si_log2.h File Reference

#include "factory/factoryconf.h"

Go to the source code of this file.

Functions
static int	SI_LOG2 (int v)
static int	SI_LOG2_LONG (long v)

Function Documentation

SI_LOG2()

int SI_LOG2 ( int v )

inlinestatic

Definition at line 6 of file si_log2.h.

{
  const unsigned int b[] = {0x2, 0xC, 0xF0, 0xFF00, 0xFFFF0000};
  const unsigned int S[] = {1, 2, 4, 8, 16};
 
  unsigned int r = 0; // result of log2(v) will go here
  if (v & b[4]) { v >>= S[4]; r |= S[4]; }
  if (v & b[3]) { v >>= S[3]; r |= S[3]; }
  if (v & b[2]) { v >>= S[2]; r |= S[2]; }
  if (v & b[1]) { v >>= S[1]; r |= S[1]; }
  if (v & b[0]) { v >>= S[0]; r |= S[0]; }
  return (int)r;
}

SI_LOG2_LONG()

int SI_LOG2_LONG ( long v )

inlinestatic

Definition at line 22 of file si_log2.h.

{
  const unsigned long b[] = {0x2, 0xC, 0xF0, 0xFF00, 0xFFFF0000, 0xFFFFFFFF00000000UL};
  const unsigned int S[] = {1, 2, 4, 8, 16, 32};
 
  unsigned int r = 0; // result of log2(v) will go here
  if (v & b[5]) { v >>= S[5]; r |= S[5]; }
  if (v & b[4]) { v >>= S[4]; r |= S[4]; }
  if (v & b[3]) { v >>= S[3]; r |= S[3]; }
  if (v & b[2]) { v >>= S[2]; r |= S[2]; }
  if (v & b[1]) { v >>= S[1]; r |= S[1]; }
  if (v & b[0]) { v >>= S[0]; r |= S[0]; }
  return (int)r;
}