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alee-forth/corewords.cpp

249 lines
6.2 KiB
C++

2 years ago
/**
* 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/>.
*/
#include "corewords.hpp"
#include <cstring>
#include <utility>
Word getword(State& state)
{
auto word = state.dict.input();
while (word.size() == 0) {
state.input(state);
word = state.dict.input();
}
return word;
}
void newdef(Dictionary& dict, Word word)
{
auto addr = dict.alignhere();
dict.addDefinition(word);
dict.write(addr,
(dict.read(addr) & 0x1F) |
((addr - dict.latest()) << 6));
dict.latest(addr);
};
void tick(State& state)
{
auto word = getword(state);
if (auto j = state.dict.find(word); j > 0)
state.push(state.dict.getexec(j));
else if (auto i = CoreWords::findi(state, word); i >= 0)
state.push(i & ~CoreWords::Immediate);
else
state.push(0);
}
void CoreWords::run(unsigned int index, State& state)
{
Cell cell;
DoubleCell dcell;
execute:
switch (index) {
default:
// must be calling a defined subroutine
state.pushr(state.ip);
state.ip = index - sizeof(Cell);
break;
case 0: // _lit
state.push(state.beyondip());
break;
case 1: // drop
state.pop();
break;
case 2: // dup
state.push(state.top());
break;
case 3: // swap
std::swap(state.top(), state.pick(1));
break;
case 4: // pick
state.push(state.pick(state.pop()));
break;
case 5: // sys
user_sys(state);
break;
case 6: // add
cell = state.pop();
state.top() += cell;
break;
case 7: // sub
cell = state.pop();
state.top() -= cell;
break;
case 8: // mul ( n n -- d )
cell = state.pop();
dcell = state.pop() * cell;
state.push(dcell);
state.push(dcell >> (sizeof(Cell) * 8));
break;
case 9: // div ( d n -- n )
cell = state.pop();
dcell = state.pop();
dcell <<= sizeof(Cell) * 8;
dcell |= state.pop();
state.push(dcell / cell);
break;
case 10: // mod ( d n -- n )
cell = state.pop();
dcell = state.pop();
dcell <<= sizeof(Cell) * 8;
dcell |= state.pop();
state.push(dcell % cell);
break;
case 11: // peek
if (state.pop())
state.push(state.dict.read(state.pop()));
else
state.push(state.dict.readbyte(state.pop()));
break;
case 12: // poke
cell = state.pop();
if (auto addr = state.pop(); cell)
state.dict.write(addr, state.pop());
else
state.dict.writebyte(addr, state.pop());
break;
case 13: // pushr
state.pushr(state.pop());
break;
case 14: // popr
state.push(state.popr());
break;
case 15: // equal
cell = state.pop();
state.top() = state.top() == cell;
break;
case 16: // lt
cell = state.pop();
state.top() = state.top() < cell;
break;
case 17: // and
cell = state.pop();
state.top() &= cell;
break;
case 18: // or
cell = state.pop();
state.top() |= cell;
break;
case 19: // xor
cell = state.pop();
state.top() ^= cell;
break;
case 20: // shl
cell = state.pop();
state.top() <<= cell;
break;
case 21: // shr
cell = state.pop();
state.top() >>= cell;
break;
case 22: // colon
newdef(state.dict, getword(state));
state.compiling(true);
break;
case 23: // tick
tick(state);
break;
case 24: // execute
index = state.pop();
goto execute;
break;
case 25: // exit
state.ip = state.popr();
break;
case 26: // semic
state.dict.add(findi("exit"));
state.compiling(false);
break;
case 27: // _jmp
state.ip = state.beyondip() - sizeof(Cell);
break;
case 28: // _jmp0
if (state.pop())
state.beyondip();
else
state.ip = state.beyondip() - sizeof(Cell);
break;
case 29: // depth
state.push(state.size());
break;
case 30: // _rdepth
state.push(state.rsize());
break;
case 31: // key
cell = state.dict.read(Dictionary::Input);
while (cell <= 0) {
state.input(state);
cell = state.dict.read(Dictionary::Input);
}
state.dict.write(Dictionary::Input, cell - 1);
state.push(
state.dict.readbyte(
Dictionary::Input + sizeof(Cell) +
Dictionary::InputCells - cell));
break;
}
}
int CoreWords::findi(const char *word)
{
const auto size = std::strlen(word);
std::size_t i;
int wordsi = 0;
for (i = 0; i < sizeof(wordsarr);) {
auto end = i;
while (wordsarr[end] > '\1')
++end;
if (size == end - i && !std::strncmp(word, wordsarr + i, size))
return wordsarr[end] == '\0' ? wordsi : (wordsi | Immediate);
++wordsi;
i = end + 1;
}
return -1;
}
int CoreWords::findi(State& state, Word word)
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{
std::size_t i;
int wordsi = 0;
for (i = 0; i < sizeof(wordsarr);) {
auto end = i;
while (wordsarr[end] > '\1')
++end;
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if (state.dict.equal(word, wordsarr + i, end - i))
return wordsarr[end] == '\0' ? wordsi : (wordsi | Immediate);
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++wordsi;
i = end + 1;
}
return -1;
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}