openpower/sv/mv.swizzle.mdwn

   1 # mv.swizzle
   2
   3 # Format
   4
   5 | 0..5 |6..10|11..15|16.20|21.....25|26.....30|31|  name   |
   6 |------|-----|------|-----|---------|---------|--|---------|
   7 | 19   | RT  | RA   |     | XO[0:4] | XO[5:9] |Rc| XL-Form |
   8 | 19   | RT  | RA   |imm  | imm     | NNNNN   |im| mv.swiz |
   9
  10 also f.mv
  11
  12 this gives an 11 bit immediate across bits 16 to 25 and bit 31.  a permutation based encoding should allow the 12 bits to be covered
  13
  14 * 3 bits X
  15 * 3 bits Y
  16 * 3 bits Z
  17 * 3 bits W
  18
  19 except that the options are:
  20
  21 * 0b1NN index 0 thru 3 to place subelement in pos XYZW
  22 * 0b000 to indicate "skip"
  23 * 0b001 to indicate "constant 0"
  24 * 0b010 to indicate "constant 1" (or 1.0)
  25 * 0b011 is not needed.
  26
  27 this "not needed" means the encoding is actually a lot less.  the sequences involve expressing how many 0s and 1s are embedded in amongst the XYZWs which gets really interesting.
  28