# Fyntv Register Definitions

REGISTER x0
  ABBR zero
  DESC Always-zero register — reads return 0, writes are discarded
  PRESERVE false
  CALLER false
  ARG false
  INDEX 0
END

REGISTER x1
  ABBR ra
  DESC Return address link register
  PRESERVE false
  CALLER false
  ARG false
  INDEX 1
END

REGISTER x2
  ABBR sp
  DESC Stack pointer
  PRESERVE true
  CALLER false
  ARG false
  INDEX 2
END

REGISTER x3
  ABBR gp
  DESC Global pointer
  PRESERVE true
  CALLER false
  ARG false
  INDEX 3
END

REGISTER x4
  ABBR tp
  DESC Thread pointer
  PRESERVE true
  CALLER false
  ARG false
  INDEX 4
END

REGISTER x5
  ABBR t0
  DESC Temporary register 0
  PRESERVE false
  CALLER true
  ARG false
  INDEX 5
END

REGISTER x6
  ABBR t1
  DESC Temporary register 1
  PRESERVE false
  CALLER true
  ARG false
  INDEX 6
END

REGISTER x7
  ABBR t2
  DESC Temporary register 2
  PRESERVE false
  CALLER true
  ARG false
  INDEX 7
END

REGISTER x8
  ABBR s0
  DESC Saved register 0 / frame pointer
  PRESERVE true
  CALLER false
  ARG false
  INDEX 8
END

REGISTER x9
  ABBR s1
  DESC Saved register 1
  PRESERVE true
  CALLER false
  ARG false
  INDEX 9
END

REGISTER x10
  ABBR a0
  DESC Function argument 0 / return value 0
  PRESERVE false
  CALLER true
  ARG true
  INDEX 10
END

REGISTER x11
  ABBR a1
  DESC Function argument 1 / return value 1
  PRESERVE false
  CALLER true
  ARG true
  INDEX 11
END

REGISTER x12
  ABBR a2
  DESC Function argument 2
  PRESERVE false
  CALLER true
  ARG true
  INDEX 12
END

REGISTER x13
  ABBR a3
  DESC Function argument 3
  PRESERVE false
  CALLER true
  ARG true
  INDEX 13
END

REGISTER x14
  ABBR a4
  DESC Function argument 4
  PRESERVE false
  CALLER true
  ARG true
  INDEX 14
END

REGISTER x15
  ABBR a5
  DESC Function argument 5
  PRESERVE false
  CALLER true
  ARG true
  INDEX 15
END

REGISTER x16
  ABBR a6
  DESC Function argument 6
  PRESERVE false
  CALLER true
  ARG true
  INDEX 16
END

REGISTER x17
  ABBR a7
  DESC Function argument 7
  PRESERVE false
  CALLER true
  ARG true
  INDEX 17
END

REGISTER x18
  ABBR s2
  DESC Saved register 2
  PRESERVE true
  CALLER false
  ARG false
  INDEX 18
END

REGISTER x19
  ABBR s3
  DESC Saved register 3
  PRESERVE true
  CALLER false
  ARG false
  INDEX 19
END

REGISTER x20
  ABBR s4
  DESC Saved register 4
  PRESERVE true
  CALLER false
  ARG false
  INDEX 20
END

REGISTER x21
  ABBR s5
  DESC Saved register 5
  PRESERVE true
  CALLER false
  ARG false
  INDEX 21
END

REGISTER x22
  ABBR s6
  DESC Saved register 6
  PRESERVE true
  CALLER false
  ARG false
  INDEX 22
END

REGISTER x23
  ABBR s7
  DESC Saved register 7
  PRESERVE true
  CALLER false
  ARG false
  INDEX 23
END

REGISTER x24
  ABBR s8
  DESC Saved register 8
  PRESERVE true
  CALLER false
  ARG false
  INDEX 24
END

REGISTER x25
  ABBR s9
  DESC Saved register 9
  PRESERVE true
  CALLER false
  ARG false
  INDEX 25
END

REGISTER x26
  ABBR s10
  DESC Saved register 10
  PRESERVE true
  CALLER false
  ARG false
  INDEX 26
END

REGISTER x27
  ABBR s11
  DESC Saved register 11
  PRESERVE true
  CALLER false
  ARG false
  INDEX 27
END

REGISTER x28
  ABBR t3
  DESC Temporary register 3
  PRESERVE false
  CALLER true
  ARG false
  INDEX 28
END

REGISTER x29
  ABBR t4
  DESC Temporary register 4
  PRESERVE false
  CALLER true
  ARG false
  INDEX 29
END

REGISTER x30
  ABBR t5
  DESC Temporary register 5
  PRESERVE false
  CALLER true
  ARG false
  INDEX 30
END

REGISTER x31
  ABBR t6
  DESC Temporary register 6
  PRESERVE false
  CALLER true
  ARG false
  INDEX 31
END