/*
	Copyright (C) 2012  fmaj7b5.info

	This program is free software: you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation, either version 2 of the License, or
	(at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "stdafx.h"
#include <cuda.h>

#include "binarize.cuh"

using namespace FM7b5;

void
FM7b5::binarize_gpu(ImageGray& out, const ImageGray& in, const uint8_t thres)
{

	if (in.width() != out.width() || in.height() != out.height()) {
		throw std::runtime_error("sizes of input and output images are diferent.");
	}

	const size_t width(in.width()), height(in.height()), bpp(in.bpp());

	uint8_t* d_in(nullptr);
	uint8_t* d_out(nullptr);
	size_t in_pitch(0), out_pitch(0);

	const size_t threads_per_dim(32);
	dim3 threads_per_block(threads_per_dim, threads_per_dim);
	dim3 blocks_per_grid((width + threads_per_block.x - 1)/ threads_per_block.x,
	                     (height + threads_per_block.y - 1)/ threads_per_block.y);

	cudaError_t status;

	// allocate input/output memories
	status = cudaMallocPitch(&d_in, &in_pitch, width * bpp, height);
	if (status != cudaSuccess) {
		goto on_error_in;
	}

	status = cudaMallocPitch(&d_out, &out_pitch, width * bpp, height);
	if (status != cudaSuccess) {
		goto on_error_out;
	}

	// copy an input image to device memory
	status = cudaMemcpy2D(d_in, in_pitch, in.data(), in.stride(), bpp * width, height, cudaMemcpyHostToDevice);
	if (status != cudaSuccess) {
		goto on_error_proc;
	}

	// launch kernel
	binarize<<<blocks_per_grid, threads_per_block>>>(d_out, out_pitch, d_in, in_pitch, width, height, thres);

	// copy the result back to host memory
	status = cudaMemcpy2D(out.data(), out.stride(), d_out, out_pitch, bpp * width, height, cudaMemcpyDeviceToHost);
	if (status != cudaSuccess) {
		goto on_error_proc;
	}

	// free device memories
	cudaFree(d_out);
	cudaFree(d_in);

	return;

	// error handling
on_error_proc:
	cudaFree(d_out);
on_error_out:
	cudaFree(d_in);
on_error_in:
		throw std::runtime_error(cudaGetErrorString(status));
}

__global__
void
FM7b5::binarize(uint8_t* out, const size_t out_pitch, const uint8_t* in, const size_t in_pitch, const size_t width, const size_t height, const uint8_t thres)
{
	const size_t w(blockDim.x * blockIdx.x + threadIdx.x);
	const size_t h(blockDim.y * blockIdx.y + threadIdx.y);

	if (w >= width || h >= height) {
		return;
	}

	out[out_pitch * h + w] = (in[in_pitch * h + w] < thres) ? 0 : 255;
}