/*
 * Copyright (c) 2017, NVIDIA CORPORATION. All rights reserved.
 *
 * 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.
 */

extern "C" {

texture<unsigned char, 2> uchar_tex;
texture<uchar2, 2>  uchar2_tex;
texture<uchar4, 2>  uchar4_tex;
texture<unsigned short, 2> ushort_tex;
texture<ushort2, 2>  ushort2_tex;
texture<ushort4, 2>  ushort4_tex;

__global__ void Subsample_Bilinear_uchar(unsigned char *dst,
                                    int dst_width, int dst_height, int dst_pitch,
                                    int src_width, int src_height)
{
    int xo = blockIdx.x * blockDim.x + threadIdx.x;
    int yo = blockIdx.y * blockDim.y + threadIdx.y;

    if (yo < dst_height && xo < dst_width)
    {
        float hscale = (float)src_width / (float)dst_width;
        float vscale = (float)src_height / (float)dst_height;
        float xi = (xo + 0.5f) * hscale;
        float yi = (yo + 0.5f) * vscale;
        // 3-tap filter weights are {wh,1.0,wh} and {wv,1.0,wv}
        float wh = min(max(0.5f * (hscale - 1.0f), 0.0f), 1.0f);
        float wv = min(max(0.5f * (vscale - 1.0f), 0.0f), 1.0f);
        // Convert weights to two bilinear weights -> {wh,1.0,wh} -> {wh,0.5,0} + {0,0.5,wh}
        float dx = wh / (0.5f + wh);
        float dy = wv / (0.5f + wv);
        int y0 = tex2D(uchar_tex, xi-dx, yi-dy);
        int y1 = tex2D(uchar_tex, xi+dx, yi-dy);
        int y2 = tex2D(uchar_tex, xi-dx, yi+dy);
        int y3 = tex2D(uchar_tex, xi+dx, yi+dy);
        dst[yo*dst_pitch+xo] = (unsigned char)((y0+y1+y2+y3+2) >> 2);
    }
}

__global__ void Subsample_Bilinear_uchar2(uchar2 *dst,
                                    int dst_width, int dst_height, int dst_pitch2,
                                    int src_width, int src_height)
{
    int xo = blockIdx.x * blockDim.x + threadIdx.x;
    int yo = blockIdx.y * blockDim.y + threadIdx.y;

    if (yo < dst_height && xo < dst_width)
    {
        float hscale = (float)src_width / (float)dst_width;
        float vscale = (float)src_height / (float)dst_height;
        float xi = (xo + 0.5f) * hscale;
        float yi = (yo + 0.5f) * vscale;
        // 3-tap filter weights are {wh,1.0,wh} and {wv,1.0,wv}
        float wh = min(max(0.5f * (hscale - 1.0f), 0.0f), 1.0f);
        float wv = min(max(0.5f * (vscale - 1.0f), 0.0f), 1.0f);
        // Convert weights to two bilinear weights -> {wh,1.0,wh} -> {wh,0.5,0} + {0,0.5,wh}
        float dx = wh / (0.5f + wh);
        float dy = wv / (0.5f + wv);
        uchar2 c0 = tex2D(uchar2_tex, xi-dx, yi-dy);
        uchar2 c1 = tex2D(uchar2_tex, xi+dx, yi-dy);
        uchar2 c2 = tex2D(uchar2_tex, xi-dx, yi+dy);
        uchar2 c3 = tex2D(uchar2_tex, xi+dx, yi+dy);
        int2 uv;
        uv.x = ((int)c0.x+(int)c1.x+(int)c2.x+(int)c3.x+2) >> 2;
        uv.y = ((int)c0.y+(int)c1.y+(int)c2.y+(int)c3.y+2) >> 2;
        dst[yo*dst_pitch2+xo] = make_uchar2((unsigned char)uv.x, (unsigned char)uv.y);
    }
}

__global__ void Subsample_Bilinear_uchar4(uchar4 *dst,
                                    int dst_width, int dst_height, int dst_pitch,
                                    int src_width, int src_height)
{
    int xo = blockIdx.x * blockDim.x + threadIdx.x;
    int yo = blockIdx.y * blockDim.y + threadIdx.y;

    if (yo < dst_height && xo < dst_width)
    {
        float hscale = (float)src_width / (float)dst_width;
        float vscale = (float)src_height / (float)dst_height;
        float xi = (xo + 0.5f) * hscale;
        float yi = (yo + 0.5f) * vscale;
        // 3-tap filter weights are {wh,1.0,wh} and {wv,1.0,wv}
        float wh = min(max(0.5f * (hscale - 1.0f), 0.0f), 1.0f);
        float wv = min(max(0.5f * (vscale - 1.0f), 0.0f), 1.0f);
        // Convert weights to two bilinear weights -> {wh,1.0,wh} -> {wh,0.5,0} + {0,0.5,wh}
        float dx = wh / (0.5f + wh);
        float dy = wv / (0.5f + wv);
        uchar4 c0 = tex2D(uchar4_tex, xi-dx, yi-dy);
        uchar4 c1 = tex2D(uchar4_tex, xi+dx, yi-dy);
        uchar4 c2 = tex2D(uchar4_tex, xi-dx, yi+dy);
        uchar4 c3 = tex2D(uchar4_tex, xi+dx, yi+dy);
        int4 res;
        res.x =  ((int)c0.x+(int)c1.x+(int)c2.x+(int)c3.x+2) >> 2;
        res.y =  ((int)c0.y+(int)c1.y+(int)c2.y+(int)c3.y+2) >> 2;
        res.z =  ((int)c0.z+(int)c1.z+(int)c2.z+(int)c3.z+2) >> 2;
        res.w =  ((int)c0.w+(int)c1.w+(int)c2.w+(int)c3.w+2) >> 2;
        dst[yo*dst_pitch+xo] = make_uchar4(
            (unsigned char)res.x, (unsigned char)res.y, (unsigned char)res.z, (unsigned char)res.w);
    }
}

__global__ void Subsample_Bilinear_ushort(unsigned short *dst,
                                    int dst_width, int dst_height, int dst_pitch,
                                    int src_width, int src_height)
{
    int xo = blockIdx.x * blockDim.x + threadIdx.x;
    int yo = blockIdx.y * blockDim.y + threadIdx.y;

    if (yo < dst_height && xo < dst_width)
    {
        float hscale = (float)src_width / (float)dst_width;
        float vscale = (float)src_height / (float)dst_height;
        float xi = (xo + 0.5f) * hscale;
        float yi = (yo + 0.5f) * vscale;
        // 3-tap filter weights are {wh,1.0,wh} and {wv,1.0,wv}
        float wh = min(max(0.5f * (hscale - 1.0f), 0.0f), 1.0f);
        float wv = min(max(0.5f * (vscale - 1.0f), 0.0f), 1.0f);
        // Convert weights to two bilinear weights -> {wh,1.0,wh} -> {wh,0.5,0} + {0,0.5,wh}
        float dx = wh / (0.5f + wh);
        float dy = wv / (0.5f + wv);
        int y0 = tex2D(ushort_tex, xi-dx, yi-dy);
        int y1 = tex2D(ushort_tex, xi+dx, yi-dy);
        int y2 = tex2D(ushort_tex, xi-dx, yi+dy);
        int y3 = tex2D(ushort_tex, xi+dx, yi+dy);
        dst[yo*dst_pitch+xo] = (unsigned short)((y0+y1+y2+y3+2) >> 2);
    }
}

__global__ void Subsample_Bilinear_ushort2(ushort2 *dst,
                                    int dst_width, int dst_height, int dst_pitch2,
                                    int src_width, int src_height)
{
    int xo = blockIdx.x * blockDim.x + threadIdx.x;
    int yo = blockIdx.y * blockDim.y + threadIdx.y;

    if (yo < dst_height && xo < dst_width)
    {
        float hscale = (float)src_width / (float)dst_width;
        float vscale = (float)src_height / (float)dst_height;
        float xi = (xo + 0.5f) * hscale;
        float yi = (yo + 0.5f) * vscale;
        // 3-tap filter weights are {wh,1.0,wh} and {wv,1.0,wv}
        float wh = min(max(0.5f * (hscale - 1.0f), 0.0f), 1.0f);
        float wv = min(max(0.5f * (vscale - 1.0f), 0.0f), 1.0f);
        // Convert weights to two bilinear weights -> {wh,1.0,wh} -> {wh,0.5,0} + {0,0.5,wh}
        float dx = wh / (0.5f + wh);
        float dy = wv / (0.5f + wv);
        ushort2 c0 = tex2D(ushort2_tex, xi-dx, yi-dy);
        ushort2 c1 = tex2D(ushort2_tex, xi+dx, yi-dy);
        ushort2 c2 = tex2D(ushort2_tex, xi-dx, yi+dy);
        ushort2 c3 = tex2D(ushort2_tex, xi+dx, yi+dy);
        int2 uv;
        uv.x = ((int)c0.x+(int)c1.x+(int)c2.x+(int)c3.x+2) >> 2;
        uv.y = ((int)c0.y+(int)c1.y+(int)c2.y+(int)c3.y+2) >> 2;
        dst[yo*dst_pitch2+xo] = make_ushort2((unsigned short)uv.x, (unsigned short)uv.y);
    }
}

__global__ void Subsample_Bilinear_ushort4(ushort4 *dst,
                                    int dst_width, int dst_height, int dst_pitch,
                                    int src_width, int src_height)
{
    int xo = blockIdx.x * blockDim.x + threadIdx.x;
    int yo = blockIdx.y * blockDim.y + threadIdx.y;

    if (yo < dst_height && xo < dst_width)
    {
        float hscale = (float)src_width / (float)dst_width;
        float vscale = (float)src_height / (float)dst_height;
        float xi = (xo + 0.5f) * hscale;
        float yi = (yo + 0.5f) * vscale;
        // 3-tap filter weights are {wh,1.0,wh} and {wv,1.0,wv}
        float wh = min(max(0.5f * (hscale - 1.0f), 0.0f), 1.0f);
        float wv = min(max(0.5f * (vscale - 1.0f), 0.0f), 1.0f);
        // Convert weights to two bilinear weights -> {wh,1.0,wh} -> {wh,0.5,0} + {0,0.5,wh}
        float dx = wh / (0.5f + wh);
        float dy = wv / (0.5f + wv);
        ushort4 c0 = tex2D(ushort4_tex, xi-dx, yi-dy);
        ushort4 c1 = tex2D(ushort4_tex, xi+dx, yi-dy);
        ushort4 c2 = tex2D(ushort4_tex, xi-dx, yi+dy);
        ushort4 c3 = tex2D(ushort4_tex, xi+dx, yi+dy);
        int4 res;
        res.x =  ((int)c0.x+(int)c1.x+(int)c2.x+(int)c3.x+2) >> 2;
        res.y =  ((int)c0.y+(int)c1.y+(int)c2.y+(int)c3.y+2) >> 2;
        res.z =  ((int)c0.z+(int)c1.z+(int)c2.z+(int)c3.z+2) >> 2;
        res.w =  ((int)c0.w+(int)c1.w+(int)c2.w+(int)c3.w+2) >> 2;
        dst[yo*dst_pitch+xo] = make_ushort4(
            (unsigned short)res.x, (unsigned short)res.y, (unsigned short)res.z, (unsigned short)res.w);
    }
}

}