[CCID3] Avoid unsigned integer overflows in usecs_div

#include "ccid3.h"

/*

 * Reason for maths with 10 here is to avoid 32 bit overflow when a is big.

 * Reason for maths here is to avoid 32 bit overflow when a is big.

 * With this we get close to the limit.

 */

static inline u32 usecs_div(const u32 a, const u32 b)

{

	const u32 tmp = a * (USEC_PER_SEC / 10);

	return b > 20 ? tmp / (b / 10) : tmp;

	const u32 div = a < (UINT_MAX / (USEC_PER_SEC /    10)) ?    10 :

			a < (UINT_MAX / (USEC_PER_SEC /    50)) ?    50 :

			a < (UINT_MAX / (USEC_PER_SEC /   100)) ?   100 :

			a < (UINT_MAX / (USEC_PER_SEC /   500)) ?   500 :

			a < (UINT_MAX / (USEC_PER_SEC /  1000)) ?  1000 :

			a < (UINT_MAX / (USEC_PER_SEC /  5000)) ?  5000 :

			a < (UINT_MAX / (USEC_PER_SEC / 10000)) ? 10000 :

			a < (UINT_MAX / (USEC_PER_SEC / 50000)) ? 50000 :

								 100000;

	const u32 tmp = a * (USEC_PER_SEC / div);

	return (b >= 2 * div) ? tmp / (b / div) : tmp;

}

static int ccid3_debug;