#include <ctype.h>
+#include <debug.h>
+#include <random.h>
#include <stdlib.h>
#include <stdbool.h>
bool negative;
int value;
+ ASSERT (s != NULL);
+
/* Skip white space. */
- while (isspace (*s))
+ while (isspace ((unsigned char) *s))
s++;
/* Parse sign. */
return value;
}
+
+/* Compares A and B by calling the AUX function. */
+static int
+compare_thunk (const void *a, const void *b, void *aux)
+{
+ int (**compare) (const void *, const void *) = aux;
+ return (*compare) (a, b);
+}
+
+/* Sorts ARRAY, which contains CNT elements of SIZE bytes each,
+ using COMPARE. When COMPARE is passed a pair of elements A
+ and B, respectively, it must return a strcmp()-type result,
+ i.e. less than zero if A < B, zero if A == B, greater than
+ zero if A > B. */
+void
+qsort (void *array, size_t cnt, size_t size,
+ int (*compare) (const void *, const void *))
+{
+ quick_sort (array, cnt, size, compare_thunk, &compare);
+}
+
+/* Swaps the SIZE bytes at A and B. */
+static void
+swap (unsigned char *a, unsigned char *b, size_t size)
+{
+ size_t i;
+
+ for (i = 0; i < size; i++)
+ {
+ unsigned char t = a[i];
+ a[i] = b[i];
+ b[i] = t;
+ }
+}
+
+/* Selects a random "pivot" element in ARRAY, which contains CNT
+ elements of SIZE bytes each, and partitions ARRAY into two
+ contiguous subranges around the pivot, so that the first N
+ elements are less than or equal to the pivot and the remaining
+ elements are greater than the pivot. Returns N.
+
+ Uses COMPARE to compare elements, passing AUX as auxiliary
+ data. When COMPARE is passed a pair of elements A and B,
+ respectively, it must return a strcmp()-type result, i.e. less
+ than zero if A < B, zero if A == B, greater than zero if A >
+ B. */
+static size_t
+randomized_partition (void *array, size_t cnt, size_t size,
+ int (*compare) (const void *, const void *, void *aux),
+ void *aux)
+{
+ unsigned char *first = array; /* Beginning of array. */
+ unsigned char *last = first + size * cnt; /* End of array. */
+ unsigned char *pivot = last - size; /* Element used as pivot. */
+ unsigned char *middle; /* Invariant: elements on left are <= pivot. */
+ unsigned char *current;
+
+ ASSERT (array != NULL);
+ ASSERT (cnt > 1);
+ ASSERT (size > 0);
+ ASSERT (compare != NULL);
+
+ /* Choose a random pivot. */
+ swap (pivot, first + (random_ulong () % cnt) * size, size);
+
+ /* Iterate through the array moving elements less than or equal
+ to the pivot to the middle. */
+ middle = array;
+ for (current = first; current < last; current += size)
+ if (compare (current, pivot, aux) <= 0)
+ {
+ swap (middle, current, size);
+ middle += size;
+ }
+
+ return (middle - first) / size;
+}
+
+/* Sorts ARRAY, which contains CNT elements of SIZE bytes each,
+ using COMPARE to compare elements, passing AUX as auxiliary
+ data. When COMPARE is passed a pair of elements A and B,
+ respectively, it must return a strcmp()-type result, i.e. less
+ than zero if A < B, zero if A == B, greater than zero if A >
+ B. */
+void
+quick_sort (void *array_, size_t cnt, size_t size,
+ int (*compare) (const void *, const void *, void *aux),
+ void *aux)
+{
+ unsigned char *array = array_;
+
+ ASSERT (array != NULL || cnt == 0);
+ ASSERT (compare != NULL);
+ ASSERT (size > 0);
+
+ if (cnt > 1)
+ {
+ size_t q = randomized_partition (array, cnt, size, compare, aux);
+
+ /* Sort smaller partition first to guarantee O(lg n) stack
+ depth limit. */
+ if (q < cnt - q)
+ {
+ quick_sort (array, q, size, compare, aux);
+ quick_sort (array + q * size, cnt - q, size, compare, aux);
+ }
+ else
+ {
+ quick_sort (array + q * size, cnt - q, size, compare, aux);
+ quick_sort (array, q, size, compare, aux);
+ }
+ }
+}
+
+/* Searches ARRAY, which contains CNT elements of SIZE bytes
+ each, for the given KEY. Returns a match is found, otherwise
+ a null pointer. If there are multiple matches, returns an
+ arbitrary one of them.
+
+ ARRAY must be sorted in order according to COMPARE.
+
+ Uses COMPARE to compare elements. When COMPARE is passed a
+ pair of elements A and B, respectively, it must return a
+ strcmp()-type result, i.e. less than zero if A < B, zero if A
+ == B, greater than zero if A > B. */
+void *
+bsearch (const void *key, const void *array, size_t cnt,
+ size_t size, int (*compare) (const void *, const void *))
+{
+ return binary_search (key, array, cnt, size, compare_thunk, &compare);
+}
+
+/* Searches ARRAY, which contains CNT elements of SIZE bytes
+ each, for the given KEY. Returns a match is found, otherwise
+ a null pointer. If there are multiple matches, returns an
+ arbitrary one of them.
+
+ ARRAY must be sorted in order according to COMPARE.
+
+ Uses COMPARE to compare elements, passing AUX as auxiliary
+ data. When COMPARE is passed a pair of elements A and B,
+ respectively, it must return a strcmp()-type result, i.e. less
+ than zero if A < B, zero if A == B, greater than zero if A >
+ B. */
+void *
+binary_search (const void *key, const void *array, size_t cnt, size_t size,
+ int (*compare) (const void *, const void *, void *aux),
+ void *aux)
+{
+ const unsigned char *first = array;
+ const unsigned char *last = array + size * cnt;
+
+ while (first < last)
+ {
+ size_t range = (last - first) / size;
+ const unsigned char *middle = first + (range / 2) * size;
+ int cmp = compare (key, middle, aux);
+
+ if (cmp < 0)
+ last = middle;
+ else if (cmp > 0)
+ first = middle + size;
+ else
+ return (void *) middle;
+ }
+
+ return NULL;
+}
+
--- /dev/null
+/* Test program for sorting and searching in lib/kernel/stdlib.c.
+
+ Attempts to test the sorting and searching functionality that
+ is not sufficiently tested elsewhere in Pintos.
+
+ This is not a test we will run on your submitted projects.
+ It is here for completeness.
+*/
+
+#undef NDEBUG
+#include <debug.h>
+#include <limits.h>
+#include <random.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include "threads/test.h"
+
+/* Maximum number of elements in an array that we will test. */
+#define MAX_CNT 4096
+
+static void shuffle (int[], size_t);
+static int compare_ints (const void *, const void *);
+static void verify_order (const int[], size_t);
+static void verify_bsearch (const int[], size_t);
+
+/* Test sorting and searching implementations. */
+void
+test (void)
+{
+ int cnt;
+
+ printf ("testing various size arrays:");
+ for (cnt = 0; cnt < MAX_CNT; cnt = cnt * 4 / 3 + 1)
+ {
+ int repeat;
+
+ printf (" %zu", cnt);
+ for (repeat = 0; repeat < 10; repeat++)
+ {
+ static int values[MAX_CNT];
+ int i;
+
+ /* Put values 0...CNT in random order in VALUES. */
+ for (i = 0; i < cnt; i++)
+ values[i] = i;
+ shuffle (values, cnt);
+
+ /* Sort VALUES, then verify ordering. */
+ qsort (values, cnt, sizeof *values, compare_ints);
+ verify_order (values, cnt);
+ verify_bsearch (values, cnt);
+ }
+ }
+
+ printf (" done\n");
+}
+
+/* Shuffles the CNT elements in ARRAY into random order. */
+static void
+shuffle (int *array, size_t cnt)
+{
+ size_t i;
+
+ for (i = 0; i < cnt; i++)
+ {
+ size_t j = i + random_ulong () % (cnt - i);
+ int t = array[j];
+ array[j] = array[i];
+ array[i] = t;
+ }
+}
+
+/* Returns 1 if *A is greater than *B,
+ 0 if *A equals *B,
+ -1 if *A is less than *B. */
+static int
+compare_ints (const void *a_, const void *b_)
+{
+ const int *a = a_;
+ const int *b = b_;
+
+ return *a < *b ? -1 : *a > *b;
+}
+
+/* Verifies that ARRAY contains the CNT ints 0...CNT-1. */
+static void
+verify_order (const int *array, size_t cnt)
+{
+ int i;
+
+ for (i = 0; (size_t) i < cnt; i++)
+ ASSERT (array[i] == i);
+}
+
+/* Checks that bsearch() works properly in ARRAY. ARRAY must
+ contain the values 0...CNT-1. */
+static void
+verify_bsearch (const int *array, size_t cnt)
+{
+ int not_in_array[] = {0, -1, INT_MAX, MAX_CNT, MAX_CNT + 1, MAX_CNT * 2};
+ int i;
+
+ /* Check that all the values in the array are found properly. */
+ for (i = 0; (size_t) i < cnt; i++)
+ ASSERT (bsearch (&i, array, cnt, sizeof *array, compare_ints)
+ == array + i);
+
+ /* Check that some values not in the array are not found. */
+ not_in_array[0] = cnt;
+ for (i = 0; (size_t) i < sizeof not_in_array / sizeof *not_in_array; i++)
+ ASSERT (bsearch (¬_in_array[i], array, cnt, sizeof *array, compare_ints)
+ == NULL);
+}
projects / pintos-anon / commitdiff