malbolge.c

/* Interpreter for Malbolge.                                          */
/* '98 Ben Olmstead.                                                  */
/*                                                                    */
/* Malbolge is the name of Dante's Eighth circle of Hell.  This       */
/* interpreter isn't even Copylefted; I hereby place it in the public */
/* domain.  Have fun...                                               */
/*                                                                    */
/* Note: in keeping with the idea that programming in Malbolge is     */
/* meant to be hell, there is no debugger.                            */
/*                                                                    */
/* By the way, this code assumes that short is 16 bits.  I haven't    */
/* seen any case where it isn't, but it might happen.  If short is    */
/* longer than 16 bits, it will still work, though it will take up    */
/* considerably more memory.                                          */
/*                                                                    */
/* If you are compiling with a 16-bit Intel compiler, you will need   */
/* >64K data arrays; this means using the HUGE memory model on most   */
/* compilers, but MS C, as of 8.00, possibly earlier as well, allows  */
/* you to specify a custom memory-model; the best model to choose in  */
/* this case is /Ashd (near code, huge data), I think.                */

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <malloc.h>
#include <string.h>

#ifdef __GNUC__
static inline
#endif
void exec( unsigned short *mem );

#ifdef __GNUC__
static inline
#endif
unsigned short op( unsigned short x, unsigned short y );

const char xlat1[] =
  "+b(29e*j1VMEKLyC})8&m#~W>qxdRp0wkrUo[D7,XTcA\"lI"
  ".v%{gJh4G\\-=O@5`_3i<?Z';FNQuY]szf$!BS/|t:Pn6^Ha";

const char xlat2[] =
  "5z]&gqtyfr$(we4{WP)H-Zn,[%\\3dL+Q;>U!pJS72FhOA1C"
  "B6v^=I_0/8|jsb9m<.TVac`uY*MK'X~xDl}REokN:#?G\"i@";

int main( int argc, char **argv )
{
  FILE *f;
  unsigned short i = 0, j;
  int x;
  unsigned short *mem;
  if ( argc != 2 )
  {
    fputs( "invalid command line\n", stderr );
    return ( 1 );
  }
  if ( ( f = fopen( argv[1], "r" ) ) == NULL )
  {
    fputs( "can't open file\n", stderr );
    return ( 1 );
  }
#ifdef _MSC_VER
  mem = (unsigned short *)_halloc( 59049, sizeof(unsigned short) );
#else
  mem = (unsigned short *)malloc( sizeof(unsigned short) * 59049 );
#endif
  if ( mem == NULL )
  {
    fclose( f );
    fputs( "can't allocate memory\n", stderr );
    return ( 1 );
  }
  while ( ( x = getc( f ) ) != EOF )
  {
    if ( isspace( x ) ) continue;
    if ( x < 127 && x > 32 )
    {
      if ( strchr( "ji*p</vo", xlat1[( x - 33 + i ) % 94] ) == NULL )
      {
        fputs( "invalid character in source file\n", stderr );
        free( mem );
        fclose( f );
        return ( 1 );
      }
    }
    if ( i == 59049 )
    {
      fputs( "input file too long\n", stderr );
      free( mem );
      fclose( f );
      return ( 1 );
    }
    mem[i++] = x;
  }
  fclose( f );
  while ( i < 59049 ) mem[i] = op( mem[i - 1], mem[i - 2] ), i++;
  exec( mem );
  free( mem );
  return ( 0 );
}

#ifdef __GNUC__
static inline
#endif
void exec( unsigned short *mem )
{
  unsigned short a = 0, c = 0, d = 0;
  int x;
  for (;;)
  {
    if ( mem[c] < 33 || mem[c] > 126 ) continue;
    switch ( xlat1[( mem[c] - 33 + c ) % 94] )
    {
      case 'j': d = mem[d]; break;
      case 'i': c = mem[d]; break;
      case '*': a = mem[d] = mem[d] / 3 + mem[d] % 3 * 19683; break;
      case 'p': a = mem[d] = op( a, mem[d] ); break;
      case '<':
#if '\n' != 10
        if ( x == 10 ) putc( '\n', stdout ); else
#endif
        putc( a, stdout );
        break;
      case '/':
        x = getc( stdin );
#if '\n' != 10
        if ( x == '\n' ) a = 10; else
#endif
        if ( x == EOF ) a = 59048; else a = x;
        break;
      case 'v': return;
    }
    mem[c] = xlat2[mem[c] - 33];
    if ( c == 59048 ) c = 0; else c++;
    if ( d == 59048 ) d = 0; else d++;
  }
}

#ifdef __GNUC__
static inline
#endif
unsigned short op( unsigned short x, unsigned short y )
{
  unsigned short i = 0, j;
  static const unsigned short p9[5] =
    { 1, 9, 81, 729, 6561 };
  static const unsigned short o[9][9] =
    {
      { 4, 3, 3, 1, 0, 0, 1, 0, 0 },
      { 4, 3, 5, 1, 0, 2, 1, 0, 2 },
      { 5, 5, 4, 2, 2, 1, 2, 2, 1 },
      { 4, 3, 3, 1, 0, 0, 7, 6, 6 },
      { 4, 3, 5, 1, 0, 2, 7, 6, 8 },
      { 5, 5, 4, 2, 2, 1, 8, 8, 7 },
      { 7, 6, 6, 7, 6, 6, 4, 3, 3 },
      { 7, 6, 8, 7, 6, 8, 4, 3, 5 },
      { 8, 8, 7, 8, 8, 7, 5, 5, 4 },
    };
  for ( j = 0; j < 5; j++ )
    i += o[y / p9[j] % 9][x / p9[j] % 9] * p9[j];
  return ( i );
}