[RFC] Vector extentions for vprintf/vscanf

[Steve Munroe]

A number of platforms support Vector (SIMD) extentions that support with 
types and builtins in gcc. This includes i386 MMX, 3Dnow!, SSE, SSE2, 
PowerPC 32 (and now PowerPC64) Altivec/VMX.

One useful extention to glibc would be adding vector formating to 
printf/scanf. This would add the type modifier prefix v to the type 
modifiers hh, h, l. For example to print a vector of 16 signed bytes 
"%vhhd", 8 signed shorts "%vhd", 4 signed ints "%vd", or 4 floats 
"%vhf". (note the form "%vf" is reserved for a vector of 2 doubles but 
most current Vector SIMD implimentations don't support double float).

We would be happy to provide the supporting patches and documentation if 
there is interrest.