not yet working

2026-01-14 13:35:00 +01:00 · 2021-04-20 09:05:18 +02:00 · 2021-04-20 09:05:18 +02:00 · 271cf2d20b
commit 271cf2d20b
parent 16ee33ee21
3 changed files with 116 additions and 1 deletions
--- a/bfi-java/src/Brainfuck.java
+++ b/bfi-java/src/Brainfuck.java
@ -0,0 +1,104 @@
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+import java.util.List;
+import java.util.stream.Collectors;
+
+public class Brainfuck {
+
+    private static final int MEM_SIZE = 0xFFFF;
+
+    public List<Character> minify(String program) {
+        List<Character> chars = List.of('>', '<', '+', '-', '.', ',', '[', ']');
+        return program.chars()
+                .mapToObj(c -> (char) c)
+                .filter(chars::contains)
+                .collect(Collectors.toList());
+    }
+
+
+    public String interpret(List<Character> pgm) {
+        StringBuilder out = new StringBuilder();
+        int pointer = 0;
+        short[] memory = new short[MEM_SIZE];
+        int pc = 0;
+
+
+        while (pc < pgm.size()) {
+            switch (pgm.get(pc)) {
+                case '>' -> {
+                    if (pointer == MEM_SIZE - 1) {
+                        pointer = 0;
+                    } else {
+                        pointer++;
+                    }
+                }
+                case '<' -> {
+                    if (pointer == 0) {
+                        pointer = MEM_SIZE - 1;
+                    } else {
+                        pointer++;
+                    }
+                }
+                case '+' -> increment(memory, pointer);
+                case '-' -> decrement(memory, pointer);
+                case '.' -> out.append((char) memory[pointer]);
+                case ',' -> {
+                } //todo implement i guess
+                case '[' -> {
+                    if (memory[pointer] == 0) {
+                        int level = 0;
+                        while (pgm.get(pc) != ']' || level > -1) {
+                            pc++;
+                            char instruction = pgm.get(pc);
+                            if (instruction == '[') level++;
+                            else if (instruction == ']') level--;
+                        }
+                    }
+                }
+                case ']' -> {
+                    if (memory[pointer] != 0) {
+                        int level = 0;
+                        while (pgm.get(pc) != '[' || level >= -1) {
+                            pc--;
+                            char instruction = pgm.get(pc);
+                            if (instruction == '[') level--;
+                            if (instruction == ']') level++;
+                        }
+                    }
+                }
+            }
+
+            pc++;
+        }
+
+        return out.toString();
+    }
+
+    private void increment(short[] memory, int pointer) {
+        if (memory[pointer] == 0xFF) {
+            memory[pointer] = 0;
+        } else {
+            memory[pointer]++;
+        }
+    }
+
+    private void decrement(short[] memory, int pointer) {
+        if (memory[pointer] == 0) {
+            memory[pointer] = 0xFF;
+        } else {
+            memory[pointer]--;
+        }
+    }
+
+    public static void main(String[] args) throws IOException {
+        Brainfuck brainfuck = new Brainfuck();
+
+        String program = Files.readString(Paths.get(args[0]));
+        List<Character> minified = brainfuck.minify(program);
+
+        String result = brainfuck.interpret(minified);
+
+        System.out.println(result);
+    }
+}