base64ct: minor code improvements #234
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newpavlov
commented
Jan 27, 2021
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| let flag = src_rem.len() == 1; | ||
| let mask = (flag as u8).wrapping_sub(1); | ||
| dst_rem[2] = (dst_rem[2] & mask) | (PAD & !mask); |
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Also note that I have replaced the explicit branch with this bit-twiddling. I wonder if there is a better way to generate mask from bool.
newpavlov
commented
Jan 27, 2021
| fn encode_string(input: &[u8], padded: bool, hi_bytes: (u8, u8)) -> String { | ||
| let elen = encoded_len(input, padded); | ||
| let elen = encoded_len_inner(input.len(), padded).expect("input is too big"); |
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Thanks to the forced inlining, the second expect used on encode result will be properly removed. This change allows this function to panic before allocation, which simplifies generated assembly a bit.
tarcieri
reviewed
Jan 27, 2021
| } else { | ||
| encode_3bytes_padded(s, d, hi_bytes); | ||
| } | ||
| if let Some(dst_rem) = dst_chunks.next() { |
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Oh neat, I guess that was all I was missing.
tarcieri
approved these changes
Jan 27, 2021
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Improves the
encodefunction by improving code reuse and removing an unreachable panic in the padded path. Also marks all inner functions with#[inline(always)]to remove call indirection. Most often crates will use only one module, so I think such inlining is warranted.