Re: Compute buffer size at compile-time

Ico wrote:

Spoon <none> wrote:

Hello,

Consider:

#define BUFFER_SIZE 1234 /* or some other value */
uint8_t buffer[BUFFER_SIZE];
int do_stuff(uint8_t *buf);

where do_stuff() does something with each octet in the buffer.

Assume I've come up with do_stuff_2() similar to do_stuff() but
that works with 16 octets at a time.

I need to compute N at compile time
such that N >= 1234 && N % 16 == 0



#define N (BS / 16) * 16 + 16 ?

Be careful of those boundary cases. If BS is divisible
by 16, the above formula adds an extra 16 instead of just
leaving it alone.

#define N ((BS + 15) & ~15)

More generally,

#define ROUNDUP(min,chunk) \
(((min) + (chunk) - 1) / (chunk) * (chunk))

--
Eric Sosman
esosman@xxxxxxxxxxxxxxxxxxx
.

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