sgn - Sign

sgn     dest, src0, src1, src2

Name	Registers
dest	An output register or temporary register.
src0	A temporary register or input register.
src1	A temporary register. Cannot specify swizzling or the negative sign.
src2	A temporary register. Cannot specify swizzling or the negative sign.

You cannot specify the same register for src1 and src2.
You cannot specify the same register for src0 and src1.
The calculation process uses src1 and src2.

Stores a value of 1, 0, or -1 in dest when src0 is positive, zero, or negative, respectively.

for ( each component )
{
    if ( src0.component < 0 )
        dest.component = -1
    else if ( src0.component == 0 )
        dest.component = 0
    else
        dest.component = 1
}

slt     src1,  src0, -src0
slt     src2, -src0,  src0
add     dest,  src2, -src1

sgn     r0, v1, r2, r3

	1	2	3	4	5	6	7
slt	read	SLT	write
slt		read	SLT	write
add			STALL	read	ADD	post	write

2011/12/20

Initial version.