RSF Comprehensive Description
RSF "files" actually consist of a header file and a data file. Normally one manipulates the header file.
This file attempts to document the actual interface implemented in file.c; it is not a formal specification, and in the event of a disagreement the code should be taken as the official reference.
This is presented to facilitate reading of file.c and development of new RSF utilities.
Corrections and improvements are welcome.
Header Files
Associated with each such data file is a header file. The header file is 7 bit ASCII (UTF-7).
Lines with no "=" are considered comments and are ignored. Lines with more than one "=" are illegal.
Lines with a single "=", with no adjacent spaces, assign a value to an alphanumeric named variable
Textstrings must be delimited by pairs of quotes. Numerical values are subject to C's parsing rules.
"in=" parameter contains the fully qualified path to the relevant data and is required
"n#" (n1, n2, n3) etc. is the number of points in a dimension. n1 is the fastest direction (maps directly onto memory).
n1 must be specified. The size of the array is the product of all n# values with the size of the fundamental type
Optional elements
In addition to the above, many filters enforce the following conventions:
"d#" is the physical spacing in the respective dimension
"o#" is the physical origin in some absolute coordinate system of the respective dimension
Data Files
Data files are rectangular arrays of data. The following data formats are supported
- ASCII (C-compatible input)
- XDR (device independent binary standard)
- native binary (default)
ASCII format is most useful for debugging, while XDR format is useful for portability across formats.
Performance is optimized for native format.
The following data formats are supported:
- unsigned byte
- byte
- int (native int)
- short (2 bytes)
- float (native float)
- complex (real, imaginary float pairs)
RSF files in streams
Input
When a Madagascar program writes a RSF file to disk (i.e.: sfprog >file.rsf), it will create a header file and a binary file as described above.
If the output is to a stream, or if the parameter --out=stdout is passed to the program, then the program will write to the stdout stream the ASCII header, followed by the sequence of three special characters: EOL EOL EOT (\014\014\004), followed by the binary.
Output
When a Madagascar program reads from the stdin stream, it expects either a EOF character indicating the end of the ASCII header (after which it transfers the stdin to reading from the binary cube), or a EOL EOL EOT sequence indicating that the data follows immediately on stdin.