diff options
Diffstat (limited to 'lib/math')
| -rw-r--r-- | lib/math/Kconfig | 7 | ||||
| -rw-r--r-- | lib/math/div64.c | 41 | ||||
| -rw-r--r-- | lib/math/prime_numbers.c | 10 | ||||
| -rw-r--r-- | lib/math/rational.c | 2 |
4 files changed, 53 insertions, 7 deletions
diff --git a/lib/math/Kconfig b/lib/math/Kconfig index 15bd50d92308..f19bc9734fa7 100644 --- a/lib/math/Kconfig +++ b/lib/math/Kconfig @@ -6,7 +6,12 @@ config CORDIC calculations are in fixed point. Module will be called cordic. config PRIME_NUMBERS - tristate + tristate "Simple prime number generator for testing" + help + This option provides a simple prime number generator for test + modules. + + If unsure, say N. config RATIONAL bool diff --git a/lib/math/div64.c b/lib/math/div64.c index 368ca7fd0d82..3952a07130d8 100644 --- a/lib/math/div64.c +++ b/lib/math/div64.c @@ -190,3 +190,44 @@ u32 iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder) return __iter_div_u64_rem(dividend, divisor, remainder); } EXPORT_SYMBOL(iter_div_u64_rem); + +#ifndef mul_u64_u64_div_u64 +u64 mul_u64_u64_div_u64(u64 a, u64 b, u64 c) +{ + u64 res = 0, div, rem; + int shift; + + /* can a * b overflow ? */ + if (ilog2(a) + ilog2(b) > 62) { + /* + * (b * a) / c is equal to + * + * (b / c) * a + + * (b % c) * a / c + * + * if nothing overflows. Can the 1st multiplication + * overflow? Yes, but we do not care: this can only + * happen if the end result can't fit in u64 anyway. + * + * So the code below does + * + * res = (b / c) * a; + * b = b % c; + */ + div = div64_u64_rem(b, c, &rem); + res = div * a; + b = rem; + + shift = ilog2(a) + ilog2(b) - 62; + if (shift > 0) { + /* drop precision */ + b >>= shift; + c >>= shift; + if (!c) + return res; + } + } + + return res + div64_u64(a * b, c); +} +#endif diff --git a/lib/math/prime_numbers.c b/lib/math/prime_numbers.c index 052f5b727be7..d42cebf7407f 100644 --- a/lib/math/prime_numbers.c +++ b/lib/math/prime_numbers.c @@ -1,5 +1,5 @@ // SPDX-License-Identifier: GPL-2.0-only -#define pr_fmt(fmt) "prime numbers: " fmt "\n" +#define pr_fmt(fmt) "prime numbers: " fmt #include <linux/module.h> #include <linux/mutex.h> @@ -253,7 +253,7 @@ static void dump_primes(void) if (buf) bitmap_print_to_pagebuf(true, buf, p->primes, p->sz); - pr_info("primes.{last=%lu, .sz=%lu, .primes[]=...x%lx} = %s", + pr_info("primes.{last=%lu, .sz=%lu, .primes[]=...x%lx} = %s\n", p->last, p->sz, p->primes[BITS_TO_LONGS(p->sz) - 1], buf); rcu_read_unlock(); @@ -273,7 +273,7 @@ static int selftest(unsigned long max) bool fast = is_prime_number(x); if (slow != fast) { - pr_err("inconsistent result for is-prime(%lu): slow=%s, fast=%s!", + pr_err("inconsistent result for is-prime(%lu): slow=%s, fast=%s!\n", x, slow ? "yes" : "no", fast ? "yes" : "no"); goto err; } @@ -282,14 +282,14 @@ static int selftest(unsigned long max) continue; if (next_prime_number(last) != x) { - pr_err("incorrect result for next-prime(%lu): expected %lu, got %lu", + pr_err("incorrect result for next-prime(%lu): expected %lu, got %lu\n", last, x, next_prime_number(last)); goto err; } last = x; } - pr_info("selftest(%lu) passed, last prime was %lu", x, last); + pr_info("%s(%lu) passed, last prime was %lu\n", __func__, x, last); return 0; err: diff --git a/lib/math/rational.c b/lib/math/rational.c index 31fb27db2deb..df75c8809693 100644 --- a/lib/math/rational.c +++ b/lib/math/rational.c @@ -27,7 +27,7 @@ * with the fractional part size described in given_denominator. * * for theoretical background, see: - * http://en.wikipedia.org/wiki/Continued_fraction + * https://en.wikipedia.org/wiki/Continued_fraction */ void rational_best_approximation( |