /* Enable peripheral clocks */
        LWESP_USART_CLK;
        LWESP_USART_DMA_CLK;
        LWESP_USART_TX_PORT_CLK;
        LWESP_USART_RX_PORT_CLK;

#if defined(LWESP_RESET_PIN)
        LWESP_RESET_PORT_CLK;
#endif /* defined(LWESP_RESET_PIN) */

#if defined(LWESP_GPIO0_PIN)
        LWESP_GPIO0_PORT_CLK;
#endif /* defined(LWESP_GPIO0_PIN) */

#if defined(LWESP_GPIO2_PIN)
        LWESP_GPIO2_PORT_CLK;
#endif /* defined(LWESP_GPIO2_PIN) */

#if defined(LWESP_CH_PD_PIN)
        LWESP_CH_PD_PORT_CLK;
#endif /* defined(LWESP_CH_PD_PIN) */

        /* Global pin configuration */
        LL_GPIO_StructInit(&gpio_init);
        gpio_init.OutputType = LL_GPIO_OUTPUT_PUSHPULL;
        gpio_init.Pull = LL_GPIO_PULL_UP;
        gpio_init.Speed = LL_GPIO_SPEED_FREQ_VERY_HIGH;
        gpio_init.Mode = LL_GPIO_MODE_OUTPUT;

#if defined(LWESP_RESET_PIN)
        /* Configure RESET pin */
        gpio_init.Pin = LWESP_RESET_PIN;
        LL_GPIO_Init(LWESP_RESET_PORT, &gpio_init);
#endif /* defined(LWESP_RESET_PIN) */

#if defined(LWESP_GPIO0_PIN)
        /* Configure GPIO0 pin */
        gpio_init.Pin = LWESP_GPIO0_PIN;
        LL_GPIO_Init(LWESP_GPIO0_PORT, &gpio_init);
        LL_GPIO_SetOutputPin(LWESP_GPIO0_PORT, LWESP_GPIO0_PIN);
#endif /* defined(LWESP_GPIO0_PIN) */

#if defined(LWESP_GPIO2_PIN)
        /* Configure GPIO2 pin */
        gpio_init.Pin = LWESP_GPIO2_PIN;
        LL_GPIO_Init(LWESP_GPIO2_PORT, &gpio_init);
        LL_GPIO_SetOutputPin(LWESP_GPIO2_PORT, LWESP_GPIO2_PIN);
#endif /* defined(LWESP_GPIO2_PIN) */

#if defined(LWESP_CH_PD_PIN)
        /* Configure CH_PD pin */
        gpio_init.Pin = LWESP_CH_PD_PIN;
        LL_GPIO_Init(LWESP_CH_PD_PORT, &gpio_init);
        LL_GPIO_SetOutputPin(LWESP_CH_PD_PORT, LWESP_CH_PD_PIN);
#endif /* defined(LWESP_CH_PD_PIN) */

        /* Configure USART pins */
        gpio_init.Mode = LL_GPIO_MODE_ALTERNATE;

        /* TX PIN */
        gpio_init.Alternate = LWESP_USART_TX_PIN_AF;
        gpio_init.Pin = LWESP_USART_TX_PIN;
        LL_GPIO_Init(LWESP_USART_TX_PORT, &gpio_init);

        /* RX PIN */
        gpio_init.Alternate = LWESP_USART_RX_PIN_AF;
        gpio_init.Pin = LWESP_USART_RX_PIN;
        LL_GPIO_Init(LWESP_USART_RX_PORT, &gpio_init);

        /* Configure UART */
        LL_USART_DeInit(LWESP_USART);
        LL_USART_StructInit(&usart_init);
        usart_init.BaudRate = baudrate;
        usart_init.DataWidth = LL_USART_DATAWIDTH_8B;
        usart_init.HardwareFlowControl = LL_USART_HWCONTROL_NONE;
        usart_init.OverSampling = LL_USART_OVERSAMPLING_16;
        usart_init.Parity = LL_USART_PARITY_NONE;
        usart_init.StopBits = LL_USART_STOPBITS_1;
        usart_init.TransferDirection = LL_USART_DIRECTION_TX_RX;
        LL_USART_Init(LWESP_USART, &usart_init);

        /* Enable USART interrupts and DMA request */
        LL_USART_EnableIT_IDLE(LWESP_USART);
        LL_USART_EnableIT_PE(LWESP_USART);
        LL_USART_EnableIT_ERROR(LWESP_USART);
        LL_USART_EnableDMAReq_RX(LWESP_USART);

        /* Enable USART interrupts */
        NVIC_SetPriority(LWESP_USART_IRQ, NVIC_EncodePriority(NVIC_GetPriorityGrouping(), 0x07, 0x00));
        NVIC_EnableIRQ(LWESP_USART_IRQ);

        /* Configure DMA */
        is_running = 0;
#if defined(LWESP_USART_DMA_RX_STREAM)
        LL_DMA_DeInit(LWESP_USART_DMA, LWESP_USART_DMA_RX_STREAM);
        dma_init.Channel = LWESP_USART_DMA_RX_CH;
#else
        LL_DMA_DeInit(LWESP_USART_DMA, LWESP_USART_DMA_RX_CH);
        dma_init.PeriphRequest = LWESP_USART_DMA_RX_REQ_NUM;
#endif /* defined(LWESP_USART_DMA_RX_STREAM) */
        dma_init.PeriphOrM2MSrcAddress = (uint32_t)&LWESP_USART->LWESP_USART_RDR_NAME;
        dma_init.MemoryOrM2MDstAddress = (uint32_t)usart_mem;
        dma_init.Direction = LL_DMA_DIRECTION_PERIPH_TO_MEMORY;
        dma_init.Mode = LL_DMA_MODE_CIRCULAR;
        dma_init.PeriphOrM2MSrcIncMode = LL_DMA_PERIPH_NOINCREMENT;
        dma_init.MemoryOrM2MDstIncMode = LL_DMA_MEMORY_INCREMENT;
        dma_init.PeriphOrM2MSrcDataSize = LL_DMA_PDATAALIGN_BYTE;
        dma_init.MemoryOrM2MDstDataSize = LL_DMA_MDATAALIGN_BYTE;
        dma_init.NbData = sizeof(usart_mem);
        dma_init.Priority = LL_DMA_PRIORITY_MEDIUM;
#if defined(LWESP_USART_DMA_RX_STREAM)
        LL_DMA_Init(LWESP_USART_DMA, LWESP_USART_DMA_RX_STREAM, &dma_init);
#else
        LL_DMA_Init(LWESP_USART_DMA, LWESP_USART_DMA_RX_CH, &dma_init);
#endif /* defined(LWESP_USART_DMA_RX_STREAM) */

        /* Enable DMA interrupts */
#if defined(LWESP_USART_DMA_RX_STREAM)
        LL_DMA_EnableIT_HT(LWESP_USART_DMA, LWESP_USART_DMA_RX_STREAM);
        LL_DMA_EnableIT_TC(LWESP_USART_DMA, LWESP_USART_DMA_RX_STREAM);
        LL_DMA_EnableIT_TE(LWESP_USART_DMA, LWESP_USART_DMA_RX_STREAM);
        LL_DMA_EnableIT_FE(LWESP_USART_DMA, LWESP_USART_DMA_RX_STREAM);
        LL_DMA_EnableIT_DME(LWESP_USART_DMA, LWESP_USART_DMA_RX_STREAM);
#else
        LL_DMA_EnableIT_HT(LWESP_USART_DMA, LWESP_USART_DMA_RX_CH);
        LL_DMA_EnableIT_TC(LWESP_USART_DMA, LWESP_USART_DMA_RX_CH);
        LL_DMA_EnableIT_TE(LWESP_USART_DMA, LWESP_USART_DMA_RX_CH);
#endif /* defined(LWESP_USART_DMA_RX_STREAM) */

        /* Enable DMA interrupts */
        NVIC_SetPriority(LWESP_USART_DMA_RX_IRQ, NVIC_EncodePriority(NVIC_GetPriorityGrouping(), 0x07, 0x00));
        NVIC_EnableIRQ(LWESP_USART_DMA_RX_IRQ);

        old_pos = 0;
        is_running = 1;

        /* Start DMA and USART */
#if defined(LWESP_USART_DMA_RX_STREAM)
        LL_DMA_EnableStream(LWESP_USART_DMA, LWESP_USART_DMA_RX_STREAM);
#else
        LL_DMA_EnableChannel(LWESP_USART_DMA, LWESP_USART_DMA_RX_CH);
#endif /* defined(LWESP_USART_DMA_RX_STREAM) */
        LL_USART_Enable(LWESP_USART);
    } else {
        osDelay(10);
        LL_USART_Disable(LWESP_USART);
        usart_init.BaudRate = baudrate;
        LL_USART_Init(LWESP_USART, &usart_init);
        LL_USART_Enable(LWESP_USART);
    }

    /* Create mbox and start thread */
    if (usart_ll_mbox_id == NULL) {
        usart_ll_mbox_id = osMessageQueueNew(10, sizeof(void*), NULL);
    }
    if (usart_ll_thread_id == NULL) {
        const osThreadAttr_t attr = {
            .stack_size = 1024
        };
        usart_ll_thread_id = osThreadNew(usart_ll_thread, usart_ll_mbox_id, &attr);
    }
}

#if defined(LWESP_RESET_PIN)
/**
 * \brief           Hardware reset callback
 */
static uint8_t
reset_device(uint8_t state) {
    if (state) {                                /* Activate reset line */
        LL_GPIO_ResetOutputPin(LWESP_RESET_PORT, LWESP_RESET_PIN);
    } else {
        LL_GPIO_SetOutputPin(LWESP_RESET_PORT, LWESP_RESET_PIN);
    }
    return 1;
}
#endif /* defined(LWESP_RESET_PIN) */

/**
 * \brief           Send data to ESP device
 * \param[in]       data: Pointer to data to send
 * \param[in]       len: Number of bytes to send
 * \return          Number of bytes sent
 */
static size_t
send_data(const void* data, size_t len) {
    const uint8_t* d = data;

    for (size_t i = 0; i < len; ++i, ++d) {
        LL_USART_TransmitData8(LWESP_USART, *d);
        while (!LL_USART_IsActiveFlag_TXE(LWESP_USART)) {}
    }
    return len;
}

/**
 * \brief           Callback function called from initialization process
 */
lwespr_t
lwesp_ll_init(lwesp_ll_t* ll) {
#if !LWESP_CFG_MEM_CUSTOM
    static uint8_t memory[LWESP_MEM_SIZE];
    lwesp_mem_region_t mem_regions[] = {
        { memory, sizeof(memory) }
    };

    if (!initialized) {
        lwesp_mem_assignmemory(mem_regions, LWESP_ARRAYSIZE(mem_regions));  /* Assign memory for allocations */
    }
#endif /* !LWESP_CFG_MEM_CUSTOM */

    if (!initialized) {
        ll->send_fn = send_data;                /* Set callback function to send data */
#if defined(LWESP_RESET_PIN)
        ll->reset_fn = reset_device;            /* Set callback for hardware reset */
#endif /* defined(LWESP_RESET_PIN) */
    }

    configure_uart(ll->uart.baudrate);          /* Initialize UART for communication */
    initialized = 1;
    return lwespOK;
}

/**
 * \brief           Callback function to de-init low-level communication part
 */
lwespr_t
lwesp_ll_deinit(lwesp_ll_t* ll) {
    if (usart_ll_mbox_id != NULL) {
        osMessageQueueId_t tmp = usart_ll_mbox_id;
        usart_ll_mbox_id = NULL;
        osMessageQueueDelete(tmp);
    }
    if (usart_ll_thread_id != NULL) {
        osThreadId_t tmp = usart_ll_thread_id;
        usart_ll_thread_id = NULL;
        osThreadTerminate(tmp);
    }
    initialized = 0;
    LWESP_UNUSED(ll);
    return lwespOK;
}

/**
 * \brief           UART global interrupt handler
 */
void
LWESP_USART_IRQHANDLER(void) {
    LL_USART_ClearFlag_IDLE(LWESP_USART);
    LL_USART_ClearFlag_PE(LWESP_USART);
    LL_USART_ClearFlag_FE(LWESP_USART);
    LL_USART_ClearFlag_ORE(LWESP_USART);
    LL_USART_ClearFlag_NE(LWESP_USART);

    if (usart_ll_mbox_id != NULL) {
        void* d = (void*)1;
        osMessageQueuePut(usart_ll_mbox_id, &d, 0, 0);
    }
}

/**
 * \brief           UART DMA stream/channel handler
 */
void
LWESP_USART_DMA_RX_IRQHANDLER(void) {
    LWESP_USART_DMA_RX_CLEAR_TC;
    LWESP_USART_DMA_RX_CLEAR_HT;

    if (usart_ll_mbox_id != NULL) {
        void* d = (void*)1;
        osMessageQueuePut(usart_ll_mbox_id, &d, 0, 0);
    }
}

#endif /* !__DOXYGEN__ */

Example: System functions for WIN32

Actual header implementation of system functions for WIN32
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/**
 * \file            lwesp_sys_port.h
 * \brief           WIN32 based system file implementation
 */

/*
 * Copyright (c) 2020 Tilen MAJERLE
 *
 * 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.
 *
 * This file is part of LwESP - Lightweight ESP-AT parser library.
 *
 * Author:          Tilen MAJERLE <tilen@majerle.eu>
 * Version:         $_version_$
 */
#ifndef LWESP_HDR_SYSTEM_PORT_H
#define LWESP_HDR_SYSTEM_PORT_H

#include <stdint.h>
#include <stdlib.h>
#include "lwesp/lwesp_opt.h"
#include "windows.h"

#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */

#if LWESP_CFG_OS && !__DOXYGEN__

typedef HANDLE                      lwesp_sys_mutex_t;
typedef HANDLE                      lwesp_sys_sem_t;
typedef HANDLE                      lwesp_sys_mbox_t;
typedef HANDLE                      lwesp_sys_thread_t;
typedef int                         lwesp_sys_thread_prio_t;

#define LWESP_SYS_MBOX_NULL           ((HANDLE)0)
#define LWESP_SYS_SEM_NULL            ((HANDLE)0)
#define LWESP_SYS_MUTEX_NULL          ((HANDLE)0)
#define LWESP_SYS_TIMEOUT             (INFINITE)
#define LWESP_SYS_THREAD_PRIO         (0)
#define LWESP_SYS_THREAD_SS           (1024)

#endif /* LWESP_CFG_OS && !__DOXYGEN__ */

#ifdef __cplusplus
}
#endif /* __cplusplus */

#endif /* LWESP_HDR_SYSTEM_PORT_H */
Actual implementation of system functions for WIN32
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/**
 * \file            lwesp_sys_win32.c
 * \brief           System dependant functions for WIN32
 */

/*
 * Copyright (c) 2020 Tilen MAJERLE
 *
 * 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.
 *
 * This file is part of LwESP - Lightweight ESP-AT parser library.
 *
 * Author:          Tilen MAJERLE <tilen@majerle.eu>
 * Version:         $_version_$
 */
#include <string.h>
#include <stdlib.h>
#include "system/lwesp_sys.h"
#include "windows.h"

#if !__DOXYGEN__

/**
 * \brief           Custom message queue implementation for WIN32
 */
typedef struct {
    lwesp_sys_sem_t sem_not_empty;              /*!< Semaphore indicates not empty */
    lwesp_sys_sem_t sem_not_full;               /*!< Semaphore indicates not full */
    lwesp_sys_sem_t sem;                        /*!< Semaphore to lock access */
    size_t in, out, size;
    void* entries[1];
} win32_mbox_t;

static LARGE_INTEGER freq, sys_start_time;
static lwesp_sys_mutex_t sys_mutex;             /* Mutex ID for main protection */

/**
 * \brief           Check if message box is full
 * \param[in]       m: Message box handle
 * \return          1 if full, 0 otherwise
 */
static uint8_t
mbox_is_full(win32_mbox_t* m) {
    size_t size = 0;
    if (m->in > m->out) {
        size = (m->in - m->out);
    } else if (m->out > m->in) {
        size = m->size - m->out + m->in;
    }
    return size == m->size - 1;
}

/**
 * \brief           Check if message box is empty
 * \param[in]       m: Message box handle
 * \return          1 if empty, 0 otherwise
 */
static uint8_t
mbox_is_empty(win32_mbox_t* m) {
    return m->in == m->out;
}

/**
 * \brief           Get current kernel time in units of milliseconds
 */
static uint32_t
osKernelSysTick(void) {
    LONGLONG ret;
    LARGE_INTEGER now;

    QueryPerformanceFrequency(&freq);           /* Get frequency */
    QueryPerformanceCounter(&now);              /* Get current time */
    ret = now.QuadPart - sys_start_time.QuadPart;
    return (uint32_t)(((ret) * 1000) / freq.QuadPart);
}

uint8_t
lwesp_sys_init(void) {
    QueryPerformanceFrequency(&freq);
    QueryPerformanceCounter(&sys_start_time);

    lwesp_sys_mutex_create(&sys_mutex);
    return 1;
}

uint32_t
lwesp_sys_now(void) {
    return osKernelSysTick();
}

#if LWESP_CFG_OS
uint8_t
lwesp_sys_protect(void) {
    lwesp_sys_mutex_lock(&sys_mutex);
    return 1;
}

uint8_t
lwesp_sys_unprotect(void) {
    lwesp_sys_mutex_unlock(&sys_mutex);
    return 1;
}

uint8_t
lwesp_sys_mutex_create(lwesp_sys_mutex_t* p) {
    *p = CreateMutex(NULL, FALSE, NULL);
    return *p != NULL;
}

uint8_t
lwesp_sys_mutex_delete(lwesp_sys_mutex_t* p) {
    return CloseHandle(*p);
}

uint8_t
lwesp_sys_mutex_lock(lwesp_sys_mutex_t* p) {
    DWORD ret;
    ret = WaitForSingleObject(*p, INFINITE);
    if (ret != WAIT_OBJECT_0) {
        return 0;
    }
    return 1;
}

uint8_t
lwesp_sys_mutex_unlock(lwesp_sys_mutex_t* p) {
    return ReleaseMutex(*p);
}

uint8_t
lwesp_sys_mutex_isvalid(lwesp_sys_mutex_t* p) {
    return p != NULL && *p != NULL;
}

uint8_t
lwesp_sys_mutex_invalid(lwesp_sys_mutex_t* p) {
    *p = LWESP_SYS_MUTEX_NULL;
    return 1;
}

uint8_t
lwesp_sys_sem_create(lwesp_sys_sem_t* p, uint8_t cnt) {
    HANDLE h;
    h = CreateSemaphore(NULL, !!cnt, 1, NULL);
    *p = h;
    return *p != NULL;
}

uint8_t
lwesp_sys_sem_delete(lwesp_sys_sem_t* p) {
    return CloseHandle(*p);
}

uint32_t
lwesp_sys_sem_wait(lwesp_sys_sem_t* p, uint32_t timeout) {
    DWORD ret;
    uint32_t tick = osKernelSysTick();

    if (timeout == 0) {
        ret = WaitForSingleObject(*p, INFINITE);
        return 1;
    } else {
        ret = WaitForSingleObject(*p, timeout);
        if (ret == WAIT_OBJECT_0) {
            return 1;
        } else {
            return LWESP_SYS_TIMEOUT;
        }
    }
}

uint8_t
lwesp_sys_sem_release(lwesp_sys_sem_t* p) {
    return ReleaseSemaphore(*p, 1, NULL);
}

uint8_t
lwesp_sys_sem_isvalid(lwesp_sys_sem_t* p) {
    return p != NULL && *p != NULL;
}

uint8_t
lwesp_sys_sem_invalid(lwesp_sys_sem_t* p) {
    *p = LWESP_SYS_SEM_NULL;
    return 1;
}

uint8_t
lwesp_sys_mbox_create(lwesp_sys_mbox_t* b, size_t size) {
    win32_mbox_t* mbox;

    *b = 0;

    mbox = malloc(sizeof(*mbox) + size * sizeof(void*));
    if (mbox != NULL) {
        memset(mbox, 0x00, sizeof(*mbox));
        mbox->size = size + 1;                  /* Set it to 1 more as cyclic buffer has only one less than size */
        lwesp_sys_sem_create(&mbox->sem, 1);
        lwesp_sys_sem_create(&mbox->sem_not_empty, 0);
        lwesp_sys_sem_create(&mbox->sem_not_full, 0);
        *b = mbox;
    }
    return *b != NULL;
}

uint8_t
lwesp_sys_mbox_delete(lwesp_sys_mbox_t* b) {
    win32_mbox_t* mbox = *b;
    lwesp_sys_sem_delete(&mbox->sem);
    lwesp_sys_sem_delete(&mbox->sem_not_full);
    lwesp_sys_sem_delete(&mbox->sem_not_empty);
    free(mbox);
    return 1;
}

uint32_t
lwesp_sys_mbox_put(lwesp_sys_mbox_t* b, void* m) {
    win32_mbox_t* mbox = *b;
    uint32_t time = osKernelSysTick();          /* Get start time */

    lwesp_sys_sem_wait(&mbox->sem, 0);          /* Wait for access */

    /*
     * Since function is blocking until ready to write something to queue,
     * wait and release the semaphores to allow other threads
     * to process the queue before we can write new value.
     */
    while (mbox_is_full(mbox)) {
        lwesp_sys_sem_release(&mbox->sem);      /* Release semaphore */
        lwesp_sys_sem_wait(&mbox->sem_not_full, 0); /* Wait for semaphore indicating not full */
        lwesp_sys_sem_wait(&mbox->sem, 0);      /* Wait availability again */
    }
    mbox->entries[mbox->in] = m;
    if (++mbox->in >= mbox->size) {
        mbox->in = 0;
    }
    lwesp_sys_sem_release(&mbox->sem_not_empty);/* Signal non-empty state */
    lwesp_sys_sem_release(&mbox->sem);          /* Release access for other threads */
    return osKernelSysTick() - time;
}

uint32_t
lwesp_sys_mbox_get(lwesp_sys_mbox_t* b, void** m, uint32_t timeout) {
    win32_mbox_t* mbox = *b;
    uint32_t time;

    time = osKernelSysTick();

    /* Get exclusive access to message queue */
    if (lwesp_sys_sem_wait(&mbox->sem, timeout) == LWESP_SYS_TIMEOUT) {
        return LWESP_SYS_TIMEOUT;
    }
    while (mbox_is_empty(mbox)) {
        lwesp_sys_sem_release(&mbox->sem);
        if (lwesp_sys_sem_wait(&mbox->sem_not_empty, timeout) == LWESP_SYS_TIMEOUT) {
            return LWESP_SYS_TIMEOUT;
        }
        lwesp_sys_sem_wait(&mbox->sem, timeout);
    }
    *m = mbox->entries[mbox->out];
    if (++mbox->out >= mbox->size) {
        mbox->out = 0;
    }
    lwesp_sys_sem_release(&mbox->sem_not_full);
    lwesp_sys_sem_release(&mbox->sem);

    return osKernelSysTick() - time;
}

uint8_t
lwesp_sys_mbox_putnow(lwesp_sys_mbox_t* b, void* m) {
    win32_mbox_t* mbox = *b;

    lwesp_sys_sem_wait(&mbox->sem, 0);
    if (mbox_is_full(mbox)) {
        lwesp_sys_sem_release(&mbox->sem);
        return 0;
    }
    mbox->entries[mbox->in] = m;
    if (mbox->in == mbox->out) {
        lwesp_sys_sem_release(&mbox->sem_not_empty);
    }
    if (++mbox->in >= mbox->size) {
        mbox->in = 0;
    }
    lwesp_sys_sem_release(&mbox->sem);
    return 1;
}

uint8_t
lwesp_sys_mbox_getnow(lwesp_sys_mbox_t* b, void** m) {
    win32_mbox_t* mbox = *b;

    lwesp_sys_sem_wait(&mbox->sem, 0);          /* Wait exclusive access */
    if (mbox->in == mbox->out) {
        lwesp_sys_sem_release(&mbox->sem);      /* Release access */
        return 0;
    }

    *m = mbox->entries[mbox->out];
    if (++mbox->out >= mbox->size) {
        mbox->out = 0;
    }
    lwesp_sys_sem_release(&mbox->sem_not_full); /* Queue not full anymore */
    lwesp_sys_sem_release(&mbox->sem);          /* Release semaphore */
    return 1;
}

uint8_t
lwesp_sys_mbox_isvalid(lwesp_sys_mbox_t* b) {
    return b != NULL && *b != NULL;
}

uint8_t
lwesp_sys_mbox_invalid(lwesp_sys_mbox_t* b) {
    *b = LWESP_SYS_MBOX_NULL;
    return 1;
}

uint8_t
lwesp_sys_thread_create(lwesp_sys_thread_t* t, const char* name, lwesp_sys_thread_fn thread_func, void* const arg, size_t stack_size, lwesp_sys_thread_prio_t prio) {
    HANDLE h;
    DWORD id;
    h = CreateThread(0, 0, (LPTHREAD_START_ROUTINE)thread_func, arg, 0, &id);
    if (t != NULL) {
        *t = h;
    }
    return h != NULL;
}

uint8_t
lwesp_sys_thread_terminate(lwesp_sys_thread_t* t) {
    HANDLE h = NULL;

    if (t == NULL) {                            /* Shall we terminate ourself? */
        h = GetCurrentThread();                 /* Get current thread handle */
    } else {                                    /* We have known thread, find handle by looking at ID */
        h = *t;
    }
    TerminateThread(h, 0);
    return 1;
}

uint8_t
lwesp_sys_thread_yield(void) {
    /* Not implemented */
    return 1;
}

#endif /* LWESP_CFG_OS */
#endif /* !__DOXYGEN__ */

Example: System functions for CMSIS-OS

Actual header implementation of system functions for CMSIS-OS based operating systems
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/**
 * \file            lwesp_sys_port.h
 * \brief           CMSIS-OS based system file
 */

/*
 * Copyright (c) 2020 Tilen MAJERLE
 *
 * 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.
 *
 * This file is part of LwESP - Lightweight ESP-AT parser library.
 *
 * Author:          Tilen MAJERLE <tilen@majerle.eu>
 * Version:         $_version_$
 */
#ifndef LWESP_HDR_SYSTEM_PORT_H
#define LWESP_HDR_SYSTEM_PORT_H

#include <stdint.h>
#include <stdlib.h>
#include "lwesp/lwesp_opt.h"
#include "cmsis_os.h"

#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */

#if LWESP_CFG_OS && !__DOXYGEN__

typedef osMutexId_t                 lwesp_sys_mutex_t;
typedef osSemaphoreId_t             lwesp_sys_sem_t;
typedef osMessageQueueId_t          lwesp_sys_mbox_t;
typedef osThreadId_t                lwesp_sys_thread_t;
typedef osPriority_t                lwesp_sys_thread_prio_t;

#define LWESP_SYS_MUTEX_NULL          ((lwesp_sys_mutex_t)0)
#define LWESP_SYS_SEM_NULL            ((lwesp_sys_sem_t)0)
#define LWESP_SYS_MBOX_NULL           ((lwesp_sys_mbox_t)0)
#define LWESP_SYS_TIMEOUT             ((uint32_t)osWaitForever)
#define LWESP_SYS_THREAD_PRIO         (osPriorityNormal)
#define LWESP_SYS_THREAD_SS           (512)

#endif /* LWESP_CFG_OS && !__DOXYGEN__ */

#ifdef __cplusplus
}
#endif /* __cplusplus */

#endif /* LWESP_HDR_SYSTEM_PORT_H */
Actual implementation of system functions for CMSIS-OS based operating systems
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/**
 * \file            lwesp_sys_cmsis_os.c
 * \brief           System dependent functions for CMSIS based operating system
 */

/*
 * Copyright (c) 2020 Tilen MAJERLE
 *
 * 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.
 *
 * This file is part of LwESP - Lightweight ESP-AT parser library.
 *
 * Author:          Tilen MAJERLE <tilen@majerle.eu>
 * Version:         $_version_$
 */
#include "system/lwesp_sys.h"
#include "cmsis_os.h"

#if !__DOXYGEN__

static osMutexId_t sys_mutex;

uint8_t
lwesp_sys_init(void) {
    lwesp_sys_mutex_create(&sys_mutex);
    return 1;
}

uint32_t
lwesp_sys_now(void) {
    return osKernelSysTick();
}

uint8_t
lwesp_sys_protect(void) {
    lwesp_sys_mutex_lock(&sys_mutex);
    return 1;
}

uint8_t
lwesp_sys_unprotect(void) {
    lwesp_sys_mutex_unlock(&sys_mutex);
    return 1;
}

uint8_t
lwesp_sys_mutex_create(lwesp_sys_mutex_t* p) {
    const osMutexAttr_t attr = {
        .attr_bits = osMutexRecursive
    };
    *p = osMutexNew(&attr);
    return *p != NULL;
}

uint8_t
lwesp_sys_mutex_delete(lwesp_sys_mutex_t* p) {
    return osMutexDelete(*p) == osOK;
}

uint8_t
lwesp_sys_mutex_lock(lwesp_sys_mutex_t* p) {
    return osMutexAcquire(*p, osWaitForever) == osOK;
}

uint8_t
lwesp_sys_mutex_unlock(lwesp_sys_mutex_t* p) {
    return osMutexRelease(*p) == osOK;
}

uint8_t
lwesp_sys_mutex_isvalid(lwesp_sys_mutex_t* p) {
    return p != NULL && *p != NULL;
}

uint8_t
lwesp_sys_mutex_invalid(lwesp_sys_mutex_t* p) {
    *p = LWESP_SYS_MUTEX_NULL;
    return 1;
}

uint8_t
lwesp_sys_sem_create(lwesp_sys_sem_t* p, uint8_t cnt) {
    return (*p = osSemaphoreNew(1, cnt > 0 ? 1 : 0, NULL)) != NULL;
}

uint8_t
lwesp_sys_sem_delete(lwesp_sys_sem_t* p) {
    return osSemaphoreDelete(*p) == osOK;
}

uint32_t
lwesp_sys_sem_wait(lwesp_sys_sem_t* p, uint32_t timeout) {
    uint32_t tick = osKernelSysTick();
    return (osSemaphoreAcquire(*p, timeout == 0 ? osWaitForever : timeout) == osOK) ? (osKernelSysTick() - tick) : LWESP_SYS_TIMEOUT;
}

uint8_t
lwesp_sys_sem_release(lwesp_sys_sem_t* p) {
    return osSemaphoreRelease(*p) == osOK;
}

uint8_t
lwesp_sys_sem_isvalid(lwesp_sys_sem_t* p) {
    return p != NULL && *p != NULL;
}

uint8_t
lwesp_sys_sem_invalid(lwesp_sys_sem_t* p) {
    *p = LWESP_SYS_SEM_NULL;
    return 1;
}

uint8_t
lwesp_sys_mbox_create(lwesp_sys_mbox_t* b, size_t size) {
    return (*b = osMessageQueueNew(size, sizeof(void*), NULL)) != NULL;
}

uint8_t
lwesp_sys_mbox_delete(lwesp_sys_mbox_t* b) {
    if (osMessageQueueGetCount(*b) > 0) {
        return 0;
    }
    return osMessageQueueDelete(*b) == osOK;
}

uint32_t
lwesp_sys_mbox_put(lwesp_sys_mbox_t* b, void* m) {
    uint32_t tick = osKernelSysTick();
    return osMessageQueuePut(*b, &m, 0, osWaitForever) == osOK ? (osKernelSysTick() - tick) : LWESP_SYS_TIMEOUT;
}

uint32_t
lwesp_sys_mbox_get(lwesp_sys_mbox_t* b, void** m, uint32_t timeout) {
    uint32_t tick = osKernelSysTick();
    return (osMessageQueueGet(*b, m, NULL, timeout == 0 ? osWaitForever : timeout) == osOK) ? (osKernelSysTick() - tick) : LWESP_SYS_TIMEOUT;
}

uint8_t
lwesp_sys_mbox_putnow(lwesp_sys_mbox_t* b, void* m) {
    return osMessageQueuePut(*b, &m, 0, 0) == osOK;
}

uint8_t
lwesp_sys_mbox_getnow(lwesp_sys_mbox_t* b, void** m) {
    return osMessageQueueGet(*b, m, NULL, 0) == osOK;
}

uint8_t
lwesp_sys_mbox_isvalid(lwesp_sys_mbox_t* b) {
    return b != NULL && *b != NULL;
}

uint8_t
lwesp_sys_mbox_invalid(lwesp_sys_mbox_t* b) {
    *b = LWESP_SYS_MBOX_NULL;
    return 1;
}

uint8_t
lwesp_sys_thread_create(lwesp_sys_thread_t* t, const char* name, lwesp_sys_thread_fn thread_func, void* const arg, size_t stack_size, lwesp_sys_thread_prio_t prio) {
    lwesp_sys_thread_t id;
    const osThreadAttr_t thread_attr = {
        .name = (char*)name,
        .priority = (osPriority)prio,
        .stack_size = stack_size > 0 ? stack_size : LWESP_SYS_THREAD_SS
    };

    id = osThreadNew(thread_func, arg, &thread_attr);
    if (t != NULL) {
        *t = id;
    }
    return id != NULL;
}

uint8_t
lwesp_sys_thread_terminate(lwesp_sys_thread_t* t) {
    if (t != NULL) {
        osThreadTerminate(*t);
    } else {
        osThreadExit();
    }
    return 1;
}

uint8_t
lwesp_sys_thread_yield(void) {
    osThreadYield();
    return 1;
}

#endif /* !__DOXYGEN__ */