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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-19 00:47:55 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-19 00:47:55 +0000 |
commit | 26a029d407be480d791972afb5975cf62c9360a6 (patch) | |
tree | f435a8308119effd964b339f76abb83a57c29483 /third_party/rust/serde_json/src/lexical/cached.rs | |
parent | Initial commit. (diff) | |
download | firefox-26a029d407be480d791972afb5975cf62c9360a6.tar.xz firefox-26a029d407be480d791972afb5975cf62c9360a6.zip |
Adding upstream version 124.0.1.upstream/124.0.1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'third_party/rust/serde_json/src/lexical/cached.rs')
-rw-r--r-- | third_party/rust/serde_json/src/lexical/cached.rs | 82 |
1 files changed, 82 insertions, 0 deletions
diff --git a/third_party/rust/serde_json/src/lexical/cached.rs b/third_party/rust/serde_json/src/lexical/cached.rs new file mode 100644 index 0000000000..ef5a9fe54d --- /dev/null +++ b/third_party/rust/serde_json/src/lexical/cached.rs @@ -0,0 +1,82 @@ +// Adapted from https://github.com/Alexhuszagh/rust-lexical. + +//! Cached powers trait for extended-precision floats. + +use super::cached_float80; +use super::float::ExtendedFloat; + +// POWERS + +/// Precalculated powers that uses two-separate arrays for memory-efficiency. +#[doc(hidden)] +pub(crate) struct ExtendedFloatArray { + // Pre-calculated mantissa for the powers. + pub mant: &'static [u64], + // Pre-calculated binary exponents for the powers. + pub exp: &'static [i32], +} + +/// Allow indexing of values without bounds checking +impl ExtendedFloatArray { + #[inline] + pub fn get_extended_float(&self, index: usize) -> ExtendedFloat { + let mant = self.mant[index]; + let exp = self.exp[index]; + ExtendedFloat { mant, exp } + } + + #[inline] + pub fn len(&self) -> usize { + self.mant.len() + } +} + +// MODERATE PATH POWERS + +/// Precalculated powers of base N for the moderate path. +#[doc(hidden)] +pub(crate) struct ModeratePathPowers { + // Pre-calculated small powers. + pub small: ExtendedFloatArray, + // Pre-calculated large powers. + pub large: ExtendedFloatArray, + /// Pre-calculated small powers as 64-bit integers + pub small_int: &'static [u64], + // Step between large powers and number of small powers. + pub step: i32, + // Exponent bias for the large powers. + pub bias: i32, +} + +/// Allow indexing of values without bounds checking +impl ModeratePathPowers { + #[inline] + pub fn get_small(&self, index: usize) -> ExtendedFloat { + self.small.get_extended_float(index) + } + + #[inline] + pub fn get_large(&self, index: usize) -> ExtendedFloat { + self.large.get_extended_float(index) + } + + #[inline] + pub fn get_small_int(&self, index: usize) -> u64 { + self.small_int[index] + } +} + +// CACHED EXTENDED POWERS + +/// Cached powers as a trait for a floating-point type. +pub(crate) trait ModeratePathCache { + /// Get cached powers. + fn get_powers() -> &'static ModeratePathPowers; +} + +impl ModeratePathCache for ExtendedFloat { + #[inline] + fn get_powers() -> &'static ModeratePathPowers { + cached_float80::get_powers() + } +} |