/******************************************************************************

                  版权所有 (C), 2018-2099, Radkil_Std

 ******************************************************************************
  文 件 名   : ringbuffer.c
  版 本 号   : 初稿
  作    者   : Radkil
  生成日期   : 2023年3月26日
  最近修改   :
  功能描述   : ringbuffer环形缓冲区实现
  
  修改历史   :
  1.日    期   : 2023年3月26日
    作    者   : Radkil
    修改内容   : 创建文件

******************************************************************************/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "ringbuffer.h"
#include "common.h"

/*----------------------------------------------*
 * 外部变量说明                                 *
 *----------------------------------------------*/

/*----------------------------------------------*
 * 外部函数原型说明                             *
 *----------------------------------------------*/

/*----------------------------------------------*
 * 内部函数原型说明                             *
 *----------------------------------------------*/

/*----------------------------------------------*
 * 全局变量                                     *
 *----------------------------------------------*/

/*----------------------------------------------*
 * 模块级变量                                   *
 *----------------------------------------------*/

/*----------------------------------------------*
 * 常量定义                                     *
 *----------------------------------------------*/
 

/*----------------------------------------------*
 * 宏定义                                       *
 *----------------------------------------------*/

/**
 * @brief Initialize the ring buffer object.
 *
 * @param rb        A pointer to the ring buffer object.
 * @param pool      A pointer to the buffer.
 * @param size      The size of the buffer in bytes.
 */
void rd_RingbufferInit(rd_ringbuf_t *rb, char *pool, int size)
{
    if(NULL == rb || NULL == pool || size <= 0)
    {
        return;
    }

    /* initialize read and write index */
    rb->m_bReadMirror = rb->m_sReadIndex = 0;
    rb->m_bWriteMirror = rb->m_sWriteIndex = 0;

    /* set buffer pool and size */
    rb->m_pcBufPtr = pool;
    rb->m_iBufsize = RD_ALIGN_DOWN(size, RD_ALIGN_SIZE);
}

/**
 * @brief Put a block of data into the ring buffer. If the capacity of ring buffer is insufficient, it will discard out-of-range data.
 *
 * @param rb            A pointer to the ring buffer object.
 * @param ptr           A pointer to the data buffer.
 * @param length        The size of data in bytes.
 *
 * @return Return the data size we put into the ring buffer.
 */
int rd_RingbufferPut(rd_ringbuf_t *rb, const char *ptr, int length)
{
    int size = 0;

    if(NULL == rb || NULL == ptr || length <= 0)
    {
        return RD_INVALUE;
    }

    /* whether has enough space */
    size = rd_RingbufferSpaceLen(rb);

    /* no space */
    if (size == 0)
    {
        return 0;
    }
    
    /* drop some data */
    if (size < length)
    {
        length = size;        
    }

    if (rb->m_iBufsize - rb->m_sWriteIndex > length)
    {
        /* m_sReadIndex - m_sWriteIndex = empty space */
        RD_MEMCPY(&rb->m_pcBufPtr[rb->m_sWriteIndex], ptr, length);
        /* this should not cause overflow because there is enough space for
         * length of data in current mirror */
        rb->m_sWriteIndex += length;
        return length;
    }

    RD_MEMCPY(&rb->m_pcBufPtr[rb->m_sWriteIndex],
           &ptr[0],
           rb->m_iBufsize - rb->m_sWriteIndex);
    RD_MEMCPY(&rb->m_pcBufPtr[0],
           &ptr[rb->m_iBufsize - rb->m_sWriteIndex],
           length - (rb->m_iBufsize - rb->m_sWriteIndex));

    /* we are going into the other side of the mirror */
    rb->m_bWriteMirror = ~rb->m_bWriteMirror;
    rb->m_sWriteIndex = length - (rb->m_iBufsize - rb->m_sWriteIndex);

    return length;
}

/**
 * @brief Put a block of data into the ring buffer. If the capacity of ring buffer is insufficient, it will overwrite the existing data in the ring buffer.
 *
 * @param rb            A pointer to the ring buffer object.
 * @param ptr           A pointer to the data buffer.
 * @param length        The size of data in bytes.
 *
 * @return Return the data size we put into the ring buffer.
 */
int rd_RingbufferPutForce(rd_ringbuf_t *rb, const char *ptr, int length)
{
    int space_length;

    if (NULL == rb || NULL == ptr || length <= 0)
    {
        return RD_INVALUE;
    }

    space_length = rd_RingbufferSpaceLen(rb);

    if (length > rb->m_iBufsize)
    {
        ptr = &ptr[length - rb->m_iBufsize];
        length = rb->m_iBufsize;
    }

    if (rb->m_iBufsize - rb->m_sWriteIndex > length)
    {
        /* m_sReadIndex - m_sWriteIndex = empty space */
        RD_MEMCPY(&rb->m_pcBufPtr[rb->m_sWriteIndex], ptr, length);
        /* this should not cause overflow because there is enough space for
         * length of data in current mirror */
        rb->m_sWriteIndex += length;

        if (length > space_length)
            rb->m_sReadIndex = rb->m_sWriteIndex;

        return length;
    }

    RD_MEMCPY(&rb->m_pcBufPtr[rb->m_sWriteIndex],
           &ptr[0],
           rb->m_iBufsize - rb->m_sWriteIndex);
    RD_MEMCPY(&rb->m_pcBufPtr[0],
           &ptr[rb->m_iBufsize - rb->m_sWriteIndex],
           length - (rb->m_iBufsize - rb->m_sWriteIndex));

    /* we are going into the other side of the mirror */
    rb->m_bWriteMirror = ~rb->m_bWriteMirror;
    rb->m_sWriteIndex = length - (rb->m_iBufsize - rb->m_sWriteIndex);

    if (length > space_length)
    {
        if (rb->m_sWriteIndex <= rb->m_sReadIndex)
            rb->m_bReadMirror = ~rb->m_bReadMirror;
        rb->m_sReadIndex = rb->m_sWriteIndex;
    }

    return length;
}

/**
 * @brief Get data from the ring buffer.
 *
 * @param rb            A pointer to the ring buffer.
 * @param ptr           A pointer to the data buffer.
 * @param length        The size of the data we want to read from the ring buffer.
 *
 * @return Return the data size we read from the ring buffer.
 */
int rd_RingbufferGet(rd_ringbuf_t *rb, char *ptr, int length)
{
    int size;

    if (NULL == rb || NULL == ptr || length <= 0)
    {
        return RD_INVALUE;
    }

    /* whether has enough data  */
    size = rd_RingbufferDataLen(rb);

    /* no data */
    if (size == 0)
    {
        return 0;        
    }

    /* less data */
    if (size < length)
    {
        length = size;        
    }

    if (rb->m_iBufsize - rb->m_sReadIndex > length)
    {
        /* copy all of data */
        RD_MEMCPY(ptr, &rb->m_pcBufPtr[rb->m_sReadIndex], length);
        /* this should not cause overflow because there is enough space for
         * length of data in current mirror */
        rb->m_sReadIndex += length;
        return length;
    }

    RD_MEMCPY(&ptr[0],
           &rb->m_pcBufPtr[rb->m_sReadIndex],
           rb->m_iBufsize - rb->m_sReadIndex);
    RD_MEMCPY(&ptr[rb->m_iBufsize - rb->m_sReadIndex],
           &rb->m_pcBufPtr[0],
           length - (rb->m_iBufsize - rb->m_sReadIndex));

    /* we are going into the other side of the mirror */
    rb->m_bReadMirror = ~rb->m_bReadMirror;
    rb->m_sReadIndex = length - (rb->m_iBufsize - rb->m_sReadIndex);

    return length;
}

/**
 * @brief Get the first readable byte of the ring buffer.
 *
 * @param rb        A pointer to the ringbuffer.
 * @param ptr       When this function return, *ptr is a pointer to the first readable byte of the ring buffer.
 *
 * @note It is recommended to read only one byte, otherwise it may cause buffer overflow.
 *
 * @return Return the size of the ring buffer.
 */
int rd_RingbufferPeak(rd_ringbuf_t *rb, char **ptr)
{
    int size;

    if (NULL == rb)
    {
        return RD_INVALUE;
    }

    *ptr = NULL;

    /* whether has enough data  */
    size = rd_RingbufferDataLen(rb);

    /* no data */
    if (size == 0)
    {
        return 0;
    }

    *ptr = &rb->m_pcBufPtr[rb->m_sReadIndex];

    if((int)(rb->m_iBufsize - rb->m_sReadIndex) > size)
    {
        return size;
    }

    size = rb->m_iBufsize - rb->m_sReadIndex;

    /* we are going into the other side of the mirror */
    //rb->m_bReadMirror = ~rb->m_bReadMirror;
    //rb->m_sReadIndex = 0;

    return size;
}

/**
 * @brief Put a byte into the ring buffer. If ring buffer is full, this operation will fail.
 *
 * @param rb        A pointer to the ring buffer object.
 * @param ch        A byte put into the ring buffer.
 *
 * @return Return the data size we put into the ring buffer. The ring buffer is full if returns 0. Otherwise, it will return 1.
 */
int rd_RingbufferPutchar(rd_ringbuf_t *rb, const char ch)
{
    if (NULL == rb)
    {
        return RD_INVALUE;    
    }

    /* whether has enough space */
    if (!rd_RingbufferSpaceLen(rb))
    {
        return 0;        
    }

    rb->m_pcBufPtr[rb->m_sWriteIndex] = ch;

    /* flip mirror */
    if (rb->m_sWriteIndex == rb->m_iBufsize-1)
    {
        rb->m_bWriteMirror = ~rb->m_bWriteMirror;
        rb->m_sWriteIndex = 0;
    }
    else
    {
        rb->m_sWriteIndex++;
    }

    return 1;
}

/**
 * @brief Put a byte into the ring buffer. If ring buffer is full, it will discard an old data and put into a new data.
 *
 * @param rb        A pointer to the ring buffer object.
 * @param ch        A byte put into the ring buffer.
 *
 * @return Return the data size we put into the ring buffer. Always return 1.
 */
int rd_RingbufferPutcharForce(rd_ringbuf_t *rb, const char ch)
{
    enum ERingBufState old_state;

    if (NULL == rb)
    {
        return RD_INVALUE;    
    }

    old_state = rd_RingbufferStatus(rb);

    rb->m_pcBufPtr[rb->m_sWriteIndex] = ch;

    /* flip mirror */
    if (rb->m_sWriteIndex == rb->m_iBufsize-1)
    {
        rb->m_bWriteMirror = ~rb->m_bWriteMirror;
        rb->m_sWriteIndex = 0;
        if (old_state == RINGBUFFER_FULL)
        {
            rb->m_bReadMirror = ~rb->m_bReadMirror;
            rb->m_sReadIndex = rb->m_sWriteIndex;
        }
    }
    else
    {
        rb->m_sWriteIndex++;
        if (old_state == RINGBUFFER_FULL)
        {
            rb->m_sReadIndex = rb->m_sWriteIndex;            
        }
    }

    return 1;
}

/**
 * @brief Get a byte from the ring buffer.
 *
 * @param rb        The pointer to the ring buffer object.
 * @param ch        A pointer to the buffer, used to store one byte.
 *
 * @return 0    The ring buffer is empty.
 * @return 1    Success
 */
int rd_RingbufferGetchar(rd_ringbuf_t *rb, char *ch)
{
    if (NULL == rb)
    {
        return RD_INVALUE;    
    }
    
    /* ringbuffer is empty */
    if (!rd_RingbufferDataLen(rb))
    {      
        return 0;
    }

    /* put byte */
    *ch = rb->m_pcBufPtr[rb->m_sReadIndex];

    if (rb->m_sReadIndex == rb->m_iBufsize-1)
    {
        rb->m_bReadMirror = ~rb->m_bReadMirror;
        rb->m_sReadIndex = 0;
    }
    else
    {
        rb->m_sReadIndex++;
    }

    return 1;
}

/**
 * @brief Get the size of data in the ring buffer in bytes.
 *
 * @param rb        The pointer to the ring buffer object.
 *
 * @return Return the size of data in the ring buffer in bytes.
 */
int rd_RingbufferDataLen(rd_ringbuf_t *rb)
{
    switch (rd_RingbufferStatus(rb))
    {
    case RINGBUFFER_EMPTY:
        return 0;
    case RINGBUFFER_FULL:
        return rb->m_iBufsize;
    case RINGBUFFER_HALFFULL:
    default:
    {
        int wi = rb->m_sWriteIndex, ri = rb->m_sReadIndex;

        if (wi > ri)
        {
            return wi - ri;            
        }
        else
        {
            return rb->m_iBufsize - (ri - wi);            
        }
    }
    }
}

/**
 * @brief Reset the ring buffer object, and clear all contents in the buffer.
 *
 * @param rb        A pointer to the ring buffer object.
 */
void rd_RingbufferReset(rd_ringbuf_t *rb)
{
    if(NULL == rb)
    {
        return;
    }

    rb->m_bReadMirror = 0;
    rb->m_sReadIndex = 0;
    rb->m_bWriteMirror = 0;
    rb->m_sWriteIndex = 0;
}

/**
 * @brief Create a ring buffer object with a given size.
 *
 * @param size      The size of the buffer in bytes.
 *
 * @return Return a pointer to ring buffer object. When the return value is RT_NULL, it means this creation failed.
 */
rd_ringbuf_t *rd_RingbufferCreate(int size)
{
    rd_ringbuf_t *rb;
    char *pool;

    if (size <= 0)
    {
        return NULL;
    }

    size = RD_ALIGN_DOWN(size, RD_ALIGN_SIZE);

    rb = (rd_ringbuf_t *)RD_MALLOC(sizeof(rd_ringbuf_t));
    if (rb == NULL)
    {
        goto exit;
    }
    
    pool = (char *)RD_MALLOC(size);
    if (pool == NULL)
    {
        RD_FREE(rb);
        rb = NULL;
        goto exit;
    }
    rd_RingbufferInit(rb, pool, size);

exit:
    return rb;
}

/**
 * @brief Destroy the ring buffer object, which is created by rt_ringbuffer_create() .
 *
 * @param rb        A pointer to the ring buffer object.
 */
void rd_RingbufferDestroy(rd_ringbuf_t *rb)
{
    if (NULL == rb)
    {
        return;
    }

    RD_FREE(rb->m_pcBufPtr);
    RD_FREE(rb);
}