##### 9.47.2.2 Register Names

`as` supports the following names for registers:

`general register 0`
  r0, zero
`general register 1`
  r1
`general register 2`
  r2, hp
`general register 3`
  r3, sp
`general register 4`
  r4, gp
`general register 5`
  r5, tp
`general register 6`
  r6
`general register 7`
  r7
`general register 8`
  r8
`general register 9`
  r9
`general register 10`
  r10
`general register 11`
  r11
`general register 12`
  r12
`general register 13`
  r13
`general register 14`
  r14
`general register 15`
  r15
`general register 16`
  r16
`general register 17`
  r17
`general register 18`
  r18
`general register 19`
  r19
`general register 20`
  r20
`general register 21`
  r21
`general register 22`
  r22
`general register 23`
  r23
`general register 24`
  r24
`general register 25`
  r25
`general register 26`
  r26
`general register 27`
  r27
`general register 28`
  r28
`general register 29`
  r29
`general register 30`
  r30, ep
`general register 31`
  r31, lp
`system register 0`
  eipc
`system register 1`
  eipsw
`system register 2`
  fepc
`system register 3`
  fepsw
`system register 4`
  ecr
`system register 5`
  psw
`system register 16`
  ctpc
`system register 17`
  ctpsw
`system register 18`
  dbpc
`system register 19`
  dbpsw
`system register 20`
  ctbp