1 ------------------------------------------------------------------------------ 2 ------------------------------------------------------------------------------ 3 -- This file is part of 'Finite Field Arithmetic', aka 'FFA'. -- 4 -- -- 5 -- (C) 2019 Stanislav Datskovskiy ( www.loper-os.org ) -- 6 -- http://wot.deedbot.org/17215D118B7239507FAFED98B98228A001ABFFC7.html -- 7 -- -- 8 -- You do not have, nor can you ever acquire the right to use, copy or -- 9 -- distribute this software ; Should you use this software for any purpose, -- 10 -- or copy and distribute it to anyone or in any manner, you are breaking -- 11 -- the laws of whatever soi-disant jurisdiction, and you promise to -- 12 -- continue doing so for the indefinite future. In any case, please -- 13 -- always : read and understand any software ; verify any PGP signatures -- 14 -- that you use - for any purpose. -- 15 -- -- 16 -- See also http://trilema.com/2015/a-new-software-licensing-paradigm . -- 17 ------------------------------------------------------------------------------ 18 ------------------------------------------------------------------------------ 19 20 with Words; use Words; 21 22 -- Fundamental Operations on Words: 23 package Word_Ops is 24 25 pragma Pure; 26 27 -- Branch-free calculation of 'carry' from a machine-word addition. 28 function W_Carry(A : in Word; B : in Word; S : in Word) 29 return WBool; 30 pragma Inline_Always(W_Carry); 31 32 -- Branch-free calculation of 'borrow' from a machine-word subtraction. 33 function W_Borrow(A : in Word; B : in Word; D : in Word) 34 return WBool; 35 pragma Inline_Always(W_Borrow); 36 37 -- Without any branching: if Sel == 0, return A; if Sel == 1, return B. 38 function W_Mux(A : in Word; B : in Word; Sel : in WBool) 39 return Word; 40 pragma Inline_Always(W_Mux); 41 42 end Word_Ops;