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 . | +-------+ | | <----------+ +-------+