70 lines
1.6 KiB
Rust
70 lines
1.6 KiB
Rust
// https://stackoverflow.com/a/43305015/1941280
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#[inline]
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pub fn f64_into_bytes(float: f64) -> Option<[u8; 8]> {
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if float.is_finite() {
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if float == 0.0 || float == -0.0 {
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return Some(xor_first_bit(0.0_f64.to_be_bytes()));
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} else if float.is_sign_negative() {
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return Some(xor_all_bits(float.to_be_bytes()));
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} else if float.is_sign_positive() {
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return Some(xor_first_bit(float.to_be_bytes()));
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}
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}
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None
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}
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#[inline]
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pub fn i64_into_bytes(int: i64) -> [u8; 8] {
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xor_first_bit(int.to_be_bytes())
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}
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#[inline]
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pub fn i64_from_bytes(bytes: [u8; 8]) -> i64 {
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i64::from_be_bytes(xor_first_bit(bytes))
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}
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#[inline]
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fn xor_first_bit(mut x: [u8; 8]) -> [u8; 8] {
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x[0] ^= 0x80;
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x
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}
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#[inline]
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fn xor_all_bits(mut x: [u8; 8]) -> [u8; 8] {
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x.iter_mut().for_each(|b| *b ^= 0xff);
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x
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}
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#[cfg(test)]
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mod tests {
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use std::cmp::Ordering::Less;
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use super::*;
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fn is_sorted<T: Ord>(x: &[T]) -> bool {
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x.windows(2).map(|x| x[0].cmp(&x[1])).all(|o| o == Less)
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}
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#[test]
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fn ordered_f64_bytes() {
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let a = -13_f64;
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let b = -10.0;
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let c = -0.0;
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let d = 1.0;
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let e = 43.0;
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let vec: Vec<_> = [a, b, c, d, e].iter().cloned().map(f64_into_bytes).collect();
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assert!(is_sorted(&vec), "{:?}", vec);
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}
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#[test]
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fn ordered_i64_bytes() {
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let a = -10_i64;
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let b = -0_i64;
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let c = 1_i64;
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let d = 43_i64;
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let vec: Vec<_> = [a, b, c, d].iter().cloned().map(i64_into_bytes).collect();
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assert!(is_sorted(&vec), "{:?}", vec);
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}
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}
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