How to write conversion functions
To convert calls to Matlab functions, mfile2sci
uses a function called
sci_<Matlab_function_name>
. All these functions are defined in sci_files
in directory SCI/modules/m2sci/macros/sci_files/. The set of sci_files
given in Scilab
distribution does not allow to convert calls to all Matlab functions yet.
However, a Scilab user can add sci_files
(for Matlab functions or for user defined functions)
to Scilab using the following tips.
In M2SCI, a function call is considered as a "tree" (it is also the case for the instructions
of the file to convert), represented in Scilab by a tlist
with following fields:
Matlab function name
number of Matlab function output parameters
list of Matlab function output parameters
list of Matlab function input parameters
A sci_function
has one input called tree
which is also the output of the function.
A sci_function
has to convert this incoming "tree" so that it is compatible with Scilab
by changing name, lhsnb, lhs and/or rhs. The other task that has to be done by this function
is inference. Incoming tree contains inference data in its lhs that have to be updated with what
can be infered for the outputs of this function.
Some useful functions have been written to help to create M2SCI tlists while writing this conversion function:
create a tree representing a function call
create a tree representing an operation
create a tree representing a variable
create a tree representing a constant value
create a tree representing inference data
create a tree representing type for inference
create a tree representing an instruction
Some other functions have been designed to get properties of operands/inputs. Considering A is tlist used in macro tree, you can use the following functions:
Function | returns %T if... |
is_empty(A) |
all dimensions of A are 0 |
not_empty(A) |
all dimensions of A are known and at least one dimension of A is not 0 |
is_a_scalar(A) |
all dimensions of A are 1 |
not_a_scalar(A) |
all dimensions of A are known and at least one dimension of A is not 1 |
is_a_vector(A) |
all dimensions of A are known and all dimensions of A but one are equal to 1 |
not_a_vector(A) |
all dimensions of A are known and at least two dimensions of A are greater than one |
is_real(A) |
A is real |
is_complex(A) |
A is complex |
isdefinedvar(A) |
A is a variable already created in M-file currently converted |
allunknown(A) |
all dimensions of A are unknown |
Some other functions have been written for specific needs while writing conversion files:
is an equivalent to firstnonsingleton for an M2SCI tlist. Syntax: dim = first_non_singleton(A)
generates a temporary variable having a name which does not already exist. Syntax:v = gettempvar()
allows to insert instructions. Syntax:m2sci_insert(Equal(...),opt)
with opt~=1
to insert before current instruction and opt=1
to insert after it.
can be used to get each operand as a variable. Syntax: [A,B] = getoperands(operation_tlist)
can be used to get each parameter as a variable. Syntax: [A,...] = getrhs(funcall_tlist)
change type of input when this type is not implemented for a particular function is Scilab. Syntax:A = convert2double(A)
To have more information about how to write such files, refer to directory SCI/modules/m2sci/macros/sci_files/ which gives many examples from very simple ones (e.g. sci_abs.sci) to very complex ones (e.g. sci_zeros.sci).