sfizz/plugins/vst/external/ring_buffer/ring_buffer/ring_buffer.cpp

//          Copyright Jean Pierre Cimalando 2018.
// Distributed under the Boost Software License, Version 1.0.
//    (See accompanying file LICENSE or copy at
//          http://www.boost.org/LICENSE_1_0.txt)

#include "ring_buffer.h"
#include <algorithm>
#include <cassert>

#if defined(__cpp_if_constexpr)
#    define if_constexpr if constexpr
#else
#    define if_constexpr if
#endif

template <bool Atomic>
Ring_Buffer_Ex<Atomic>::Ring_Buffer_Ex(size_t capacity)
    : cap_(capacity + 1),
      rbdata_(new uint8_t[capacity + 1])
{
}

template <bool Atomic>
Ring_Buffer_Ex<Atomic>::~Ring_Buffer_Ex()
{
}

template <bool Atomic>
size_t Ring_Buffer_Ex<Atomic>::size_used() const
{
    const size_t rp = rp_, wp = wp_, cap = cap_;
    return wp + ((wp < rp) ? cap : 0) - rp;
}

template <bool Atomic>
bool Ring_Buffer_Ex<Atomic>::discard(size_t len)
{
    return getbytes_ex_(nullptr, len, true);
}

template <bool Atomic>
size_t Ring_Buffer_Ex<Atomic>::size_free() const
{
    const size_t rp = rp_, wp = wp_, cap = cap_;
    return rp + ((rp <= wp) ? cap : 0) - wp - 1;
}

template <bool Atomic>
bool Ring_Buffer_Ex<Atomic>::getbytes_(void *data, size_t len)
{
    return getbytes_ex_(data, len, true);
}

template <bool Atomic>
bool Ring_Buffer_Ex<Atomic>::peekbytes_(void *data, size_t len) const
{
    auto *ncthis = const_cast<Ring_Buffer_Ex<Atomic> *>(this);
    return ncthis->getbytes_ex_(data, len, false);
}

template <bool Atomic>
bool Ring_Buffer_Ex<Atomic>::getbytes_ex_(void *data, size_t len, bool advp)
{
    if (size_used() < len)
        return false;

    const size_t rp = rp_, cap = cap_;
    const uint8_t *src = rbdata_.get();
    uint8_t *dst = (uint8_t *)data;

    if (data) {
        const size_t taillen = std::min(len, cap - rp);
        if_constexpr (Atomic)
            std::atomic_thread_fence(std::memory_order_acquire);
        std::copy_n(&src[rp], taillen, dst);
        std::copy_n(src, len - taillen, dst + taillen);
    }

    if (advp)
        rp_ = (rp + len < cap) ? (rp + len) : (rp + len - cap);
    return true;
}

template <bool Atomic>
bool Ring_Buffer_Ex<Atomic>::putbytes_(const void *data, size_t len)
{
    if (size_free() < len)
        return false;

    const size_t wp = wp_, cap = cap_;
    const uint8_t *src = (const uint8_t *)data;
    uint8_t *dst = rbdata_.get();

    const size_t taillen = std::min(len, cap - wp);
    std::copy_n(src, taillen, &dst[wp]);
    std::copy_n(src + taillen, len - taillen, dst);
    if_constexpr (Atomic)
        std::atomic_thread_fence(std::memory_order_release);

    wp_ = (wp + len < cap) ? (wp + len) : (wp + len - cap);
    return true;
}

template class Ring_Buffer_Ex<true>;
template class Ring_Buffer_Ex<false>;