Add hb-sort-r, a portable qsort_r() replacement
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Behdad Esfahbod
parent
923a8f520a
commit
538da7496d
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@ -40,6 +40,7 @@ HB_BASE_sources = \
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hb-shaper-impl-private.hh \
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hb-shaper-private.hh \
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hb-shaper.cc \
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hb-sort-r.hh \
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hb-string-array.hh \
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hb-unicode-private.hh \
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hb-unicode.cc \
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@ -0,0 +1,227 @@
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/* Isaac Turner 29 April 2014 Public Domain */
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#ifndef HB_SORT_R_HH
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#define HB_SORT_R_HH
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#include <hb-private.hh>
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/* From https://github.com/noporpoise/sort_r */
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/*
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hb_sort_r function to be exported.
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Parameters:
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base is the array to be sorted
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nel is the number of elements in the array
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width is the size in bytes of each element of the array
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compar is the comparison function
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arg is a pointer to be passed to the comparison function
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void hb_sort_r(void *base, size_t nel, size_t width,
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int (*compar)(const void *_a, const void *_b, void *_arg),
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void *arg);
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*/
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#define _SORT_R_INLINE inline
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#if (defined __APPLE__ || defined __MACH__ || defined __DARWIN__ || \
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defined __FreeBSD__ || defined __DragonFly__)
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# define _SORT_R_BSD
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#elif (defined _GNU_SOURCE || defined __gnu_hurd__ || defined __GNU__ || \
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defined __linux__ || defined __MINGW32__ || defined __GLIBC__)
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# define _SORT_R_LINUX
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#elif (defined _WIN32 || defined _WIN64 || defined __WINDOWS__)
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# define _SORT_R_WINDOWS
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# undef _SORT_R_INLINE
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# define _SORT_R_INLINE __inline
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#else
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/* Using our own recursive quicksort sort_r_simple() */
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#endif
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#if (defined NESTED_QSORT && NESTED_QSORT == 0)
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# undef NESTED_QSORT
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#endif
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/* swap a, b iff a>b */
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/* __restrict is same as restrict but better support on old machines */
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static _SORT_R_INLINE int sort_r_cmpswap(char *__restrict a, char *__restrict b, size_t w,
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int (*compar)(const void *_a, const void *_b,
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void *_arg),
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void *arg)
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{
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char tmp, *end = a+w;
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if(compar(a, b, arg) > 0) {
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for(; a < end; a++, b++) { tmp = *a; *a = *b; *b = tmp; }
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return 1;
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}
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return 0;
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}
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/* Implement recursive quicksort ourselves */
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/* Note: quicksort is not stable, equivalent values may be swapped */
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static _SORT_R_INLINE void sort_r_simple(void *base, size_t nel, size_t w,
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int (*compar)(const void *_a, const void *_b,
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void *_arg),
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void *arg)
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{
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char *b = (char *)base, *end = b + nel*w;
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if(nel < 7) {
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/* Insertion sort for arbitrarily small inputs */
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char *pi, *pj;
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for(pi = b+w; pi < end; pi += w) {
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for(pj = pi; pj > b && sort_r_cmpswap(pj-w,pj,w,compar,arg); pj -= w) {}
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}
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}
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else
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{
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/* nel > 6; Quicksort */
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/* Use median of first, middle and last items as pivot */
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char *x, *y, *xend, ch;
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char *pl, *pr;
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char *last = b+w*(nel-1), *tmp;
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char *l[3];
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l[0] = b;
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l[1] = b+w*(nel/2);
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l[2] = last;
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if(compar(l[0],l[1],arg) > 0) { tmp=l[0]; l[0]=l[1]; l[1]=tmp; }
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if(compar(l[1],l[2],arg) > 0) {
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tmp=l[1]; l[1]=l[2]; l[2]=tmp; /* swap(l[1],l[2]) */
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if(compar(l[0],l[1],arg) > 0) { tmp=l[0]; l[0]=l[1]; l[1]=tmp; }
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}
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/* swap l[id], l[2] to put pivot as last element */
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for(x = l[1], y = last, xend = x+w; x<xend; x++, y++) {
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ch = *x; *x = *y; *y = ch;
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}
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pl = b;
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pr = last;
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while(pl < pr) {
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for(; pl < pr; pl += w) {
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if(sort_r_cmpswap(pl, pr, w, compar, arg)) {
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pr -= w; /* pivot now at pl */
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break;
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}
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}
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for(; pl < pr; pr -= w) {
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if(sort_r_cmpswap(pl, pr, w, compar, arg)) {
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pl += w; /* pivot now at pr */
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break;
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}
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}
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}
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sort_r_simple(b, (pl-b)/w, w, compar, arg);
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sort_r_simple(pl+w, (end-(pl+w))/w, w, compar, arg);
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}
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}
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#if defined NESTED_QSORT
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static _SORT_R_INLINE void hb_sort_r(void *base, size_t nel, size_t width,
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int (*compar)(const void *_a, const void *_b,
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void *aarg),
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void *arg)
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{
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int nested_cmp(const void *a, const void *b)
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{
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return compar(a, b, arg);
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}
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qsort(base, nel, width, nested_cmp);
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}
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#else /* !NESTED_QSORT */
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/* Declare structs and functions */
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#if defined _SORT_R_BSD
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/* Ensure qsort_r is defined */
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extern void qsort_r(void *base, size_t nel, size_t width, void *thunk,
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int (*compar)(void *_thunk, const void *_a, const void *_b));
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#endif
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#if defined _SORT_R_BSD || defined _SORT_R_WINDOWS
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/* BSD (qsort_r), Windows (qsort_s) require argument swap */
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struct sort_r_data
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{
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void *arg;
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int (*compar)(const void *_a, const void *_b, void *_arg);
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};
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static _SORT_R_INLINE int sort_r_arg_swap(void *s, const void *a, const void *b)
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{
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struct sort_r_data *ss = (struct sort_r_data*)s;
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return (ss->compar)(a, b, ss->arg);
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}
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#endif
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#if defined _SORT_R_LINUX
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#if 0 /* BE: To avoid redeclaration warning. */
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typedef int(* __compar_d_fn_t)(const void *, const void *, void *);
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extern void qsort_r(void *base, size_t nel, size_t width,
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__compar_d_fn_t __compar, void *arg)
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__attribute__((nonnull (1, 4)));
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#endif
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#endif
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/* implementation */
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static _SORT_R_INLINE void hb_sort_r(void *base, size_t nel, size_t width,
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int (*compar)(const void *_a, const void *_b, void *_arg),
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void *arg)
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{
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#if defined _SORT_R_LINUX
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#if defined __GLIBC__ && ((__GLIBC__ < 2) || (__GLIBC__ == 2 && __GLIBC_MINOR__ < 8))
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/* no qsort_r in glibc before 2.8, need to use nested qsort */
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sort_r_simple(base, nel, width, compar, arg);
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#else
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qsort_r(base, nel, width, compar, arg);
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#endif
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#elif defined _SORT_R_BSD
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struct sort_r_data tmp;
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tmp.arg = arg;
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tmp.compar = compar;
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qsort_r(base, nel, width, &tmp, sort_r_arg_swap);
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#elif defined _SORT_R_WINDOWS
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struct sort_r_data tmp;
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tmp.arg = arg;
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tmp.compar = compar;
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qsort_s(base, nel, width, sort_r_arg_swap, &tmp);
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#else
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/* Fall back to our own quicksort implementation */
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sort_r_simple(base, nel, width, compar, arg);
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#endif
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}
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#endif /* !NESTED_QSORT */
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#undef _SORT_R_INLINE
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#undef _SORT_R_WINDOWS
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#undef _SORT_R_LINUX
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#undef _SORT_R_BSD
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#endif /* HB_SORT_R_HH */
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