Dynamic array starting at 1

[marmin]

You can always use out of range tricks:

type
parr = ^tarr;
tarr = array[1..1] of Byte;

var
src: array of Byte;
mask: parr;

...

SetLength(src, 100);
mask := @src[0]; // does it work with "mask := src;" ? maybe...

for i := 1 to Length(src) do
mask[i] := x;

...

But I think that will overwrite memory space tthat's used?