Merge pull request #41373 from volth/bitwise

lib: bitAnd, bitOr, bitXor
This commit is contained in:
Jörg Thalheim 2018-06-03 11:38:56 +01:00 committed by GitHub
commit d036073bcf
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3 changed files with 62 additions and 4 deletions

View file

@ -56,10 +56,10 @@ let
hasAttr head isAttrs isBool isInt isList isString length
lessThan listToAttrs pathExists readFile replaceStrings seq
stringLength sub substring tail;
inherit (trivial) id const concat or and boolToString mergeAttrs
flip mapNullable inNixShell min max importJSON warn info
nixpkgsVersion version mod compare splitByAndCompare
functionArgs setFunctionArgs isFunction;
inherit (trivial) id const concat or and bitAnd bitOr bitXor
boolToString mergeAttrs flip mapNullable inNixShell min max
importJSON warn info nixpkgsVersion version mod compare
splitByAndCompare functionArgs setFunctionArgs isFunction;
inherit (fixedPoints) fix fix' extends composeExtensions
makeExtensible makeExtensibleWithCustomName;

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@ -45,6 +45,21 @@ runTests {
expected = true;
};
testBitAnd = {
expr = (bitAnd 3 10);
expected = 2;
};
testBitOr = {
expr = (bitOr 3 10);
expected = 11;
};
testBitXor = {
expr = (bitXor 3 10);
expected = 9;
};
# STRINGS
testConcatMapStrings = {

View file

@ -1,4 +1,38 @@
{ lib }:
let
zipIntBits = f: x: y:
let
# (intToBits 6) -> [ 0 1 1 ]
intToBits = x:
if x==0 then
[]
else
let
headbit = if (x / 2) * 2 != x then 1 else 0; # x & 1
tailbits = if x < 0 then 9223372036854775807 + ((x+1) / 2) else x / 2; # x >>> 1
in
[headbit] ++ (intToBits tailbits);
# (bitsToInt [ 0 1 1 ]) -> 6
bitsToInt = l:
if l==[] then
0
else
(builtins.head l) + (2 * (bitsToInt (builtins.tail l)));
zipListsWith' = fst: snd:
if fst==[] && snd==[] then
[]
else if fst==[] then
[(f 0 (builtins.head snd))] ++ (zipListsWith' [] (builtins.tail snd))
else if snd==[] then
[(f (builtins.head fst) 0 )] ++ (zipListsWith' (builtins.tail fst) [] )
else
[(f (builtins.head fst) (builtins.head snd))] ++ (zipListsWith' (builtins.tail fst) (builtins.tail snd));
in
assert (builtins.isInt x) && (builtins.isInt y);
bitsToInt (zipListsWith' (intToBits x) (intToBits y));
in
rec {
/* The identity function
@ -31,6 +65,15 @@ rec {
/* boolean and */
and = x: y: x && y;
/* bitwise and */
bitAnd = builtins.bitAnd or zipIntBits (a: b: if a==1 && b==1 then 1 else 0);
/* bitwise or */
bitOr = builtins.bitOr or zipIntBits (a: b: if a==1 || b==1 then 1 else 0);
/* bitwise xor */
bitXor = builtins.bitXor or zipIntBits (a: b: if a!=b then 1 else 0);
/* Convert a boolean to a string.
Note that toString on a bool returns "1" and "".
*/