docs: document the unformat '%_' option

Type: docs

Change-Id: Id864fcff768a78aa313b193f2eaabe545d95bec4
Signed-off-by: Paul Vinciguerra <pvinci@vinciconsulting.com>

diff --git a/docs/gettingstarted/developers/infrastructure.md b/docs/gettingstarted/developers/infrastructure.md
index 12f96d5..e50972d 100644 (file)
--- a/docs/gettingstarted/developers/infrastructure.md
+++ b/docs/gettingstarted/developers/infrastructure.md
@@ -278,6 +278,20 @@ The phrase "bitzero %|" means "set the specified bit in the supplied
 bitmask" if unformat parses "bitzero". Although it looks like it could
 be fairly handy, it's very lightly used in the code base.
 
 bitmask" if unformat parses "bitzero". Although it looks like it could
 be fairly handy, it's very lightly used in the code base.
 

+`%_` toggles whether or not to skip input white space.
+
+For transition from skip to no-skip in middle of format string, skip input white space.  For example, the following:
+
+```c     
+fmt = "%_%d.%d%_->%_%d.%d%_"
+unformat (input, fmt, &one, &two, &three, &four);
+```
+matches input "1.2 -> 3.4".
+Without this, the space after -> does not get skipped.
+
+
+```
+

 ### How to parse a single input line
 
 Debug CLI command functions MUST NOT accidentally consume input
 ### How to parse a single input line
 
 Debug CLI command functions MUST NOT accidentally consume input