diff options
Diffstat (limited to 'lib/math')
| -rw-r--r-- | lib/math/Makefile | 1 | ||||
| -rw-r--r-- | lib/math/rational-test.c | 56 | ||||
| -rw-r--r-- | lib/math/rational.c | 16 |
3 files changed, 68 insertions, 5 deletions
diff --git a/lib/math/Makefile b/lib/math/Makefile index 7456edb864fc..bfac26ddfc22 100644 --- a/lib/math/Makefile +++ b/lib/math/Makefile @@ -6,3 +6,4 @@ obj-$(CONFIG_PRIME_NUMBERS) += prime_numbers.o obj-$(CONFIG_RATIONAL) += rational.o obj-$(CONFIG_TEST_DIV64) += test_div64.o +obj-$(CONFIG_RATIONAL_KUNIT_TEST) += rational-test.o diff --git a/lib/math/rational-test.c b/lib/math/rational-test.c new file mode 100644 index 000000000000..01611ddff420 --- /dev/null +++ b/lib/math/rational-test.c @@ -0,0 +1,56 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include <kunit/test.h> + +#include <linux/rational.h> + +struct rational_test_param { + unsigned long num, den; + unsigned long max_num, max_den; + unsigned long exp_num, exp_den; + + const char *name; +}; + +static const struct rational_test_param test_parameters[] = { + { 1230, 10, 100, 20, 100, 1, "Exceeds bounds, semi-convergent term > 1/2 last term" }, + { 34567,100, 120, 20, 120, 1, "Exceeds bounds, semi-convergent term < 1/2 last term" }, + { 1, 30, 100, 10, 0, 1, "Closest to zero" }, + { 1, 19, 100, 10, 1, 10, "Closest to smallest non-zero" }, + { 27,32, 16, 16, 11, 13, "Use convergent" }, + { 1155, 7735, 255, 255, 33, 221, "Exact answer" }, + { 87, 32, 70, 32, 68, 25, "Semiconvergent, numerator limit" }, + { 14533, 4626, 15000, 2400, 7433, 2366, "Semiconvergent, denominator limit" }, +}; + +static void get_desc(const struct rational_test_param *param, char *desc) +{ + strscpy(desc, param->name, KUNIT_PARAM_DESC_SIZE); +} + +/* Creates function rational_gen_params */ +KUNIT_ARRAY_PARAM(rational, test_parameters, get_desc); + +static void rational_test(struct kunit *test) +{ + const struct rational_test_param *param = (const struct rational_test_param *)test->param_value; + unsigned long n = 0, d = 0; + + rational_best_approximation(param->num, param->den, param->max_num, param->max_den, &n, &d); + KUNIT_EXPECT_EQ(test, n, param->exp_num); + KUNIT_EXPECT_EQ(test, d, param->exp_den); +} + +static struct kunit_case rational_test_cases[] = { + KUNIT_CASE_PARAM(rational_test, rational_gen_params), + {} +}; + +static struct kunit_suite rational_test_suite = { + .name = "rational", + .test_cases = rational_test_cases, +}; + +kunit_test_suites(&rational_test_suite); + +MODULE_LICENSE("GPL v2"); diff --git a/lib/math/rational.c b/lib/math/rational.c index 9781d521963d..c0ab51d8fbb9 100644 --- a/lib/math/rational.c +++ b/lib/math/rational.c @@ -12,6 +12,7 @@ #include <linux/compiler.h> #include <linux/export.h> #include <linux/minmax.h> +#include <linux/limits.h> /* * calculate best rational approximation for a given fraction @@ -78,13 +79,18 @@ void rational_best_approximation( * found below as 't'. */ if ((n2 > max_numerator) || (d2 > max_denominator)) { - unsigned long t = min((max_numerator - n0) / n1, - (max_denominator - d0) / d1); + unsigned long t = ULONG_MAX; - /* This tests if the semi-convergent is closer - * than the previous convergent. + if (d1) + t = (max_denominator - d0) / d1; + if (n1) + t = min(t, (max_numerator - n0) / n1); + + /* This tests if the semi-convergent is closer than the previous + * convergent. If d1 is zero there is no previous convergent as this + * is the 1st iteration, so always choose the semi-convergent. */ - if (2u * t > a || (2u * t == a && d0 * dp > d1 * d)) { + if (!d1 || 2u * t > a || (2u * t == a && d0 * dp > d1 * d)) { n1 = n0 + t * n1; d1 = d0 + t * d1; } |