ring_buffer.c

/******************************************************************************
* File Name:   ring_buffer.c
*
* Description: This is the source code for the XMC MCU: Flash BMI Example
*              for ModusToolbox. This file implements a ringbuffer.
*              Used to receive and send data from/to UART.
*
* Related Document: See README.md
*
******************************************************************************
*
* Copyright (c) 2015-2021, Infineon Technologies AG
* All rights reserved.
*
* Boost Software License - Version 1.0 - August 17th, 2003
*
* Permission is hereby granted, free of charge, to any person or organization
* obtaining a copy of the software and accompanying documentation covered by
* this license (the "Software") to use, reproduce, display, distribute,
* execute, and transmit the Software, and to prepare derivative works of the
* Software, and to permit third-parties to whom the Software is furnished to
* do so, all subject to the following:
*
* The copyright notices in the Software and this entire statement, including
* the above license grant, this restriction and the following disclaimer,
* must be included in all copies of the Software, in whole or in part, and
* all derivative works of the Software, unless such copies or derivative
* works are solely in the form of machine-executable object code generated by
* a source language processor.
*
* 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, TITLE AND NON-INFRINGEMENT. IN NO EVENT
* SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
* FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*
*****************************************************************************/

#include "ring_buffer.h"

/*******************************************************************************
* Function Name: ring_buffer_is_empty
********************************************************************************
* Summary:
* Check if ringbuffer is empty
*
* Parameters:
*  ring_buffer_t *const rb: Pointer to ring buffer
*
* Return:
*  bool: RING_BUFFER_EMPTY     - if ring buffer is empty
*        RING_BUFFER_NOT_EMPTY - if ring buffer is not empty
*
*******************************************************************************/
static bool ring_buffer_is_empty(ring_buffer_t *const rb)
{
    uint32_t head = rb->head;
    uint32_t tail = rb->tail;
    return (head == tail);
}

/*******************************************************************************
* Function Name: ring_buffer_is_full
********************************************************************************
* Summary:
* Check if ringbuffer is full
*
* Parameters:
*  ring_buffer_t *const rb: Pointer to ring buffer
*
* Return:
*  bool: RING_BUFFER_FULL      - if ring buffer is full
*        RING_BUFFER_NOT_FULL  - if ring buffer is not full
*
*******************************************************************************/
static bool ring_buffer_is_full(ring_buffer_t *const rb)
{
    uint32_t head = rb->head;
    uint32_t tail = rb->tail;
    return (((head + 1) % rb->len) == tail);
}

/*******************************************************************************
* Function Name: ring_buffer_avail
********************************************************************************
* Summary:
* Check for available space inside ring buffer
*
* Parameters:
*  ring_buffer_t *const rb: Pointer to ring buffer
*
* Return:
*  uint32_t: available space
*
*******************************************************************************/
uint32_t ring_buffer_avail(ring_buffer_t *const rb)
{
    uint32_t head = rb->head;
    uint32_t tail = rb->tail;
    return (head - tail) % rb->len;
}

/*******************************************************************************
* Function Name: ring_buffer_put
********************************************************************************
* Summary:
* Push one character item into ringbuffer
*
* Parameters:
*  ring_buffer_t *const rb: Pointer to ring buffer
*  uint8_t c: Character to put into ring buffer
*
* Return:
*  int32_t: RING_BUFFER_OK         - on success
*           RING_BUFFER_FULL_ERROR - on buffer full error
*
*******************************************************************************/
int32_t ring_buffer_put(ring_buffer_t *const rb, uint8_t c)
{
    if (ring_buffer_is_full(rb))
    {
        return RING_BUFFER_FULL_ERROR;
    }

    rb->buffer[rb->head] = c;
    rb->head = (rb->head + 1) % rb->len;

    return RING_BUFFER_OK;

}

/*******************************************************************************
* Function Name: ring_buffer_get
********************************************************************************
* Summary:
* Pop one character item from ringbuffer
*
* Parameters:
*  ring_buffer_t *const rb: Pointer to ring buffer
*  uint8_t *const c: Pointer of character popped from ringbuffer
*
* Return:
*  int32_t: RING_BUFFER_OK          - on success
*           RING_BUFFER_EMPTY_ERROR - on buffer empty error
*
*******************************************************************************/
int32_t ring_buffer_get(ring_buffer_t *const rb, uint8_t *const c)
{
    if (ring_buffer_is_empty(rb))
    {
        return RING_BUFFER_EMPTY_ERROR;
    }

    *c = rb->buffer[rb->tail];
    rb->tail = (rb->tail + 1) % rb->len;

    return RING_BUFFER_OK;
}

/* [] END OF FILE */