/*********************************************************************************
 *      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 *rb, unsigned char *buf, int size)
{
    memset(rb, 0, sizeof (struct ring_buffer));
    rb->rd_pointer = 0;
    rb->wr_pointer = 0;
    rb->buffer= buf;
    rb->size = size;
}

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

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

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

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)];
}

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_read(struct ring_buffer *rb, unsigned char *buf, int bytes)
{
    int                  total;
    int                  i;

    total = rb_data_size(rb);

    if(bytes > total)
        bytes = total;

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

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

    return total;
}

int rb_copy(struct ring_buffer *rb, unsigned char *buf, int bytes)
{
    int                  total;
    int                  i;

    total = rb_data_size(rb);

    if(bytes > total)
        bytes = total;

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

    memcpy(buf, rb->buffer + i, bytes);

    return total;
}