Given the following code:
uint HASHTABLE = 1917507215;
for (uint i = 5; i != 0; i--)
{
HASHTABLE = (HASHTABLE ^ ((HASHTABLE << 10 ^ HASHTABLE) << 9 ^ HASHTABLE) << 5) & 0x7fffffff ^ (((HASHTABLE << 7 ^ HASHTABLE) << 10 ^ HASHTABLE) << 9 ^ HASHTABLE) << 5;
HASHTABLE = HASHTABLE >> 1 | (HASHTABLE & 1) << 0x1f;
}
I am trying to convert this code to JavaScript, but I have noticed that there has been an inconsistency in the calculation.
In C#, the value of the HASHTABLE after the loop finished, is 1871861428
While in Javascript, the value is -275622220.
I suspect the problem comes from the fact that in c#, the value is supposed to be unsigned.
Besides, Javascript can do bitwise operators up to 32 bits.
Which is why, I have attempted to go ahead and use the Long library (https://www.npmjs.com/package/long)
I have therefore set my HASHTABLE value to be Long.fromValue(HASHTABLE, true), and proceeded with doing the operations using Long, as follows:
hashTable = Long.fromValue(hashTable, true);
for (let i = 5; i != 0; i--) {
hashTable = hashTable.xor(
hashTable.shiftLeft(10).xor(hashTable).shiftLeft(9).xor(hashTable).shiftLeft(5)
).and(0x7fffffff).xor(
hashTable.shiftLeft(7).xor(hashTable).shiftLeft(10).xor(hashTable).shiftLeft(9).xor(hashTable).shiftLeft(5)
);
hashTable = hashTable.shiftRight(1).or(hashTable.and(1).shiftLeft(0x1f));
}
hashTable = hashTable.toInt();
However, even after using Long, my HASHTABLE value will be 4019345076 in Javascript.
Basically, in Javascript I will get 0xEF9256B4 while in C# I will correctly get 0x6F9256B4, the difference beeing that the 32nd (most signifficant bit) is set in JavaScript, and in C# it isn’t.
What am I missing here, and why, even after using the Long library, there is this inconsistency between JavaScript and C#?
>Solution :
let HASHTABLE = 1917507215;
for (let i = 5; i != 0; i--) {
HASHTABLE = (HASHTABLE ^ ((HASHTABLE << 10 ^ HASHTABLE) << 9 ^ HASHTABLE) << 5) & 0x7fffffff ^ (((HASHTABLE << 7 ^ HASHTABLE) << 10 ^ HASHTABLE) << 9 ^ HASHTABLE) << 5;
HASHTABLE = HASHTABLE >>> 1 | (HASHTABLE & 1) << 0x1f;
}
console.log(HASHTABLE);