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/**
* Alee Forth: A portable and concise Forth implementation in modern C++.
* Copyright (C) 2023 Clyne Sullivan <clyne@bitgloo.com>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#ifndef ALEEFORTH_STATE_HPP
#define ALEEFORTH_STATE_HPP
#include "dictionary.hpp"
#include "types.hpp"
#include <csetjmp>
#include <cstddef>
constexpr unsigned DataStackSize = 16;
constexpr unsigned ReturnStackSize = 16;
struct State
{
enum class Error : int {
none,
push,
pop,
pushr,
popr,
top,
pick
};
Addr ip = 0;
Dictionary& dict;
void (*input)(State&);
Cell dstack[DataStackSize] = {};
Cell rstack[ReturnStackSize] = {};
Cell *dsp = dstack - 1;
Cell *rsp = rstack - 1;
std::jmp_buf jmpbuf = {};
constexpr State(Dictionary& d, void (*i)(State&)):
dict(d), input(i) {}
bool compiling() const;
void compiling(bool);
Error execute(Addr);
std::size_t size() const noexcept;
std::size_t rsize() const noexcept;
inline void push(Cell value) {
if (dsp == dstack + DataStackSize - 1)
std::longjmp(jmpbuf, static_cast<int>(Error::push));
*++dsp = value;
}
inline Cell pop() {
if (dsp < dstack)
std::longjmp(jmpbuf, static_cast<int>(Error::pop));
return *dsp--;
}
inline Cell beyondip() {
ip += sizeof(Cell);
return dict.read(ip);
}
inline void pushr(Cell value) {
if (rsp == rstack + ReturnStackSize - 1)
std::longjmp(jmpbuf, static_cast<int>(Error::pushr));
*++rsp = value;
}
inline Cell popr() {
if (rsp < rstack)
std::longjmp(jmpbuf, static_cast<int>(Error::popr));
return *rsp--;
}
inline Cell& top() {
if (dsp < dstack)
std::longjmp(jmpbuf, static_cast<int>(Error::top));
return *dsp;
}
inline Cell& pick(std::size_t i) {
if (dsp - i < dstack)
std::longjmp(jmpbuf, static_cast<int>(Error::pick));
return *(dsp - i);
}
};
#endif // ALEEFORTH_STATE_HPP
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