/* TRIVIAL VALUE */

// spmat.h:PREFIX##find_element

#define spmat_IMPLEMENT_mix(MATRIX_TYPE,PREFIX,ELEM_TYPE) \
  spmat_DECLARE_mix(MATRIX_TYPE,PREFIX,ELEM_TYPE) \
    { spmat_pos_t posC = 0; \
      PREFIX##_entry_t *eCprev = NULL; /* Last entry stored into {C}. */ \
       \
      auto void mix_entries \
        ( spmat_index_t row, \
          spmat_index_t col, \
          const ELEM_TYPE Aij, \
          const ELEM_TYPE Bij \
        ); \
       \
      void mix_entries \
        ( spmat_index_t row, \
          spmat_index_t col, \
          const ELEM_TYPE Aij, \
          const ELEM_TYPE Bij \
        ) \
        { ELEM_TYPE val; \
          if (PREFIX##_elem_is_trivial(Aij)) \
            { val = PREFIX##_elem_mul(b, Bij); } \
          else if (PREFIX##_elem_is_trivial(Bij)) \
            { val = PREFIX##_elem_mul(a, Aij); } \
          else \
            { ELEM_TYPE va = PREFIX##_elem_mul(a, Aij); \
              ELEM_TYPE vb = PREFIX##_elem_mul(b, Bij); \
              val = PREFIX##_elem_add(va, vb); \
            } \
          if (! PREFIX##_elem_is_trivial(val)) \
            { PREFIX##_expand(C, posC); \
              PREFIX##_entry_t *eC = &(C->e[posC]); \
              eC->row = row; eC->col = col; eC->val = val; \
              eCprev = eC; \
              posC++; \
            } \
        } \
       \
      C->rows = A->rows; \
      C->cols = A->cols; \
      PREFIX##_merge(A, B, &mix_entries); \
      PREFIX##_trim(C, posC); \
    }

  /* The parameters {orow,ocol} specify the order of the entries
    {M->e[posIni..posLim-1]}, as described under
    {PREFIX##_sort_entries} below; if they are not {0,0} (meaning
    `arbitrary order') the procedure will use binary search whenever
    possible. */

#define spmat_DECLARE_TRIVIAL_ELEM(MATRIX_TYPE,PREFIX,ELEM_TYPE) \
  ELEM_TYPE PREFIX##_trivial_elem(void)
/*
  This macro declares the function {PREFIX##_trivial_elem}.

  The call {val = PREFIX##_trivial_elem()} (with no arguments)
  will append into the variable {val} (of type {ELEM_TYPE})
  the value . */

#define spmat_DECLARE_ELEM_IS_TRIVIAL(MATRIX_TYPE,PREFIX,ELEM_TYPE) \
/*
  This macro declares the function {PREFIX##_elem_is_trivial}.

  The call {b = PREFIX##_elem_is_trivial(val)}
  will return the boolean value {TRUE} iff {val} is the
  element value which is not stored explicitly in the matrix. */

/* GENERIC SPARSE MATRIX DESCRIPTORS */

typedef struct spmat_t /* General sparse matrix descriptor. */
  { uint32_t rows;   /* Number of rows. */
    uint32_t cols;   /* Number of columns. */
    void *e;         /* Pointer to the first explicit entry. */
    uint32_t ents;   /* Number of explicit entries. */
  } spmat_t;
  /* A {spmat_t} {M} describes a uni-dimensional array of {M.ents} elements
    of the same size and type, stored in consecutive memory locations, starting
    at address {M.e}. */