From 538da7496d70c86b41070ecf52592e52920d8808 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Sun, 29 Oct 2017 16:38:58 -0600
Subject: [PATCH] Add hb-sort-r, a portable qsort_r() replacement

---
 src/Makefile.sources |   1 +
 src/hb-sort-r.hh     | 227 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 228 insertions(+)
 create mode 100644 src/hb-sort-r.hh

diff --git a/src/Makefile.sources b/src/Makefile.sources
index d162ebef2..578752131 100644
--- a/src/Makefile.sources
+++ b/src/Makefile.sources
@@ -40,6 +40,7 @@ HB_BASE_sources = \
 	hb-shaper-impl-private.hh \
 	hb-shaper-private.hh \
 	hb-shaper.cc \
+	hb-sort-r.hh \
 	hb-string-array.hh \
 	hb-unicode-private.hh \
 	hb-unicode.cc \
diff --git a/src/hb-sort-r.hh b/src/hb-sort-r.hh
new file mode 100644
index 000000000..1b91b4da6
--- /dev/null
+++ b/src/hb-sort-r.hh
@@ -0,0 +1,227 @@
+/* Isaac Turner 29 April 2014 Public Domain */
+#ifndef HB_SORT_R_HH
+#define HB_SORT_R_HH
+
+#include <hb-private.hh>
+
+/* From https://github.com/noporpoise/sort_r */
+/*
+
+hb_sort_r function to be exported.
+
+Parameters:
+  base is the array to be sorted
+  nel is the number of elements in the array
+  width is the size in bytes of each element of the array
+  compar is the comparison function
+  arg is a pointer to be passed to the comparison function
+
+void hb_sort_r(void *base, size_t nel, size_t width,
+               int (*compar)(const void *_a, const void *_b, void *_arg),
+               void *arg);
+
+*/
+
+#define _SORT_R_INLINE inline
+
+#if (defined __APPLE__ || defined __MACH__ || defined __DARWIN__ || \
+     defined __FreeBSD__ || defined __DragonFly__)
+#  define _SORT_R_BSD
+#elif (defined _GNU_SOURCE || defined __gnu_hurd__ || defined __GNU__ || \
+       defined __linux__ || defined __MINGW32__ || defined __GLIBC__)
+#  define _SORT_R_LINUX
+#elif (defined _WIN32 || defined _WIN64 || defined __WINDOWS__)
+#  define _SORT_R_WINDOWS
+#  undef _SORT_R_INLINE
+#  define _SORT_R_INLINE __inline
+#else
+  /* Using our own recursive quicksort sort_r_simple() */
+#endif
+
+#if (defined NESTED_QSORT && NESTED_QSORT == 0)
+#  undef NESTED_QSORT
+#endif
+
+/* swap a, b iff a>b */
+/* __restrict is same as restrict but better support on old machines */
+static _SORT_R_INLINE int sort_r_cmpswap(char *__restrict a, char *__restrict b, size_t w,
+                                         int (*compar)(const void *_a, const void *_b,
+                                                       void *_arg),
+                                         void *arg)
+{
+  char tmp, *end = a+w;
+  if(compar(a, b, arg) > 0) {
+    for(; a < end; a++, b++) { tmp = *a; *a = *b; *b = tmp; }
+    return 1;
+  }
+  return 0;
+}
+
+/* Implement recursive quicksort ourselves */
+/* Note: quicksort is not stable, equivalent values may be swapped */
+static _SORT_R_INLINE void sort_r_simple(void *base, size_t nel, size_t w,
+                                         int (*compar)(const void *_a, const void *_b,
+                                                       void *_arg),
+                                         void *arg)
+{
+  char *b = (char *)base, *end = b + nel*w;
+  if(nel < 7) {
+    /* Insertion sort for arbitrarily small inputs */
+    char *pi, *pj;
+    for(pi = b+w; pi < end; pi += w) {
+      for(pj = pi; pj > b && sort_r_cmpswap(pj-w,pj,w,compar,arg); pj -= w) {}
+    }
+  }
+  else
+  {
+    /* nel > 6; Quicksort */
+
+    /* Use median of first, middle and last items as pivot */
+    char *x, *y, *xend, ch;
+    char *pl, *pr;
+    char *last = b+w*(nel-1), *tmp;
+    char *l[3];
+    l[0] = b;
+    l[1] = b+w*(nel/2);
+    l[2] = last;
+
+    if(compar(l[0],l[1],arg) > 0) { tmp=l[0]; l[0]=l[1]; l[1]=tmp; }
+    if(compar(l[1],l[2],arg) > 0) {
+      tmp=l[1]; l[1]=l[2]; l[2]=tmp; /* swap(l[1],l[2]) */
+      if(compar(l[0],l[1],arg) > 0) { tmp=l[0]; l[0]=l[1]; l[1]=tmp; }
+    }
+
+    /* swap l[id], l[2] to put pivot as last element */
+    for(x = l[1], y = last, xend = x+w; x<xend; x++, y++) {
+      ch = *x; *x = *y; *y = ch;
+    }
+
+    pl = b;
+    pr = last;
+
+    while(pl < pr) {
+      for(; pl < pr; pl += w) {
+        if(sort_r_cmpswap(pl, pr, w, compar, arg)) {
+          pr -= w; /* pivot now at pl */
+          break;
+        }
+      }
+      for(; pl < pr; pr -= w) {
+        if(sort_r_cmpswap(pl, pr, w, compar, arg)) {
+          pl += w; /* pivot now at pr */
+          break;
+        }
+      }
+    }
+
+    sort_r_simple(b, (pl-b)/w, w, compar, arg);
+    sort_r_simple(pl+w, (end-(pl+w))/w, w, compar, arg);
+  }
+}
+
+
+#if defined NESTED_QSORT
+
+  static _SORT_R_INLINE void hb_sort_r(void *base, size_t nel, size_t width,
+                                       int (*compar)(const void *_a, const void *_b,
+                                                     void *aarg),
+                                       void *arg)
+  {
+    int nested_cmp(const void *a, const void *b)
+    {
+      return compar(a, b, arg);
+    }
+
+    qsort(base, nel, width, nested_cmp);
+  }
+
+#else /* !NESTED_QSORT */
+
+  /* Declare structs and functions */
+
+  #if defined _SORT_R_BSD
+
+    /* Ensure qsort_r is defined */
+    extern void qsort_r(void *base, size_t nel, size_t width, void *thunk,
+                        int (*compar)(void *_thunk, const void *_a, const void *_b));
+
+  #endif
+
+  #if defined _SORT_R_BSD || defined _SORT_R_WINDOWS
+
+    /* BSD (qsort_r), Windows (qsort_s) require argument swap */
+
+    struct sort_r_data
+    {
+      void *arg;
+      int (*compar)(const void *_a, const void *_b, void *_arg);
+    };
+
+    static _SORT_R_INLINE int sort_r_arg_swap(void *s, const void *a, const void *b)
+    {
+      struct sort_r_data *ss = (struct sort_r_data*)s;
+      return (ss->compar)(a, b, ss->arg);
+    }
+
+  #endif
+
+  #if defined _SORT_R_LINUX
+
+#if 0 /* BE: To avoid redeclaration warning. */
+    typedef int(* __compar_d_fn_t)(const void *, const void *, void *);
+    extern void qsort_r(void *base, size_t nel, size_t width,
+                        __compar_d_fn_t __compar, void *arg)
+      __attribute__((nonnull (1, 4)));
+#endif
+
+  #endif
+
+  /* implementation */
+
+  static _SORT_R_INLINE void hb_sort_r(void *base, size_t nel, size_t width,
+                                       int (*compar)(const void *_a, const void *_b, void *_arg),
+                                       void *arg)
+  {
+    #if defined _SORT_R_LINUX
+
+      #if defined __GLIBC__ && ((__GLIBC__ < 2) || (__GLIBC__ == 2 && __GLIBC_MINOR__ < 8))
+
+        /* no qsort_r in glibc before 2.8, need to use nested qsort */
+        sort_r_simple(base, nel, width, compar, arg);
+
+      #else
+
+        qsort_r(base, nel, width, compar, arg);
+
+      #endif
+
+    #elif defined _SORT_R_BSD
+
+      struct sort_r_data tmp;
+      tmp.arg = arg;
+      tmp.compar = compar;
+      qsort_r(base, nel, width, &tmp, sort_r_arg_swap);
+
+    #elif defined _SORT_R_WINDOWS
+
+      struct sort_r_data tmp;
+      tmp.arg = arg;
+      tmp.compar = compar;
+      qsort_s(base, nel, width, sort_r_arg_swap, &tmp);
+
+    #else
+
+      /* Fall back to our own quicksort implementation */
+      sort_r_simple(base, nel, width, compar, arg);
+
+    #endif
+  }
+
+#endif /* !NESTED_QSORT */
+
+#undef _SORT_R_INLINE
+#undef _SORT_R_WINDOWS
+#undef _SORT_R_LINUX
+#undef _SORT_R_BSD
+
+#endif /* HB_SORT_R_HH */