From 900158523106eadf2a80216acbd4d46c58afa144 Mon Sep 17 00:00:00 2001
From: h2-addad <hamza2.addad@live.uwe.ac.uk>
Date: Sun, 16 Jul 2023 15:29:32 +0000
Subject: [PATCH] Upload New File
---
src/tests/vm/qsort.c | 136 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 136 insertions(+)
create mode 100644 src/tests/vm/qsort.c
diff --git a/src/tests/vm/qsort.c b/src/tests/vm/qsort.c
new file mode 100644
index 0000000..922572c
--- /dev/null
+++ b/src/tests/vm/qsort.c
@@ -0,0 +1,136 @@
+#include "tests/vm/qsort.h"
+#include <stdbool.h>
+#include <debug.h>
+#include <random.h>
+
+/* Picks a pivot for the quicksort from the SIZE bytes in BUF. */
+static unsigned char
+pick_pivot (unsigned char *buf, size_t size)
+{
+ ASSERT (size >= 1);
+ return buf[random_ulong () % size];
+}
+
+/* Checks whether the SIZE bytes in ARRAY are divided into an
+ initial LEFT_SIZE elements all less than PIVOT followed by
+ SIZE - LEFT_SIZE elements all greater than or equal to
+ PIVOT. */
+static bool
+is_partitioned (const unsigned char *array, size_t size,
+ unsigned char pivot, size_t left_size)
+{
+ size_t i;
+
+ for (i = 0; i < left_size; i++)
+ if (array[i] >= pivot)
+ return false;
+
+ for (; i < size; i++)
+ if (array[i] < pivot)
+ return false;
+
+ return true;
+}
+
+/* Swaps the bytes at *A and *B. */
+static void
+swap (unsigned char *a, unsigned char *b)
+{
+ unsigned char t = *a;
+ *a = *b;
+ *b = t;
+}
+
+/* Partitions ARRAY in-place in an initial run of bytes all less
+ than PIVOT, followed by a run of bytes all greater than or
+ equal to PIVOT. Returns the length of the initial run. */
+static size_t
+partition (unsigned char *array, size_t size, int pivot)
+{
+ size_t left_size = size;
+ unsigned char *first = array;
+ unsigned char *last = first + left_size;
+
+ for (;;)
+ {
+ /* Move FIRST forward to point to first element greater than
+ PIVOT. */
+ for (;;)
+ {
+ if (first == last)
+ {
+ ASSERT (is_partitioned (array, size, pivot, left_size));
+ return left_size;
+ }
+ else if (*first >= pivot)
+ break;
+
+ first++;
+ }
+ left_size--;
+
+ /* Move LAST backward to point to last element no bigger
+ than PIVOT. */
+ for (;;)
+ {
+ last--;
+
+ if (first == last)
+ {
+ ASSERT (is_partitioned (array, size, pivot, left_size));
+ return left_size;
+ }
+ else if (*last < pivot)
+ break;
+ else
+ left_size--;
+ }
+
+ /* By swapping FIRST and LAST we extend the starting and
+ ending sequences that pass and fail, respectively,
+ PREDICATE. */
+ swap (first, last);
+ first++;
+ }
+}
+
+/* Returns true if the SIZE bytes in BUF are in nondecreasing
+ order, false otherwise. */
+static bool
+is_sorted (const unsigned char *buf, size_t size)
+{
+ size_t i;
+
+ for (i = 1; i < size; i++)
+ if (buf[i - 1] > buf[i])
+ return false;
+
+ return true;
+}
+
+/* Sorts the SIZE bytes in BUF into nondecreasing order, using
+ the quick-sort algorithm. */
+void
+qsort_bytes (unsigned char *buf, size_t size)
+{
+ if (!is_sorted (buf, size))
+ {
+ int pivot = pick_pivot (buf, size);
+
+ unsigned char *left_half = buf;
+ size_t left_size = partition (buf, size, pivot);
+ unsigned char *right_half = left_half + left_size;
+ size_t right_size = size - left_size;
+
+ if (left_size <= right_size)
+ {
+ qsort_bytes (left_half, left_size);
+ qsort_bytes (right_half, right_size);
+ }
+ else
+ {
+ qsort_bytes (right_half, right_size);
+ qsort_bytes (left_half, left_size);
+ }
+ }
+}
--
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