gist DatumGetPointer returns pointer to corrupted data

I index these structures in gist:

typedef struct {
    uint8 type_flag;
    float8 xi;
    float8 yi;
    Timestamp ti;
    float8 xe;
    float8 ye;
    Timestamp te;
    int32 id;
} typ_s_flagged;

typedef struct {
    uint8 type_flag;
    float8 xl;
    float8 yl;
    Timestamp tl;
    float8 xh;
    float8 yh;
    Timestamp th;
} typ_b_flagged;

typ_s_flagged is the type of leaf entries and typ_b_flagged is for non-leaf entries.
This is how I determine which type it is in functions union, picksplit, penalty etc (I tried to use GIST_LEAF but it produced errors in execution time!, anyway I know this might not be a best practice but it is not wrong).

GISTENTRY *entry = (GISTENTRY *) PG_GETARG_POINTER(0); //in penalty, consistent

//or GistEntryVector *entryvec = (GistEntryVector *) PG_GETARG_POINTER(0); entry = &entryvec->vector[i]; in union and picksplit
uint8 *type_flag = (uint8 *) DatumGetPointer(entry->key);
if (*type_flag == 0) {
      typ_s_flagged *p1 = (typ_s_flagged *) DatumGetPointer(entry->key);
} else if(*type_flag == 1){
      typ_b_flagged *p2 = (typ_b_flagged *) DatumGetPointer(entry->key);
}