#undef DEBUG_LOG2 #ifdef DEBUG_LOG2 #include <console/console.h> #endif #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 i = 1ULL << (sizeof(x)* CHAR_BIT - 1ULL); unsigned long pow = sizeof(x) * CHAR_BIT - 1ULL; if (! x) { #ifdef DEBUG_LOG2 printk(BIOS_WARNING, "%s called with invalid parameter of 0\n", __func__); #endif return -1; } for(; i > x; i >>= 1, pow--) ; return pow; }