Zig 0.17.0-dev (Split by item)

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signMask

Creates a mask from the sign bit of a signed integer. Returns all 1s (0xFF...FF) if x < 0, all 0s if x >= 0.

ml_kem.signMask

fn signMask(comptime T: type, x: T) @Int(.unsigned, @typeInfo(T).int.bits)

File

lib/std/crypto/ml_kem.zig:1849

Code

fn signMask(comptime T: type, x: T) @Int(.unsigned, @typeInfo(T).int.bits) {
    const type_info = @typeInfo(T);
    if (type_info != .int) {
        @compileError("signMask requires an integer type");
    }

    const bits = type_info.int.bits;
    const SignedT = @Int(.signed, bits);

    // Convert to signed if needed, arithmetic right shift to propagate sign bit
    const x_signed: SignedT = if (type_info.int.signedness == .signed) x else @bitCast(x);
    const shifted = x_signed >> (bits - 1);
    return @bitCast(shifted);
}