Interpret assembly syntax

.clang-format

@@ -37,3 +37,4 @@ WhitespaceSensitiveMacros:
   - testcase
   - testgroup
   - TEST_ITEM
+  - DESTRINGIFY_NAME

CHANGELOG.md

@@ -4,6 +4,10 @@ All notable changes to this project will be documented in this file. See [Keep a
 
 ## Unreleased
 
+### Added
+
+- The interpreter can now handle assembly syntax, with the `-A` flag in the command line and a checkbox in the online interpreter. Currently, interactive debugging of assembly is not supported in the web interpreter.
+
 ### Changed
 
 - Fixed C++23 support

README.md

@@ -17,6 +17,7 @@ Trilangle is a 2-D, stack-based programming language inspired by [Hexagony].
 > - [Interpreter flags](#interpreter-flags)
 > - [Exit codes](#exit-codes)
 > - [The disassembler](#the-disassembler)
+>   - [Assembly syntax](#assembly-syntax)
 > - [C compiler](#c-compiler)
 > - [Sample programs](#sample-programs)
 >   - [cat](#cat)
@@ -225,6 +226,36 @@ For example, when passing [the cat program below](#cat) with the flags `-Dn`, th
 2.2:	EXT
 ```
 
+### Assembly syntax
+
+In addition to producing this syntax, Trilangle is capable of interpreting this syntax. Currently, the output with `--hide-nops` is not guaranteed to be interpretable, as it may be missing jump targets. Each line can maximally consist of a label, an instruction, and a comment. The syntax can be described with the following extended Backus-Naur form:
+
+```
+program = line, {newline, line};
+line = [label, [":"]], [multiple_whitespace, instruction], {whitespace}, [comment];
+
+newline = ? U+000A END OF LINE ?;
+tab = ? U+0009 CHARACTER TABULATION ?;
+whitespace = " " | ? U+000D CARRIAGE RETURN ? | tab;
+non_whitespace = ? Any single unicode character not in 'newline' or 'whitespace' ?;
+multiple_whitespace = whitespace, {whitespace};
+
+label = non_whitespace, {non_whitespace};
+comment = ";", {non_whitespace | whitespace};
+
+instruction = instruction_with_target | instruction_with_argument | plain_instruction;
+instruction_with_target = ("BNG" | "TSP" | "JMP"), multiple_whitespace, label;
+instruction_with_argument = ("PSI" | "PSC"), multiple_whitespace, number_literal;
+plain_instruction = ? Any three-character instruction besides the five already covered ?;
+
+number_literal = character_literal | decimal_literal | hex_literal;
+character_literal = "'", (non_whitespace | tab), "'";
+decimal_literal = "#", decimal_digit;
+hex_literal = "0x", hex_digit, {hex_digit};
+decimal_digit = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9";
+hex_digit = "a" | "b" | "c" | "d" | "e" | "f" | "A" | "B" | "C" | "D" | "E" | "F" | decimal_digit;
+```
+
 ## C compiler
 
 When using the `-c` flag, the input program will be translated into C code. The C code is not meant to be idiomatic or easy to read, as it is a literal translation of the input. Optimizers such as those used by clang and GCC tend to do a good job of improving the program, in some cases removing the heap allocation altogether; MSVC does not.

qdeql/disassembly.txt

@@ -296,7 +296,7 @@ ct_bgn_not_end:
 ct_bgn_not_end_cleanup:
 	POP	; Remove the uop from the stack
 	DEC	; Advance the PC
-	JMP ct_find_end_loop
+	JMP ct_bgn_find_end_loop
 ct_bgn_found_end:
 ; If PC is pointing at the end uop, the stack layout is this:
 ; +======+------+----+

src/any_program_holder.hh

@@ -0,0 +1,13 @@
+#pragma once
+
+#include <functional>
+#include "instruction.hh"
+
+template<typename IP>
+class any_program_holder {
+public:
+    virtual void advance(IP& ip, std::function<bool()> go_left) = 0;
+    virtual instruction at(const IP& ip) = 0;
+    virtual std::string raw_at(const IP& ip) = 0;
+    virtual std::pair<size_t, size_t> get_coords(const IP& ip) const = 0;
+};

src/assembly_scanner.cpp

@@ -0,0 +1,293 @@
+#include "assembly_scanner.hh"
+#include <cinttypes>
+#include <cstring>
+#include <iostream>
+#include <set>
+#include <sstream>
+
+using std::cerr;
+using std::endl;
+using std::string;
+using std::string_view;
+using std::string_view_literals::operator""sv;
+
+#define WHITESPACE " \n\r\t"
+
+[[noreturn]] static void invalid_literal(const string& argument) {
+    cerr << "Invalid format for literal: " << argument << endl;
+    exit(EXIT_FAILURE);
+}
+
+const std::vector<instruction>& assembly_scanner::get_instructions() {
+    if (!m_instructions.empty()) {
+        return m_instructions;
+    }
+
+    // We need to do two passes: one to resolve labels, and one to assign targets to jumps. During the first pass, the
+    // fragments are actually constructed. However, jumps may not have valid targets yet, so we need some way to store
+    // the label's name inside an IP. This code relies on the following assumption:
+    static_assert(sizeof(NONNULL_PTR(const string)) <= sizeof(IP), "Cannot fit string pointer inside IP");
+    // Using an ordered set over any other container so that references are not invalidated after insertion
+    std::set<string> label_names;
+
+    auto label_to_fake_location = [&](const string& name) -> IP {
+        auto iter = label_names.find(name);
+        if (iter == label_names.end()) {
+            auto p = label_names.insert(name);
+            iter = p.first;
+        }
+        NONNULL_PTR(const string) ptr = &*iter;
+        return reinterpret_cast<uintptr_t>(ptr);
+    };
+
+    // First pass
+    size_t line_end = 0;
+    while (true) {
+        size_t line_start = m_program.find_first_not_of('\n', line_end);
+        if (line_start >= m_program.size()) {
+            break;
+        }
+        line_end = m_program.find_first_of('\n', line_start);
+        string_view curr_line = string_view(m_program).substr(line_start, line_end - line_start);
+
+        // Unquoted semicolons are comments. Remove them.
+        size_t i;
+        for (i = 0; i < curr_line.size(); ++i) {
+            if (curr_line[i] != ';') {
+                continue;
+            }
+            if (i == 0 || curr_line[i - 1] != '\'') {
+                break;
+            }
+        }
+        if (i < curr_line.size()) {
+            curr_line.remove_suffix(curr_line.size() - i);
+        }
+        // If the line is only a comment, move on
+        if (curr_line.empty()) {
+            continue;
+        }
+        // Remove trailing whitespace. If there's only whitespace, skip this line
+        i = curr_line.find_last_not_of(WHITESPACE);
+        if (i == string::npos) {
+            continue;
+        } else {
+            curr_line.remove_suffix(curr_line.size() - i - 1);
+        }
+
+        // Look for labels (non-whitespace in the first column)
+        i = curr_line.find_first_not_of(WHITESPACE ":");
+        assert(i != string::npos);
+        if (i == 0) {
+            // Label, find end
+            i = curr_line.find_first_of(WHITESPACE ":");
+            if (i == string::npos) {
+                i = curr_line.size();
+            }
+            string label(curr_line.substr(0, i));
+
+            [[maybe_unused]] auto _0 = label_names.insert(label);
+            auto [_, inserted] = m_label_locations.insert({ label, m_instructions.size() });
+
+            if (!inserted) {
+                cerr << "Label '" << label << "' appears twice" << endl;
+                exit(EXIT_FAILURE);
+            }
+
+            // Set i to the first non-whitespace character after the label
+            i = curr_line.find_first_not_of(WHITESPACE ":", i + 1);
+            if (i == string::npos) {
+                // Line was only a label
+                continue;
+            }
+        }
+
+        // Remove leading whitespace, and label if there is one
+        curr_line.remove_prefix(i);
+
+        // Line should only be the opcode and, if there is one, the argument
+        if (curr_line.size() < 3) {
+            cerr << "Instruction too short: " << curr_line << endl;
+            exit(EXIT_FAILURE);
+        }
+        if (curr_line.size() > 3 && !strchr(WHITESPACE, curr_line[3])) {
+            cerr << "Instruction too long: " << curr_line << endl;
+            exit(EXIT_FAILURE);
+        }
+
+        string_view instruction_name(curr_line.data(), 3);
+        instruction::operation opcode = assembly_scanner::opcode_for_name(instruction_name);
+        switch (opcode) {
+            case instruction::operation::JMP: {
+                size_t label_start = curr_line.find_first_not_of(WHITESPACE, 3);
+                instruction::argument arg;
+                string label(curr_line.substr(label_start));
+                arg.next = { SIZE_C(0), label_to_fake_location(label) };
+                m_instructions.push_back({ opcode, arg });
+                m_slices.push_back(curr_line);
+                break;
+            }
+            case instruction::operation::BNG:
+            case instruction::operation::TSP: {
+                size_t label_start = curr_line.find_first_not_of(WHITESPACE, 3);
+                instruction::argument arg;
+                string label(curr_line.substr(label_start));
+                arg.choice = { { SIZE_C(0), m_instructions.size() + 1 }, { SIZE_C(0), label_to_fake_location(label) } };
+                m_instructions.push_back({ opcode, arg });
+                m_slices.push_back(curr_line);
+                break;
+            }
+            case instruction::operation::PSI:
+            case instruction::operation::PSC: {
+                size_t arg_start = curr_line.find_first_not_of(WHITESPACE, 3);
+                if (arg_start == string::npos) {
+                    cerr << "Missing argument for push instruction" << endl;
+                    exit(EXIT_FAILURE);
+                }
+
+                string argument(curr_line.substr(arg_start));
+                int24_t arg_value;
+                // Should be in one of three formats:
+                // - 'c' (single UTF-8 character)
+                // - 0xff (arbitrary length hex number)
+                // - #9 (single decimal digit)
+                if (argument[0] == '\'' && argument.back() == '\'') {
+                    if (argument.size() < 3 || argument.size() > 6) {
+                        // One UTF-8 character is 1 to 4 bytes
+                        invalid_literal(argument);
+                    }
+                    i = 1;
+                    arg_value = parse_unichar([&]() { return argument[i++]; });
+                    if (arg_value < INT24_C(0) || i != argument.size() - 1) {
+                        invalid_literal(argument);
+                    }
+                } else if (argument[0] == '0' && argument[1] == 'x') {
+                    char* last = nullptr;
+                    unsigned long ul = strtoul(argument.c_str(), &last, 16);
+                    if (*last != '\0' || ul > 0x1f'ffffUL) {
+                        invalid_literal(argument);
+                    }
+                    arg_value = static_cast<int24_t>(ul);
+                } else if (argument[0] == '#' && argument.size() == 2) {
+                    arg_value = static_cast<int24_t>(argument[1] - '0');
+                    if (arg_value < INT24_C(0) || arg_value > INT24_C(9)) {
+                        invalid_literal(argument);
+                    }
+                } else {
+                    invalid_literal(argument);
+                }
+
+                if (opcode == instruction::operation::PSI) {
+                    // PSI expects to be given the digit, not the actual value
+                    auto p = arg_value.add_with_overflow('0');
+                    assert(!p.first);
+                    arg_value = p.second;
+                }
+
+                instruction::argument arg;
+                arg.number = arg_value;
+                m_instructions.push_back({ opcode, arg });
+                m_slices.push_back(curr_line);
+                break;
+            }
+            default:
+                m_instructions.push_back({ opcode, instruction::argument() });
+                m_slices.push_back(curr_line);
+                break;
+        }
+    }
+
+    if (!m_instructions.empty()) {
+        const auto& last_instr = m_instructions.back();
+        if (!(last_instr.is_exit() || last_instr.m_op == instruction::operation::JMP)) {
+            cerr << "Program does not end in an exit instruction or loop" << endl;
+            exit(EXIT_FAILURE);
+        }
+    }
+
+    // Second pass
+    for (auto& instr : m_instructions) {
+        if (instr.m_op == instruction::operation::JMP) {
+            fake_location_to_real(instr.m_arg.next);
+        } else if (instr.m_op == instruction::operation::TSP || instr.m_op == instruction::operation::BNG) {
+            fake_location_to_real(instr.m_arg.choice.second);
+        }
+    }
+
+    return m_instructions;
+}
+
+void assembly_scanner::advance(IP& ip, std::function<bool()> go_left) {
+    instruction i = at(ip);
+
+    if (i.get_op() == instruction::operation::JMP) {
+        ip = i.get_arg().next.second;
+        return;
+    }
+
+    const auto* to_left = i.second_if_branch();
+    if (to_left != nullptr && go_left()) {
+        ip = to_left->second;
+        return;
+    }
+
+    ip++;
+}
+
+void assembly_scanner::fake_location_to_real(std::pair<size_t, size_t>& p) const {
+    uintptr_t reconstructed = static_cast<uintptr_t>(p.second);
+    auto ptr = reinterpret_cast<NONNULL_PTR(const string)>(reconstructed);
+    const string& str = *ptr;
+    auto loc = m_label_locations.find(str);
+    if (loc == m_label_locations.end()) {
+        cerr << "Undeclared label '" << str << "'" << endl;
+        exit(EXIT_FAILURE);
+    }
+    p = { SIZE_C(0), loc->second };
+}
+
+#define DESTRINGIFY_NAME(op) \
+    if (name == #op##sv) \
+    return instruction::operation::op
+
+instruction::operation assembly_scanner::opcode_for_name(const string_view& name) noexcept {
+    DESTRINGIFY_NAME(BNG);
+    DESTRINGIFY_NAME(JMP);
+    DESTRINGIFY_NAME(TKL);
+    DESTRINGIFY_NAME(TSP);
+    DESTRINGIFY_NAME(TJN);
+    DESTRINGIFY_NAME(TKL);
+    DESTRINGIFY_NAME(NOP);
+    DESTRINGIFY_NAME(ADD);
+    DESTRINGIFY_NAME(SUB);
+    DESTRINGIFY_NAME(MUL);
+    DESTRINGIFY_NAME(DIV);
+    DESTRINGIFY_NAME(UDV);
+    DESTRINGIFY_NAME(MOD);
+    DESTRINGIFY_NAME(PSI);
+    DESTRINGIFY_NAME(PSC);
+    DESTRINGIFY_NAME(POP);
+    DESTRINGIFY_NAME(EXT);
+    DESTRINGIFY_NAME(INC);
+    DESTRINGIFY_NAME(DEC);
+    DESTRINGIFY_NAME(AND);
+    DESTRINGIFY_NAME(IOR);
+    DESTRINGIFY_NAME(XOR);
+    DESTRINGIFY_NAME(NOT);
+    DESTRINGIFY_NAME(GTC);
+    DESTRINGIFY_NAME(PTC);
+    DESTRINGIFY_NAME(GTI);
+    DESTRINGIFY_NAME(PTI);
+    DESTRINGIFY_NAME(PTU);
+    DESTRINGIFY_NAME(IDX);
+    DESTRINGIFY_NAME(DUP);
+    DESTRINGIFY_NAME(DP2);
+    DESTRINGIFY_NAME(RND);
+    DESTRINGIFY_NAME(EXP);
+    DESTRINGIFY_NAME(SWP);
+    DESTRINGIFY_NAME(GTM);
+    DESTRINGIFY_NAME(GDT);
+
+    cerr << "Unrecognized opcode '" << name << '\'' << endl;
+    exit(EXIT_FAILURE);
+}