rcpp_framework/libs/brynet/base/Buffer.hpp

#pragma once

#include <cstdlib>
#include <cstring>

namespace brynet { namespace base {

struct buffer_s
{
    char* data;
    size_t data_len;

    size_t write_pos;
    size_t read_pos;
};

static void buffer_delete(struct buffer_s* self)
{
    if (self == nullptr)
    {
        return;
    }

    if (self->data != nullptr)
    {
        free(self->data);
        self->data = nullptr;
    }

    free(self);
    self = nullptr;
}

static struct buffer_s* buffer_new(size_t buffer_size)
{
    struct buffer_s* ret = (struct buffer_s*) malloc(sizeof(struct buffer_s));
    if (ret == nullptr)
    {
        return nullptr;
    }

    ret->data_len = 0;
    ret->read_pos = 0;
    ret->write_pos = 0;
    ret->data = (char*) malloc(sizeof(char) * buffer_size);

    if (ret->data != nullptr)
    {
        ret->data_len = buffer_size;
    }
    else
    {
        buffer_delete(ret);
        ret = nullptr;
    }

    return ret;
}

static size_t buffer_getreadvalidcount(struct buffer_s* self)
{
    return self->write_pos - self->read_pos;
}

static void buffer_adjustto_head(struct buffer_s* self)
{
    if (self->read_pos == 0)
    {
        return;
    }

    const auto len = buffer_getreadvalidcount(self);
    if (len > 0)
    {
        memmove(self->data, self->data + self->read_pos, len);
    }

    self->read_pos = 0;
    self->write_pos = len;
}

static void buffer_init(struct buffer_s* self)
{
    self->read_pos = 0;
    self->write_pos = 0;
}

static size_t buffer_getwritepos(struct buffer_s* self)
{
    return self->write_pos;
}

static size_t buffer_getreadpos(struct buffer_s* self)
{
    return self->read_pos;
}

static bool buffer_addwritepos(struct buffer_s* self, size_t value)
{
    const size_t temp = self->write_pos + value;
    if (temp <= self->data_len)
    {
        self->write_pos = temp;
        return true;
    }
    else
    {
        return false;
    }
}

static bool buffer_addreadpos(struct buffer_s* self, size_t value)
{
    const size_t temp = self->read_pos + value;
    if (temp <= self->data_len)
    {
        self->read_pos = temp;
        return true;
    }
    else
    {
        return false;
    }
}

static size_t buffer_getwritevalidcount(struct buffer_s* self)
{
    return self->data_len - self->write_pos;
}

static size_t buffer_getsize(struct buffer_s* self)
{
    return self->data_len;
}

static char* buffer_getwriteptr(struct buffer_s* self)
{
    if (self->write_pos < self->data_len)
    {
        return self->data + self->write_pos;
    }
    else
    {
        return nullptr;
    }
}

static char* buffer_getreadptr(struct buffer_s* self)
{
    if (self->read_pos < self->data_len)
    {
        return self->data + self->read_pos;
    }
    else
    {
        return nullptr;
    }
}

static bool buffer_write(struct buffer_s* self, const char* data, size_t len)
{
    bool write_ret = true;

    if (buffer_getwritevalidcount(self) >= len)
    {
        memcpy(buffer_getwriteptr(self), data, len);
        buffer_addwritepos(self, len);
    }
    else
    {
        size_t left_len = self->data_len - buffer_getreadvalidcount(self);
        if (left_len >= len)
        {
            buffer_adjustto_head(self);
            buffer_write(self, data, len);
        }
        else
        {
            write_ret = false;
        }
    }

    return write_ret;
}

}}// namespace brynet::base