sha3.c: neon: refactor, add documentation

- switch row_eor() from macro to static inline function
- compress rho rotate values into from 15 128-bit registers to two to
  reduce register pressure (still spilling, though)
- remove PERMUTE macro
- switch from unrolled loop with macro in body of permute_n_neon() to
  regular loop
- add documentation for register/lane layout and for compressed rho
  rotations

with these changes the neon backend is still uses ~50% more cycles than
the scalar backend, so i will probably leave it disabled for the initial
release.

scalar (pi5):
  > ./bench 2000
  info: cpucycles: version=20240318 implementation=arm64-vct persecond=2400000000
  info: backend=scalar num_trials=2000 src_lens=64,256,1024,4096,16384 dst_lens=32
  function,dst_len,64,256,1024,4096,16384
  sha3_224,28,20.2,10.3,10.3,9.3,9.2
  sha3_256,32,20.2,10.3,10.3,9.9,9.7
  sha3_384,48,20.9,15.3,12.8,12.7,12.5
  sha3_512,64,20.2,20.2,18.9,25.3,17.9
  shake128,32,20.2,10.1,9.0,8.1,7.9
  shake256,32,20.2,10.3,10.3,9.9,9.7

neon backend bench results (pi5):
  > ./bench 2000
  info: cpucycles: version=20240318 implementation=arm64-vct persecond=2400000000
  info: backend=neon num_trials=2000 src_lens=64,256,1024,4096,16384 dst_lens=32
  function,dst_len,64,256,1024,4096,16384
  sha3_224,28,32.7,16.3,16.4,14.9,14.6
  sha3_256,32,32.0,16.2,16.4,15.9,15.5
  sha3_384,48,32.7,24.2,20.4,20.2,20.0
  sha3_512,64,32.0,32.2,30.1,28.6,28.5
  shake128,32,32.7,16.2,14.2,12.8,12.5
  shake256,32,32.7,16.2,16.3,15.7,15.4

0 files changed, 0 insertions, 0 deletions