func (c *sigctxt) r7() uint64  { return c.regs().mc_gpregs.gp_x[7] }
func (c *sigctxt) r8() uint64  { return c.regs().mc_gpregs.gp_x[8] }
func (c *sigctxt) r9() uint64  { return c.regs().mc_gpregs.gp_x[9] }
func (c *sigctxt) r10() uint64 { return c.regs().mc_gpregs.gp_x[10] }
func (c *sigctxt) r11() uint64 { return c.regs().mc_gpregs.gp_x[11] }
func (c *sigctxt) r12() uint64 { return c.regs().mc_gpregs.gp_x[12] }

	si_signo  int32
	si_errno  int32
	si_code   int32
	si_pid    int32
	si_uid    uint32
	si_status int32
	si_addr   uint64
	si_value  [8]byte
	_reason   [40]byte
}

type gpregs struct {
	gp_x    [30]uint64
	gp_lr   uint64
	gp_sp   uint64
	gp_elr  uint64
	gp_spsr uint32
	gp_pad  int32
}

type fpregs struct {
	fp_q     [64]uint64 // actually [32]uint128
	fp_sr    uint32

func (c *sigctxt) a2() uint64  { return c.regs().mc_gpregs.gp_a[2] }
func (c *sigctxt) a3() uint64  { return c.regs().mc_gpregs.gp_a[3] }
func (c *sigctxt) a4() uint64  { return c.regs().mc_gpregs.gp_a[4] }
func (c *sigctxt) a5() uint64  { return c.regs().mc_gpregs.gp_a[5] }
func (c *sigctxt) a6() uint64  { return c.regs().mc_gpregs.gp_a[6] }
func (c *sigctxt) a7() uint64  { return c.regs().mc_gpregs.gp_a[7] }

}

type gpregs struct {
	gp_ra      uint64
	gp_sp      uint64
	gp_gp      uint64
	gp_tp      uint64
	gp_t       [7]uint64
	gp_s       [12]uint64
	gp_a       [8]uint64
	gp_sepc    uint64
	gp_sstatus uint64
}

type fpregs struct {
	fp_x     [64]uint64 // actually __uint64_t fp_x[32][2]
	fp_fcsr  uint64
	fp_flags int32
	pad      int32
}

type mcontext struct {
	mc_gpregs gpregs

	op_UNPKA   uint32 = 0xEA00 // FORMAT_SS1        UNPACK ASCII
	op_UNPKU   uint32 = 0xE200 // FORMAT_SS1        UNPACK UNICODE
	op_UPT     uint32 = 0x0102 // FORMAT_E          UPDATE TREE
	op_X       uint32 = 0x5700 // FORMAT_RX1        EXCLUSIVE OR (32)
	op_XC      uint32 = 0xD700 // FORMAT_SS1        EXCLUSIVE OR (character)
	op_XG      uint32 = 0xE382 // FORMAT_RXY1       EXCLUSIVE OR (64)