Source bits.nas
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# SPDX-License-Identifier: GPL-2.0-or-later
#
# NOTE! This copyright does *not* cover user models that use these Nasal
# services by normal function calls - this is merely considered normal
# use of the code, and does *not* fall under the heading of "derived
# work."
#
# Copyright (C) 2008 by mfranz
var bit = [var _ = 1];
for (var i = 1; i < 32; i += 1)
append(bit, _ += _);
# checks whether bit <b> is set in number <n>
var test = func(n, b) {
n /= bit[b];
return int(n) != int(n / 2) * 2;
}
# returns number <n> with bit <b> set
var set = func(n, b) n + !test(n, b) * bit[b];
# returns number <n> with bit <b> cleared
var clear = func(n, b) n - test(n, b) * bit[b];
# returns number <n> with bit <b> toggled
var toggle = func(n, b) test(n, b) ? n - bit[b] : n + bit[b];
# returns number <n> with bit <b> set to value <v>
var switch = func(n, b, v) n - (test(n, b) - !!v) * bit[b];
# returns number <n> as bit string, zero-padded to <len> digits:
# bits.string(6) -> "110"
# bits.string(6, 8) -> "00000110"
var string = func(n, len = 1) {
var s = "";
while (n) {
var v = int(n / 2);
s = (v + v != n) ~ s;
n = v;
}
for (var i = size(s); i < len; i += 1)
s = '0' ~ s;
return s;
}
# returns bit string <s> as number: bits.value("110") -> 6
var value = func(s) {
var n = 0;
var len = size(s);
for (var i = 0; i < len; i += 1)
n += n + (s[i] != `0`);
return n;
}