multiple_of macro seems wrong

Hi all,

Looking at the new LAME 3.100 release candidate I found the multiple_of macro defined in machine.h to be wrong.

#define multiple_of(CHUNK, COUNT) ((COUNT) + ((COUNT) % (CHUNK)))

It seems like it is meant to round up the value of COUNT to the next multiple of CHUNK, but it doesn't. Filling the values 16 and 5 like in the definition of ABButter in gain_analysis.c gives 5 + (5 % 16) = 10 instead of 16.

A correct definition of the macro would be:

#define multiple_of(CHUNK, COUNT) ((COUNT) + (CHUNK) - 1 - ((COUNT) + (CHUNK) - 1) % (CHUNK))

or:

#define multiple_of(CHUNK, COUNT) ((((COUNT) + (CHUNK) - 1) / (CHUNK)) * (CHUNK))

(Inspired by the answers to this question on StackOverflow: https://stackoverflow.com/questions/3407012/)

Also, I think using a multiple of 4 should be enough for ABYule and ABButter. You want 16 byte alignment for vectorization and float is 4 bytes, so 4 * 4 = 16 should be fine.

Cheers,
Robert
----
Robert Kausch
[email protected]

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