Function alignPointer [src]

Aligns a given pointer value to a specified alignment factor. Returns an aligned pointer or null if one of the following conditions is met: The aligned pointer would not fit the address space, The delta required to align the pointer is not a multiple of the pointee's type.

Prototype

pub fn alignPointer(ptr: anytype, align_to: usize) ?@TypeOf(ptr)

Parameters

align_to: usize

Example

 test alignPointer {
    const S = struct {
        fn checkAlign(comptime T: type, base: usize, align_to: usize, expected: usize) !void {
            const ptr: T = @ptrFromInt(base);
            const aligned = alignPointer(ptr, align_to);
            try testing.expectEqual(expected, @intFromPtr(aligned));
        }
    };

    try S.checkAlign([*]u8, 0x123, 0x200, 0x200);
    try S.checkAlign([*]align(4) u8, 0x10, 2, 0x10);
    try S.checkAlign([*]u32, 0x10, 2, 0x10);
    try S.checkAlign([*]u32, 0x4, 16, 0x10);
    // Misaligned.
    try S.checkAlign([*]align(1) u32, 0x3, 2, 0);
    // Overflow.
    try S.checkAlign([*]u32, math.maxInt(usize) - 3, 8, 0);
}

Source

  pub fn alignPointer(ptr: anytype, align_to: usize) ?@TypeOf(ptr) {
    const adjust_off = alignPointerOffset(ptr, align_to) orelse return null;
    // Avoid the use of ptrFromInt to avoid losing the pointer provenance info.
    return @alignCast(ptr + adjust_off);
}  