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// endian/example/uses_cases.cpp -----------------------------------------------------//
// Copyright Beman Dawes 2014
// Distributed under the Boost Software License, Version 1.0.
// See http://www.boost.org/LICENSE_1_0.txt
//--------------------------------------------------------------------------------------//
#ifndef _SCL_SECURE_NO_WARNINGS
# define _SCL_SECURE_NO_WARNINGS
#endif
#ifndef _CRT_SECURE_NO_WARNINGS
# define _CRT_SECURE_NO_WARNINGS
#endif
#include <boost/endian/conversion.hpp>
#include <boost/endian/buffers.hpp>
#include <boost/endian/arithmetic.hpp>
#include <iostream>
using namespace boost::endian;
using std::cout;
using std::endl;
{ // Use case 2 - Endian buffer types
struct Record
{
big_ubuf32_t count; // big endian
big_buf32_t value; // big endian
};
Record rec;
read(&rec, sizeof(Record));
uint32_t count = rec.count.value();
int32_t value = rec.value.value();
++count;
value += fee;
rec.count = count;
rec.value = value;
write(&rec, sizeof(Record));
}
{ // Use case 3a - Endian arithmetic types
struct Record
{
big_uint32_t count; // big endian
big_int32_t value; // big endian
};
Record rec;
read(&rec, sizeof(Record));
++rec.count;
rec.value += fee;
write(&rec, sizeof(Record));
}
{ // Use case 3b - Endian arithmetic types
struct Record
{
big_uint32_t count; // big endian
big_int32_t value; // big endian
};
Record rec;
read(&rec, sizeof(Record));
uint32_t count = rec.count;
int32_t value = rec.value;
++count;
value += fee;
rec.count = count;
rec.value = value;
write(&rec, sizeof(Record));
}
// Recommended approach when conversion time is not a concern
//
// Conversion time is not a concert with this application because the minimum
// possible number of conversions is performed and because I/O time will be
// much greater than conversion time.
{
struct Record
{
big_uint32_t count; // big endian
big_int32_t value; // big endian
};
Record rec;
read(&rec, sizeof(Record));
++rec.count;
rec.value += fee;
write(&rec, sizeof(Record));
}
// Recommended approach when conversion time is a concern
//
// Conversion time is a concert with this application because (1) any conversions
// performed in the loop will consume a great deal of time and because (2)
// computation time will be much greater than I/O time.
{
struct Record
{
big_uint32_t count; // big endian
big_int32_t value; // big endian
};
Record rec;
read(&rec, sizeof(Record));
uint32_t count = rec.count;
int32_t value = rec.value;
for (long long i = 0; i < several_gazillion; ++i) // (1)
{
... immensely complex computation using rec variables many times // (2)
}
rec.count = count;
rec.value = value;
write(&rec, sizeof(Record));
}
}
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