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来自「最著名最快的分子模拟软件」· 代码 · 共 63 行

This directory contains Altivec implementations for some
of the most important Gromacs nonbonded functions.

Altivec is really a special set of machine code instructions to
work on several (4) floating-point numbers in a single register,
but Apple, Motorola & IBM provide a set of non-ANSI C language
wrappers for the instructions. This way we can define special
variables containing 4 floating point numbers and let the compiler
take care of saving/restoring registers. 

That's the theory - in practice the compiler isn't always very good
at saving/restoring things efficiently, so for some of the most 
important loops I have reverted back to only using ~30 variables
and placing them all in registers. Unfortunately this means that
the names (e.g v2) don't have any special meaning, and they are reused.

Just as for SSE, there are special sections to take care of the
remaining odd elements when neighborlists are not a multiple of 4.
When changing this code you might have to be careful and zero the
unused elements; if the first three positions are valid but the 4th
NaN (not a number), the energy would be NaN if we add them!


The following loops have been implemented in Altivec:
(There are also non-force versions in each file)

nb010_altivec (No Coul, VdW=Lennard-Jones, no water optimization)
nb030_altivec (No Coul, VdW=Table, no water optimization)
nb100_altivec (Coul=Normal, No VdW, no water optimization)
nb101_altivec (Coul=Normal, No VdW, water=SPC/TIP3P-other atom)
nb102_altivec (Coul=Normal, No VdW, water=SPC/TIP3P-SPC/TIP3P)
nb103_altivec (Coul=Normal, No VdW, water=TIP4P-other atom)
nb104_altivec (Coul=Normal, No VdW, water=TIP4P-TIP4P)
nb111_altivec (Coul=Normal, VdW=L-J, water=SPC/TIP3P-other atom)
nb112_altivec (Coul=Normal, VdW=L-J, water=SPC/TIP3P-SPC/TIP3P)
nb113_altivec (Coul=Normal, VdW=L-J, water=TIP4P-other atom)
nb114_altivec (Coul=Normal, VdW=L-J, water=TIP4P-TIP4P)
nb201_altivec (Coul=RF, No VdW, water=SPC/TIP3P-other atom)
nb202_altivec (Coul=RF, No VdW, water=SPC/TIP3P-SPC/TIP3P)
nb203_altivec (Coul=RF, No VdW, water=TIP4P-other atom)
nb204_altivec (Coul=RF, No VdW, water=TIP4P-TIP4P)
nb211_altivec (Coul=RF, VdW=L-J, water=SPC/TIP3P-other atom)
nb212_altivec (Coul=RF, VdW=L-J, water=SPC/TIP3P-SPC/TIP3P)
nb213_altivec (Coul=RF, VdW=L-J, water=TIP4P-other atom)
nb214_altivec (Coul=RF, VdW=L-J, water=TIP4P-TIP4P)
nb301_altivec (Coul=Table, No VdW, water=SPC/TIP3P-other atom)
nb302_altivec (Coul=Table, No VdW, water=SPC/TIP3P-SPC/TIP3P)
nb303_altivec (Coul=Table, No VdW, water=TIP4P-other atom)
nb304_altivec (Coul=Table, No VdW, water=TIP4P-TIP4P)
nb311_altivec (Coul=Table, VdW=L-J, water=SPC/TIP3P-other atom)
nb312_altivec (Coul=Table, VdW=L-J, water=SPC/TIP3P-SPC/TIP3P)
nb313_altivec (Coul=Table, VdW=L-J, water=TIP4P-other atom)
nb314_altivec (Coul=Table, VdW=L-J, water=TIP4P-TIP4P)
nb331_altivec (Coul=Table, VdW=Table, water=SPC/TIP3P-other atom)
nb332_altivec (Coul=Table, VdW=Table, water=SPC/TIP3P-SPC/TIP3P)
nb333_altivec (Coul=Table, VdW=Table, water=TIP4P-other atom)
nb334_altivec (Coul=Table, VdW=Table, water=TIP4P-TIP4P)
nb400_altivec (Coul=GB, No VdW, no water optimization)
nb410_altivec (Coul=GB, VdW=L-J, no water optimization)
nb430_altivec (Coul=GB, VdW=Table, no water optimization)