/*********************************************************************************
 *      Copyright:  (C) 2023 LingYun IoT System Studio.
 *                  All rights reserved.
 *
 *       Filename:  ringbuf.c
 *    Description:  This file is common ring buffer API functions
 *                 
 *        Version:  1.0.0(11/08/23)
 *         Author:  Guo Wenxue <guowenxue@gmail.com>
 *      ChangeLog:  1, Release initial version on "11/08/23 16:18:43"
 *                 
 ********************************************************************************/

#include <string.h>
#include <assert.h>
#include "ringbuf.h"

void rb_init (struct ring_buffer *ring, unsigned char* buff, int size)
{
    memset (ring, 0, sizeof (struct ring_buffer));
    ring->rd_pointer = 0;
    ring->wr_pointer = 0;
    ring->buffer= buff;
    ring->size = size;
}


int rb_write (struct ring_buffer *rb, unsigned char * buf, int len)
{
    int                  total;
    int                  i;

    /* total = len = min(space, len) */
    total = rb_free_size(rb);
    if(len > total)
        len = total;
    else
        total = len;

    i = rb->wr_pointer;
    if(i + len > rb->size)
    {
        memcpy(rb->buffer + i, buf, rb->size - i);
        buf += rb->size - i;
        len -= rb->size - i;
        i = 0;
    }

    memcpy(rb->buffer + i, buf, len);
    rb->wr_pointer = i + len;
    return total;
}


int rb_free_size (struct ring_buffer *rb)
{
    return (rb->size - 1 - rb_data_size(rb));
}


int rb_read (struct ring_buffer *rb, unsigned char * buf, int max)
{
    int                  total;
    int                  i;

    /* total = len = min(used, len) */
    total = rb_data_size(rb);

    if(max > total)
        max = total;
    else
        total = max;


    i = rb->rd_pointer;
    if(i + max > rb->size)
    {
        memcpy(buf, rb->buffer + i, rb->size - i);
        buf += rb->size - i;
        max -= rb->size - i;
        i = 0;
    }

    memcpy(buf, rb->buffer + i, max);
    rb->rd_pointer = i + max;

    return total;
}

int rb_data_size (struct ring_buffer *rb)
{
    return ((rb->wr_pointer - rb->rd_pointer) & (rb->size-1));
}

void rb_clear (struct ring_buffer *rb)
{
    memset(rb->buffer,0,rb->size);
    rb->rd_pointer=0;
    rb->wr_pointer=0;
}

unsigned char rb_peek(struct ring_buffer* rb, int index)
{
	assert(index < rb_data_size(rb));

	return rb->buffer[((rb->rd_pointer + index) % rb->size)];
}