/* Copyright (c) 2002, 2021, Oracle and/or its affiliates.
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.

   This program is also distributed with certain software (including
   but not limited to OpenSSL) that is licensed under separate terms,
   as designated in a particular file or component or in included license
   documentation.  The authors of MySQL hereby grant you an additional
   permission to link the program and your derivative works with the
   separately licensed software that they have included with MySQL.

   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, version 2.0, 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA */

#include "myisamdef.h"
#include "rt_index.h"
#include "rt_mbr.h"

#define INTERSECT_CMP(amin, amax, bmin, bmax) ((amin >  bmax) || (bmin >  amax))
#define CONTAIN_CMP(amin, amax, bmin, bmax) ((bmin > amin)  || (bmax <  amax))
#define WITHIN_CMP(amin, amax, bmin, bmax) ((amin > bmin)  || (amax <  bmax))
#define DISJOINT_CMP(amin, amax, bmin, bmax) ((amin <= bmax) && (bmin <= amax))
#define EQUAL_CMP(amin, amax, bmin, bmax) ((amin != bmin) || (amax != bmax))

#define FCMP(A, B) ((int)(A) - (int)(B))
#define p_inc(A, B, X)  {A += X; B += X;}

#define RT_CMP(nextflag) \
  if (nextflag & MBR_INTERSECT) \
  { \
    if (INTERSECT_CMP(amin, amax, bmin, bmax)) \
      return 1; \
  } \
  else if (nextflag & MBR_CONTAIN) \
  { \
    if (CONTAIN_CMP(amin, amax, bmin, bmax)) \
      return 1; \
  } \
  else if (nextflag & MBR_WITHIN) \
  { \
    if (WITHIN_CMP(amin, amax, bmin, bmax)) \
      return 1; \
  } \
  else if (nextflag & MBR_EQUAL)  \
  { \
    if (EQUAL_CMP(amin, amax, bmin, bmax)) \
      return 1; \
  } \
  else if (nextflag & MBR_DISJOINT) \
  { \
    if (DISJOINT_CMP(amin, amax, bmin, bmax)) \
      return 1; \
  }\
  else /* if unknown comparison operator */ \
  { \
    assert(0);                                  \
  }

#define RT_CMP_KORR(type, korr_func, len, nextflag) \
{ \
  type amin, amax, bmin, bmax; \
  amin = korr_func(a); \
  bmin = korr_func(b); \
  amax = korr_func(a+len); \
  bmax = korr_func(b+len); \
  RT_CMP(nextflag); \
}

#define RT_CMP_GET(type, get_func, len, nextflag) \
{ \
  type amin, amax, bmin, bmax; \
  get_func(amin, a); \
  get_func(bmin, b); \
  get_func(amax, a+len); \
  get_func(bmax, b+len); \
  RT_CMP(nextflag); \
}

/*
 Compares two keys a and b depending on nextflag
 nextflag can contain these flags:
   MBR_INTERSECT(a,b)  a overlaps b
   MBR_CONTAIN(a,b)    a contains b
   MBR_DISJOINT(a,b)   a disjoint b
   MBR_WITHIN(a,b)     a within   b
   MBR_EQUAL(a,b)      All coordinates of MBRs are equal
   MBR_DATA(a,b)       Data reference is the same
 Returns 0 on success.
*/
int rtree_key_cmp(HA_KEYSEG *keyseg, uchar *b, uchar *a, uint key_length, 
                  uint nextflag)
{
  for (; (int) key_length > 0; keyseg += 2 )
  {
    uint32 keyseg_length;
    switch ((enum ha_base_keytype) keyseg->type) {
    case HA_KEYTYPE_INT8:
      RT_CMP_KORR(int8, mi_sint1korr, 1, nextflag);
      break;
    case HA_KEYTYPE_BINARY:
      RT_CMP_KORR(uint8, mi_uint1korr, 1, nextflag);
      break;
    case HA_KEYTYPE_SHORT_INT:
      RT_CMP_KORR(int16, mi_sint2korr, 2, nextflag);
      break;
    case HA_KEYTYPE_USHORT_INT:
      RT_CMP_KORR(uint16, mi_uint2korr, 2, nextflag);
      break;
    case HA_KEYTYPE_INT24:
      RT_CMP_KORR(int32, mi_sint3korr, 3, nextflag);
      break;
    case HA_KEYTYPE_UINT24:
      RT_CMP_KORR(uint32, mi_uint3korr, 3, nextflag);
      break;
    case HA_KEYTYPE_LONG_INT:
      RT_CMP_KORR(int32, mi_sint4korr, 4, nextflag);
      break;
    case HA_KEYTYPE_ULONG_INT:
      RT_CMP_KORR(uint32, mi_uint4korr, 4, nextflag);
      break;
    case HA_KEYTYPE_LONGLONG:
      RT_CMP_KORR(longlong, mi_sint8korr, 8, nextflag)
      break;
    case HA_KEYTYPE_ULONGLONG:
      RT_CMP_KORR(ulonglong, mi_uint8korr, 8, nextflag)
      break;
    case HA_KEYTYPE_FLOAT:
      /* The following should be safe, even if we compare doubles */
      RT_CMP_GET(float, mi_float4get, 4, nextflag);
      break;
    case HA_KEYTYPE_DOUBLE:
      RT_CMP_GET(double, mi_float8get, 8, nextflag);
      break;
    case HA_KEYTYPE_END:
      goto end;
    default:
      return 1;
    }
    keyseg_length= keyseg->length * 2;
    key_length-= keyseg_length;
    a+= keyseg_length;
    b+= keyseg_length;
  }

end:
  if (nextflag & MBR_DATA)
  {
    uchar *end = a + keyseg->length;
    do
    {
      if (*a++ != *b++)
        return FCMP(a[-1], b[-1]);
    } while (a != end);
  }
  return 0;
}

#define RT_VOL_KORR(type, korr_func, len, cast) \
{ \
  type amin, amax; \
  amin = korr_func(a); \
  amax = korr_func(a+len); \
  res *= (cast(amax) - cast(amin)); \
}

#define RT_VOL_GET(type, get_func, len, cast) \
{ \
  type amin, amax; \
  get_func(amin, a); \
  get_func(amax, a+len); \
  res *= (cast(amax) - cast(amin)); \
}

/*
 Calculates rectangle volume
*/
double rtree_rect_volume(HA_KEYSEG *keyseg, uchar *a, uint key_length)
{
  double res = 1;
  for (; (int)key_length > 0; keyseg += 2)
  {
    uint32 keyseg_length;
    switch ((enum ha_base_keytype) keyseg->type) {
    case HA_KEYTYPE_INT8:
      RT_VOL_KORR(int8, mi_sint1korr, 1, (double));
      break;
    case HA_KEYTYPE_BINARY:
      RT_VOL_KORR(uint8, mi_uint1korr, 1, (double));
      break;
    case HA_KEYTYPE_SHORT_INT:
      RT_VOL_KORR(int16, mi_sint2korr, 2, (double));
      break;
    case HA_KEYTYPE_USHORT_INT:
      RT_VOL_KORR(uint16, mi_uint2korr, 2, (double));
      break;
    case HA_KEYTYPE_INT24:
      RT_VOL_KORR(int32, mi_sint3korr, 3, (double));
      break;
    case HA_KEYTYPE_UINT24:
      RT_VOL_KORR(uint32, mi_uint3korr, 3, (double));
      break;
    case HA_KEYTYPE_LONG_INT:
      RT_VOL_KORR(int32, mi_sint4korr, 4, (double));
      break;
    case HA_KEYTYPE_ULONG_INT:
      RT_VOL_KORR(uint32, mi_uint4korr, 4, (double));
      break;
    case HA_KEYTYPE_LONGLONG:
      RT_VOL_KORR(longlong, mi_sint8korr, 8, (double));
      break;
    case HA_KEYTYPE_ULONGLONG:
      RT_VOL_KORR(longlong, mi_sint8korr, 8, ulonglong2double);
      break;
    case HA_KEYTYPE_FLOAT:
      RT_VOL_GET(float, mi_float4get, 4, (double));
      break;
    case HA_KEYTYPE_DOUBLE:
      RT_VOL_GET(double, mi_float8get, 8, (double));
      break;
    case HA_KEYTYPE_END:
      key_length = 0;
      break;
    default:
      return -1;
    }
    keyseg_length= keyseg->length * 2;
    key_length-= keyseg_length;
    a+= keyseg_length;
  }
  return res;
}

#define RT_D_MBR_KORR(type, korr_func, len, cast) \
{ \
  type amin, amax; \
  amin = korr_func(a); \
  amax = korr_func(a+len); \
  *res++ = cast(amin); \
  *res++ = cast(amax); \
}

#define RT_D_MBR_GET(type, get_func, len, cast) \
{ \
  type amin, amax; \
  get_func(amin, a); \
  get_func(amax, a+len); \
  *res++ = cast(amin); \
  *res++ = cast(amax); \
}


/*
  Creates an MBR as an array of doubles.
*/

int rtree_d_mbr(HA_KEYSEG *keyseg, uchar *a, uint key_length, double *res)
{
  for (; (int)key_length > 0; keyseg += 2)
  {
    uint32 keyseg_length;
    switch ((enum ha_base_keytype) keyseg->type) {
    case HA_KEYTYPE_INT8:
      RT_D_MBR_KORR(int8, mi_sint1korr, 1, (double));
      break;
    case HA_KEYTYPE_BINARY:
      RT_D_MBR_KORR(uint8, mi_uint1korr, 1, (double));
      break;
    case HA_KEYTYPE_SHORT_INT:
      RT_D_MBR_KORR(int16, mi_sint2korr, 2, (double));
      break;
    case HA_KEYTYPE_USHORT_INT:
      RT_D_MBR_KORR(uint16, mi_uint2korr, 2, (double));
      break;
    case HA_KEYTYPE_INT24:
      RT_D_MBR_KORR(int32, mi_sint3korr, 3, (double));
      break;
    case HA_KEYTYPE_UINT24:
      RT_D_MBR_KORR(uint32, mi_uint3korr, 3, (double));
      break;
    case HA_KEYTYPE_LONG_INT:
      RT_D_MBR_KORR(int32, mi_sint4korr, 4, (double));
      break;
    case HA_KEYTYPE_ULONG_INT:
      RT_D_MBR_KORR(uint32, mi_uint4korr, 4, (double));
      break;
    case HA_KEYTYPE_LONGLONG:
      RT_D_MBR_KORR(longlong, mi_sint8korr, 8, (double));
      break;
    case HA_KEYTYPE_ULONGLONG:
      RT_D_MBR_KORR(longlong, mi_sint8korr, 8, ulonglong2double);
      break;
    case HA_KEYTYPE_FLOAT:
      RT_D_MBR_GET(float, mi_float4get, 4, (double));
      break;
    case HA_KEYTYPE_DOUBLE:
      RT_D_MBR_GET(double, mi_float8get, 8, (double));
      break;
    case HA_KEYTYPE_END:
      key_length = 0;
      break;
    default:
      return 1;
    }
    keyseg_length= keyseg->length * 2;
    key_length-= keyseg_length;
    a+= keyseg_length;
  }
  return 0;
}

#define RT_COMB_KORR(type, korr_func, store_func, len) \
{ \
  type amin, amax, bmin, bmax; \
  amin = korr_func(a); \
  bmin = korr_func(b); \
  amax = korr_func(a+len); \
  bmax = korr_func(b+len); \
  amin = MY_MIN(amin, bmin); \
  amax = MY_MAX(amax, bmax); \
  store_func(c, amin); \
  store_func(c+len, amax); \
}

#define RT_COMB_GET(type, get_func, store_func, len) \
{ \
  type amin, amax, bmin, bmax; \
  get_func(amin, a); \
  get_func(bmin, b); \
  get_func(amax, a+len); \
  get_func(bmax, b+len); \
  amin = MY_MIN(amin, bmin); \
  amax = MY_MAX(amax, bmax); \
  store_func(c, amin); \
  store_func(c+len, amax); \
}

/*
  Creates common minimal bounding rectungle
  for two input rectagnles a and b
  Result is written to c
*/

int rtree_combine_rect(HA_KEYSEG *keyseg, uchar* a, uchar* b, uchar* c, 
		       uint key_length)
{
  for ( ; (int) key_length > 0 ; keyseg += 2)
  {
    uint32 keyseg_length;
    switch ((enum ha_base_keytype) keyseg->type) {
    case HA_KEYTYPE_INT8:
      RT_COMB_KORR(int8, mi_sint1korr, mi_int1store, 1);
      break;
    case HA_KEYTYPE_BINARY:
      RT_COMB_KORR(uint8, mi_uint1korr, mi_int1store, 1);
      break;
    case HA_KEYTYPE_SHORT_INT:
      RT_COMB_KORR(int16, mi_sint2korr, mi_int2store, 2);
      break;
    case HA_KEYTYPE_USHORT_INT:
      RT_COMB_KORR(uint16, mi_uint2korr, mi_int2store, 2);
      break;
    case HA_KEYTYPE_INT24:
      RT_COMB_KORR(int32, mi_sint3korr, mi_int3store, 3);
      break;
    case HA_KEYTYPE_UINT24:
      RT_COMB_KORR(uint32, mi_uint3korr, mi_int3store, 3);
      break;
    case HA_KEYTYPE_LONG_INT:
      RT_COMB_KORR(int32, mi_sint4korr, mi_int4store, 4);
      break;
    case HA_KEYTYPE_ULONG_INT:
      RT_COMB_KORR(uint32, mi_uint4korr, mi_int4store, 4);
      break;
    case HA_KEYTYPE_LONGLONG:
      RT_COMB_KORR(longlong, mi_sint8korr, mi_int8store, 8);
      break;
    case HA_KEYTYPE_ULONGLONG:
      RT_COMB_KORR(ulonglong, mi_uint8korr, mi_int8store, 8);
      break;
    case HA_KEYTYPE_FLOAT:
      RT_COMB_GET(float, mi_float4get, mi_float4store, 4);
      break;
    case HA_KEYTYPE_DOUBLE:
      RT_COMB_GET(double, mi_float8get, mi_float8store, 8);
      break;
    case HA_KEYTYPE_END:
      return 0;
    default:
      return 1;
    }
    keyseg_length= keyseg->length * 2;
    key_length-= keyseg_length;
    a+= keyseg_length;
    b+= keyseg_length;
    c+= keyseg_length;
  }
  return 0;
}


#define RT_OVL_AREA_KORR(type, korr_func, len) \
{ \
  type amin, amax, bmin, bmax; \
  amin = korr_func(a); \
  bmin = korr_func(b); \
  amax = korr_func(a+len); \
  bmax = korr_func(b+len); \
  amin = MY_MAX(amin, bmin); \
  amax = MY_MIN(amax, bmax); \
  if (amin >= amax) \
    return 0; \
  res *= amax - amin; \
}

#define RT_OVL_AREA_GET(type, get_func, len) \
{ \
  type amin, amax, bmin, bmax; \
  get_func(amin, a); \
  get_func(bmin, b); \
  get_func(amax, a+len); \
  get_func(bmax, b+len); \
  amin = MY_MAX(amin, bmin); \
  amax = MY_MIN(amax, bmax); \
  if (amin >= amax)  \
    return 0; \
  res *= amax - amin; \
}

/*
Calculates overlapping area of two MBRs a & b
*/
double rtree_overlapping_area(HA_KEYSEG *keyseg, uchar* a, uchar* b, 
                             uint key_length)
{
  double res = 1;
  for (; (int) key_length > 0 ; keyseg += 2)
  {
    uint32 keyseg_length;
    switch ((enum ha_base_keytype) keyseg->type) {
    case HA_KEYTYPE_INT8:
      RT_OVL_AREA_KORR(int8, mi_sint1korr, 1);
      break;
    case HA_KEYTYPE_BINARY:
      RT_OVL_AREA_KORR(uint8, mi_uint1korr, 1);
      break;
    case HA_KEYTYPE_SHORT_INT:
      RT_OVL_AREA_KORR(int16, mi_sint2korr, 2);
      break;
    case HA_KEYTYPE_USHORT_INT:
      RT_OVL_AREA_KORR(uint16, mi_uint2korr, 2);
      break;
    case HA_KEYTYPE_INT24:
      RT_OVL_AREA_KORR(int32, mi_sint3korr, 3);
      break;
    case HA_KEYTYPE_UINT24:
      RT_OVL_AREA_KORR(uint32, mi_uint3korr, 3);
      break;
    case HA_KEYTYPE_LONG_INT:
      RT_OVL_AREA_KORR(int32, mi_sint4korr, 4);
      break;
    case HA_KEYTYPE_ULONG_INT:
      RT_OVL_AREA_KORR(uint32, mi_uint4korr, 4);
      break;
    case HA_KEYTYPE_LONGLONG:
      RT_OVL_AREA_KORR(longlong, mi_sint8korr, 8);
      break;
    case HA_KEYTYPE_ULONGLONG:
      RT_OVL_AREA_KORR(longlong, mi_sint8korr, 8);
      break;
    case HA_KEYTYPE_FLOAT:
      RT_OVL_AREA_GET(float, mi_float4get, 4);
      break;
    case HA_KEYTYPE_DOUBLE:
      RT_OVL_AREA_GET(double, mi_float8get, 8);
      break;
    case HA_KEYTYPE_END:
      return res;
    default:
      return -1;
    }
    keyseg_length= keyseg->length * 2;
    key_length-= keyseg_length;
    a+= keyseg_length;
    b+= keyseg_length;
  }
  return res;
}

#define RT_AREA_INC_KORR(type, korr_func, len) \
{ \
   type amin, amax, bmin, bmax; \
   amin = korr_func(a); \
   bmin = korr_func(b); \
   amax = korr_func(a+len); \
   bmax = korr_func(b+len); \
   a_area *= (((double)amax) - ((double)amin)); \
   loc_ab_area *= ((double)MY_MAX(amax, bmax) - (double)MY_MIN(amin, bmin)); \
}

#define RT_AREA_INC_GET(type, get_func, len)\
{\
   type amin, amax, bmin, bmax; \
   get_func(amin, a); \
   get_func(bmin, b); \
   get_func(amax, a+len); \
   get_func(bmax, b+len); \
   a_area *= (((double)amax) - ((double)amin)); \
   loc_ab_area *= ((double)MY_MAX(amax, bmax) - (double)MY_MIN(amin, bmin)); \
}

/*
  Calculates MBR_AREA(a+b) - MBR_AREA(a)
  Note: when 'a' and 'b' objects are far from each other,
  the area increase can be really big, so this function
  can return 'inf' as a result.
*/
double rtree_area_increase(HA_KEYSEG *keyseg, uchar* a, uchar* b, 
                          uint key_length, double *ab_area)
{
  double a_area= 1.0;
  double loc_ab_area= 1.0;
  
  *ab_area= 1.0;
  for (; (int)key_length > 0; keyseg += 2)
  {
    uint32 keyseg_length;

    if (keyseg->null_bit)                       /* Handle NULL part */
      return -1;

    switch ((enum ha_base_keytype) keyseg->type) {
    case HA_KEYTYPE_INT8:
      RT_AREA_INC_KORR(int8, mi_sint1korr, 1);
      break;
    case HA_KEYTYPE_BINARY:
      RT_AREA_INC_KORR(uint8, mi_uint1korr, 1);
      break;
    case HA_KEYTYPE_SHORT_INT:
      RT_AREA_INC_KORR(int16, mi_sint2korr, 2);
      break;
    case HA_KEYTYPE_USHORT_INT:
      RT_AREA_INC_KORR(uint16, mi_uint2korr, 2);
      break;
    case HA_KEYTYPE_INT24:
      RT_AREA_INC_KORR(int32, mi_sint3korr, 3);
      break;
    case HA_KEYTYPE_UINT24:
      RT_AREA_INC_KORR(int32, mi_uint3korr, 3);
      break;
    case HA_KEYTYPE_LONG_INT:
      RT_AREA_INC_KORR(int32, mi_sint4korr, 4);
      break;
    case HA_KEYTYPE_ULONG_INT:
      RT_AREA_INC_KORR(uint32, mi_uint4korr, 4);
      break;
    case HA_KEYTYPE_LONGLONG:
      RT_AREA_INC_KORR(longlong, mi_sint8korr, 8);
      break;
    case HA_KEYTYPE_ULONGLONG:
      RT_AREA_INC_KORR(longlong, mi_sint8korr, 8);
      break;
    case HA_KEYTYPE_FLOAT:
      RT_AREA_INC_GET(float, mi_float4get, 4);
      break;
    case HA_KEYTYPE_DOUBLE:
      RT_AREA_INC_GET(double, mi_float8get, 8);
      break;
    case HA_KEYTYPE_END:
      goto safe_end;
    default:
      return -1;
    }
    keyseg_length= keyseg->length * 2;
    key_length-= keyseg_length;
    a+= keyseg_length;
    b+= keyseg_length;
  }
safe_end:
  *ab_area= loc_ab_area;
  return loc_ab_area - a_area;
}

#define RT_PERIM_INC_KORR(type, korr_func, len) \
{ \
   type amin, amax, bmin, bmax; \
   amin = korr_func(a); \
   bmin = korr_func(b); \
   amax = korr_func(a+len); \
   bmax = korr_func(b+len); \
   a_perim+= (((double)amax) - ((double)amin)); \
   *ab_perim+= ((double)MY_MAX(amax, bmax) - (double)MY_MIN(amin, bmin)); \
}

#define RT_PERIM_INC_GET(type, get_func, len)\
{\
   type amin, amax, bmin, bmax; \
   get_func(amin, a); \
   get_func(bmin, b); \
   get_func(amax, a+len); \
   get_func(bmax, b+len); \
   a_perim+= (((double)amax) - ((double)amin)); \
   *ab_perim+= ((double)MY_MAX(amax, bmax) - (double)MY_MIN(amin, bmin)); \
}

/*
Calculates MBR_PERIMETER(a+b) - MBR_PERIMETER(a)
*/
double rtree_perimeter_increase(HA_KEYSEG *keyseg, uchar* a, uchar* b, 
				uint key_length, double *ab_perim)
{
  double a_perim = 0.0;
  
  *ab_perim= 0.0;
  for (; (int)key_length > 0; keyseg += 2)
  {
    uint32 keyseg_length;

    if (keyseg->null_bit)                       /* Handle NULL part */
      return -1;

    switch ((enum ha_base_keytype) keyseg->type) {
    case HA_KEYTYPE_INT8:
      RT_PERIM_INC_KORR(int8, mi_sint1korr, 1);
      break;
    case HA_KEYTYPE_BINARY:
      RT_PERIM_INC_KORR(uint8, mi_uint1korr, 1);
      break;
    case HA_KEYTYPE_SHORT_INT:
      RT_PERIM_INC_KORR(int16, mi_sint2korr, 2);
      break;
    case HA_KEYTYPE_USHORT_INT:
      RT_PERIM_INC_KORR(uint16, mi_uint2korr, 2);
      break;
    case HA_KEYTYPE_INT24:
      RT_PERIM_INC_KORR(int32, mi_sint3korr, 3);
      break;
    case HA_KEYTYPE_UINT24:
      RT_PERIM_INC_KORR(int32, mi_uint3korr, 3);
      break;
    case HA_KEYTYPE_LONG_INT:
      RT_PERIM_INC_KORR(int32, mi_sint4korr, 4);
      break;
    case HA_KEYTYPE_ULONG_INT:
      RT_PERIM_INC_KORR(uint32, mi_uint4korr, 4);
      break;
    case HA_KEYTYPE_LONGLONG:
      RT_PERIM_INC_KORR(longlong, mi_sint8korr, 8);
      break;
    case HA_KEYTYPE_ULONGLONG:
      RT_PERIM_INC_KORR(longlong, mi_sint8korr, 8);
      break;
    case HA_KEYTYPE_FLOAT:
      RT_PERIM_INC_GET(float, mi_float4get, 4);
      break;
    case HA_KEYTYPE_DOUBLE:
      RT_PERIM_INC_GET(double, mi_float8get, 8);
      break;
    case HA_KEYTYPE_END:
      return *ab_perim - a_perim;
    default:
      return -1;
    }
    keyseg_length= keyseg->length * 2;
    key_length-= keyseg_length;
    a+= keyseg_length;
    b+= keyseg_length;
  }
  return *ab_perim - a_perim;
}


#define RT_PAGE_MBR_KORR(type, korr_func, store_func, len) \
{ \
  type amin, amax, bmin, bmax; \
  amin = korr_func(k + inc); \
  amax = korr_func(k + inc + len); \
  k = rt_PAGE_NEXT_KEY(k, k_len, nod_flag); \
  for (; k < last; k = rt_PAGE_NEXT_KEY(k, k_len, nod_flag)) \
{ \
    bmin = korr_func(k + inc); \
    bmax = korr_func(k + inc + len); \
    if (amin > bmin) \
      amin = bmin; \
    if (amax < bmax) \
      amax = bmax; \
} \
  store_func(c, amin); \
  c += len; \
  store_func(c, amax); \
  c += len; \
  inc += 2 * len; \
}

#define RT_PAGE_MBR_GET(type, get_func, store_func, len) \
{ \
  type amin, amax, bmin, bmax; \
  get_func(amin, k + inc); \
  get_func(amax, k + inc + len); \
  k = rt_PAGE_NEXT_KEY(k, k_len, nod_flag); \
  for (; k < last; k = rt_PAGE_NEXT_KEY(k, k_len, nod_flag)) \
{ \
    get_func(bmin, k + inc); \
    get_func(bmax, k + inc + len); \
    if (amin > bmin) \
      amin = bmin; \
    if (amax < bmax) \
      amax = bmax; \
} \
  store_func(c, amin); \
  c += len; \
  store_func(c, amax); \
  c += len; \
  inc += 2 * len; \
}

/*
Calculates key page total MBR = MBR(key1) + MBR(key2) + ...
*/
int rtree_page_mbr(MI_INFO *info, HA_KEYSEG *keyseg, uchar *page_buf,
                  uchar *c, uint key_length)
{
  uint inc = 0;
  uint k_len = key_length;
  uint nod_flag = mi_test_if_nod(page_buf);
  uchar *k;
  uchar *last = rt_PAGE_END(page_buf);

  for (; (int)key_length > 0; keyseg += 2)
  {
    key_length -= keyseg->length * 2;
    
    /* Handle NULL part */
    if (keyseg->null_bit)
    {
      return 1;
    }

    k = rt_PAGE_FIRST_KEY(page_buf, nod_flag);

    switch ((enum ha_base_keytype) keyseg->type) {
    case HA_KEYTYPE_INT8:
      RT_PAGE_MBR_KORR(int8, mi_sint1korr, mi_int1store, 1);
      break;
    case HA_KEYTYPE_BINARY:
      RT_PAGE_MBR_KORR(uint8, mi_uint1korr, mi_int1store, 1);
      break;
    case HA_KEYTYPE_SHORT_INT:
      RT_PAGE_MBR_KORR(int16, mi_sint2korr, mi_int2store, 2);
      break;
    case HA_KEYTYPE_USHORT_INT:
      RT_PAGE_MBR_KORR(uint16, mi_uint2korr, mi_int2store, 2);
      break;
    case HA_KEYTYPE_INT24:
      RT_PAGE_MBR_KORR(int32, mi_sint3korr, mi_int3store, 3);
      break;
    case HA_KEYTYPE_UINT24:
      RT_PAGE_MBR_KORR(uint32, mi_uint3korr, mi_int3store, 3);
      break;
    case HA_KEYTYPE_LONG_INT:
      RT_PAGE_MBR_KORR(int32, mi_sint4korr, mi_int4store, 4);
      break;
    case HA_KEYTYPE_ULONG_INT:
      RT_PAGE_MBR_KORR(uint32, mi_uint4korr, mi_int4store, 4);
      break;
    case HA_KEYTYPE_LONGLONG:
      RT_PAGE_MBR_KORR(longlong, mi_sint8korr, mi_int8store, 8);
      break;
    case HA_KEYTYPE_ULONGLONG:
      RT_PAGE_MBR_KORR(ulonglong, mi_uint8korr, mi_int8store, 8);
      break;
    case HA_KEYTYPE_FLOAT:
      RT_PAGE_MBR_GET(float, mi_float4get, mi_float4store, 4);
      break;
    case HA_KEYTYPE_DOUBLE:
      RT_PAGE_MBR_GET(double, mi_float8get, mi_float8store, 8);
      break;
    case HA_KEYTYPE_END:
      return 0;
    default:
      return 1;
    }
  }
  return 0;
}
