tustvold commented on code in PR #1905:
URL: https://github.com/apache/arrow-rs/pull/1905#discussion_r901063604
##########
parquet/src/util/bit_util.rs:
##########
@@ -133,38 +133,23 @@ where
memcpy(&source.as_bytes()[..num_bytes], target)
}
-/// Returns the ceil of value/divisor
+/// Returns the ceil of value/divisor.
+///
+/// This function should be removed after
+/// [`int_roundings`](https://github.com/rust-lang/rust/issues/88581) is
stable.
#[inline]
pub fn ceil(value: i64, divisor: i64) -> i64 {
- value / divisor + ((value % divisor != 0) as i64)
-}
-
-/// Returns ceil(log2(x))
-#[inline]
-pub fn log2(mut x: u64) -> i32 {
- if x == 1 {
- return 0;
- }
- x -= 1;
- let mut result = 0;
- while x > 0 {
- x >>= 1;
- result += 1;
- }
- result
+ num::Integer::div_ceil(&value, &divisor)
}
/// Returns the `num_bits` least-significant bits of `v`
#[inline]
pub fn trailing_bits(v: u64, num_bits: usize) -> u64 {
- if num_bits == 0 {
- return 0;
- }
if num_bits >= 64 {
- return v;
+ v
+ } else {
Review Comment:
Aah yes, forgot you can't just overflow. I presume LLVM is smart enough to
turn the if into a mask, i.e.
```
1 << (num_bits & 64)
```
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