cbuf.cpp

/*
 cbuf.cpp - Circular buffer implementation
 Copyright (c) 2014 Ivan Grokhotkov. All rights reserved.
 This file is part of the esp8266 core for Arduino environment.

 This library is free software; you can redistribute it and/or
 modify it under the terms of the GNU Lesser General Public
 License as published by the Free Software Foundation; either
 version 2.1 of the License, or (at your option) any later version.

 This library is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 Lesser General Public License for more details.

 You should have received a copy of the GNU Lesser General Public
 License along with this library; if not, write to the Free Software
 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

#include "cbuf.h"
#include "esp32-hal-log.h"

#if CONFIG_DISABLE_HAL_LOCKS
#define CBUF_MUTEX_CREATE()
#define CBUF_MUTEX_LOCK()
#define CBUF_MUTEX_UNLOCK()
#define CBUF_MUTEX_DELETE()
#else
#define CBUF_MUTEX_CREATE()  if(_lock == NULL){_lock = xSemaphoreCreateMutex(); if(_lock == NULL){log_e("failed to create mutex");}}
#define CBUF_MUTEX_LOCK()    if(_lock != NULL){xSemaphoreTakeRecursive(_lock, portMAX_DELAY);}
#define CBUF_MUTEX_UNLOCK()  if(_lock != NULL){xSemaphoreGiveRecursive(_lock);}
#define CBUF_MUTEX_DELETE()  if(_lock != NULL){SemaphoreHandle_t l = _lock; _lock = NULL; vSemaphoreDelete(l);}
#endif

cbuf::cbuf(size_t size) :
    next(NULL),
    has_peek(false),
    peek_byte(0),
    _buf(xRingbufferCreate(size, RINGBUF_TYPE_BYTEBUF))
{
    if(_buf == NULL) {
        log_e("failed to allocate ring buffer");
    }
    CBUF_MUTEX_CREATE();
}

cbuf::~cbuf()
{
    CBUF_MUTEX_LOCK();
    if(_buf != NULL){
        RingbufHandle_t b = _buf;
        _buf = NULL;
        vRingbufferDelete(b);
    }
    CBUF_MUTEX_UNLOCK();
    CBUF_MUTEX_DELETE();
}

size_t cbuf::resizeAdd(size_t addSize)
{
    return resize(size() + addSize);
}

size_t cbuf::resize(size_t newSize)
{
    CBUF_MUTEX_LOCK();
    size_t _size = size();
    if(newSize == _size) {
        return _size;
    }

    // not lose any data
    // if data can be lost use remove or flush before resize
    size_t bytes_available = available();
    if(newSize < bytes_available) {
        CBUF_MUTEX_UNLOCK();
        log_e("new size is less than the currently available data size");
        return _size;
    }

    RingbufHandle_t newbuf = xRingbufferCreate(newSize, RINGBUF_TYPE_BYTEBUF);
    if(newbuf == NULL) {
        CBUF_MUTEX_UNLOCK();
        log_e("failed to allocate new ring buffer");
        return _size;
    }

    if(_buf != NULL) {
        if(bytes_available){
            char * old_data = (char *)malloc(bytes_available);
            if(old_data == NULL){
                vRingbufferDelete(newbuf);
                CBUF_MUTEX_UNLOCK();
                log_e("failed to allocate temporary buffer");
                return _size;
            }
            bytes_available = read(old_data, bytes_available);
            if(!bytes_available){
                free(old_data);
                vRingbufferDelete(newbuf);
                CBUF_MUTEX_UNLOCK();
                log_e("failed to read previous data");
                return _size;
            }
            if(xRingbufferSend(newbuf, (void*)old_data, bytes_available, 0) != pdTRUE){
                write(old_data, bytes_available);
                free(old_data);
                vRingbufferDelete(newbuf);
                CBUF_MUTEX_UNLOCK();
                log_e("failed to restore previous data");
                return _size;
            }
            free(old_data);
        }
        
        RingbufHandle_t b = _buf;
        _buf = newbuf;
        vRingbufferDelete(b);
    } else {
        _buf = newbuf;
    }
    CBUF_MUTEX_UNLOCK();
    return newSize;
}

size_t cbuf::available() const
{
    size_t available = 0;
    if(_buf != NULL){
        vRingbufferGetInfo(_buf, NULL, NULL, NULL, NULL, (UBaseType_t *)&available);
    }
    if (has_peek) available++;
    return available;
}

size_t cbuf::size()
{
    size_t _size = 0;
    if(_buf != NULL){
        _size = xRingbufferGetMaxItemSize(_buf);
    }
    return _size;
}

size_t cbuf::room() const
{
    size_t _room = 0;
    if(_buf != NULL){
        _room = xRingbufferGetCurFreeSize(_buf);
    }
    return _room;
}

bool cbuf::empty() const
{
    return available() == 0;
}

bool cbuf::full() const
{
    return room() == 0;
}

int cbuf::peek()
{
    if (!available()) {
        return -1;
    }

    int c;

    CBUF_MUTEX_LOCK();
    if (has_peek) {
        c = peek_byte;
    } else {
        c = read();
        if (c >= 0) {
            has_peek = true;
            peek_byte = c;
        }
    }
    CBUF_MUTEX_UNLOCK();
    return c;
}

int cbuf::read()
{
    char result = 0;
    if(!read(&result, 1)){
        return -1;
    }
    return static_cast<int>(result);
}

size_t cbuf::read(char* dst, size_t size)
{
    CBUF_MUTEX_LOCK();
    size_t bytes_available = available();
    if(!bytes_available || !size){
        CBUF_MUTEX_UNLOCK();
        return 0;
    }

    if (has_peek) {
        if (dst != NULL) {
            *dst++ = peek_byte;
        }
        size--;
    }

    size_t size_read = 0;
    if (size) {
        size_t received_size = 0;
        size_t size_to_read = (size < bytes_available) ? size : bytes_available;
        uint8_t *received_buff = (uint8_t *)xRingbufferReceiveUpTo(_buf, &received_size, 0, size_to_read);
        if (received_buff != NULL) {
            if(dst != NULL){
                memcpy(dst, received_buff, received_size);
            }
            vRingbufferReturnItem(_buf, received_buff);
            size_read = received_size;
            size_to_read -= received_size;
            // wrap around data
            if(size_to_read){
                received_size = 0;
                received_buff = (uint8_t *)xRingbufferReceiveUpTo(_buf, &received_size, 0, size_to_read);
                if (received_buff != NULL) {
                    if(dst != NULL){
                        memcpy(dst+size_read, received_buff, received_size);
                    }
                    vRingbufferReturnItem(_buf, received_buff);
                    size_read += received_size;
                } else {
                    log_e("failed to read wrap around data from ring buffer");
                }
            }
        } else {
            log_e("failed to read from ring buffer");
        }
    }

    if (has_peek) {
        has_peek = false;
        size_read++;
    }

    CBUF_MUTEX_UNLOCK();
    return size_read;
}

size_t cbuf::write(char c)
{
    return write(&c, 1);
}

size_t cbuf::write(const char* src, size_t size)
{
    CBUF_MUTEX_LOCK();
    size_t bytes_available = room();
    if(!bytes_available || !size){
        CBUF_MUTEX_UNLOCK();
        return 0;
    }
    size_t size_to_write = (size < bytes_available) ? size : bytes_available;
    if(xRingbufferSend(_buf, (void*)src, size_to_write, 0) != pdTRUE){
        CBUF_MUTEX_UNLOCK();
        log_e("failed to write to ring buffer");
        return 0;
    }
    CBUF_MUTEX_UNLOCK();
    return size_to_write;
}

void cbuf::flush()
{
    read(NULL, available());
}

size_t cbuf::remove(size_t size)
{
    CBUF_MUTEX_LOCK();
    size_t bytes_available = available();
    if(bytes_available && size){
        size_t size_to_remove = (size < bytes_available) ? size : bytes_available;
        bytes_available -= read(NULL, size_to_remove);
    }
    CBUF_MUTEX_UNLOCK();
    return bytes_available;
}