Remove rate::ilog64()

src/rate.rs

@@ -13,8 +13,7 @@ use crate::quantize::ac_q;
 use crate::quantize::dc_q;
 use crate::quantize::select_ac_qi;
 use crate::quantize::select_dc_qi;
-use crate::util::clamp;
-use crate::util::Pixel;
+use crate::util::{clamp, ILog, Pixel};
 
 // The number of frame sub-types for which we track distinct parameters.
 // This does not include FRAME_SUBTYPE_SEF, because we don't need to do any
@@ -80,16 +79,6 @@ const DQP_Q57: &[i64; FRAME_NSUBTYPES] = &[
   (2.0 * (33_810_170.0 / 86_043_287.0) * (1i64 << 57) as f64) as i64
 ];
 
-// Integer binary logarithm of a 64-bit value.
-// v: A 64-bit value.
-// Returns floor(log2(v)) + 1, or 0 if v == 0.
-// This is the number of bits that would be required to represent v in two's
-//  complement notation with all of the leading zeros stripped.
-// TODO: Mark const once leading_zeros() as a constant function stabilizes.
-fn ilog64(v: i64) -> i32 {
-  64 - (v.leading_zeros() as i32)
-}
-
 // Convert an integer into a Q57 fixed-point fraction.
 // The integer must be in the range -64 to 63, inclusive.
 pub(crate) const fn q57(v: i32) -> i64 {
@@ -218,7 +207,7 @@ fn blog64(w: i64) -> i64 {
   if w <= 0 {
     return -1;
   }
-  let ipart = ilog64(w) - 1;
+  let ipart = w.ilog() as i32 - 1;
   if ipart > 61 {
     w >>= ipart - 61;
   } else {

src/util.rs

@@ -165,6 +165,11 @@ impl_cast_from_pixel_to_primitive!(i32);
 impl_cast_from_pixel_to_primitive!(u32);
 
 pub trait ILog: PrimInt {
+  // Integer binary logarithm of an integer value.
+  // Returns floor(log2(self)) + 1, or 0 if self == 0.
+  // This is the number of bits that would be required to represent self in two's
+  //  complement notation with all of the leading zeros stripped.
+  // TODO: Mark const once leading_zeros() as a constant function stabilizes.
   fn ilog(self) -> Self {
     Self::from(size_of::<Self>() * 8 - self.leading_zeros() as usize).unwrap()
   }