Brainfuckという言語の通訳を書いています
コマンドラインを使用しました
java bfinterpreter/BFInterpreter >output.bin
bf プログラムは 00 ～ FF を 16 進数で出力するはずですが、
00 01 02 03 04 05 06 ... 7f 3f 3f 3f 3f 3f ... a0 a1 a2 ... ff
... は 16 進数で +1 のシーケンスを表します
3f は 80 を 9f に置き換えますが、その理由がわかりません
ソース：
package bfinterpreter;
/**
*
* @author Nicki von Bulow
*/
public class BFInterpreter {
private char[] program;
private StringBuilder output;
private byte[] input;
private short inputPosition;
private short[] data;
private short dataPosition;
private boolean debug;
private boolean valid;
public static final char INPUT = ',';
public static final char OUTPUT = '.';
public static final char INCREASEPOINTER = '>';
public static final char DECREASEPOINTER = '<';
public static final char INCREASE = '+';
public static final char DECREASE = '-';
public static final char LOOPSTART = '[';
public static final char LOOPEND = ']';
public static final char DEBUG = '#';
public BFInterpreter(char[] program, byte[] input, boolean debug) {
this.program = program;
this.input = input;
this.debug = debug;
output = new StringBuilder();;
valid = true;
data = new short[32767];
}
public void execute(){
execute(program);
}
private void execute(char[] program) {
short programPosition = 0;
for (char b:program){
if (b == INPUT) {
if(inputPosition >= input.length) break;
data[dataPosition] = input[inputPosition];
inputPosition++;
}
else if (b == OUTPUT) {
if (data[dataPosition] >=0) output.append((char) (short) data[dataPosition]);
else {
short a = data[dataPosition];
System.err.println(a + 256);
output.append((char) (a + 256));
}
}
else if (b == INCREASEPOINTER) {
if (dataPosition == 32766) dataPosition = 0;
else dataPosition++;
}
else if (b == DECREASEPOINTER) {
if (dataPosition == 0) dataPosition = 32766;
else dataPosition--;
}
else if (b == INCREASE) {
if (data[dataPosition] != 255) data[dataPosition]++;
else data[dataPosition] = 0;
}
else if (b == DECREASE) {
if (data[dataPosition] != 0) data[dataPosition]--;
else data[dataPosition] = 255;
}
else if (b == LOOPSTART) {
short loopcount = 1;
char[] newProg = new char[program.length - programPosition];
System.arraycopy(program, programPosition, newProg, 0, newProg.length);
int at = 0;
for (char d:newProg) {
if(loopcount == 0) break;
if (d == '[') loopcount++;
else if(d == ']') loopcount--;
at++;
}
char[] finalNewProg = new char[at];
System.arraycopy(newProg, 1, finalNewProg, 0, at-2);
while (data[dataPosition] != 0) execute(finalNewProg);
}
else if (b == LOOPEND);
programPosition++;
}
}
private boolean analyze(char[] prog) {
return true;
}
public String output() {
return output.toString();
}
public static void main(String args[]){
BFInterpreter a = new BFInterpreter("+[.+]".toCharArray(), "".getBytes(), false);
a.execute();
System.out.println(a.output());
for(byte b:a.output().getBytes()) System.err.print(b + " ");
}
}
コマンドプロンプトの出力は
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56
57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83
84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107
108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127
63 63 63 63 63 63 63 63 63 63 63 63 63 63 63 63 63 63 63 63 63 63 63 63 63 63 63
63 63 63 63 63 -96 -95 -94 -93 -92 -91 -90 -89 -88 -87 -86 -85 -84 -83 -82 -81
-80 -79 -78 -77 -76 -75 -74 -73 -72 -71 -70 -69 -68 -67 -66 -65 -64 -63 -62 -61
-60 -59 -58 -57 -56 -55 -54 -53 -52 -51 -50 -49 -48 -47 -46 -45 -44 -43 -42 -41
-40 -39 -38 -37 -36 -35 -34 -33 -32 -31 -30 -29 -28 -27 -26 -25 -24 -23 -22 -21
-20 -19 -18 -17 -16 -15 -14 -13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0