qsort.c File Reference

#include <stdlib.h>
#include <string.h>
#include <strings.h>

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Macros
#define	min(a, b)   (a) < (b) ? a : b
#define	swapcode(TYPE, parmi, parmj, n)
#define	SWAPINIT(a, es)   swaptype = (uintptr_t)a % sizeof(long) || es % sizeof(long) ? 2 : es == sizeof(long) ? 0 : 1;
#define	swap(a, b)   swapfunc(a, b, (size_t)es, (size_t)swaptype)
#define	vecswap(a, b, n)
#define	CMP(t, x, y)   (cmp((x), (y)))
#define	DEPTH(x)   (2 * (fls((int)(x)) - 1))
#define	thunk   NULL

Typedefs
typedef int	cmp_t(const void *, const void *)

Functions
static char *	med3 (char *a, char *b, char *c, cmp_t *cmd, void *thunk) __attribute__((always_inline))
static void	swapfunc (char *a, char *b, size_t n, size_t swaptype) __attribute__((always_inline))
static char *	med3 (char *a, char *b, char *c, cmp_t *cmp, void *thunk __attribute__((unused)))
static void	_qsort (void *a, size_t n, size_t es, #define thunk cmp_t *cmp, int depth_limit)
void	qsort (void *a, size_t n, size_t es, cmp_t *cmp)

Macro Definition Documentation

CMP

#define CMP	(		t,
			x,
			y
	)		(cmp((x), (y)))

Definition at line 95 of file qsort.c.

DEPTH

#define DEPTH

(

x

)

(2 * (fls((int)(x)) - 1))

Definition at line 112 of file qsort.c.

min

#define min	(		a,
			b
	)		(a) < (b) ? a : b

Definition at line 44 of file qsort.c.

swap

#define swap	(		a,
			b
	)		swapfunc(a, b, (size_t)es, (size_t)swaptype)

Definition at line 83 of file qsort.c.

swapcode

#define swapcode	(		TYPE,
			parmi,
			parmj,
			n
	)

Value:

{                                   \
        size_t i = (n) / sizeof(TYPE);  \
        TYPE* pi = (TYPE*)(parmi);      \
        TYPE* pj = (TYPE*)(parmj);      \
        do                              \
        {                               \
            TYPE t = *pi;               \
            *pi++ = *pj;                \
            *pj++ = t;                  \
        } while(--i > 0);               \
    }

Definition at line 49 of file qsort.c.

SWAPINIT

#define SWAPINIT	(		a,
			es
	)		swaptype = (uintptr_t)a % sizeof(long) || es % sizeof(long) ? 2 : es == sizeof(long) ? 0 : 1;

Definition at line 62 of file qsort.c.

thunk

#define thunk   NULL

vecswap

#define vecswap	(		a,
			b,
			n
	)

Value:

if((n) > 0)          \
    swapfunc(a, b, n, swaptype ? (size_t)swaptype : 1)

Definition at line 88 of file qsort.c.

Typedef Documentation

cmp_t

typedef int cmp_t(const void *, const void *)

Definition at line 37 of file qsort.c.

Function Documentation

_qsort()

static void _qsort ( void *  a, size_t  n, size_t  es, #define thunk cmp_t *  cmp, int  depth_limit  )

static

Definition at line 115 of file qsort.c.

{
    char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
    size_t d, r, swap_cnt;
    int cmp_result;
    int swaptype;

loop:
    if(depth_limit-- <= 0)
    {
#ifdef I_AM_QSORT_R
        heapsort_r(a, n, es, thunk, cmp);
#else
        heapsort(a, n, es, cmp);
#endif
        return;
    }
    SWAPINIT(a, es);
    swap_cnt = 0;
    if(n < 7)
    {
        for(pm = (char*)a + es; pm < (char*)a + n * es; pm += es)
        {
            for(pl = pm; pl > (char*)a && CMP(thunk, pl - es, pl) > 0; pl -= es)
            {
                swap(pl, pl - es);
            }
        }
        return;
    }
    pm = (char*)a + (n / 2) * es;
    if(n > 7)
    {
        pl = a;
        pn = (char*)a + (n - 1) * es;
        if(n > 40)
        {
            d = (n / 8) * es;
            pl = med3(pl, pl + d, pl + 2 * d, cmp, thunk);
            pm = med3(pm - d, pm, pm + d, cmp, thunk);
            pn = med3(pn - 2 * d, pn - d, pn, cmp, thunk);
        }
        pm = med3(pl, pm, pn, cmp, thunk);
    }
    swap(a, (void*)pm);
    pa = pb = (char*)a + es;

    pc = pd = (char*)a + (n - 1) * es;
    for(;;)
    {
        while(pb <= pc && (cmp_result = CMP(thunk, pb, a)) <= 0)
        {
            if(cmp_result == 0)
            {
                swap_cnt = 1;
                swap(pa, pb);
                pa += es;
            }
            pb += es;
        }
        while(pb <= pc && (cmp_result = CMP(thunk, pc, a)) >= 0)
        {
            if(cmp_result == 0)
            {
                swap_cnt = 1;
                swap(pc, pd);
                pd -= es;
            }
            pc -= es;
        }
        if(pb > pc)
        {
            break;
        }
        swap(pb, pc);
        swap_cnt = 1;
        pb += es;
        pc -= es;
    }

    pn = (char*)a + n * es;
    r = min((uintptr_t)pa - (uintptr_t)a, (uintptr_t)pb - (uintptr_t)pa);
    vecswap(a, pb - r, r);
    r = min((uintptr_t)pd - (uintptr_t)pc, (uintptr_t)pn - (uintptr_t)pd - (uintptr_t)es);
    vecswap(pb, pn - r, r);

    if(swap_cnt == 0)
    { /* Switch to insertion sort */
        r = 1 + n / 4; /* n >= 7, so r >= 2 */
        for(pm = (char*)a + es; pm < (char*)a + n * es; pm += es)
        {
            for(pl = pm; pl > (char*)a && CMP(thunk, pl - es, pl) > 0; pl -= es)
            {
                swap(pl, pl - es);
                if(++swap_cnt > r)
                {
                    goto nevermind;
                }
            }
        }
        return;
    }

nevermind:
    if((r = (uintptr_t)pb - (uintptr_t)pa) > es)
    {
#ifdef I_AM_QSORT_R
        _qsort(a, r / es, es, thunk, cmp, depth_limit);
#else
        _qsort(a, r / es, es, cmp, depth_limit);
#endif
    }
    if((r = (uintptr_t)pd - (uintptr_t)pc) > es)
    {
        /* Iterate rather than recurse to save stack space */
        a = pn - r;
        n = r / es;
        goto loop;
    }
    /*      qsort(pn - r, r / es, es, cmp);*/
}

References CMP, cmp(), heapsort(), heapsort_r(), med3(), min, swap, SWAPINIT, thunk, and vecswap.

Referenced by qsort().

med3() [1/2]

static char* med3 ( char *  a, char *  b, char *  c, cmp_t *  cmd, void *  thunk  )

inlinestatic

Referenced by _qsort().

med3() [2/2]

static char* med3 ( char *  a, char *  b, char *  c, cmp_t *  cmp, void *thunk   __attribute__(unused)  )

inlinestatic

Definition at line 98 of file qsort.c.

{
    return CMP(thunk, a, b) < 0 ? (CMP(thunk, b, c) < 0 ? b : (CMP(thunk, a, c) < 0 ? c : a))
                                : (CMP(thunk, b, c) > 0 ? b : (CMP(thunk, a, c) < 0 ? a : c));
}

References CMP, and thunk.

qsort()

void qsort	(	void *	a,
		size_t	n,
		size_t	es,
		cmp_t *	cmp
	)

Definition at line 247 of file qsort.c.

{
    _qsort(a, n, es,
#ifdef I_AM_QSORT_R
           thunk,
#endif
           cmp, DEPTH(n));
}

References _qsort(), cmp(), DEPTH, I_AM_QSORT_R, and thunk.

swapfunc()

static void swapfunc ( char *  a, char *  b, size_t  n, size_t  swaptype  )

inlinestatic

Definition at line 65 of file qsort.c.

{
    if(swaptype == 0)
    {
        long t = *(long*)(void*)(a);
        *(long*)(void*)(a) = *(long*)(void*)(b);
        *(long*)(void*)(b) = t;
    }
    else if(swaptype == 1)
    {
        swapcode(long, (void*)a, (void*)b, n)
    }
    else
    {
        swapcode(char, a, b, n)
    }
}

References swapcode.