fb59626 · elk · git.iko.soy

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Change from division to bit shifting

fb59626Christian Widera13 years ago

libraries/Native/Array.js+8−12

compare with master

unifiedsplit

@@ -35,9 +35,11 @@ Elm.Native.Array.make = function(elm) {

36 function unsafeGet(i, array) {

37 for (var x = array.height; x > 0; x--) {

38− var slot = Math.floor(i / cache[x]);

38+ var slot = i >> (x * 5);

39− while (array.lengths[slot] <= i) { slot++; }

39+ if (slot > 0) {

40+ while (array.lengths[slot - 1] > i) { slot--; }

40− if (slot > 0) { i -= array.lengths[slot - 1]; }

41+ i -= array.lengths[slot - 1];

42+ }

41 array = array.table[slot];

43 array = array.table[slot];

42 }

44 }

43 return array.table[i];

45 return array.table[i];

@@ -530,18 +532,12 @@ Elm.Native.Array.make = function(elm) {

530 }

532 }

531 }

533 }

532

534

533− // Cache for Math.pow(M, i)

534− cache = new Array(10);

535− for (var i = 0; i < cache.length; i++) {

536− cache[i] = Math.pow(M, i);

537− }

538−

539 // Calculates in which slot of "table" the item probably is, then

535 // Calculates in which slot of "table" the item probably is, then

540 // find the exact slot via forward searching in "lengths". Returns the index.

536 // find the exact slot via forward searching in "lengths". Returns the index.

541 function getSlot(i, a) {

537 function getSlot(i, a) {

542− var slot = Math.floor(i / cache[a.height]);

538+ var slot = i << (5 * a.height);

543− while (a.lengths[slot] <= i) {

539+ while (a.lengths[slot - 1] > i) {

544− slot++

540+ slot++;

545 }

541 }

546 return slot;

542 return slot;

547 }

543 }