+/*
+ * Copyright © 2018 Intel Corporation
+ * Copyright © 2019 Valve Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#undef NDEBUG
+
+#include <gtest/gtest.h>
+#include "util/fast_urem_by_const.h"
+
+#define RAND_TEST_ITERATIONS 100000
+
+static uint32_t
+rand_uint(unsigned min)
+{
+ /* Make sure we get some small and large numbers and powers of two every
+ * once in a while
+ */
+ int k = rand() % 64;
+ if (k == 17) {
+ return min + (rand() % 16);
+ } else if (k == 42) {
+ return UINT32_MAX - (rand() % 16);
+ } else if (k == 9) {
+ uint32_t r;
+ do {
+ r = 1ull << (rand() % 32);
+ } while (r < min);
+ return r;
+ }
+
+ if (min == 0) {
+ uint32_t r = 0;
+ for (unsigned i = 0; i < 4; i++)
+ r |= ((uint32_t)rand() & 0xf) << i * 8;
+ return r >> (31 - (rand() % 32));
+ } else {
+ uint64_t r;
+ do {
+ r = rand_uint(0);
+ } while (r < min);
+ return r;
+ }
+}
+
+static void
+test_case(uint32_t n, uint32_t d)
+{
+ assert(d >= 1);
+ uint64_t magic = REMAINDER_MAGIC(d);
+ /* Note: there's already an assert inside util_fast_urem32(), so the
+ * EXPECT_EQ is only here to make sure the test fails with a wrong result
+ * even if asserts are disabled. Ideally we could disable the assert just
+ * for the test to get a better error message, but that doesn't seem too
+ * easy.
+ */
+ EXPECT_EQ(util_fast_urem32(n, d, magic), n % d);
+}
+
+TEST(fast_urem_by_const, random)
+{
+ for (unsigned i = 0; i < RAND_TEST_ITERATIONS; i++) {
+ uint64_t n = rand_uint(0);
+ uint64_t d = rand_uint(1);
+ test_case(n, d);
+ }
+}
+
+TEST(fast_urem_by_const, special_cases)
+{
+ test_case(0, 1);
+ test_case(0, UINT32_MAX);
+ test_case(UINT32_MAX, 1);
+ test_case(1, UINT32_MAX);
+ test_case(UINT32_MAX, UINT32_MAX);
+ test_case(UINT32_MAX, UINT32_MAX - 1);
+ test_case(UINT32_MAX - 1, UINT32_MAX - 1);
+ test_case(UINT32_MAX - 2, UINT32_MAX - 1);
+}
+