#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;
+}
+
projects / pintos-anon / blobdiff