Messages in this thread | | | Date | Fri, 27 May 2005 09:25:26 +0200 | From | Mikael Pettersson <> | Subject | Re: 387 emulator hack - mutant AAD trick - any objections? |
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cutaway@bellsouth.net writes: > Will there be any objections to using a quasi-documented mutation of the > x86's AAD instruction in the 387 emulator? Every CPU around has to do this > mutation correctly or a LOT of existing code will break... > > The performance of storing to user space of BCD numbers in the 387 emulator > code could be improved significantly by using the mutant AAD instruction > trick (i.e. alter its implicit base from 10 to 16). See reg_ld_str.c, in > function FPU_store_bcd()
What do you mean by "quasi-documented" and "mutant"? Intel certainly documents the "D5 ib" form as being a valid way to change the base from the default 10.
The only issue AFAIK is that assemblers may only recognise the plain base-10 AAD syntax. No biggie.
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