--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lib-src/qsort.c	Mon Aug 13 08:45:50 2007 +0200
@@ -0,0 +1,237 @@
+/* Plug-compatible replacement for UNIX qsort.
+   Copyright (C) 1989 Free Software Foundation, Inc.
+   Written by Douglas C. Schmidt (schmidt@ics.uci.edu)
+
+This file is part of GNU CC.
+
+GNU QSORT is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+GNU QSORT is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU QSORT; see the file COPYING.  If not, write to
+the Free the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+Boston, MA 02111-1307, USA. */
+
+/* Synched up with: FSF 19.28. */
+
+#ifdef sparc
+#include <alloca.h>
+#endif
+
+/* Invoke the comparison function, returns either 0, < 0, or > 0. */
+#define CMP(A,B) ((*cmp)((A),(B)))
+
+/* Byte-wise swap two items of size SIZE. */
+#define SWAP(A,B,SIZE) do {int sz = (SIZE); char *a = (A); char *b = (B); \
+    do { char _temp = *a;*a++ = *b;*b++ = _temp;} while (--sz);} while (0)
+
+/* Copy SIZE bytes from item B to item A. */
+#define COPY(A,B,SIZE) {int sz = (SIZE); do { *(A)++ = *(B)++; } while (--sz); }
+
+/* This should be replaced by a standard ANSI macro. */
+#define BYTES_PER_WORD 8
+
+/* The next 4 #defines implement a very fast in-line stack abstraction. */
+#define STACK_SIZE (BYTES_PER_WORD * sizeof (long))
+#define PUSH(LOW,HIGH) do {top->lo = LOW;top++->hi = HIGH;} while (0)
+#define POP(LOW,HIGH)  do {LOW = (--top)->lo;HIGH = top->hi;} while (0)
+#define STACK_NOT_EMPTY (stack < top)                
+
+/* Discontinue quicksort algorithm when partition gets below this size.
+   This particular magic number was chosen to work best on a Sun 4/260. */
+#define MAX_THRESH 4
+
+/* Stack node declarations used to store unfulfilled partition obligations. */
+typedef struct 
+{
+  char *lo;
+  char *hi;
+} stack_node;
+
+/* Order size using quicksort.  This implementation incorporates
+   four optimizations discussed in Sedgewick:
+   
+   1. Non-recursive, using an explicit stack of pointer that store the 
+      next array partition to sort.  To save time, this maximum amount 
+      of space required to store an array of MAX_INT is allocated on the 
+      stack.  Assuming a 32-bit integer, this needs only 32 * 
+      sizeof (stack_node) == 136 bits.  Pretty cheap, actually.
+
+   2. Chose the pivot element using a median-of-three decision tree.
+      This reduces the probability of selecting a bad pivot value and 
+      eliminates certain extraneous comparisons.
+
+   3. Only quicksorts TOTAL_ELEMS / MAX_THRESH partitions, leaving
+      insertion sort to order the MAX_THRESH items within each partition.  
+      This is a big win, since insertion sort is faster for small, mostly
+      sorted array segments.
+   
+   4. The larger of the two sub-partitions is always pushed onto the
+      stack first, with the algorithm then concentrating on the
+      smaller partition.  This *guarantees* no more than log (n)
+      stack size is needed (actually O(1) in this case)! */
+      
+int 
+qsort (base_ptr, total_elems, size, cmp)
+     char *base_ptr;
+     int total_elems;
+     int size;
+     int (*cmp)();
+{
+  /* Allocating SIZE bytes for a pivot buffer facilitates a better 
+     algorithm below since we can do comparisons directly on the pivot. */
+  char *pivot_buffer = (char *) alloca (size);
+  int   max_thresh   = MAX_THRESH * size;
+
+  if (total_elems > MAX_THRESH)
+    {
+      char       *lo = base_ptr;
+      char       *hi = lo + size * (total_elems - 1);
+      stack_node stack[STACK_SIZE]; /* Largest size needed for 32-bit int!!! */
+      stack_node *top = stack + 1;
+
+      while (STACK_NOT_EMPTY)
+        {
+          char *left_ptr;
+          char *right_ptr;
+          {
+            char *pivot = pivot_buffer;
+            {
+              /* Select median value from among LO, MID, and HI. Rearrange
+                 LO and HI so the three values are sorted. This lowers the 
+                 probability of picking a pathological pivot value and 
+                 skips a comparison for both the LEFT_PTR and RIGHT_PTR. */
+
+              char *mid = lo + size * ((hi - lo) / size >> 1);
+
+              if (CMP (mid, lo) < 0)
+                SWAP (mid, lo, size);
+              if (CMP (hi, mid) < 0)
+                SWAP (mid, hi, size);
+              else 
+                goto jump_over;
+              if (CMP (mid, lo) < 0)
+                SWAP (mid, lo, size);
+            jump_over:
+              COPY (pivot, mid, size);
+              pivot = pivot_buffer;
+            }
+            left_ptr  = lo + size;
+            right_ptr = hi - size; 
+
+            /* Here's the famous ``collapse the walls'' section of quicksort.  
+               Gotta like those tight inner loops!  They are the main reason 
+               that this algorithm runs much faster than others. */
+            do 
+              {
+                while (CMP (left_ptr, pivot) < 0)
+                  left_ptr += size;
+
+                while (CMP (pivot, right_ptr) < 0)
+                  right_ptr -= size;
+
+                if (left_ptr < right_ptr) 
+                  {
+                    SWAP (left_ptr, right_ptr, size);
+                    left_ptr += size;
+                    right_ptr -= size;
+                  }
+                else if (left_ptr == right_ptr) 
+                  {
+                    left_ptr += size;
+                    right_ptr -= size;
+                    break;
+                  }
+              } 
+            while (left_ptr <= right_ptr);
+
+          }
+
+          /* Set up pointers for next iteration.  First determine whether
+             left and right partitions are below the threshold size. If so, 
+             ignore one or both.  Otherwise, push the larger partition's
+             bounds on the stack and continue sorting the smaller one. */
+
+          if ((right_ptr - lo) <= max_thresh)
+            {
+              if ((hi - left_ptr) <= max_thresh) /* Ignore both small partitions. */
+                POP (lo, hi); 
+              else              /* Ignore small left partition. */  
+                lo = left_ptr;
+            }
+          else if ((hi - left_ptr) <= max_thresh) /* Ignore small right partition. */
+            hi = right_ptr;
+          else if ((right_ptr - lo) > (hi - left_ptr)) /* Push larger left partition indices. */
+            {                   
+              PUSH (lo, right_ptr);
+              lo = left_ptr;
+            }
+          else                  /* Push larger right partition indices. */
+            {                   
+              PUSH (left_ptr, hi);
+              hi = right_ptr;
+            }
+        }
+    }
+
+  /* Once the BASE_PTR array is partially sorted by quicksort the rest
+     is completely sorted using insertion sort, since this is efficient 
+     for partitions below MAX_THRESH size. BASE_PTR points to the beginning 
+     of the array to sort, and END_PTR points at the very last element in
+     the array (*not* one beyond it!). */
+
+#define MIN(X,Y) ((X) < (Y) ? (X) : (Y))
+
+  {
+    char *end_ptr = base_ptr + size * (total_elems - 1);
+    char *run_ptr;
+    char *tmp_ptr = base_ptr;
+    char *thresh  = MIN (end_ptr, base_ptr + max_thresh);
+
+    /* Find smallest element in first threshold and place it at the
+       array's beginning.  This is the smallest array element,
+       and the operation speeds up insertion sort's inner loop. */
+
+    for (run_ptr = tmp_ptr + size; run_ptr <= thresh; run_ptr += size)
+      if (CMP (run_ptr, tmp_ptr) < 0)
+        tmp_ptr = run_ptr;
+
+    if (tmp_ptr != base_ptr)
+      SWAP (tmp_ptr, base_ptr, size);
+
+    /* Insertion sort, running from left-hand-side up to `right-hand-side.' 
+       Pretty much straight out of the original GNU qsort routine. */
+
+    for (run_ptr = base_ptr + size; (tmp_ptr = run_ptr += size) <= end_ptr; )
+      {
+
+        while (CMP (run_ptr, tmp_ptr -= size) < 0)
+          ;
+
+        if ((tmp_ptr += size) != run_ptr)
+          {
+            char *trav;
+
+            for (trav = run_ptr + size; --trav >= run_ptr;)
+              {
+                char c = *trav;
+                char *hi, *lo;
+
+                for (hi = lo = trav; (lo -= size) >= tmp_ptr; hi = lo)
+                  *hi = *lo;
+                *hi = c;
+              }
+          }
+
+      }
+  }
+  return 1;
+}
+