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Add more integer conversions 

Closes zcash/zip32#7.
This commit is contained in:
Jack Grigg 2023-12-06 08:39:19 +00:00
parent 0aff4887a2
commit 43f48d540a
1 changed files with 72 additions and 5 deletions
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75
src/lib.rs
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@ -169,13 +169,38 @@ impl From<[u8; 11]> for DiversifierIndex {
} }
} }
impl TryFrom<DiversifierIndex> for u32 { impl TryFrom<u128> for DiversifierIndex {
type Error = TryFromIntError;
fn try_from(value: u128) -> Result<Self, Self::Error> {
if (value >> 88) == 0 {
Ok(Self(value.to_le_bytes()[..11].try_into().unwrap()))
} else {
Err(TryFromIntError(()))
}
}
}
macro_rules! di_try_into {
($n:ident) => {
impl TryFrom<DiversifierIndex> for $n {
type Error = core::num::TryFromIntError; type Error = core::num::TryFromIntError;
fn try_from(di: DiversifierIndex) -> Result<u32, Self::Error> { fn try_from(di: DiversifierIndex) -> Result<Self, Self::Error> {
u128::from(di).try_into()
}
}
};
}
di_try_into!(u32);
di_try_into!(u64);
di_try_into!(usize);
impl From<DiversifierIndex> for u128 {
fn from(di: DiversifierIndex) -> Self {
let mut u128_bytes = [0u8; 16]; let mut u128_bytes = [0u8; 16];
u128_bytes[0..11].copy_from_slice(&di.0[..]); u128_bytes[0..11].copy_from_slice(&di.0[..]);
u128::from_le_bytes(u128_bytes).try_into() u128::from_le_bytes(u128_bytes)
} }
} }
@ -248,15 +273,57 @@ mod tests {
0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
]); ]);
assert_eq!(u32::try_from(two), Ok(2)); assert_eq!(u32::try_from(two), Ok(2));
assert_eq!(DiversifierIndex::from(2_u32), two);
let max_u32 = DiversifierIndex([ let max_u32 = DiversifierIndex([
0xff, 0xff, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
]); ]);
assert_eq!(u32::try_from(max_u32), Ok(u32::MAX)); assert_eq!(u32::try_from(max_u32), Ok(u32::MAX));
assert_eq!(DiversifierIndex::from(u32::MAX), max_u32);
let too_big = DiversifierIndex([ let too_big = DiversifierIndex([
0xff, 0xff, 0xff, 0xff, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
]); ]);
assert_matches!(u32::try_from(too_big), Err(_)); assert_matches!(u32::try_from(too_big), Err(_));
} }
#[test]
fn diversifier_index_to_u64() {
let two = DiversifierIndex([
0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
]);
assert_eq!(u64::try_from(two), Ok(2));
assert_eq!(DiversifierIndex::from(2_u64), two);
let max_u64 = DiversifierIndex([
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00, 0x00, 0x00,
]);
assert_eq!(u64::try_from(max_u64), Ok(u64::MAX));
assert_eq!(DiversifierIndex::from(u64::MAX), max_u64);
let too_big = DiversifierIndex([
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00,
]);
assert_matches!(u64::try_from(too_big), Err(_));
}
#[test]
fn diversifier_index_to_u128() {
let two = DiversifierIndex([
0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
]);
assert_eq!(u128::from(two), 2);
assert_eq!(DiversifierIndex::try_from(2_u128).unwrap(), two);
let max_di = DiversifierIndex([
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
]);
assert_eq!(u128::try_from(max_di), Ok(0x00ff_ffff_ffff_ffff_ffff_ffff));
assert_eq!(
DiversifierIndex::try_from(0x00ff_ffff_ffff_ffff_ffff_ffff_u128).unwrap(),
max_di,
);
assert!(DiversifierIndex::try_from(0x0100_0000_0000_0000_0000_0000_u128).is_err());
}
} }