fixed

commit f098f9b85289d68975db2f5ba8a6fbdc02ba737a
parent db88f9116371c803128d240d3b16e9ea31ae6271
Author: Jared Tobin <jared@jtobin.io>
Date:   Sun,  7 Dec 2025 09:08:50 +0400

lib: add constant-time wider selection

Diffstat:
M
lib/Data/Choice.hs
 | 
14
++++++++++++++

1 file changed, 14 insertions(+), 0 deletions(-)
diff --git a/lib/Data/Choice.hs b/lib/Data/Choice.hs
@@ -48,6 +48,7 @@ module Data.Choice (
   -- * Constant-time Selection
   , ct_select_word#
   , ct_select_wide#
+  , ct_select_wider#
 
   -- * Constant-time Equality
   , ct_eq_word#
@@ -289,6 +290,19 @@ ct_select_wide# a b (Choice w) =
   in  xor_w# a (and_w# mask (xor_w# a b))
 {-# INLINE ct_select_wide# #-}
 
+ct_select_wider#
+  :: (# Word#, Word#, Word#, Word# #)
+  -> (# Word#, Word#, Word#, Word# #)
+  -> Choice
+  -> (# Word#, Word#, Word#, Word# #)
+ct_select_wider# (# a0, a1, a2, a3 #) (# b0, b1, b2, b3 #) (Choice w) =
+  let !w0 = xor# a0 (and# w (xor# a0 b0))
+      !w1 = xor# a1 (and# w (xor# a1 b1))
+      !w2 = xor# a2 (and# w (xor# a2 b2))
+      !w3 = xor# a3 (and# w (xor# a3 b3))
+  in  (# w0, w1, w2, w3 #)
+{-# INLINE ct_select_wider# #-}
+
 -- constant-time equality -----------------------------------------------------
 
 ct_eq_word# :: Word# -> Word# -> Choice