cmpkey.c

免费的Sql数据库系统

/*  cmpkey.c  - Comparision of keys
 *              Kernel of GNU SQL-server. Sorter   
 *
 * This file is a part of GNU SQL Server
 *
 *  Copyright (c) 1996, 1997, Free Software Foundation, Inc
 *  Developed at the Institute of System Programming
 *  This file is written by  Vera Ponomarenko
 *
 *  This program 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.
 *
 *  This program 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 this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 *  Contacts:   [e-mail]
 *
 */

/* $Id: cmpkey.c,v 1.245 1997/03/31 03:46:38 kml Exp $ */

#include "dessrt.h"
#include "pupsi.h"
#include "f1f2decl.h"
#include "fdclsrt.h"

extern char *nonsense;
extern u2_t kn;

int
cmpkey (u2_t *afn, struct des_field *df, char *drctn, char *pk1, char *pk2)
{
  i4_t d, kk, k, v;
  char *k1, *kval1, *k2, *kval2;
  u2_t n1, n2;

  if (pk1 == nonsense)
    return (1);			/* The first is absent */
  if (pk2 == nonsense)
    return (-1);		/* The second is absent */
  pk1 += size2b + tidsize;
  pk2 += size2b + tidsize;
  k1 = kval1 = pk1 + scscal (pk1);
  k2 = kval2 = pk2 + scscal (pk2);
  if (*drctn == GROW)
    d = 1;
  else
    d = -1;  
  v = 0;
  for (kk = 0, k = 0; kk < kn && pk1 < k1 && pk2 < k2; kk++, k++)
    {
      if (k == 7)
	{
	  k = 0;
	  pk1++;
	  if (pk1 >= k1)
	    break;
	  pk2++;
	  if (pk2 >= k2)
	    break;
	}
      if (*drctn++ == GROW)
	d = 1;
      else
	d = -1;
      if ((*pk1 & BITVL(k)) != 0)
	{
	  if ((*pk2 & BITVL(k)) != 0)
	    {			/* both are defined */
	      switch ((df + afn[kk])->field_type)
		{
		case T1B:
		  if ((v = f1b (kval1, kval2, size1b, size1b)) != 0)
		    return (v * d);
		  kval1++;
		  kval2++;
		  break;
		case T2B:
		  if ((v = f2b (kval1, kval2, size2b, size2b)) != 0)
		    return (v * d);
		  kval1 += size2b;
		  kval2 += size2b;
		  break;
		case T4B:
		  if ((v = f4b (kval1, kval2, size4b, size4b)) != 0)
		    return (v * d);
		  kval1 += size4b;
		  kval2 += size4b;
		  break;
		case TFLOAT:
		  if ((v = flcmp (kval1, kval2, size4b, size4b)) != 0)
		    return (v * d);
		  kval1 += size4b;
		  kval2 += size4b;
		  break;
		case TFL:
		  n1 = t2bunpack (kval1);
		  kval1 += size2b;
		  n2 = t2bunpack (kval2);
		  kval2 += size2b;		  
		  if ((v = ffloat (kval1, kval2, n1, n2)) != 0)
		    return (v * d);
		  kval1 += n1;
		  kval2 += n2;
		  break;
		case TCH:
		  n1 = t2bunpack (kval1);
		  kval1 += size2b;
		  n2 = t2bunpack (kval2);
		  kval2 += size2b;			  
		  if ((v = chcmp (kval1, kval2, n1, n2)) != 0)
		    return (v * d);
		  kval1 += n1;
		  kval2 += n2;
		  break;
		default:
		  perror ("SRT.cmpkey: This data type doesn't exist");
		  break;
		}
	    }
	  else
	    return (-1);	/* The second not defined */
	}
      else if ((*pk2 & BITVL(k)) != 0)
	return (1);		/*The first isn't defined */
    }
  if (kk < kn)
    {
      if (pk1 == k1)
	{
	  if (pk2 == k2)
	    return (0);
	  else
	    return (1);
	}
      else
	return (-1);
    }
  return (0);
}

u2_t 
scscal (char *a)
{
  char *c;
  for (c = a; (*a & EOSC) == 0; a++);
  return (a + 1 - c);
}