lttv/doc/developer/lttng-format-string.txt

   1
   2 LTTng format string parsing
   3 July 26, 2007
   4
   5 "%lu"
   6 "#4b%u"
   7 "#lu%u" (no sign extension)
   8 "#ld%c" (sign extension)
   9 "#lld%p" (sign extension)
  10
  11 Parsing:
  12
  13 When # is encountered
  14   Deal with ## case (escaped)
  15   Read length modifier
  16     gcc-like
  17     trace specific : 1, 2, 4, 8, n, b
  18       in both cases, save the output type size (1, 2, 4, 8).
  19   Read conversion specifier
  20       save the output type size if no length modifier is involved (1, 2, 4, 8).
  21       save the signedness.
  22
  23 (vsnprintf-like part)
  24 When % is encountered
  25   Deal with %% case (escaped)
  26   (deal with field width, precision. Skip them.)
  27   Read length modifier
  28     if output type size is 0, set it to the gcc type size.
  29   Read conversion specifier
  30     if output type size is 0, set it to the gcc type size if no length modifier
  31         is involved.
  32   Perform trace write with conversion.
  33   Reset output type size to 0
  34
  35
  36
  37