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Diffstat (limited to 'lib/rational.c')
-rw-r--r-- | lib/rational.c | 65 |
1 files changed, 0 insertions, 65 deletions
diff --git a/lib/rational.c b/lib/rational.c deleted file mode 100644 index ba7443677c90..000000000000 --- a/lib/rational.c +++ /dev/null @@ -1,65 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0 -/* - * rational fractions - * - * Copyright (C) 2009 emlix GmbH, Oskar Schirmer <oskar@scara.com> - * - * helper functions when coping with rational numbers - */ - -#include <linux/rational.h> -#include <linux/compiler.h> -#include <linux/export.h> - -/* - * calculate best rational approximation for a given fraction - * taking into account restricted register size, e.g. to find - * appropriate values for a pll with 5 bit denominator and - * 8 bit numerator register fields, trying to set up with a - * frequency ratio of 3.1415, one would say: - * - * rational_best_approximation(31415, 10000, - * (1 << 8) - 1, (1 << 5) - 1, &n, &d); - * - * you may look at given_numerator as a fixed point number, - * with the fractional part size described in given_denominator. - * - * for theoretical background, see: - * http://en.wikipedia.org/wiki/Continued_fraction - */ - -void rational_best_approximation( - unsigned long given_numerator, unsigned long given_denominator, - unsigned long max_numerator, unsigned long max_denominator, - unsigned long *best_numerator, unsigned long *best_denominator) -{ - unsigned long n, d, n0, d0, n1, d1; - n = given_numerator; - d = given_denominator; - n0 = d1 = 0; - n1 = d0 = 1; - for (;;) { - unsigned long t, a; - if ((n1 > max_numerator) || (d1 > max_denominator)) { - n1 = n0; - d1 = d0; - break; - } - if (d == 0) - break; - t = d; - a = n / d; - d = n % d; - n = t; - t = n0 + a * n1; - n0 = n1; - n1 = t; - t = d0 + a * d1; - d0 = d1; - d1 = t; - } - *best_numerator = n1; - *best_denominator = d1; -} - -EXPORT_SYMBOL(rational_best_approximation); |