176 lines
6.2 KiB
C
176 lines
6.2 KiB
C
/*
|
|
* $Id: brqsort.c 2.3 1996/02/17 18:00:39 sam Exp $
|
|
* $Locker: $
|
|
*
|
|
* Local quicksort for brender
|
|
*
|
|
* Based on a public domain verion by Raymond Gardner,
|
|
* Englewood CO February 1991
|
|
*/
|
|
|
|
#include "brender.h"
|
|
|
|
BR_RCS_ID("$Id: brqsort.c 2.3 1996/02/17 18:00:39 sam Exp $")
|
|
|
|
#if defined(_MSC_VER)
|
|
#include <stdlib.h>
|
|
|
|
void BR_RESIDENT_ENTRY BrQsort(void *basep, unsigned int nelems, unsigned int size,
|
|
br_qsort_cbfn *comp)
|
|
{
|
|
qsort(basep, nelems, size, comp);
|
|
}
|
|
|
|
#elif defined(__IBMC__)
|
|
/*
|
|
* Pull qsort from a BRender specific DLL
|
|
*/
|
|
void _System BrSupport1(br_qsort_cbfn *comp, unsigned int size, void *basep, unsigned int nelems);
|
|
|
|
void BR_RESIDENT_ENTRY BrQsort(void *basep, unsigned int nelems, unsigned int size,
|
|
br_qsort_cbfn *comp)
|
|
{
|
|
BrSupport1(comp,size,basep,nelems);
|
|
}
|
|
#else
|
|
|
|
static void swap_chars(char *, char *, unsigned int);
|
|
|
|
#define SWAP_INTS 1
|
|
|
|
/*
|
|
** Compile with -DSWAP_INTS if your machine can access an int at an
|
|
** arbitrary location with reasonable efficiency. (Some machines
|
|
** cannot access an int at an odd address at all, so be careful.)
|
|
*/
|
|
|
|
#ifdef SWAP_INTS
|
|
static void swap_ints(char *, char *, unsigned int);
|
|
static void swap_int_1(char *ap, char *bp, unsigned int nints);
|
|
|
|
#define SWAP(a, b) (swap_func((char *)(a), (char *)(b), width))
|
|
#else
|
|
#define SWAP(a, b) (swap_chars((char *)(a), (char *)(b), size))
|
|
#endif
|
|
|
|
#define COMP(a, b) ((*comp)((void *)(a), (void *)(b)))
|
|
|
|
#define T 7 /* subfiles of T or fewer elements will */
|
|
/* be sorted by a simple insertion sort */
|
|
/* Note! T must be at least 3 */
|
|
|
|
void BR_RESIDENT_ENTRY BrQsort(void *basep, unsigned int nelems, unsigned int size,
|
|
br_qsort_cbfn *comp)
|
|
{
|
|
char *stack[40], **sp; /* stack and stack pointer */
|
|
char *i, *j, *limit; /* scan and limit pointers */
|
|
unsigned int thresh; /* size of T elements in bytes */
|
|
char *base; /* base pointer as char * */
|
|
|
|
#ifdef SWAP_INTS
|
|
unsigned int width; /* width of array element */
|
|
void (*swap_func)(char *, char *, unsigned int); /* swap func pointer*/
|
|
|
|
width = size; /* save size for swap routine */
|
|
swap_func = swap_chars; /* choose swap function */
|
|
if ( size == sizeof(int)) { /* size is == int */
|
|
swap_func = swap_int_1; /* use int swap function */
|
|
} else if ( size % sizeof(int) == 0 ) { /* size is multiple of ints */
|
|
width /= sizeof(int); /* set width in ints */
|
|
swap_func = swap_ints; /* use int swap function */
|
|
}
|
|
#endif
|
|
|
|
base = (char *)basep; /* set up char * base pointer */
|
|
thresh = T * size; /* init threshold */
|
|
sp = stack; /* init stack pointer */
|
|
limit = base + nelems * size;/* pointer past end of array */
|
|
for ( ;; ) { /* repeat until break... */
|
|
if ( (unsigned)(limit - base) > thresh ) { /* if more than T elements */
|
|
/* swap base with middle */
|
|
SWAP((((limit-base)/size)/2)*size+base, base);
|
|
i = base + size; /* i scans left to right */
|
|
j = limit - size; /* j scans right to left */
|
|
if ( COMP(i, j) > 0 ) /* Sedgewick's */
|
|
SWAP(i, j); /* three-element sort */
|
|
if ( COMP(base, j) > 0 ) /* sets things up */
|
|
SWAP(base, j); /* so that */
|
|
if ( COMP(i, base) > 0 ) /* *i <= *base <= *j */
|
|
SWAP(i, base); /* *base is pivot element */
|
|
for ( ;; ) { /* loop until break */
|
|
do /* move i right */
|
|
i += size; /* until *i >= pivot */
|
|
while ( COMP(i, base) < 0 );
|
|
do /* move j left */
|
|
j -= size; /* until *j <= pivot */
|
|
while ( COMP(j, base) > 0 );
|
|
if ( i > j ) /* if pointers crossed */
|
|
break; /* break loop */
|
|
SWAP(i, j); /* else swap elements, keep scanning*/
|
|
}
|
|
SWAP(base, j); /* move pivot into correct place */
|
|
if ( j - base > limit - i ) { /* if left subfile larger */
|
|
sp[0] = base; /* stack left subfile base */
|
|
sp[1] = j; /* and limit */
|
|
base = i; /* sort the right subfile */
|
|
} else { /* else right subfile larger*/
|
|
sp[0] = i; /* stack right subfile base */
|
|
sp[1] = limit; /* and limit */
|
|
limit = j; /* sort the left subfile */
|
|
}
|
|
sp += 2; /* increment stack pointer */
|
|
} else { /* else subfile is small, use insertion sort */
|
|
for ( j = base, i = j+size; i < limit; j = i, i += size )
|
|
for ( ; COMP(j, j+size) > 0; j -= size ) {
|
|
SWAP(j, j+size);
|
|
if ( j == base )
|
|
break;
|
|
}
|
|
if ( sp != stack ) { /* if any entries on stack */
|
|
sp -= 2; /* pop the base and limit */
|
|
base = sp[0];
|
|
limit = sp[1];
|
|
} else /* else stack empty, done */
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
** swap nbytes between a and b
|
|
*/
|
|
|
|
static void swap_chars(char *a, char *b, unsigned int nbytes)
|
|
{
|
|
char tmp;
|
|
do {
|
|
tmp = *a; *a++ = *b; *b++ = tmp;
|
|
} while ( --nbytes );
|
|
}
|
|
|
|
#ifdef SWAP_INTS
|
|
|
|
/*
|
|
** swap nints between a and b
|
|
*/
|
|
|
|
static void swap_ints(char *ap, char *bp, unsigned int nints)
|
|
{
|
|
int *a = (int *)ap, *b = (int *)bp;
|
|
int tmp;
|
|
do {
|
|
tmp = *a; *a++ = *b; *b++ = tmp;
|
|
} while ( --nints );
|
|
}
|
|
|
|
static void swap_int_1(char *ap, char *bp, unsigned int nints)
|
|
{
|
|
int *a = (int *)ap, *b = (int *)bp;
|
|
int tmp;
|
|
|
|
tmp = *a; *a++ = *b; *b++ = tmp;
|
|
}
|
|
|
|
#endif
|
|
#endif
|
|
|