Trit shifting operations
Usage:
var shl = require('trit-shift').shl;
var shr = require('trit-shift').shr;
// shift left
shl(input, carryIn);
shl(1, 0); // 1 ('01') -> 3 ('10'), shift in zero from left
shl(1, -1); // 1 ('01') -> 2 ('1i'), shift in negative from left
// shift right
shr(input, width, carryIn);
shr(3, 5, 0); // 3 ('10') -> 1 ('01'), shifted right
Balanced ternary base 3 trit shifting, analogous to base 2 bit shifting operations. See also balanced-ternary.
Both shift left and shift right take a required parameter for the trit to shift in (carryIn);
zero is not assumed since shifting in -1 or +1 may be desired (for example, for tritmasks).
Shifting left is equivalent to multiplication by three, plus the carry:
shl(x, 0); // x * 3
shl(x, 1); // x * 3 + 1
shl(x, -1); // x * 3 - 1
Shifting right is equivalent to division by three, rounded to the nearest integer, plus the
carry input trit at the most-significant trit position (which is why the width parameter
is required, set to number of trits in the input value).
shr(x, N, 0); // Math.round(x / 3)
Used to simulate ternary shift registers. The shifted-out value is not returned but can
be computed separately using lst for shr, and
trit-getset at the most significant trit for
shl.