VFPU prefixes

holger · Post by **holger** » Thu Oct 06, 2005 5:37 am

Hi,

it seems that some VFPU instructions can swizzle/negate/replace-by-constant/mask/saturate vector components on the fly, nevertheless the opcode encoding rules seem somewhat complicated. Did anybody documented them somewhere?

see svn.pspdev.org/binutils-psp/opcodes/mips-dis.c, lines 1236 and below for an example.

Post by **mrbrown** » Thu Oct 06, 2005 5:43 am

You seem to be ignoring binutils-psp/gas/config/tc-mips.c where all of the VFPU operands execept for rotate and registers are implemented.

binutils-psp/include/opcode/mips.h may also be helpful.

holger · Post by **holger** » Thu Oct 06, 2005 5:48 am

oops, yes... thanks for the hint!

holger · Post by **holger** » Thu Oct 06, 2005 5:52 am

errrmmm... is it correct that prefixes in generated code actually appear as seperate vpfx instructions?

Post by **mrbrown** » Thu Oct 06, 2005 5:53 am

Yes, AFAIK.

holger · Post by **holger** » Thu Oct 06, 2005 5:55 am

ok, that brings light into the darkness.