Niels Lohmann 44fba02ec2 Format the digits of numbers in vector registers and without reloads ...

- zmij::to_shortest() keeps the last digit apart from the 15 or 16 digits
  before it, and dtoa_impl::write_shortest() converts those at once: with
  SSE2 on x86-64 and NEON on 64-bit Arm (no CPU check needed), else eight
  digits at a time. The decimal point is inserted in the register; reading
  the digits back right after storing them stalled store forwarding.
- json::dump() writes floats and integers straight into its write buffer
  instead of copying them from number_buffer, and integers below 10^16
  eight digits at a time.
- json_view's dump() writes doubles from their bits and tokens of up to 15
  digits through the same code; its own NEON writer is removed.

to_chars() on canada.json: 35 -> 29 ns per double (x86-64), 18.8 -> 14.2 ns
(Apple M1); json::dump() of canada.json 16-29% faster, of citm_catalog.json
14-19%.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

2026-10-05 22:28:58 +02:00

..

from_json.hpp

Remove dead metaprogramming and duplicated code in traits and pointers (#5728)

2026-10-04 11:50:42 +02:00

to_chars.hpp

Format the digits of numbers in vector registers and without reloads

2026-10-05 22:28:58 +02:00

to_json.hpp

Remove dead metaprogramming and duplicated code in traits and pointers (#5728)

2026-10-04 11:50:42 +02:00

zmij.hpp

Format the digits of numbers in vector registers and without reloads

2026-10-05 22:28:58 +02:00