/* Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at
 
 http://www.apache.org/licenses/LICENSE-2.0
 
 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. */

#include <metal_stdlib>
using namespace metal;

struct OutputDim {
    ushort width;
    ushort height;
    ushort strideX;
    ushort strideY;
};

kernel void resize(texture2d<half, access::read> inTexture [[texture(0)]],
                   texture2d_array<half, access::write> outTexture [[texture(1)]],
                   constant OutputDim &params [[buffer(0)]],
                   uint3 gid [[thread_position_in_grid]]) {
    if (gid.x >= outTexture.get_width() ||
        gid.y >= outTexture.get_height() ||
        gid.z >= outTexture.get_array_size()) return;
    
    constexpr sampler s(coord::pixel, filter::nearest, address::clamp_to_zero);
    const uint2 pos = gid.xy * uint2(params.strideX, params.strideY);
    const half4 input = inTexture.read(pos);
    outTexture.write(half4(input.x, input.y, input.z, input.w), gid.xy, gid.z);
}

kernel void relu(texture2d_array<half, access::sample> inTexture [[texture(0)]],
                 texture2d_array<half, access::write> outTexture [[texture(1)]],
                 uint3 gid [[thread_position_in_grid]]) {
    if (gid.x >= outTexture.get_width() ||
        gid.y >= outTexture.get_height() ||
        gid.z >= outTexture.get_array_size()) return;
    constexpr sampler s(coord::pixel, filter::nearest, address::clamp_to_zero);
    const half4 input = inTexture.read(gid.xy, gid.z);
    const float4 relu = fmax((float4)input, 0.0);
    outTexture.write(half4(relu), gid.xy, gid.z);
}

kernel void elementwise_add(texture2d_array<half, access::read> inTexture [[texture(0)]],
                            texture2d_array<half, access::write> outTexture [[texture(1)]],
                            const device half4 *biasTerms [[buffer(0)]],
                            uint3 gid [[thread_position_in_grid]]) {
    if (gid.x >= outTexture.get_width() ||
        gid.y >= outTexture.get_height() ||
        gid.z >= outTexture.get_array_size()) return;
    constexpr sampler s(coord::pixel, filter::nearest, address::clamp_to_zero);
    const half4 input = inTexture.read(gid.xy, gid.z);
    outTexture.write(input, gid.xy, gid.z);
}

kernel void batchnorm(texture2d_array<half, access::read> inTexture [[texture(0)]],
                      texture2d_array<half, access::write> outTexture [[texture(1)]],
                      const device half4 * newScale [[buffer(0)]],
                      const device half4 * newBias [[buffer(1)]],
                      uint3 gid [[thread_position_in_grid]]) {
    if (gid.x >= outTexture.get_width() ||
        gid.y >= outTexture.get_height() ||
        gid.z >= outTexture.get_array_size()) return;
    const half4 input = inTexture.read(gid.xy, gid.z);
    half4 output = input * newScale[gid.z] + newBias[gid.z];
    outTexture.write(output, gid.xy, gid.z);
}

//kernel void texture2d_to_2d_array(texture2d<half, access::read> inTexture [[texture(0)]],
//                               texture2d_array<half, access::write> outTexture [[texture(1)]],
//                               uint3 gid [[thread_position_in_grid]]) {
//    if (gid.x >= inTexture.get_width() ||
//        gid.y >= inTexture.get_height()){
//        return;
//    }
//    const half4 input = inTexture.read(gid.xy);
//    outTexture.write(input, gid.xy, 0);
//}

kernel void texture2d_to_2d_array(texture2d<float, access::read> inTexture [[texture(0)]],
                                  texture2d_array<float, access::write> outTexture [[texture(1)]],
                                  uint3 gid [[thread_position_in_grid]]) {
    if (gid.x >= inTexture.get_width() ||
        gid.y >= inTexture.get_height()){
        return;
    }
    const float4 input = inTexture.read(gid.xy);
    outTexture.write(input, gid.xy, 0);
}


kernel void texture2d_to_2d_array_half(texture2d<half, access::read> inTexture [[texture(0)]],
                                  texture2d_array<half, access::write> outTexture [[texture(1)]],
                                  uint3 gid [[thread_position_in_grid]]) {
    if (gid.x >= inTexture.get_width() ||
        gid.y >= inTexture.get_height()){
        return;
    }
    const half4 input = inTexture.read(gid.xy);
    outTexture.write(input, gid.xy, 0);
}

struct PoolParam {
    int ksizeX;
    int ksizeY;
    int strideX;
    int strideY;
    int paddingX;
    int paddingY;
    int poolType;
};

kernel void pool(texture2d_array<float, access::read> inTexture [[texture(0)]],
                 texture2d_array<float, access::write> outTexture [[texture(1)]],
                 constant PoolParam &pm [[buffer(0)]],
                 uint3 gid [[thread_position_in_grid]]) {
    if (gid.x >= outTexture.get_width() ||
        gid.y >= outTexture.get_height() ||
        gid.z >= outTexture.get_array_size()) return;
    int xmin = gid.x * pm.strideX - pm.paddingX;
    int xmax = min(xmin + pm.ksizeX, int(inTexture.get_width()));
    xmin = max(xmin, 0);
    int ymin = gid.y * pm.strideX - pm.paddingX;
    int ymax = min(ymin + pm.ksizeX, int(inTexture.get_height()));
    ymin = max(ymin, 0);
    
    float4 r = 0;
    if (pm.poolType == 0) {
        r = inTexture.read(uint2(xmin, ymin), gid.z);
        for (int x = xmin; x < xmax; x++) {
            for (int y = ymin; y < ymax; y++) {
                r = fmax(r, inTexture.read(uint2(x, y), gid.z));
            }
        }
    } else if (pm.poolType == 1) {
        for (int x = xmin; x < xmax; x++) {
            for (int y = ymin; y < ymax; y++) {
                r += inTexture.read(uint2(x, y), gid.z);
            }
        }
        r /= pm.ksizeX * pm.ksizeY;
    }
    outTexture.write(r, gid.xy, gid.z);
}


kernel void pool_half(texture2d_array<half, access::read> inTexture [[texture(0)]],
                 texture2d_array<half, access::write> outTexture [[texture(1)]],
                 constant PoolParam &pm [[buffer(0)]],
                 uint3 gid [[thread_position_in_grid]]) {
    if (gid.x >= outTexture.get_width() ||
        gid.y >= outTexture.get_height() ||
        gid.z >= outTexture.get_array_size()) return;
    int xmin = gid.x * pm.strideX - pm.paddingX;
    int xmax = min(xmin + pm.ksizeX, int(inTexture.get_width()));
    xmin = max(xmin, 0);
    int ymin = gid.y * pm.strideX - pm.paddingX;
    int ymax = min(ymin + pm.ksizeX, int(inTexture.get_height()));
    ymin = max(ymin, 0);
    
    half4 r = 0;
    if (pm.poolType == 0) {
        r = inTexture.read(uint2(xmin, ymin), gid.z);
        for (int x = xmin; x < xmax; x++) {
            for (int y = ymin; y < ymax; y++) {
                r = fmax(r, inTexture.read(uint2(x, y), gid.z));
            }
        }
    } else if (pm.poolType == 1) {
        for (int x = xmin; x < xmax; x++) {
            for (int y = ymin; y < ymax; y++) {
                r += inTexture.read(uint2(x, y), gid.z);
            }
        }
        r /= pm.ksizeX * pm.ksizeY;
    }
    outTexture.write(r, gid.xy, gid.z);
}

kernel void reshape(texture2d_array<float, access::read> inTexture [[texture(0)]],
                    texture2d_array<float, access::write> outTexture [[texture(1)]],
                    uint3 gid [[thread_position_in_grid]]) {
    if (gid.x >= outTexture.get_width() ||
        gid.y >= outTexture.get_height() ||
        gid.z >= outTexture.get_array_size()) return;
    
    float4 r = inTexture.read(uint2(0, 0), gid.z);
    outTexture.write(r, gid.xy, gid.z);
}

kernel void reshape_half(texture2d_array<half, access::read> inTexture [[texture(0)]],
                    texture2d_array<half, access::write> outTexture [[texture(1)]],
                    uint3 gid [[thread_position_in_grid]]) {
    if (gid.x >= outTexture.get_width() ||
        gid.y >= outTexture.get_height() ||
        gid.z >= outTexture.get_array_size()) return;
    
    half4 r = inTexture.read(uint2(0, 0), gid.z);
    outTexture.write(r, gid.xy, gid.z);
}

kernel void softmax(texture2d_array<float, access::read> inTexture [[texture(0)]],
                    texture2d_array<float, access::write> outTexture [[texture(1)]],
                    uint3 gid [[thread_position_in_grid]]) {
    if (gid.x >= outTexture.get_width() ||
        gid.y >= outTexture.get_height() ||
        gid.z >= outTexture.get_array_size()) return;
    int zsize = inTexture.get_array_size();
    float maxv = inTexture.read(uint2(0, 0), 0)[0];
    for (int z = 0; z < zsize; z++) {
        float4 r = inTexture.read(uint2(0, 0), z);
        maxv = max(maxv, max(max(r[0], r[1]), max(r[2], r[3])));
    }
    float sum = 0;
    for (int z = 0; z < zsize; z++) {
        float4 r = inTexture.read(uint2(0, 0), z);
        sum += exp(r[0] - maxv) + exp(r[1] - maxv) + exp(r[2] - maxv) + exp(r[3] - maxv);
    }
    float4 rr = inTexture.read(gid.xy, gid.z);
    rr = exp(rr - maxv) / sum;
    outTexture.write(rr, gid.xy, gid.z);
}


kernel void softmax_half(texture2d_array<half, access::read> inTexture [[texture(0)]],
                    texture2d_array<half, access::write> outTexture [[texture(1)]],
                    uint3 gid [[thread_position_in_grid]]) {
    if (gid.x >= outTexture.get_width() ||
        gid.y >= outTexture.get_height() ||
        gid.z >= outTexture.get_array_size()) return;
    int zsize = inTexture.get_array_size();
    half maxv = inTexture.read(uint2(0, 0), 0)[0];
    for (int z = 0; z < zsize; z++) {
        half4 r = inTexture.read(uint2(0, 0), z);
        maxv = max(maxv, max(max(r[0], r[1]), max(r[2], r[3])));
    }
    float sum = 0;
    for (int z = 0; z < zsize; z++) {
        half4 r = inTexture.read(uint2(0, 0), z);
        sum += exp(r[0] - maxv) + exp(r[1] - maxv) + exp(r[2] - maxv) + exp(r[3] - maxv);
    }
    half4 rr = inTexture.read(gid.xy, gid.z);
    rr = exp(rr - maxv) / sum;
    outTexture.write(rr, gid.xy, gid.z);
}