To create a value 2^k, you can just say (1 << k). I need the inverse
function.
Given a value 2 ^ k, does anyone know how to efficiently extract k
(other than a shift loop?)
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In return for reading my email, here's an algorithmic goodie for you:
To answer the question: Is the memory address, A, N-byte aligned?
you ask
if (!(long(A) & (N-1)))
To make A N-byte aligned, you say
A = alloc(length + N - 1);
A' = (long(A) + N-1) & ~(N-1);
You knew that.
But do you know how to answer the question, "what IS the byte alignment
of address A?"
The answer is:
byte alignment = A & -A; // cast A to unsigned value
For example, 1536 &-1536 = 256, 1152 & -1152 = 128, etc....
(In the windows calculator, you can perform unsigned(-X) by typing in -X
and hitting Hex, Dec.)
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