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m4 - macro processor
PD m4 is based on the macro tool distributed with the software
tools (VOS) package, and described in the "SOFTWARE TOOLS" and
"SOFTWARE TOOLS IN PASCAL" books. It has been expanded to include
most of the command set of SysV m4, the standard UN*X macro processor.
Since both PD m4 and UN*X m4 are based on SOFTWARE TOOLS macro,
there may be certain implementation similarities between
the two. The PD m4 was produced without ANY references to m4
sources.
written by: Ozan S. Yigit
References:
Software Tools distribution: macro
Kernighan, Brian W. and P. J. Plauger, SOFTWARE
TOOLS IN PASCAL, Addison-Wesley, Mass. 1981
Kernighan, Brian W. and P. J. Plauger, SOFTWARE
TOOLS, Addison-Wesley, Mass. 1976
Kernighan, Brian W. and Dennis M. Ritchie,
THE M4 MACRO PROCESSOR, Unix Programmer's Manual,
Seventh Edition, Vol. 2, Bell Telephone Labs, 1979
System V man page for M4
Implementation Notes:
[1] PD m4 uses a different (and simpler) stack mechanism than the one
described in Software Tools and Software Tools in Pascal books.
The triple stack thing is replaced with a single stack containing
the call frames and the arguments. Each frame is back-linked to a
previous stack frame, which enables us to rewind the stack after
each nested call is completed. Each argument is a character pointer
to the beginning of the argument string within the string space.
The only exceptions to this are (*) arg 0 and arg 1, which are
the macro definition and macro name strings, stored dynamically
for the hash table.
. .
| . | <-- sp | . |
+-------+ +-----+
| arg 3 ------------------------------->| str |
+-------+ | . |
| arg 2 --------------+ .
+-------+ |
* | | |
+-------+ | +-----+
| plev | <-- fp +---------------->| str |
+-------+ | . |
| type | .
+-------+
| prcf -----------+ plev: paren level
+-------+ | type: call type
| . | | prcf: prev. call frame
. |
+-------+ |
| <----------+
+-------+
|
