The file dm.h

In order to maximize transportability of code across different computers, the file dm.h in diffmic/c/util provides several definitions.

• It does #include <sys/types.h> so that one can refer to data types that (unlike short int, int, or long int which can vary in size from one compiler/processor to another) are of known size on any machine, like u_int16_t for a 16 bit unsigned integer, and so on.
• It also includes the file endian.h so that BYTE_ORDER is set to either LITTLE_ENDIAN=1234 (such as on Intel processors) or BIG_ENDIAN=4321 (such as on PowerPC and SPARC processors)^1.2.
• Depending on the presence or absence of the preprocessor #define of DIST_FFT, it either includes dist_fft.h or fftw3.h (see Sec. 6.2).
• It defines dm_array_real which is either float or double, according to the absence or presence of the preprocessor #define of DM_ARRAY_DOUBLE as described below.
• It defines dm_array_index_t which is an integer large enough to index an entire complex 3D array. This is presently set to u_int32_t. (Should this be set to size_t?)
• It defines array structures dm_array_complex_struct, dm_array_real_struct, and dm_array_byte_struct, as described in Sec. 1.4.5.
• For complex arrays, it defines the macros c_re() and c_im(), and memory allocation routines, as described in Sec. 1.4.4.
• It defines structures dm_adi_struct (see Sec. 2.2.2), dm_spt_struct (see Sec. 2.2.6), and dm_itn_struct (see Sec. 2.2.7) containing parameters relevant to different data or calculations.