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129 lines
3.7 KiB
C++
129 lines
3.7 KiB
C++
// sprit-forth: A portable subroutine-threaded Forth.
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// Copyright (C) 2023 Clyne Sullivan <clyne@bitgloo.com>
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//
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// This library is free software; you can redistribute it and/or modify it
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// under the terms of the GNU Library General Public License as published by
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// the Free Software Foundation; either version 2 of the License, or (at your
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// option) any later version.
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//
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// This library is distributed in the hope that it will be useful, but WITHOUT
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// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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// FOR A PARTICULAR PURPOSE. See the GNU Library General Public License for
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// more details.
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//
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// You should have received a copy of the GNU Library General Public License
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// along with this library; if not, write to the Free Software Foundation, Inc.,
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// 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
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#include "core.hpp"
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#include "state.hpp"
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#include <csetjmp>
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#include <cstring>
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FuncList IP = nullptr;
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std::array<Cell, DictSize> DICT;
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Cell& HERE = DICT[DIdxHere];
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Cell& LATEST = DICT[DIdxLatest];
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Cell& STATE = DICT[DIdxState];
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static std::jmp_buf jmpbuf;
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static Cell *SP = DICT.data() + DICT.size() - DS;
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static Cell *RP = DICT.data() + DICT.size() - DS - RS;
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void push(Cell value) {
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if (SP >= DICT.data() + DICT.size())
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std::longjmp(jmpbuf, static_cast<int>(Error::push));
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*++SP = value;
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}
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Cell pop() {
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if (SP - 1 < DICT.data() + DICT.size() - DS)
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std::longjmp(jmpbuf, static_cast<int>(Error::pop));
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return *SP--;
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}
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Cell *sp() {
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return SP;
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}
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void rpush(Cell value) {
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if (RP >= DICT.data() + DICT.size() - DS)
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std::longjmp(jmpbuf, static_cast<int>(Error::rpush));
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*++RP = value;
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}
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Cell rpop() {
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if (RP - 1 < DICT.data() + DICT.size() - DS - RS)
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std::longjmp(jmpbuf, static_cast<int>(Error::rpop));
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return *RP--;
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}
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Cell *rp() {
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return RP;
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}
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Error executor(FuncList *list)
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{
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auto result = static_cast<Error>(setjmp(jmpbuf));
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FuncList body;
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if (static_cast<int>(result) == 0) {
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result = Error::none;
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// We are given the pointer to a list of function pointers.
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// Dereference once to retrieve the function pointer list.
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// We do not work with IP initially since it needs to be set to zero if
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// this is a top-level call/execution.
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body = *list;
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// Enter the execution loop.
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goto entry;
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// Execution continues so long as IP is not zero.
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// If this is a top-level execution of a pre-defined word, then IP will
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// remain zero'd and the loop will immediately exit.
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// If this is a defined word's execution, then its "call" will overwrite
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// IP (and push the initial zero-IP to the return stack); execution will
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// continue until we return to the zero-IP.
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while (IP) {
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// Retrieve next function pointer list.
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body = (FuncList)*++IP;
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entry:
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// Dereference `body` to get the first function in the list.
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// This is casted to take a FuncList as an argument since defined
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// words need to know their addresses so that they can perform
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// their "calls".
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// If the word is pre-defined then the argument will simply be
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// ignored.
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auto func = (void (*)(FuncList))*body;
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func(body);
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}
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}
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return result;
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}
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Error execute1(Word *word)
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{
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// IP must initially be zero if executing a word at the top level.
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IP = 0;
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return executor(&word->list);
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}
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Word *find(const char *s, int len)
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{
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for (auto w = (Word *)LATEST; w; w = w->link) {
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if (len == (int)strlen(w->name) && strncmp(s, w->name, len) == 0)
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return w;
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}
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return nullptr;
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}
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