Zig 0.17.0-dev (Split by item)

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rotl

Rotates left. Only unsigned values can be rotated. Negative shift values result in shift modulo the bit count.

math.rotl

pub fn rotl(comptime T: type, x: T, r: anytype) T

File

lib/std/math.zig:739

Code

pub fn rotl(comptime T: type, x: T, r: anytype) T {
    if (@typeInfo(T) == .vector) {
        const C = @typeInfo(T).vector.child;
        if (C == u0) return @splat(0);

        if (@typeInfo(C).int.signedness == .signed) {
            @compileError("cannot rotate signed integers");
        }
        const ar: Log2Int(C) = @intCast(@mod(r, @typeInfo(C).int.bits));
        return (x << @splat(ar)) | (x >> @splat(1 +% ~ar));
    } else if (@typeInfo(T).int.signedness == .signed) {
        @compileError("cannot rotate signed integer");
    } else {
        if (T == u0) return 0;

        if (comptime isPowerOfTwo(@typeInfo(T).int.bits)) {
            const ar: Log2Int(T) = @intCast(@mod(r, @typeInfo(T).int.bits));
            return x << ar | x >> 1 +% ~ar;
        } else {
            const ar = @mod(r, @typeInfo(T).int.bits);
            return shl(T, x, ar) | shr(T, x, @typeInfo(T).int.bits - ar);
        }
    }
}