diff --git a/lib/default.nix b/lib/default.nix index aca484d9a8e..c1a4a1e39a8 100644 --- a/lib/default.nix +++ b/lib/default.nix @@ -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 bitNot + 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; diff --git a/lib/tests/misc.nix b/lib/tests/misc.nix index c683df7d7ca..eab20d0f14d 100644 --- a/lib/tests/misc.nix +++ b/lib/tests/misc.nix @@ -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 = { diff --git a/lib/trivial.nix b/lib/trivial.nix index 251cb796db0..0bcefcbc28d 100644 --- a/lib/trivial.nix +++ b/lib/trivial.nix @@ -1,4 +1,41 @@ { lib }: +let + zipIntBits = f: x: y: + let + # (intToBits 6) -> [ 0 1 1 ] + intToBits = x: + if x == 0 || x == -1 then + [] + else + let + headbit = if (x / 2) * 2 != x then 1 else 0; # x & 1 + tailbits = if x < 0 then ((x + 1) / 2) - 1 else x / 2; # x >> 1 + in + [headbit] ++ (intToBits tailbits); + + # (bitsToInt [ 0 1 1 ] 0) -> 6 + # (bitsToInt [ 0 1 0 ] 1) -> -6 + bitsToInt = l: signum: + if l == [] then + (if signum == 0 then 0 else -1) + else + (builtins.head l) + (2 * (bitsToInt (builtins.tail l) signum)); + + xsignum = if x < 0 then 1 else 0; + ysignum = if y < 0 then 1 else 0; + zipListsWith' = fst: snd: + if fst==[] && snd==[] then + [] + else if fst==[] then + [(f xsignum (builtins.head snd))] ++ (zipListsWith' [] (builtins.tail snd)) + else if snd==[] then + [(f (builtins.head fst) ysignum )] ++ (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)) (f xsignum ysignum); +in rec { /* The identity function @@ -31,6 +68,18 @@ 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); + + /* bitwise “not” */ + bitNot = builtins.sub (-1); + /* Convert a boolean to a string. Note that toString on a bool returns "1" and "". */