Commit Graph

2 Commits

Author SHA1 Message Date
Michael Jones 6f80339b18 [libc][NFC] Add supporting class for atof implementation
This change adds the High Precision Decimal described here:
https://nigeltao.github.io/blog/2020/parse-number-f64-simple.html
It will be used for the atof implementation later, but is complete and
tested now.

The code is inspired by the golang implmentation of the HPD class, which
can be found here: https://github.com/golang/go/blob/release-branch.go1.16/src/strconv/decimal.go

Reviewed By: sivachandra

Differential Revision: https://reviews.llvm.org/D110454
2021-10-04 21:08:02 +00:00
Tue Ly 4e5f8b4d8d [libc] Add implementation of expm1f.
Use expm1f(x) = exp(x) - 1 for |x| > ln(2).
For |x| <= ln(2), divide it into 3 subintervals: [-ln2, -1/8], [-1/8, 1/8], [1/8, ln2]
and use a degree-6 polynomial approximation generated by Sollya's fpminmax for each interval.
Errors < 1.5 ULPs when we use fma to evaluate the polynomials.

Differential Revision: https://reviews.llvm.org/D101134
2021-06-10 14:58:34 -04:00