#include <stdio.h>

void swap2(char a[2]);		/* swap 2 bytes */
void swap4(char a[4]);		/* swap 4 bytes */
void printvar(FILE *fp,char* s); /* print a variable */

main(int argc, char* argv[]) {
  FILE *fp;
  short int lineno;
  short int linelen;
  short int linect = 0;
  int linestart,lineend;
  unsigned char opcode;
  unsigned char slen;		/* string length */
  int i;
  char stmp[256];		/* temporary string */
  unsigned char ctmp; 		/* temporary value */
  int itmp;
  float ftmp;

  if ((fp = fopen(argv[1],"r")) == NULL) {
    fprintf(stderr,"error opening file\n");
    exit(1);
  }
  
  fseek(fp,64,SEEK_CUR);
  fread(&lineno,2,1,fp);	/* trash extra unkown bytes */
  while (fread(&lineno,2,1,fp)) {
    swap2((char*) &lineno);
    fread(&linelen,2,1,fp);
    swap2((char *) &linelen);
    printf("lineno: %4d length: %3d\n", lineno,linelen);
    lineend = ftell(fp) + linelen;
    while (ftell(fp) < lineend) {
      opcode = fgetc(fp);
      switch (opcode) {
      case 0001:
	printvar(fp,"<fetch scalar variable>");
	break;
      case 0002:
	printvar(fp,"<fetch array variable>");
	break;
      case 0003:
	printvar(fp,"<fetch string variable>");
	break;
      case 0004:		/* 8 byte real number */
	fread(&ftmp,8,1,fp);
	swap4((char *) &ftmp);
	swap4((char *) &ftmp+4);
	printf("<real>%f\n",ftmp);
	break;
      case 0005:
	printvar(fp,"<string>");
	break;
      case 0006:
	slen = (unsigned char) fgetc(fp);
	printf("<comment string>");
	fread(stmp,(long) slen,1,fp);
	stmp[slen] = '\0';
	printf("\"%s\"\n",stmp);
	if (slen % 2) {		/* odd length string */
	  opcode = (unsigned char) fgetc(fp);
	  switch(opcode) {
	  case 0031:		/* normal padding character */
	    break;
	  case 0016:            /* can terminate line  */
	    printf("<end line>\n");
	    break;
	  default:
	    fprintf(stdout,"*** bad odd length string terminator: \\%03o\n",
		    opcode);
	    //exit(1);
	  }
	}
	break;
      case 0007:
	printf("<store string variable?>\n");
	break;
      case 0010:
	printf("<store numeric variable>\n");
	break;
      case 0011:
	printf("<1d integer? array subscript>\n");
	break;
      case 0012:
	printf("<2d integer? array subscript>\n");
	break;
      case 0013:
	printf("<1d real? array subscript>\n");
	break;
      case 0014:
	printf("<2d real? array subscript>\n");
	break;
      case 0016:
	printf("<end line>\n");
	linect++;
	break;
      case 0017:
	printvar(fp,"<\\017 unknown fetch string variable>");
	break;
      case 0021:
	printvar(fp,"<fetch scalar variable address>");
	break;
      case 0022:
	printvar(fp,"<fetch array variable address>");
	break;
      case 0023:
	printvar(fp,"<fetch string variable address>");
	break;
      case 0024:
        printf("<store numeric, multiple assignment?>\n");
	break;
      case 0026:
	printf("<FN call>");
	slen = fgetc(fp);
	fread(stmp,(long) slen,1,fp);
	stmp[slen] = '\0';
	printf("\"%s\"",stmp);
	printf(" (number of arguments: %02d)\n",fgetc(fp));
	break;
      case 0030:
	printf("<GOTO? integer>");
	fread(&itmp,4,1,fp);
	swap4((char *) &itmp);
	printf("%d\n",itmp);
	break;
      case 0031:
	printf("<pad>\n");	/* for word alignment */
	break;
      case 0032:
	printf("<integer>");
	fread(&itmp,4,1,fp);
	swap4((char *) &itmp);
	printf("%d\n",itmp);
	break;
      case 0033:
	printf("<THEN>");
	fread(&itmp,4,1,fp);
	swap4((char *) &itmp);
	printf("%d\n",itmp);
	break;
      case 0034:
	printf("<ELSE>");
	fread(&itmp,4,1,fp);
	swap4((char *) &itmp);
	printf("%d\n",itmp);
	break;
      case 0035:
	printf("<1d string subscript>\n");
	break;
      case 0036:
	printf("<substring lookup?>\n");
	break;
      case 0040:
	printvar(fp,"<2d string? array variable fetch>");
	break;
      case 0041:
	printvar(fp,"<THEN jump to string label>");
	break;
      case 0043:
	printf("<&>\n");	/* string concatenation */
	break;
      case 0044:
	printf("<;>\n");
	break;
      case 0045:
	printf("<end function parameter list>\n");
	break;
      case 0046:
	printf("<*>\n");
	break;
      case 0047:
	printf("<+>\n");
	break;
      case 0050:
	printf("<->\n");
	break;
      case 0051:
	printf("</>\n");	/* floating point divide */
	break;
      case 0052:
	printf("<^>\n");
	break;
      case 0057:
	printf("<string equality?>\n");
	break;
      case 0062:
	printf("<change sign>\n");
	break;
      case 0063:
	printf("< # (not equal?) >\n");
	break;
      case 0064:
	printf("< <= >\n");
	break;
      case 0065:
	printf("< >= >\n");
	break;
      case 0066:
	printf("< <> >\n");
	break;
      case 0067:
	printf("< = >\n");
	break;
      case 0070:
	printf("< > >\n");
	break;
      case 0071:
	printf("< < >\n");
	break;
      case 0072:
	printf("<@ statement separator>\n");
	break;
      case 073:
	printf("<ON ERROR>\n");
	break;
      case 074:
	printf("<OFF ERROR>\n");
	break;
      case 0113:
	printf("<DEG>\n");	/* enter degrees mode */
	break;
      case 0114:
	printf("<DISP>\n");
	break;
      case 0117:
	printf("<GOTO linenum>");
	fread(&itmp,4,1,fp);
	swap4((char *) &itmp);
	printf("%d\n",itmp);
	break;
      case 0120:
	printf("<GOSUB>");
	fread(&itmp,4,1,fp);
	swap4((char *) &itmp);
	printf("%d\n",itmp);
	break;
      case 0123:
	printf("<INPUT>\n");
	break;
      case 0124:
	printf("<FN dereference>\n");
	break;
      case 0127:
	printf("<\\127 IF arithmatic 3-way?>\n");
        break;
      case 0131:
	printf("<PLOT>\n");
	break;
      case 0132:
	printf("<PRINT>\n");
	break;
      case 0135:
	printf("<READ>\n");
	break;
      case 0136:
	opcode = fgetc(fp);
	printf("<READ#>%03d,",opcode);
	fread(&itmp,4,1,fp);
	swap4((char *) &itmp);
	printf("%d\n",itmp);
	break;
      case 0137:
	printf("<RETURN>\n");
	break;
      case 0152:
	printf("<control bytes?>");
	opcode = fgetc(fp);
	printf("%02d\n",opcode);
	break;
      case 0153:
	printf("<INTEGER?>\n");
	break;
      case 0156:
	printf("<SCALE>\n");
	break;
      case 0162:
	printf("<DATA>\n");
	break;
      case 0164:
	printf("<DIM>\n");
	break;
      case 0166:
	printf("<END>\n");
	break;
      case 0167:
	printf("<END FN>\n");
	break;
      case 0170:
	printf("<FOR>\n");
	break;
      case 0173:
	printf("<NEXT>\n");
	break;
      case 0174:
	printf("<multi line function assignment?>\n");
	break;
      case 0175:
	printf("<single line function assignment?>\n");
	break;
      case 0177:
	printf("<PAUSE>");
	break;
      case 0203:
	printf("<!>");
	break;
      case 0205:
	printf("<PEN>\n");
	break;
      case 0207:
	printf("<IMOVE?>\n");
	break;
      case 0213:
	printf("<TO>\n");
	break;
      case 0214:
	printf("<OR>\n");
	break;
      case 0216:
	printf("<TIME>\n");
	break;
      case 0225:
	printf("<ATN2?>\n");
	break;
      case 0226:
	printvar(fp,"<statement label>");
	break;
      case 0227:
	printf("<SQRT>\n");
	break;
      case 0230:
	printf("<RMD?>\n");
	break;
      case 0231:
	printvar(fp,"<GOTO label>");
	break;
      case 0232:
	printf("<ABS>\n");
	break;
      case 0233:
	printf("<ASN?>\n");
	break;
      case 0234:
	printf("<ACS?>\n");
	break;
      case 0235:
	printf("<ATN?>\n");
	break;
      case 0236:
	printf("<SGN>\n");
	break;
      case 0244:
	printf("<INT>\n");
	break;
      case 0246:
	printf("<LOG>\n");
	break;
      case 0251:
	printf("<CHR$>\n");
	break;
      case 0252:
	printf("<VAL$>\n");
	break;
      case 0253:
	printf("<VAL>\n");
	break;
      case 0257:
        printf("<RND>\n");
	break;
      case 0260:
	printf("<PI>\n");
	break;
      case 0262:
	printf("<LABEL USING?>\n");
	break;
      case 0263:
	printf("<STEP>\n");
	break;
      case 0265:
	printf("<NOT>\n");
	break;
      case 0266:
	printf("<DIV>\n");
	break;
      case 0271:
	printf("<AND>\n");
	break;
      case 0272:
	printf("<MOD>\n");
	break;
      case 0273:
	printf("<SIN>\n");
	break;
      case 0274:
	printf("<COS>\n");
	break;
      case 0275:
	printf("<TAN>\n");
	break;
      case 0306:
	printf("<input value from DATA>\n");
	break;
      case 0310:
	printf("<input value from keyboard>\n");
	break;
      case 0312:
	printf("<DEF FN>\n");
	break;
	//case 0315:
	//printf("<send output with CRLF?>\n");
	//break;
	//case 0317:
	//printf("<send output without CRLF?>\n");
	//break;
      case 0321:
	printvar(fp,"<fetch 1d? array address>");
	break;
      case 0322:
	printvar(fp,"<fetch 2d? array address>");
	break;
      case 0323:
	printvar(fp,"<fetch 2d array address for printing?>");
	break;
      case 0325:		/* subroutine calls ? */
	opcode = (unsigned char) fgetc(fp);
	switch (opcode) {
	case 0015:
	  printf("<CALL>\n");
	  break;
	case 0016:
	  printf("<enter subroutine?>\n");
	  break;
	case 0021:
	  printf("<push numeric onto subroutine stack>\n");
	  break;
	case 0022:
	  printf("<push address onto subroutine stack>\n");
	  break;
	case 0023:
	  printf("<push string onto subroutine stack>\n");
	  break;
	case 0025:
	  printf("<end parameters?>\n");
	  break;
	case 0026:
	  printf("<enter multi-parameter subroutine?>\n");
	  break;
	case 0052:
	  printf("<RPT$>\n");	/* repeat string? */
	  break;
	case 0055:
	  printf("<SUBEND>\n");
	  break;
	case 0064:
	  printf("<SUB>\n");
	  break;
	default:
	  printf("\\325 \\%03o unknown subroutine opcode\n",opcode);
	  break;
	}
	break;
      case 0324:
	/* fall through */
      case 0326:		/* I/O call */
	opcode = (unsigned char) fgetc(fp);
	switch (opcode) {
	case 0001:
	  printf("<BPLOT>\n");
	  break;
	  //case 0004:
	  //printf("<I/O commands follow?>\n");
	  //break;
        case 0017:
	  printf("<IDRAW>\n");
	  break;
	case 0027:
	  printf("<MOVE>\n");
	  break;
	case 0032:
	  printf("<DRAW>\n");
	  break;
	case 0045:
	  printf("<PRINTER IS?>\n");
	  break;
	case 0046:
	  printf("<PLOTTER IS?>\n");
	  break;
	default:
	  //break;
	  printf("\\326 \\%03o unknown I/O opcode\n",opcode);
	  break;
	}
	break;

      case 0327:		/* I/O call */
	opcode = (unsigned char) fgetc(fp);
	switch (opcode) {
	case 0122:
	  printf("<ASSIGN#>\n");
	  break;
	default:
	  //break;
	  printf("\\327 \\%03o unknown I/O opcode\n",opcode);
	  break;
	}
	break;

      default:
	//break;
	if (opcode >= 0324) { /* two byte opcode */
	  printf("\\%03o ",opcode);
	  opcode = fgetc(fp);
	  printf("\\%03o unknown two byte opcode\n",opcode);
	} else {
	  printf("\\%03o\n",opcode);
	}
	break;
      } 
    }
    fseek(fp,lineend,SEEK_SET);	/* recover from parse error */
    printf("\n");
  }
  printf("linect: %d\n",linect);
}

void printvar(FILE *fp,char* s) {
  int slen;
  char stmp[256];
  slen = fgetc(fp);
  fread(stmp,(long) slen,1,fp);
  stmp[slen] = '\0';
  printf("%s\"%s\"\n",s,stmp);
}


void swap2(char a[2]) {
  char tmp;
  tmp = a[0];
  a[0] = a[1];
  a[1] = tmp;
}

void swap4(char a[4]) {
  char tmp;
  tmp = a[0];
  a[0] = a[3];
  a[3] = tmp;
  tmp = a[1];
  a[1] = a[2];
  a[2] = tmp;
}