ctz
Returns the number of trailing zeros in twos-complement form.
Function parameters
Parameters
Used to indicate either limit of a 2s-complement integer.
Types
- TwosCompIntLimit
- Used to indicate either limit of a 2s-complement integer.
- Mutable
- A arbitrary-precision big integer, with a fixed set of mutable limbs.
- Const
- A arbitrary-precision big integer, with a fixed set of immutable limbs.
- Managed
- An arbitrary-precision big integer along with an allocator which manages the memory.
Returns the number of limbs needed to store `scalar`, which must be a
Functions
- calcLimbLen
- Returns the number of limbs needed to store `scalar`, which must be a
- calcSetStringLimbCount
- Assumes `string_len` doesn't account for minus signs if the number is negative.
- calcNonZeroTwosCompLimbCount
- Compute the number of limbs required to store a 2s-complement number of `bit_count` bits.
- calcTwosCompLimbCount
- Compute the number of limbs required to store a 2s-complement number of `bit_count` bits.
- addMulLimbWithCarry
- a + b * c + *carry, sets carry to the overflow bits
- llcmp
- Returns -1, 0, 1 if |a| < |b|, |a| == |b| or |a| > |b| respectively for limbs.
Source
Implementation
pub fn ctz(a: Const, bits: Limb) Limb {
// Limbs are stored in little-endian order. Converting a negative number to twos-complement
// flips all bits above the lowest set bit, which does not affect the trailing zero count.
if (a.eqlZero()) return bits;
var result: Limb = 0;
for (a.limbs) |limb| {
const limb_tz = @ctz(limb);
result += limb_tz;
if (limb_tz != @bitSizeOf(Limb)) break;
}
return @min(result, bits);
}