#include "src/common/tile_repeat_helper.h"

#include <cstring>
#include "src/common/utils.h"

namespace megdnn {

// Tile (m, n) to (m, n*times) or Repeat (m, n) to (m*times, n)
template <typename T>
void tile_or_repeat_single_axis(
        const T* __restrict src, T* __restrict dst, const size_t m, const size_t n,
        const size_t times) {
    rep(i, m) {
        // copy Ts of length n to dst
        std::memcpy(dst, src, sizeof(T) * n);
        size_t k = 1u;
        while (k * 2 <= times) {
            std::memcpy(dst + k * n, dst, sizeof(T) * (k * n));
            k *= 2;
        }
        if (k < times) {
            std::memcpy(dst + k * n, dst, sizeof(T) * (times - k) * n);
        }
        src += n;
        dst += n * times;
    }
}

template <typename T>
void init_tile_repeat_state(
        const T* src, T* dst, T* workspace0, T* /* workspace1 */, T*& current, T*& next,
        size_t& state, size_t nr_reduces) {
    current = const_cast<T*>(src);
    if (nr_reduces == 1) {
        next = dst;
    } else {
        next = workspace0;
    }
    state = 0;
}

template <typename T>
void update_tile_repeat_state(
        const T* /* src */, T* dst, T* workspace0, T* workspace1, T*& current, T*& next,
        size_t& state, size_t nr_reduces) {
    current = next;
    if (nr_reduces == 1) {
        next = nullptr;
    } else if (nr_reduces == 2) {
        if (state == 0) {
            next = dst;
        } else {
            next = nullptr;
        }
    } else {
        if (state == 0) {
            next = workspace1;
        } else if (state + 1 == nr_reduces) {
            next = nullptr;
        } else if (state + 2 == nr_reduces) {
            next = dst;
        } else {
            megdnn_assert(
                    current == workspace0 || current == workspace1,
                    "Impossible happened; internal bug.");
            next = (current == workspace0 ? workspace1 : workspace0);
        }
    }
    ++state;
}

#define INST(T)                                                      \
    template void tile_or_repeat_single_axis<T>(                     \
            const T*, T*, const size_t, const size_t, const size_t); \
    template void init_tile_repeat_state<T>(                         \
            const T*, T*, T*, T*, T*&, T*&, size_t&, size_t);        \
    template void update_tile_repeat_state<T>(                       \
            const T*, T*, T*, T*, T*&, T*&, size_t&, size_t);

#define INST_DT(d) INST(DTypeTrait<d>::ctype)

MEGDNN_FOREACH_COMPUTING_DTYPE(INST_DT)

}  // namespace megdnn

// vim: syntax=cpp.doxygen