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/* Copyright (c) 1987, 1989, 2012 University of Maryland Department of
Computer Science.
Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation, the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions: The above copyright notice, this permission
notice and the disclaimer statement shall be included in all copies
or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
/*
* Key search routines (for a 32 bit key)
*
* SCreate initializes the search control area.
*
* SSearch returns the address of the data area (if found or created)
* or a null pointer (if not). The last argument controls the disposition
* in various cases, and is a ``value-result'' parameter.
*
* SEnumerate calls the given function on each data object within the
* search table. Note that no ordering is specified (though currently
* it runs in increasing-key-value sequence).
*/
#include "types.h"
#include "search.h"
#if vax || mc68000 || ns32000 || pyr
#define HARD_ALIGNMENT 4
#else
#define HARD_ALIGNMENT 16 /* should suffice for most everyone */
#endif
static int DOffset; /* part of alignment code */
#ifndef KPATHSEA
char *malloc(), *realloc();
#endif
struct search *
SCreate(unsigned int dsize)
{
register struct search *s;
if ((s = (struct search *) malloc(sizeof *s)) == 0)
return (0);
if (DOffset == 0) {
#ifndef HARD_ALIGNMENT
DOffset = sizeof(i32);
#else
DOffset = (sizeof(i32) + HARD_ALIGNMENT - 1) &
~(HARD_ALIGNMENT - 1);
#endif
}
dsize += DOffset; /* tack on space for keys */
#ifdef HARD_ALIGNMENT
/*
* For machines with strict alignment constraints, it may be
* necessary to align the data at a multiple of some positive power
* of two. In general, it would suffice to make dsize a power of
* two, but this could be very space-wasteful, so instead we align it
* to HARD_ALIGNMENT. 64 bit machines might ``#define HARD_ALIGNMENT
* 8'', for example. N.B.: we assume that HARD_ALIGNMENT is a power
* of two.
*/
dsize = (dsize + HARD_ALIGNMENT - 1) & ~(HARD_ALIGNMENT - 1);
#endif
s->s_dsize = dsize; /* save data object size */
s->s_space = 10; /* initially, room for 10 objects */
s->s_n = 0; /* and none in the table */
if ((s->s_data = malloc(s->s_space * dsize)) == 0) {
free((char *)s);
return (0);
}
return (s);
}
/*
* We actually use a binary search right now - this may change.
*/
char *
SSearch(struct search *s, i32 key, int *disp)
{
register char *keyaddr;
int itemstomove;
*disp &= S_CREATE | S_EXCL; /* clear return codes */
if (s->s_n) { /* look for the key */
register int h, l, m;
h = s->s_n - 1;
l = 0;
while (l <= h) {
m = (l + h) >> 1;
keyaddr = s->s_data + m * s->s_dsize;
if (*(i32 *) keyaddr > key)
h = m - 1;
else if (*(i32 *) keyaddr < key)
l = m + 1;
else { /* found it, now what? */
if (*disp & S_EXCL) {
*disp |= S_COLL;
return (0); /* collision */
}
*disp |= S_FOUND;
return (keyaddr + DOffset);
}
}
keyaddr = s->s_data + l * s->s_dsize;
} else
keyaddr = s->s_data;
/* keyaddr is now where the key should have been found, if anywhere */
if ((*disp & S_CREATE) == 0)
return (0); /* not found */
/* avoid using realloc so as to retain old data if out of memory */
if (s->s_space <= 0) { /* must expand; double it */
register char *new;
if ((new = malloc((s->s_n << 1) * s->s_dsize)) == 0) {
*disp |= S_ERROR; /* no space */
return (0);
}
keyaddr = (keyaddr - s->s_data) + new; /* relocate */
bcopy(s->s_data, new, s->s_n * s->s_dsize);
free(s->s_data);
s->s_data = new;
s->s_space = s->s_n;
}
/* now move any keyed data that is beyond keyaddr down */
itemstomove = s->s_n - (keyaddr - s->s_data) / s->s_dsize;
if (itemstomove) {
#ifndef BLOCK_COPY
register char *from, *to;
from = s->s_data + s->s_n * s->s_dsize;
to = from + s->s_dsize;
while (from > keyaddr)
*--to = *--from;
#else
BLOCK_COPY(keyaddr, keyaddr + s->s_dsize,
itemstomove * s->s_dsize);
#endif
}
*disp |= S_NEW;
s->s_n++;
s->s_space--;
*(i32 *) keyaddr = key;
keyaddr += DOffset; /* now actually dataaddr */
/* the bzero is just a frill... */
bzero(keyaddr, s->s_dsize - DOffset);
return (keyaddr);
}
/*
* Call function `f' for each element in the search table `s'.
*/
void
SEnumerate(struct search *s, void(*f)(char*,i32))
{
register int n;
register char *p;
n = s->s_n;
p = s->s_data;
while (--n >= 0) {
(*f)(p + DOffset, *(i32 *)p);
p += s->s_dsize;
}
}
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