diff options
Diffstat (limited to 'users/sterni/nix/int')
| -rw-r--r-- | users/sterni/nix/int/default.nix | 124 | ||||
| -rw-r--r-- | users/sterni/nix/int/tests/default.nix | 203 |
2 files changed, 327 insertions, 0 deletions
diff --git a/users/sterni/nix/int/default.nix b/users/sterni/nix/int/default.nix new file mode 100644 index 000000000000..b3157571272f --- /dev/null +++ b/users/sterni/nix/int/default.nix @@ -0,0 +1,124 @@ +{ depot, lib, ... }: + +let + + # TODO(sterni): implement nix.float and figure out which of these + # functions can be split out into a common nix.num + # library. + + inherit (depot.users.sterni.nix) + string + ; + + inherit (builtins) + bitOr + bitAnd + bitXor + mul + div + add + sub + ; + + abs = i: if i < 0 then -i else i; + + exp = base: pow: + if pow > 0 + then base * (exp base (pow - 1)) + else if pow < 0 + then 1.0 / exp base (abs pow) + else 1; + + bitShiftR = bit: count: + if count == 0 + then bit + else div (bitShiftR bit (count - 1)) 2; + + bitShiftL = bit: count: + if count == 0 + then bit + else 2 * (bitShiftL bit (count - 1)); + + hexdigits = "0123456789ABCDEF"; + + toHex = int: + let + go = i: + if i == 0 + then "" + else go (bitShiftR i 4) + + string.charAt (bitAnd i 15) hexdigits; + sign = lib.optionalString (int < 0) "-"; + in + if int == 0 + then "0" + else "${sign}${go (abs int)}"; + + fromHexMap = builtins.listToAttrs + (lib.imap0 (i: c: { name = c; value = i; }) + (lib.stringToCharacters hexdigits)); + + fromHex = literal: + let + negative = string.charAt 0 literal == "-"; + start = if negative then 1 else 0; + len = builtins.stringLength literal; + # reversed list of all digits + digits = builtins.genList + (i: string.charAt (len - 1 - i) literal) + (len - start); + parsed = builtins.foldl' + (v: d: { + val = v.val + (fromHexMap."${d}" * v.mul); + mul = v.mul * 16; + }) + { val = 0; mul = 1; } digits; + in + if negative + then -parsed.val + else parsed.val; + + # A nix integer is a 64bit signed integer + maxBound = 9223372036854775807; + + # fun fact: -9223372036854775808 is the lower bound + # for a nix integer (as you would expect), but you can't + # use it as an integer literal or you'll be greeted with: + # error: invalid integer '9223372036854775808' + # This is because all int literals when parsing are + # positive, negative "literals" are positive literals + # which are preceded by the arithmetric negation operator. + minBound = -9223372036854775807 - 1; + + odd = x: bitAnd x 1 == 1; + even = x: bitAnd x 1 == 0; + + # div and mod behave like quot and rem in Haskell, + # i. e. they truncate towards 0 + mod = a: b: let res = a / b; in a - (res * b); + + inRange = a: b: x: x >= a && x <= b; + +in { + inherit + maxBound + minBound + abs + exp + odd + even + add + sub + mul + div + mod + bitShiftR + bitShiftL + bitOr + bitAnd + bitXor + toHex + fromHex + inRange + ; +} diff --git a/users/sterni/nix/int/tests/default.nix b/users/sterni/nix/int/tests/default.nix new file mode 100644 index 000000000000..fac45dd251e1 --- /dev/null +++ b/users/sterni/nix/int/tests/default.nix @@ -0,0 +1,203 @@ +{ depot, lib, ... }: + +let + + inherit (depot.nix.runTestsuite) + runTestsuite + it + assertEq + ; + + inherit (depot.users.sterni.nix) + int + string + fun + ; + + testBounds = it "checks minBound and maxBound" [ + # this is gonna blow up in my face because + # integer overflow is undefined behavior in + # C++, so most likely anything could happen? + (assertEq "maxBound is the maxBound" true + (int.maxBound + 1 < int.maxBound)) + (assertEq "minBound is the minBound" true + (int.minBound - 1 > int.minBound)) + (assertEq "maxBound overflows to minBound" + (int.maxBound + 1) + int.minBound) + (assertEq "minBound overflows to maxBound" + (int.minBound - 1) + int.maxBound) + ]; + + expectedBytes = [ + "00" "01" "02" "03" "04" "05" "06" "07" "08" "09" "0A" "0B" "0C" "0D" "0E" "0F" + "10" "11" "12" "13" "14" "15" "16" "17" "18" "19" "1A" "1B" "1C" "1D" "1E" "1F" + "20" "21" "22" "23" "24" "25" "26" "27" "28" "29" "2A" "2B" "2C" "2D" "2E" "2F" + "30" "31" "32" "33" "34" "35" "36" "37" "38" "39" "3A" "3B" "3C" "3D" "3E" "3F" + "40" "41" "42" "43" "44" "45" "46" "47" "48" "49" "4A" "4B" "4C" "4D" "4E" "4F" + "50" "51" "52" "53" "54" "55" "56" "57" "58" "59" "5A" "5B" "5C" "5D" "5E" "5F" + "60" "61" "62" "63" "64" "65" "66" "67" "68" "69" "6A" "6B" "6C" "6D" "6E" "6F" + "70" "71" "72" "73" "74" "75" "76" "77" "78" "79" "7A" "7B" "7C" "7D" "7E" "7F" + "80" "81" "82" "83" "84" "85" "86" "87" "88" "89" "8A" "8B" "8C" "8D" "8E" "8F" + "90" "91" "92" "93" "94" "95" "96" "97" "98" "99" "9A" "9B" "9C" "9D" "9E" "9F" + "A0" "A1" "A2" "A3" "A4" "A5" "A6" "A7" "A8" "A9" "AA" "AB" "AC" "AD" "AE" "AF" + "B0" "B1" "B2" "B3" "B4" "B5" "B6" "B7" "B8" "B9" "BA" "BB" "BC" "BD" "BE" "BF" + "C0" "C1" "C2" "C3" "C4" "C5" "C6" "C7" "C8" "C9" "CA" "CB" "CC" "CD" "CE" "CF" + "D0" "D1" "D2" "D3" "D4" "D5" "D6" "D7" "D8" "D9" "DA" "DB" "DC" "DD" "DE" "DF" + "E0" "E1" "E2" "E3" "E4" "E5" "E6" "E7" "E8" "E9" "EA" "EB" "EC" "ED" "EE" "EF" + "F0" "F1" "F2" "F3" "F4" "F5" "F6" "F7" "F8" "F9" "FA" "FB" "FC" "FD" "FE" "FF" + ]; + + hexByte = i: string.fit { width = 2; char = "0"; } (int.toHex i); + + hexInts = [ + { left = 0; right = "0"; } + { left = 1; right = "1"; } + { left = 11; right = "B"; } + { left = 123; right = "7B"; } + { left = 9000; right = "2328"; } + { left = 2323; right = "913"; } + { left = 4096; right = "1000"; } + { left = int.maxBound; right = "7FFFFFFFFFFFFFFF"; } + { left = int.minBound; right = "-8000000000000000"; } + ]; + + testHex = it "checks conversion to hex" (lib.flatten [ + (lib.imap0 (i: hex: [ + (assertEq "hexByte ${toString i} == ${hex}" (hexByte i) hex) + (assertEq "${toString i} == fromHex ${hex}" i (int.fromHex hex)) + ]) expectedBytes) + (builtins.map ({ left, right }: [ + (assertEq "toHex ${toString left} == ${right}" (int.toHex left) right) + (assertEq "${toString left} == fromHex ${right}" left (int.fromHex right)) + ]) hexInts) + ]); + + testBasic = it "checks basic int operations" [ + (assertEq "122 is even" (int.even 122 && !(int.odd 122)) true) + (assertEq "123 is odd" (int.odd 123 && !(int.even 123)) true) + (assertEq "abs -4959" (int.abs (-4959)) 4959) + ]; + + expNumbers = [ + { left = -3; right = 0.125; } + { left = -2; right = 0.25; } + { left = -1; right = 0.5; } + { left = 0; right = 1; } + { left = 1; right = 2; } + { left = 2; right = 4; } + { left = 3; right = 8; } + { left = 4; right = 16; } + { left = 5; right = 32; } + { left = 16; right = 65536; } + ]; + + testExp = it "checks exponentiation" + (builtins.map ({ left, right }: + assertEq + "2 ^ ${toString left} == ${toString right}" + (int.exp 2 left) right) expNumbers); + + shifts = [ + { a = 2; b = 5; c = 64; op = "<<"; } + { a = -2; b = 5; c = -64; op = "<<"; } + { a = 123; b = 4; c = 1968; op = "<<"; } + { a = 1; b = 8; c = 256; op = "<<"; } + { a = 256; b = 8; c = 1; op = ">>"; } + { a = 374; b = 2; c = 93; op = ">>"; } + { a = 2; b = 2; c = 0; op = ">>"; } + { a = 99; b = 9; c = 0; op = ">>"; } + ]; + + checkShift = { a, b, c, op }@args: + let + f = string.match op { + "<<" = int.bitShiftL; + ">>" = int.bitShiftR; + }; + in assertEq "${toString a} ${op} ${toString b} == ${toString c}" (f a b) c; + + checkShiftRDivExp = n: + assertEq "${toString n} >> 5 == ${toString n} / 2 ^ 5" + (int.bitShiftR n 5) (int.div n (int.exp 2 5)); + + checkShiftLMulExp = n: + assertEq "${toString n} >> 6 == ${toString n} * 2 ^ 6" + (int.bitShiftL n 5) (int.mul n (int.exp 2 5)); + + testBit = it "checks bitwise operations" (lib.flatten [ + (builtins.map checkShift shifts) + (builtins.map checkShiftRDivExp [ + 1 + 2 + 3 + 5 + 7 + 23 + 1623 + 238 + 34 + 348 + 2834 + 834 + 348 + ]) + (builtins.map checkShiftLMulExp [ + 1 + 2 + 3 + 5 + 7 + 23 + 384 + 3 + 2 + 5991 + 85109 + 38 + ]) + ]); + + divisions = [ + { a = 2; b = 1; c = 2; mod = 0;} + { a = 2; b = 2; c = 1; mod = 0;} + { a = 20; b = 10; c = 2; mod = 0;} + { a = 12; b = 5; c = 2; mod = 2;} + { a = 23; b = 4; c = 5; mod = 3;} + ]; + + checkDiv = n: { a, b, c, mod }: [ + (assertEq "${n}: div result" (int.div a b) c) + (assertEq "${n}: mod result" (int.mod a b) mod) + (assertEq "${n}: divMod law" ((int.div a b) * b + (int.mod a b)) a) + ]; + + testDivMod = it "checks integer division and modulo" + (lib.flatten [ + (builtins.map (checkDiv "+a / +b") divisions) + (builtins.map (fun.rl (checkDiv "-a / +b") (x: x // { + a = -x.a; + c = -x.c; + mod = -x.mod; + })) divisions) + (builtins.map (fun.rl (checkDiv "+a / -b") (x: x // { + b = -x.b; + c = -x.c; + })) divisions) + (builtins.map (fun.rl (checkDiv "-a / -b") (x: x // { + a = -x.a; + b = -x.b; + mod = -x.mod; + })) divisions) + ]); + +in + runTestsuite "nix.int" [ + testBounds + testHex + testBasic + testExp + testBit + testDivMod + ] |