#include <stdio.h>
#include <stdint.h>
 
static uint32_t calc_napot_granularity(uint32_t addr)
{
    /* In NAPOT mode the size of a region is determined
     * by the number of least significant bits set, that is
     * the size is 2^(3+LSZB) (LSZB = least significant zero bit).
     * That is if the address is 0x20009ff, then the size is encoded
     * by bits 0x1ff, which are bits 0~8, so LSZB=9, so the size of the region is
     * 2^(3+9) = 4096
     * That is the granularity in terms of G required for this size is
     * G = LSZB + 1
     */
    uint32_t index = 0;
    while ((addr >> index & 0x1) == 1)
        index ++;
 
    return index;
}
 
int main(void) {
	printf("%u\n", calc_napot_granularity(0x20009FF));
	return 0;
}
 

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