Adjust implementations of set_value and set_value_at_indices to more closely follow BMI standard

[SnowHydrology]

Our current implementations of set_value and set_value_at_indices are not consistent with the BMI 2.0 standard and should be adjusted for compliance.

Current behavior

The bmi_cfe.c code treats set_value as a special case of set_value_at_indices where the former calls the latter. This is not correct.

This non-standard set_value implementation also makes the sometimes-okay-but-not-always assumption that all variables are scalar by hard-coding the inds variable dimension and the length argument in the function call to set_value_at_indices.

Furthermore, in this configuration, CFE parameters are settable via set_value_at_indices, which only works as a result of the non-standard implementation of set_value. Also of note is that the index values are not passed to the variables in set_value_at_indices, which only works if the variable is a scalar.

Expected behavior

set_value should copy the values from a source array to a destination array in the model, corresponding to the given variable (obviously the array sizes must match).

set_value_at_indices, similarly, sets a value or values, but only corresponding to the index or indices provided.

In C, both functions rely on the memcpy function. Given the syntax (memcpy (dest, array, nbytes); for set_value vs. memcpy (CHAR_CAST to + offset, ptr, itemsize); for set_value_at_indices), it appears more that the latter is a specific case of the former, rather than vice versa.

The set_value function should follow the code provided in TOPMODEL and in the BMI C example.

The set_value_at_indices function should also follow the code provided in TOPMODEL and in the BMI C example.

These changes will additionally require an update to the implementation of calibratable parameters in CFE. At minimum, these should be moved to set_value from set_value_at_indices.

Further discussion can be found here.