Function boolMask [src]

Returns a mask of all ones if value is true, and a mask of all zeroes if value is false. Compiles to one instruction for register sized integers.

Prototype

pub inline fn boolMask(comptime MaskInt: type, value: bool) MaskInt

Parameters

MaskInt: typevalue: bool

Example

 test boolMask {
    const runTest = struct {
        fn runTest() !void {
            try testing.expectEqual(@as(u1, 0), boolMask(u1, false));
            try testing.expectEqual(@as(u1, 1), boolMask(u1, true));

            try testing.expectEqual(@as(i1, 0), boolMask(i1, false));
            try testing.expectEqual(@as(i1, -1), boolMask(i1, true));

            try testing.expectEqual(@as(u13, 0), boolMask(u13, false));
            try testing.expectEqual(@as(u13, 0x1FFF), boolMask(u13, true));

            try testing.expectEqual(@as(i13, 0), boolMask(i13, false));
            try testing.expectEqual(@as(i13, -1), boolMask(i13, true));

            try testing.expectEqual(@as(u32, 0), boolMask(u32, false));
            try testing.expectEqual(@as(u32, 0xFFFF_FFFF), boolMask(u32, true));

            try testing.expectEqual(@as(i32, 0), boolMask(i32, false));
            try testing.expectEqual(@as(i32, -1), boolMask(i32, true));
        }
    }.runTest;
    try runTest();
    try comptime runTest();
}

Source

  pub inline fn boolMask(comptime MaskInt: type, value: bool) MaskInt {
    if (@typeInfo(MaskInt) != .int)
        @compileError("boolMask requires an integer mask type.");

    if (MaskInt == u0 or MaskInt == i0)
        @compileError("boolMask cannot convert to u0 or i0, they are too small.");

    // The u1 and i1 cases tend to overflow,
    // so we special case them here.
    if (MaskInt == u1) return @intFromBool(value);
    if (MaskInt == i1) {
        // The @as here is a workaround for #7950
        return @as(i1, @bitCast(@as(u1, @intFromBool(value))));
    }

    return -%@as(MaskInt, @intCast(@intFromBool(value)));
}  