portapack-mayhem/firmware/common/convert.hpp
Kyle Reed 6574272ca8
Freqman improvements (#1276)
* Show .1 MHz in pretty freqman string

* Refactor load to user FreqmanDB

* Recon file parsing cleanup

* use strtol for parse_int

* recon file cleanup

* Fix bugs in Recon changes

* PR feedback

---------

Co-authored-by: kallanreed <kallanreed@noreply.github.com>
2023-07-17 11:43:37 -07:00

92 lines
3.0 KiB
C++

/*
* Copyright (C) 2023 Kyle Reed
*
* This file is part of PortaPack.
*
* 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, 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; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street,
* Boston, MA 02110-1301, USA.
*/
#ifndef __CONVERT_H__
#define __CONVERT_H__
#include <cstdlib>
#include <cstring>
#include <limits>
#include <string>
#include <string_view>
#include <type_traits>
constexpr size_t max_parse_int_length = 64;
/* This undefined type is used to see the size of the
* unhandled type and to create a compilation error. */
template <size_t N>
struct UnhandledSize;
/* Returns true when errno is ERANGE. */
inline bool range_error() {
return errno == ERANGE;
}
/* Assigns 'value' to 'out_val' and returns true if 'value' is
* in bounds for type TOut. */
template <typename TVal, typename TOut>
bool checked_assign(TVal value, TOut& out_val) {
// No chance for overflow, just return.
if constexpr (sizeof(TVal) <= sizeof(TOut)) {
out_val = value;
return true;
}
out_val = static_cast<TOut>(value);
return value >= static_cast<TVal>(std::numeric_limits<TOut>::min()) &&
value <= static_cast<TVal>(std::numeric_limits<TOut>::max());
}
/* Zero-allocation conversion helper. 'str' must be smaller than 'max_parse_int_length'. */
template <typename T>
std::enable_if_t<std::is_integral_v<T>, bool> parse_int(std::string_view str, T& out_val, int base = 10) {
// Always initialize the output.
out_val = {};
if (str.size() > max_parse_int_length)
return false;
// Copy onto the stack and null terminate.
char zstr[max_parse_int_length + 1];
std::memcpy(zstr, str.data(), str.size());
zstr[str.size()] = '\0';
// A little C++ type magic to select the correct conversion function.
if constexpr (sizeof(T) == sizeof(long long)) {
if constexpr (std::is_unsigned_v<T>)
return checked_assign(strtoull(zstr, nullptr, base), out_val) && !range_error();
else
return checked_assign(strtoll(zstr, nullptr, base), out_val) && !range_error();
} else if constexpr (sizeof(T) <= sizeof(long)) {
if constexpr (std::is_unsigned_v<T>)
return checked_assign(strtoul(zstr, nullptr, base), out_val) && !range_error();
else
return checked_assign(strtol(zstr, nullptr, base), out_val) && !range_error();
} else {
UnhandledSize<sizeof(T) * 8> unhandled_case;
return false;
}
return true;
}
#endif /*__CONVERT_H__*/