src/cpu/kernels/cast/generic/neon/bfloat16.cpp

/*
 * Copyright (c) 2016-2022 Arm Limited.
 *
 * SPDX-License-Identifier: MIT
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
 * deal in the Software without restriction, including without limitation the
 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
 * sell copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
#if defined(ARM_COMPUTE_ENABLE_BF16)

#include "arm_compute/core/TensorInfo.h"
#include "src/core/NEON/wrapper/wrapper.h"
#include "src/cpu/kernels/CpuCastKernel.h"
#include "src/cpu/kernels/cast/list.h"
#include "support/SaturateCast.h"

namespace arm_compute
{
namespace cpu
{
void neon_fp32_to_bfloat16_cast(const ITensor *_src, ITensor *_dst, const ThreadInfo &info, ConvertPolicy _policy, const Window &window)
{
    ARM_COMPUTE_UNUSED(info);
    ARM_COMPUTE_UNUSED(_policy);

    const auto window_start_x = static_cast<int>(window.x().start());
    const auto window_end_x   = static_cast<int>(window.x().end());
    const int  window_step_x  = 16;

    ARM_COMPUTE_ERROR_ON_NULLPTR(_src, _dst);
    ARM_COMPUTE_ERROR_ON(_src == _dst);

    ARM_COMPUTE_ERROR_ON_NULLPTR(_src, _dst);

    Window win{ window };
    win.set(Window::DimX, Window::Dimension(0, 1, 1));

    Iterator src(_src, win);
    Iterator dst(_dst, win);

    /* Down-conversion F32 -> BFLOAT16 */
    execute_window_loop(win, [&](const Coordinates &)
    {
        const auto src_ptr = reinterpret_cast<const float *>(src.ptr());
        const auto dst_ptr = reinterpret_cast<bfloat16 *>(dst.ptr());

        int x = window_start_x;
        for(; x <= (window_end_x - window_step_x); x += window_step_x)
        {
            wrapper::vcvt_bf16_f32(reinterpret_cast<float *>(src.ptr()),
                                   reinterpret_cast<uint16_t *>(dst.ptr()));
            wrapper::vcvt_bf16_f32(reinterpret_cast<float *>(src.ptr()) + 8,
                                   reinterpret_cast<uint16_t *>(dst.ptr()) + 8);
        }

        for(; x < window_end_x; ++x)
        {
            *(dst_ptr + x) = *(src_ptr + x);
        }
    },
    src, dst);
}

void neon_bfloat16_to_fp32_cast(const ITensor *_src, ITensor *_dst, const ThreadInfo &info, ConvertPolicy _policy, const Window &window)
{
    ARM_COMPUTE_UNUSED(info);
    ARM_COMPUTE_UNUSED(_policy);

    const auto window_start_x = static_cast<int>(window.x().start());
    const auto window_end_x   = static_cast<int>(window.x().end());
    const int  window_step_x  = 16;

    ARM_COMPUTE_ERROR_ON_NULLPTR(_src, _dst);
    ARM_COMPUTE_ERROR_ON(_src == _dst);

    ARM_COMPUTE_ERROR_ON_NULLPTR(_src, _dst);

    Window win{ window };
    win.set(Window::DimX, Window::Dimension(0, 1, 1));

    Iterator src(_src, win);
    Iterator dst(_dst, win);
    switch(_dst->info()->data_type())
    {
        case DataType::F32:
        {
            /* Up-conversion BFLOAT16 -> F32 */
            execute_window_loop(win, [&](const Coordinates &)
            {
                const auto src_ptr = reinterpret_cast<const bfloat16 *>(src.ptr());
                const auto dst_ptr = reinterpret_cast<float *>(dst.ptr());

                int x = window_start_x;
                for(; x <= (window_end_x - window_step_x); x += window_step_x)
                {
                    const uint16x8x2_t texels =
                    {
                        {
                            vld1q_u16(reinterpret_cast<uint16_t *>(src.ptr())),
                            vld1q_u16(reinterpret_cast<uint16_t *>(src.ptr()) + 8)
                        }
                    };

                    vst1q_f32(reinterpret_cast<float *>(dst.ptr()),
                              vreinterpretq_f32_u32(vshlq_n_u32(vmovl_u16(vget_low_u16(texels.val[0])), 16)));
                    vst1q_f32(reinterpret_cast<float *>(dst.ptr()) + 4,
                              vreinterpretq_f32_u32(vshlq_n_u32(vmovl_u16(vget_high_u16(texels.val[0])), 16)));
                    vst1q_f32(reinterpret_cast<float *>(dst.ptr()) + 8,
                              vreinterpretq_f32_u32(vshlq_n_u32(vmovl_u16(vget_low_u16(texels.val[1])), 16)));
                    vst1q_f32(reinterpret_cast<float *>(dst.ptr()) + 12,
                              vreinterpretq_f32_u32(vshlq_n_u32(vmovl_u16(vget_high_u16(texels.val[1])), 16)));
                }

                for(; x < window_end_x; ++x)
                {
                    *(dst_ptr + x) = float(*(src_ptr + x));
                }
            },
            src, dst);
            break;
        }
        default:
            ARM_COMPUTE_ERROR("dst data type unsupported");
    }
}

} // namespace cpu
} // namespace arm_compute

#endif /* defined(ARM_COMPUTE_ENABLE_BF16) */