Function calcLimbLen [src]

Returns the number of limbs needed to store scalar, which must be a primitive integer or float value. Note: A comptime-known upper bound of this value that may be used instead if scalar is not already comptime-known is calcTwosCompLimbCount(@typeInfo(@TypeOf(scalar)).int.bits)

Prototype

pub fn calcLimbLen(scalar: anytype) usize

Source

  pub fn calcLimbLen(scalar: anytype) usize {
    switch (@typeInfo(@TypeOf(scalar))) {
        .int, .comptime_int => {
            if (scalar == 0) return 1;
            const w_value = @abs(scalar);
            return @as(usize, @intCast(@divFloor(@as(Limb, @intCast(math.log2(w_value))), limb_bits) + 1));
        },
        .float => {
            const repr: std.math.FloatRepr(@TypeOf(scalar)) = @bitCast(scalar);
            return switch (repr.exponent) {
                .denormal => 1,
                else => return calcNonZeroTwosCompLimbCount(@as(usize, 2) + @max(repr.exponent.unbias(), 0)),
                .infinite => 0,
            };
        },
        .comptime_float => return calcLimbLen(@as(f128, scalar)),
        else => @compileError("expected float or int, got " ++ @typeName(@TypeOf(scalar))),
    }
}  