coreboot-kgpe-d16/src/lib/clog2.c
Edward O'Callaghan 8fac0b3e90 src/lib/clog2.c: Fix style and clarity, remove some cruft
Change-Id: I6b37cf945db12d2cf8096c9f49fff9e0bec139d6
Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-on: http://review.coreboot.org/6058
Tested-by: build bot (Jenkins)
Reviewed-by: Idwer Vollering <vidwer@gmail.com>
2014-06-20 08:06:51 +02:00

37 lines
558 B
C

#include <console/console.h>
#include <lib.h>
/* Assume 8 bits per byte */
#define CHAR_BIT 8
unsigned long log2(unsigned long x)
{
/* assume 8 bits per byte. */
unsigned long pow = sizeof(x) * CHAR_BIT - 1ULL;
unsigned long i = 1ULL << pow;
if (!x) {
printk(BIOS_WARNING, "%s called with invalid parameter of 0\n",
__func__);
return -1;
}
for (; i > x; i >>= 1, pow--);
return pow;
}
unsigned long log2_ceil(unsigned long x)
{
unsigned long pow;
if (!x)
return -1;
pow = log2(x);
if (x > (1ULL << pow))
pow++;
return pow;
}