search: Add tests.

Author: lorinder

test/CMakeLists.txt

@@ -20,6 +20,7 @@ set(tests_c
 #	rng_mt_test.c
 	runif_getf_test.c
 	runif_geti_test.c
+	search_test.c
 	time_test1.c
 	util_test0.c
 	x_asprintf_test.c

test/search_test.c

@@ -0,0 +1,108 @@
+/* Tests for the Bsearch and Lsearch macros */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <inttypes.h>
+
+#define CSNIP_SHORT_NAMES
+#include <csnip/mem.h>
+#include <csnip/search.h>
+#include <csnip/sort.h>
+#include <csnip/util.h>
+
+static uint32_t rnext(uint64_t* pstate)
+{
+	*pstate *= UINT64_C(6364136223846793005);
+	*pstate += 1;
+
+	return (uint32_t)(*pstate >> 32);
+}
+
+static uint32_t reduce_to_bits(int n_bits, uint32_t v)
+{
+	if (n_bits == 0)
+		return 0;
+	return v >> (32 - n_bits);
+}
+
+int main(int argc, char** argv)
+{
+	uint64_t rstate = 1234;
+	const int Ns[] = { 0, 1, 2, 3, 10, 100, 1000 };
+	const int bs[] = { 0, 1, 2, 3, 4, 8, 16, 32 };
+	int k = 3;
+
+	for (int Ni = 0; Ni < Static_len(Ns); ++Ni) {
+		const int N = Ns[Ni];
+		printf("N = %d\n", N);
+
+		/* Create the instance */
+		uint32_t* a;
+		mem_Alloc(N, a, _);
+		for (int i = 0; i < N; ++i) {
+			a[i] = rnext(&rstate);
+		}
+		Qsort(u, v, a[u] < a[v], Tswap(uint32_t, a[u], a[v]), N);
+
+		/* Check with different bit widths.
+		 *
+		 * The point here is that down projecting to a fixed
+		 * number of bits causes progressively more comparisons
+		 * to the same values, which changes the nature of the
+		 * search.
+		 */
+		for (int bi = 0; bi < Static_len(bs); ++bi) {
+			const int b = bs[bi];
+			printf("  b = %d\n", b);
+			for (int i = 0; i < k; ++i) {
+				int idx;
+#define red(x) reduce_to_bits(b, (x))
+				uint32_t d = red(rnext(&rstate));
+
+				/* Variant 1: smallest i s.t. a[i] >= key */
+				Bsearch(int, u, red(a[u]) < d, N, idx);
+				printf("    d = %"PRIu32" -> V1_idx = %d ", d, idx);
+				if (idx < 0 || idx > N) {
+					fprintf(stderr, "Error:  Result out "
+					  "of range (N = %d): %d\n", N, idx);
+					return 1;
+				}
+				if (idx < N && red(a[idx]) < d) {
+					fprintf(stderr, "Error: V1 constraint "
+					  "not met.\n");
+					return 1;
+				}
+				if (idx > 0 && red(a[idx - 1]) >= d) {
+					fprintf(stderr, "Error: V1 minimality "
+					  "not satisfied.\n");
+					return 1;
+				}
+
+				/* Variant 2: lowest i s.t. a[i] > key */
+				Bsearch(int, u, red(a[u]) <= d, N, idx);
+				printf("V2_idx = %d ", idx);
+				if (idx < 0 || idx > N) {
+					fprintf(stderr, "Error:  Result out "
+					  "of range (N = %d): %d\n", N, idx);
+					return 1;
+				}
+				if (idx < N && red(a[idx]) <= d) {
+					fprintf(stderr, "Error: V2 constraint "
+					  "not met.\n");
+					return 1;
+				}
+				if (idx > 0 && red(a[idx - 1]) > d) {
+					fprintf(stderr, "Error: V2 minimality "
+					  "not satisfied.\n");
+					return 1;
+				}
+#undef red
+
+				putchar('\n');
+			}
+
+			printf("    All checks pass.\n");
+		}
+	}
+	return 0;
+}