-- =============================================
-- Author:		<Author,,Name>
-- Create date: <Create Date,,>
-- Description:	Преобразование utf8 в utf16 (nchar)
-- =============================================
/* 
declare @b as varbinary(max) = 0xD09CD0BED180D0B520D0A2D180D18DD0B2D0B5D0BB2E20D094D09ED09AD0A3D09CD095D09DD0A2D0AB20D094D09BD0AF20D09AD09BD098D095D09DD0A2D09020D0BFD0BE20D182D183D180D1832054523830393230303034;
select * from dbo.[utf8-to-utf16](@b)
*/
ALTER FUNCTION [dbo].[utf8-to-utf16]( @utf8 varbinary(max) )
RETURNS TABLE 
AS
RETURN 
(
with b as ( select b = substring(@utf8, n, 1), n from dbo.N where n between 1 and len(@utf8) )
   , bn as ( select b, n from b where b&128 = 0 or b&224 = 192 or b&240 = 224 or b&248 = 240 )
   , chs as ( select b = case  
                            when b&128 = 0   then      b 
                            when b&224 = 192 then     (b&31) * 64 | ( substring(@utf8, n+1, 1) & 63 ) 
                            when b&240 = 224 then   ( (b&15) * 64 | ( substring(@utf8, n+1, 1) & 63 ) ) * 64 | ( substring(@utf8, n+2, 1) & 63 ) 
                            else                  ( ( (b&07) * 64 | ( substring(@utf8, n+1, 1) & 63 ) ) * 64 | ( substring(@utf8, n+2, 1) & 63 ) ) * 64 | ( substring(@utf8, n+3, 1) & 63 ) 
                         end
                   , n
               from bn
           )
    select utf16 = ( select nchar(b) from chs order by n asc for xml path(''), type ).value('.', 'nvarchar(max)')
)