/* i/n/x.h
**
** This file is in the public domain.
*/
  /**  Constants.
  **/
    /* Conventional axes for gate call.
    */
#     define u3x_pay      3       //  payload
#     define u3x_sam      6       //  sample
#       define u3x_sam_1  6
#       define u3x_sam_2  12
#       define u3x_sam_3  13
#       define u3x_sam_4  24
#       define u3x_sam_5  25
#       define u3x_sam_6  26
#       define u3x_sam_12 52
#       define u3x_sam_13 53
#       define u3x_sam_7  27
#       define u3x_sam_14 54
#       define u3x_sam_15 55
#       define u3x_sam_30 110
#       define u3x_sam_31 111
#     define u3x_con      7       //  context
#     define u3x_con_2    14      //  context
#     define u3x_con_3    15      //  context
#     define u3x_con_sam  30      //  sample in gate context
#     define u3x_bat      2       //  battery


  /**  Macros.
  **/
    /* Word axis macros.  For 31-bit axes only.
    */
      /* u3x_dep(): number of axis bits.
      */
#       define u3x_dep(a_w)   (c3_bits_word(a_w) - 1)

      /* u3x_cap(): root axis, 2 or 3.
      */
#       define u3x_cap(a_w) ({                        \
          c3_assert( 1 < a_w );                       \
          (0x2 | (a_w >> (u3x_dep(a_w) - 1))); })

      /* u3x_mas(): remainder after cap.
      */
#       define u3x_mas(a_w) ({                        \
          c3_assert( 1 < a_w );                       \
          ( (a_w & ~(1 << u3x_dep(a_w))) | (1 << (u3x_dep(a_w) - 1)) ); })

      /* u3x_peg(): connect two axes.
      */
#       define u3x_peg(a_w, b_w) \
          ( (a_w << u3x_dep(b_w)) | (b_w &~ (1 << u3x_dep(b_w))) )

  /**  Functions.
  **/
    /** u3x_*: read, but bail with c3__exit on a crash.
    **/
#if 1
#     define u3x_h(som)  u3a_h(som)
#     define u3x_t(som)  u3a_t(som)
#else
      /* u3x_h (u3h): head.
      */
        u3_noun
        u3x_h(u3_noun som);

      /* u3x_t (u3t): tail.
      */
        u3_noun
        u3x_t(u3_noun som);
#endif
      /* u3x_good(): test for u3_none.
      */
        u3_noun
        u3x_good(u3_weak som);

      /* u3x_at (u3at): fragment.
      */
        u3_noun
        u3x_at(u3_noun axe, u3_noun som);

      /* u3x_cell():
      **
      **   Divide `a` as a cell `[b c]`.
      */
        void
        u3x_cell(u3_noun  a,
                   u3_noun* b,
                   u3_noun* c);

      /* u3x_trel():
      **
      **   Divide `a` as a trel `[b c d]`, or bail.
      */
        void
        u3x_trel(u3_noun  a,
                   u3_noun* b,
                   u3_noun* c,
                   u3_noun* d);

      /* u3x_qual():
      **
      **   Divide `a` as a quadruple `[b c d e]`.
      */
        void
        u3x_qual(u3_noun  a,
                   u3_noun* b,
                   u3_noun* c,
                   u3_noun* d,
                   u3_noun* e);

      /* u3x_quil():
      **
      **   Divide `a` as a quintuple `[b c d e f]`.
      */
        void
        u3x_quil(u3_noun  a,
                   u3_noun* b,
                   u3_noun* c,
                   u3_noun* d,
                   u3_noun* e,
                   u3_noun* f);

      /* u3x_hext():
      **
      **   Divide `a` as a hextuple `[b c d e f g]`.
      */
        void
        u3x_hext(u3_noun  a,
                   u3_noun* b,
                   u3_noun* c,
                   u3_noun* d,
                   u3_noun* e,
                   u3_noun* f,
                   u3_noun* g);