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/*******************************************************
* Copyright (c) 2014, ArrayFire
* All rights reserved.
*
* This file is distributed under 3-clause BSD license.
* The complete license agreement can be obtained at:
* http://arrayfire.com/licenses/BSD-3-Clause
********************************************************/
#pragma once
#include <iostream>
#include <fstream>
#include <stdexcept>
#include <vector>
#include <algorithm>
#include <arrayfire.h>
union Data
{
unsigned dim;
char bytes[4];
};
unsigned char reverse_char(unsigned char b)
{
b = (b & 0xF0) >> 4 | (b & 0x0F) << 4;
b = (b & 0xCC) >> 2 | (b & 0x33) << 2;
b = (b & 0xAA) >> 1 | (b & 0x55) << 1;
return b;
}
// http://stackoverflow.com/a/9144870/2192361
unsigned reverse(unsigned x)
{
x = ((x >> 1) & 0x55555555u) | ((x & 0x55555555u) << 1);
x = ((x >> 2) & 0x33333333u) | ((x & 0x33333333u) << 2);
x = ((x >> 4) & 0x0f0f0f0fu) | ((x & 0x0f0f0f0fu) << 4);
x = ((x >> 8) & 0x00ff00ffu) | ((x & 0x00ff00ffu) << 8);
x = ((x >> 16) & 0xffffu) | ((x & 0xffffu) << 16);
return x;
}
template<class ty>
void read_idx(std::vector<dim_t> &dims, std::vector<ty> &data, const char *name)
{
std::ifstream f(name, std::ios::in | std::ios::binary);
if (!f.is_open()) throw std::runtime_error("Unable to open file");
Data d;
f.read(d.bytes, sizeof(d.bytes));
if (d.bytes[2] != 8) {
throw std::runtime_error("Unsupported data type");
}
unsigned numdims = d.bytes[3];
unsigned elemsize = 1;
// Read the dimensions
size_t elem = 1;
dims = std::vector<dim_t>(numdims);
for (unsigned i = 0; i < numdims; i++) {
f.read(d.bytes, sizeof(d.bytes));
// Big endian to little endian
for (int j = 0; j < 4; j++) d.bytes[j] = reverse_char(d.bytes[j]);
unsigned dim = reverse(d.dim);
elem *= dim;
dims[i] = (dim_t)dim;
}
// Read the data
std::vector<char> cdata(elem);
f.read(&cdata[0], elem * elemsize);
std::vector<unsigned char> ucdata(cdata.begin(), cdata.end());
data = std::vector<ty>(ucdata.begin(), ucdata.end());
f.close();
return;
}
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