Zig 0.17.0-dev (Split by item)

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ffsXi2

count0bits.ffsXi2

inline fn ffsXi2(comptime T: type, a: T) i32

File

lib/compiler_rt/count0bits.zig:200

Code

inline fn ffsXi2(comptime T: type, a: T) i32 {
    var x: @Int(.unsigned, @typeInfo(T).int.bits) = @bitCast(a);
    var n: T = 1;
    // adapted from Number of trailing zeroes (see ctzXi2)
    var mask: @TypeOf(x) = std.math.maxInt(@TypeOf(x));
    comptime var shift = @bitSizeOf(T);
    // In contrast to ctz return 0
    if (x == 0) return 0;
    inline while (shift > 1) {
        shift = shift >> 1;
        mask = mask >> shift;
        if ((x & mask) == 0) {
            n = n + shift;
            x = x >> shift;
        }
    }
    // return ctz + 1
    return @as(i32, @intCast(n - @as(T, @bitCast((x & 1))))) + 1;
}