/*
 * Copyright 2003-2005,2016,2021 Ronald S. Burkey <info@sandroid.org>
 *
 * This file is part of yaAGC.
 *
 * yaAGC is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * yaAGC is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with yaAGC; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Filename:	CheckDec.c
 * Purpose:	This is a small utility program, mainly for checking to
 *              see how DEC or 2DEC constants are converted to octal
 *              by yaYUL.
 * Mods:	11/02/03 RSB	Added the GPL header.
 *              05/09/04 RSB	Converted from a simple main program to
 *                              a function and an optional main program.
 *                              This allows me to call the function
 *                              from within yaAGC.
 *              06/13/04 RSB	Corrected the sign of the parenthesized
 *                              getoct value.
 *              05/14/05 RSB	Corrected website reference.
 *              08/01/15 RSB    Check return value of fgets to avoid a
 *                              compiler warning.
 *              05/24/21 RSB    Workaround for bad cygwin pow() function.
 *              05/24/21 RSB    My workarounds were bogus.  I've rolled them back.
 */

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

// ----------------------------------------------------------------------
// Prints a line-feed terminated conversion to octal from one of the 
// following formats:
//	%o %o * E%d B%d
//	%o %o
//	%s / %s		(%s hex or floating-point decimal)
//	%s * %s
//	%s

void
CheckDec(char *s)
{
  char s1[133], s2[133], SignC;
  double x, xx, scalar;
  int Value;
  int i, n2, n10;
  int Sign;
  int Oct1, Oct2;

  if (4 == (i = sscanf(s, "%o %o * E%d B%d", &Oct1, &Oct2, &n10, &n2)))
    {
      scalar = pow(2.0, n2) * pow(10.0, n10);
      goto Oct2Dec;
    }
  if (2 == (i = sscanf(s, "%o %o", &Oct1, &Oct2)))
    {
      printf("%05o %05o -> ", Oct1, Oct2);
      scalar = 1;
      Oct2Dec: if (0 != (040000 & Oct1))
        {
          Oct1 = ~Oct1;
          Oct2 = ~Oct2;
          Sign = -1;
          SignC = '-';
        }
      else
        {
          Sign = 1;
          SignC = '+';
        }
      i = ((Oct1 & 037777) << 14) | (Oct2 & 037777);
      scalar *= pow(2.0, -28);
      x = Sign * scalar * i;
      printf("(%c%010o) %.10g\n", SignC, i, x);
      return;
    }
  if (2 == (i = sscanf(s, "%s / %s", s1, s2)))
    {
      xx = strtod(s1, NULL);
      scalar = strtod(s2, NULL);
      x = xx / scalar;
    }
  else
    {
      if (1 == (i = sscanf(s, "%s * %s", s1, s2)))
        scalar = 1.0;
      else if (i == 2)
        scalar = strtod(s2, NULL);
      else
        {
          printf("?\n");
          return;
        }
      xx = strtod(s1, NULL);
      x = xx * scalar;
    }
  Sign = 0;
  if (x < 0)
    {
      Sign = 1;
      x = -x;
    }
  if (x >= 1.0)
    {
      printf("Illegal value: Must be <1.0 according to AGC rules.\n");
      return;
    }
  for (Value = 0, i = 0; i < 28; i++)
    {
      Value = Value << 1;
      if (x >= 0.5)
        {
          Value++;
          x -= 0.5;
        }
      x *= 2;
    }
  if (x >= 0.5)
    Value++;
  i = Value & 0x00003fff;
  Value = (Value >> 14) & 0x00003fff;
  if (Sign)
    {
      Value = ~Value;
      i = ~i;
      i &= 0x00007fff;
      Value &= 0x00007fff;
    }
  printf("%05o %05o\n", Value, i);

}

#ifdef MAIN_PROGRAM

int
main(void)
{
  char s[133];

  printf("(c)2003-2005 Ronald S. Burkey\n");
  printf(
      "Refer to http://www.ibiblio.org/apollo/index.html for more information.\n");
  printf("\n");
  printf(
      "This program is interactive.  The main purpose is to enter DEC or 2DEC\n");
  printf(
      "constants to see how yaYUL would convert them to octal in the core-rope\n");
  printf(
      "image file, however some other formats are accepted as well.  This is\n");
  printf("useful when working with corrupted assembly listings of AGC code.\n");
  printf("Enter one of the following:\n");
  printf("\tCtrl-C to exit.\n");
  printf("\toctal octal * Edecimal Bdecimal\n");
  printf("\toctal octal\n");
  printf("\tdecimal\n");
  printf("\tdecimal / decimal\n");
  printf("\tdecimal * decimal\n");
  printf(
      "Decimal numbers can include a sign and decimal point, octals cannot.\n");
  printf(
      "The output is two 5-octal-digit numbers, the more-signficant being first.\n");

  for (;;)
    {
      printf("> ");
      s[sizeof(s) - 1] = 0;
      if (NULL != fgets(s, sizeof(s) - 1, stdin))
        CheckDec(s);
    }
}

#endif //MAIN_PROGRAM