31:[] 2f:{"title":"Bit Twiddling Problems","cells":[{"id":0,"value":"md`# Bit Twiddling Problems`","pinned":false,"hidden":false,"mode":"ojs"},{"id":78,"value":"md`## 1. Test kth bit.`","pinned":false,"hidden":false,"mode":"ojs"},{"id":79,"value":"function isBitSet(n, k) {\n return n & (1 << k) != 0;\n}","pinned":true,"hidden":false,"mode":"ojs"},{"id":85,"value":"isBitSet(5, 2)","pinned":true,"hidden":false,"mode":"ojs"},{"id":98,"value":"md`## 2. Set kth bit.`","pinned":false,"hidden":false,"mode":"ojs"},{"id":109,"value":"function setBit(n, k) {\n return n | (1 << k);\n}","pinned":true,"hidden":false,"mode":"ojs"},{"id":111,"value":"setBit(5, 1) // 0111 (\"7 in base 10\")","pinned":true,"hidden":false,"mode":"ojs"},{"id":120,"value":"md`## 3. Turn off kth bit`","pinned":false,"hidden":false,"mode":"ojs"},{"id":125,"value":"function unsetBit(n, k) {\n return n & ~(1 << k); // XOR\n}","pinned":true,"hidden":false,"mode":"ojs"},{"id":129,"value":"setBit(unsetBit(unsetBit(5, 0), 2), 5)","pinned":true,"hidden":false,"mode":"ojs"},{"id":149,"value":"md`## 4. Toggle kth bit`","pinned":false,"hidden":false,"mode":"ojs"},{"id":150,"value":"function toggleBit(n, k) {\n return n ^ (1 << k);\n}","pinned":true,"hidden":false,"mode":"ojs"},{"id":156,"value":"toggleBit(toggleBit(5, 2), 5) // 5 -> 1 --> 33 ","pinned":false,"hidden":false,"mode":"ojs"},{"id":159,"value":"md`## 5. Check if a number is a power of 2`","pinned":false,"hidden":false,"mode":"ojs"},{"id":162,"value":"function isPowerOf2(n) {\n return 0 == (n & (n - 1)); // two's complement, test for overlap\n}","pinned":true,"hidden":false,"mode":"ojs"},{"id":211,"value":"isPowerOf2(32)","pinned":false,"hidden":false,"mode":"ojs"},{"id":213,"value":"md`## 6. Get index of highest order bit`","pinned":false,"hidden":false,"mode":"ojs"},{"id":214,"value":"function highestOrderBit(n) {\n let test = 31; \n \n if (n == 0) return -1;\n \n while (test > 0) {\n if (n & (1 << test)) {\n return test;\n }\n test--;\n }\n \n \n}","pinned":true,"hidden":false,"mode":"ojs"},{"id":219,"value":"highestOrderBit(17) // 10001","pinned":true,"hidden":false,"mode":"ojs"},{"id":226,"value":"highestOrderBit(32) // 100000","pinned":true,"hidden":false,"mode":"ojs"},{"id":233,"value":"highestOrderBit(35) // 100011","pinned":true,"hidden":false,"mode":"ojs"},{"id":239,"value":"// Unsigned integer. Assume 32 bits unsigned integer.\n// A kind of cheeky solution that uses parseInt and toString with\n// a binary radix specified.\nfunction reverseBits(n) {\n const BIT_SIZE = 32;\n \n let s = n.toString(2);\n \n for (let i = BIT_SIZE - s.length; i > 0; i--) {\n s = \"0\" + s; // left pad zeros;\n }\n \n return parseInt(s.split('').reverse().join(''), 2);\n}","pinned":true,"hidden":false,"mode":"ojs"},{"id":249,"value":"highestOrderBit(43261596) // 00000010100101000001111010011100 in binary, 32 bits in total","pinned":true,"hidden":false,"mode":"ojs"},{"id":266,"value":"reverseBits(43261596)","pinned":true,"hidden":false,"mode":"ojs"}],"files":"$W31","stdlib":"1","titling":"auto"}