ringbuffer.c

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/*
 * ether2ser - Ethernet <-> synchronous V.24 (RS-232/V.28) bridge
 *
 * File:    src/system/ringbuffer.c
 * Purpose: Generic ring buffer implementation.
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Copyright (c) 2026 Florian <f.leuze@outlook.de>
 */
 
// Related headers
#include "ringbuffer.h"
 
// Standard library headers
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
// Project Headers
 
// Generated headers
 
// Project Headers
 
int RbInit(Ringbuffer* bufferStruct, void* bufferPointer, size_t capacity, size_t itemSizeInByte)
{
    bufferStruct->buffer = bufferPointer;
    if (bufferStruct->buffer == NULL)
    {
        return -1;
    }
    bufferStruct->bufferEnd      = (uint8_t*)bufferStruct->buffer + capacity * itemSizeInByte;
    bufferStruct->capacity       = capacity;
    bufferStruct->count          = 0U;
    bufferStruct->itemSizeInByte = itemSizeInByte;
    bufferStruct->head           = bufferStruct->buffer;
    bufferStruct->tail           = bufferStruct->buffer;
    memset(bufferStruct->buffer, 0U, capacity * itemSizeInByte);
    return 0;
}
 
int RbPushBack(Ringbuffer* bufferStruct, const void* element)
{
    if (bufferStruct->count == bufferStruct->capacity)
    {
        return -1;
    }
    memcpy(bufferStruct->head, element, bufferStruct->itemSizeInByte);
    bufferStruct->head = (uint8_t*)bufferStruct->head + bufferStruct->itemSizeInByte;
    if (bufferStruct->head == bufferStruct->bufferEnd)
    {
        bufferStruct->head = bufferStruct->buffer;
    }
    ++bufferStruct->count;
    return 0;
}
 
int RbPopFront(Ringbuffer* bufferStruct, void* element)
{
    if (bufferStruct->count == 0U)
    {
        return -1;
    }
    memcpy(element, bufferStruct->tail, bufferStruct->itemSizeInByte);
    bufferStruct->tail = (uint8_t*)bufferStruct->tail + bufferStruct->itemSizeInByte;
    if (bufferStruct->tail == bufferStruct->bufferEnd)
    {
        bufferStruct->tail = bufferStruct->buffer;
    }
    --bufferStruct->count;
    return 0;
}
 
void RbPushBackWrap(Ringbuffer* bufferStruct, const void* element)
{
    if (bufferStruct->count == bufferStruct->capacity)
    {
        // Buffer is full, overwrite the oldest element
        bufferStruct->tail = (uint8_t*)bufferStruct->tail + bufferStruct->itemSizeInByte;
        if (bufferStruct->tail == bufferStruct->bufferEnd)
        {
            bufferStruct->tail = bufferStruct->buffer; // Wrap around
        }
    }
    else
    {
        // Increment count only if the buffer was not full
        ++bufferStruct->count;
    }
 
    // Add the new element at the head position
    memcpy(bufferStruct->head, element, bufferStruct->itemSizeInByte);
    bufferStruct->head = (uint8_t*)bufferStruct->head + bufferStruct->itemSizeInByte;
    if (bufferStruct->head == bufferStruct->bufferEnd)
    {
        bufferStruct->head = bufferStruct->buffer; // Wrap around
    }
}