text: // Tencent is pleased to support the open source community by making ncnn available.
  //
  // Copyright (C) 2021 THL A29 Limited, a Tencent company. All rights reserved.
  //
  // Licensed under the BSD 3-Clause License (the "License"); you may not use this file except
  // in compliance with the License. You may obtain a copy of the License at
  //
  // https://opensource.org/licenses/BSD-3-Clause
  //
  // Unless required by applicable law or agreed to in writing, software distributed
  // under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
  // CONDITIONS OF ANY KIND, either express or implied. See the License for the
  // specific language governing permissions and limitations under the License.
  
  static void requantize_relu_pack8_neon(const Mat& bottom_blob, Mat& top_blob, const Mat& scale_in_data, const Mat& scale_out_data, const Mat& bias_data, const Option& opt)
  {
      int w = bottom_blob.w;
      int h = bottom_blob.h;
      int channels = bottom_blob.c;
      int size = w * h;
  
      int scale_in_data_size = scale_in_data.w;
      int scale_out_data_size = scale_out_data.w;
      int bias_data_size = bias_data.w;
  
      // int8(relu(v * scale_in) * scale_out)
      // int8_relu(v * (scale_in * scale_out))
  
      // int8(relu(v * scale_in + bias) * scale_out)
      // int8_relu(v * (scale_in * scale_out) + (bias * scale_out))
  
      if (bias_data_size == 0)
      {
          #pragma omp parallel for num_threads(opt.num_threads)
          for (int q = 0; q < channels; q++)
          {
              const int* intptr = bottom_blob.channel(q);
              signed char* ptr = top_blob.channel(q);
  
              float32x4_t _scale_in0 = scale_in_data_size == 1 ? vdupq_n_f32(scale_in_data[0]) : vld1q_f32((const float*)scale_in_data + q * 8);
              float32x4_t _scale_in1 = scale_in_data_size == 1 ? vdupq_n_f32(scale_in_data[0]) : vld1q_f32((const float*)scale_in_data + q * 8 + 4);
              float32x4_t _scale_out0 = scale_out_data_size == 1 ? vdupq_n_f32(scale_out_data[0]) : vld1q_f32((const float*)scale_out_data + q * 8);
              float32x4_t _scale_out1 = scale_out_data_size == 1 ? vdupq_n_f32(scale_out_data[0]) : vld1q_f32((const float*)scale_out_data + q * 8 + 4);
  
              float32x4_t _scale0 = vmulq_f32(_scale_in0, _scale_out0);
              float32x4_t _scale1 = vmulq_f32(_scale_in1, _scale_out1);
  
              int i = 0;
  #if __aarch64__
              for (; i + 3 < size; i += 4)
              {
                  float32x4_t _v0 = vcvtq_f32_s32(vld1q_s32(intptr));
                  float32x4_t _v1 = vcvtq_f32_s32(vld1q_s32(intptr + 4));
                  float32x4_t _v2 = vcvtq_f32_s32(vld1q_s32(intptr + 8));
                  float32x4_t _v3 = vcvtq_f32_s32(vld1q_s32(intptr + 12));
                  float32x4_t _v4 = vcvtq_f32_s32(vld1q_s32(intptr + 16));
                  float32x4_t _v5 = vcvtq_f32_s32(vld1q_s32(intptr + 20));
                  float32x4_t _v6 = vcvtq_f32_s32(vld1q_s32(intptr + 24));
                  float32x4_t _v7 = vcvtq_f32_s32(vld1q_s32(intptr + 28));
                  _v0 = vmulq_f32(_v0, _scale0);
                  _v1 = vmulq_f32(_v1, _scale1);
                  _v2 = vmulq_f32(_v2, _scale0);
                  _v3 = vmulq_f32(_v3, _scale1);
                  _v4 = vmulq_f32(_v4, _scale0);
                  _v5 = vmulq_f32(_v5, _scale1);
                  _v6 = vmulq_f32(_v6, _scale0);
                  _v7 = vmulq_f32(_v7, _scale1);
                  vst1_s8(ptr, float2int8relu(_v0, _v1));
                  vst1_s8(ptr + 8, float2int8relu(_v2, _v3));
                  vst1_s8(ptr + 16, float2int8relu(_v4, _v5));
                  vst1_s8(ptr + 24, float2int8relu(_v6, _v7));
  
                  intptr += 32;
                  ptr += 32;
              }
  #endif // __aarch64__
              for (; i + 1 < size; i += 2)
              {
                  float32x4_t _v0 = vcvtq_f32_s32(vld1q_s32(intptr));
                  float32x4_t _v1 = vcvtq_f32_s32(vld1q_s32(intptr + 4));
                  float32x4_t _v2 = vcvtq_f32_s32(vld1q_s32(intptr + 8));
                  float32x4_t _v3 = vcvtq_f32_s32(vld1q_s32(intptr + 12));
                  _v0 = vmulq_f32(_v0, _scale0);
                  _v1 = vmulq_f32(_v1, _scale1);
                  _v2 = vmulq_f32(_v2, _scale0);
                  _v3 = vmulq_f32(_v3, _scale1);
                  vst1_s8(ptr, float2int8relu(_v0, _v1));
                  vst1_s8(ptr + 8, float2int8relu(_v2, _v3));
  
                  intptr += 16;
                  ptr += 16;
              }
              for (; i < size; i++)
              {
                  float32x4_t _v0 = vcvtq_f32_s32(vld1q_s32(intptr));
                  float32x4_t _v1 = vcvtq_f32_s32(vld1q_s32(intptr + 4));
                  _v0 = vmulq_f32(_v0, _scale0);
                  _v1 = vmulq_f32(_v1, _scale1);
                  vst1_s8(ptr, float2int8relu(_v0, _v1));
  
                  intptr += 8;
                  ptr += 8;
              }
          }
      }
      else
      {
          #pragma omp parallel for num_threads(opt.num_threads)
          for (int q = 0; q < channels; q++)
          {
              const int* intptr = bottom_blob.channel(q);
              signed char* ptr = top_blob.channel(q);
  
              float32x4_t _scale_in0 = scale_in_data_size == 1 ? vdupq_n_f32(scale_in_data[0]) : vld1q_f32((const float*)scale_in_data + q * 8);
              float32x4_t _scale_in1 = scale_in_data_size == 1 ? vdupq_n_f32(scale_in_data[0]) : vld1q_f32((const float*)scale_in_data + q * 8 + 4);
              float32x4_t _scale_out0 = scale_out_data_size == 1 ? vdupq_n_f32(scale_out_data[0]) : vld1q_f32((const float*)scale_out_data + q * 8);
              float32x4_t _scale_out1 = scale_out_data_size == 1 ? vdupq_n_f32(scale_out_data[0]) : vld1q_f32((const float*)scale_out_data + q * 8 + 4);
              float32x4_t _bias0 = bias_data_size == 1 ? vdupq_n_f32(bias_data[0]) : vld1q_f32((const float*)bias_data + q * 8);
              float32x4_t _bias1 = bias_data_size == 1 ? vdupq_n_f32(bias_data[0]) : vld1q_f32((const float*)bias_data + q * 8 + 4);
  
              float32x4_t _scale0 = vmulq_f32(_scale_in0, _scale_out0);
              float32x4_t _scale1 = vmulq_f32(_scale_in1, _scale_out1);
              _bias0 = vmulq_f32(_bias0, _scale_out0);
              _bias1 = vmulq_f32(_bias1, _scale_out1);
  
              int i = 0;
  #if __aarch64__
              for (; i + 3 < size; i += 4)
              {
                  float32x4_t _v0 = vcvtq_f32_s32(vld1q_s32(intptr));
                  float32x4_t _v1 = vcvtq_f32_s32(vld1q_s32(intptr + 4));
                  float32x4_t _v2 = vcvtq_f32_s32(vld1q_s32(intptr + 8));
                  float32x4_t _v3 = vcvtq_f32_s32(vld1q_s32(intptr + 12));
                  float32x4_t _v4 = vcvtq_f32_s32(vld1q_s32(intptr + 16));
                  float32x4_t _v5 = vcvtq_f32_s32(vld1q_s32(intptr + 20));
                  float32x4_t _v6 = vcvtq_f32_s32(vld1q_s32(intptr + 24));
                  float32x4_t _v7 = vcvtq_f32_s32(vld1q_s32(intptr + 28));
  
                  _v0 = vfmaq_f32(_bias0, _v0, _scale0);
                  _v1 = vfmaq_f32(_bias1, _v1, _scale1);
                  _v2 = vfmaq_f32(_bias0, _v2, _scale0);
                  _v3 = vfmaq_f32(_bias1, _v3, _scale1);
                  _v4 = vfmaq_f32(_bias0, _v4, _scale0);
                  _v5 = vfmaq_f32(_bias1, _v5, _scale1);
                  _v6 = vfmaq_f32(_bias0, _v6, _scale0);
                  _v7 = vfmaq_f32(_bias1, _v7, _scale1);
  
                  vst1_s8(ptr, float2int8relu(_v0, _v1));
                  vst1_s8(ptr + 8, float2int8relu(_v2, _v3));
                  vst1_s8(ptr + 16, float2int8relu(_v4, _v5));
                  vst1_s8(ptr + 24, float2int8relu(_v6, _v7));
  
                  intptr += 32;
                  ptr += 32;
              }
  #endif // __aarch64__
              for (; i + 1 < size; i += 2)
              {
                  float32x4_t _v0 = vcvtq_f32_s32(vld1q_s32(intptr));
                  float32x4_t _v1 = vcvtq_f32_s32(vld1q_s32(intptr + 4));
                  float32x4_t _v2 = vcvtq_f32_s32(vld1q_s32(intptr + 8));
                  float32x4_t _v3 = vcvtq_f32_s32(vld1q_s32(intptr + 12));
  
  #if __aarch64__
                  _v0 = vfmaq_f32(_bias0, _v0, _scale0);
                  _v1 = vfmaq_f32(_bias1, _v1, _scale1);
                  _v2 = vfmaq_f32(_bias0, _v2, _scale0);
                  _v3 = vfmaq_f32(_bias1, _v3, _scale1);
  #else  // __aarch64__
                  _v0 = vmlaq_f32(_bias0, _v0, _scale0);
                  _v1 = vmlaq_f32(_bias1, _v1, _scale1);
                  _v2 = vmlaq_f32(_bias0, _v2, _scale0);
                  _v3 = vmlaq_f32(_bias1, _v3, _scale1);
  #endif // __aarch64__
  
                  vst1_s8(ptr, float2int8relu(_v0, _v1));
                  vst1_s8(ptr + 8, float2int8relu(_v2, _v3));
  
                  intptr += 16;
                  ptr += 16;
              }
              for (; i < size; i++)
              {
                  float32x4_t _v0 = vcvtq_f32_s32(vld1q_s32(intptr));
                  float32x4_t _v1 = vcvtq_f32_s32(vld1q_s32(intptr + 4));
  #if __aarch64__
                  _v0 = vfmaq_f32(_bias0, _v0, _scale0);
                  _v1 = vfmaq_f32(_bias1, _v1, _scale1);
  #else  // __aarch64__
                  _v0 = vmlaq_f32(_bias0, _v0, _scale0);
                  _v1 = vmlaq_f32(_bias1, _v1, _scale1);
  #endif // __aarch64__
                  vst1_s8(ptr, float2int8relu(_v0, _v1));
  
                  intptr += 8;
                  ptr += 8;
              }
          }
      }
  }
  