Mail Archives: djgpp/1997/02/25/23:13:47
nikki (nikki AT gameboutique DOT co) wrote:
: > Actually... The fpu memcpy and MMX memcpy which both copy 8 bytes at a time
: > are basically the same. They're both using the same processor and fpu stack.
: >
: > hmm.. gotta learn djgpp style asm so I can port it to djgpp..
: if y'all want an fpu memcopy in inline asm for djgpp i wrote one here :)
: sadly it's not as good as the old rep movsd though :( basically fpu memcopy
: will outperform anything given that you can guarentee none of the 8bytes you
: are moving will cause an fpu exception. if they do you have to do it the
how can they cause an exception? When moving 8 bytes at a time (with
fild/fistp) you're using integers all the way. If you on the other hand use
fld/fstp (and can copy up to 10bytes at a time, but loose accuracy and get
exceptions and additional cache misses) I understand..
: 'safe' way which gives you a transfer rate of 16bytes/16cycles and 1/2 as
: many cache write misses. if it's 686 or higher you get 1/4 write cache misses.
: sadly, if it's 686 or higher the rep movsd will go faster ;(
: basically fpu memcopy is not all it's cracked up to be.
who's got a 686 anyway (or PPro?) ?
- Raw text -