stringio_examples

stringio_examples — Enhancement-11 string-formatting & file-reading functions

End-to-end verification of the Verilog-AMS string-formatting and file-reading system functions implemented in Enhancement-11 (the counterparts to the file-output set in ../fileio_examples/), using version11's own openvaf-r and ngspice-46.

Functions covered: $swrite, $sformat, $sscanf, $fgets, $fscanf, $ferror.

Files

File	Purpose
stringio_demo.va	Formats strings ($sformat/$swrite), parses a literal ($sscanf), round-trips a file read ($fgets/$fscanf over a file it wrote itself), queries $ferror, and writes a report.
verify_stringio.py	Runs a .op and checks the report against expected values.
stringio_out.txt, _sio.cir, *.osdi	Artifacts.

Run

python3 verify_stringio.py

Expected tail:

ALL PASS (6/6)

What it checks (stringio_out.txt)

sformat=[R=1000 G=0.001]
swrite=[n= 5 ok]
sscanf=3 42 3.14 [hello]
fgets=13
fscanf=2 99 2.5
ferror=0 []

• $sformat/$swrite format into a string variable ($swrite concatenates like $write).
• $sscanf("42 3.14 hello", ...) parses an int / real / string and returns the match count (3).
• $fgets reads the line "line seven 7\n" back from a file (length 13, including the newline).
• $fscanf parses "99 2.5" from a file (count 2).
• $ferror on a good descriptor returns code 0 and an empty message.

Notes

The scanner parses each field by the destination variable's type (int via strtol, real via strtod, string as the next whitespace-delimited token) rather than by interpreting the C format string — adequate for the usual whitespace-separated input. As with the file-output functions, keep string/file I/O parameter/setup-derived so it runs once in the model's initialization code (see ../Enhancement-11.md §1.3, §6).