~drizzle-trunk/drizzle/development

File   : README

Author : Richard A. O'Keefe.

Updated: 30 April 1984

Purpose: Explain the new strings package.

    The UNIX string libraries (described in the string(3) manual page)

differ from UNIX to UNIX (e.g. strtok is not in V7 or 4.1bsd).  Worse,

the sources are not in the public domain, so that if there is a string

routine which is nearly what you want but not quite you can't  take  a

copy  and  modify it.  And of course C programmers on non-UNIX systems

are at the mercy of their supplier.

    This package was designed to let me do reasonable things with  C's

strings  whatever UNIX (V7, PaNiX, UX63, 4.1bsd) I happen to be using.

Everything in the System III manual is here and does just what the  S3

manual  says  it does.  There are also lots of new goodies.  I'm sorry

about the names, but the routines do have to work  on  asphyxiated-at-

birth  systems  which  truncate identifiers.  The convention is that a

routine is called

 str [n] [c] <operation>

If there is an "n", it means that the function takes an (int) "length"

argument, which bounds the number of characters to be moved or  looked

at.  If the function has a "set" argument, a "c" in the name indicates

that  the complement of the set is used.  Functions or variables whose

names start with _ are support routines which aren't really meant  for

general  use.  I don't know what the "p" is doing in "strpbrk", but it

is there in the S3 manual so it's here too.  "istrtok" does not follow

this rule, but with 7 letters what can you do?

    I have included new versions of atoi(3) and atol(3) as well.  They

use a new primitive str2int, which takes a pair of bounds and a radix,

and does much more thorough checking than the normal atoi and atol do.

The result returned by atoi & atol is valid if and only if errno == 0.

There is also an output conversion routine int2str, with itoa and ltoa

as interface macros.  Only after writing int2str did I notice that the

str2int routine has no provision for unsigned numbers.  On reflection,

I don't greatly care.   I'm afraid that int2str may depend on your "C"

compiler in unexpected ways.  Do check the code with -S.

    Several of these routines have "asm" inclusions conditional on the

VaxAsm option.  These insertions can make the routines which have them

quite a bit faster, but there is a snag.  The VAX architects, for some

reason best known to themselves and their therapists, decided that all

"strings" were shorter than 2^16 bytes.  Even when the length operands

are in 32-bit registers, only 16 bits count.  So the "asm" versions do

not work for long strings.  If you can guarantee that all your strings

will be short, define VaxAsm in the makefile, but in general, and when

using other machines, do not define it.

    To use this library, you need the "strings.a" library file and the

"strings.h" and "ctypes.h" header files.  The other header  files  are

for compiling the library itself, though if you are hacking extensions

you  may  find  them useful.  General users really shouldn't see them.

I've defined a few macros I find useful in "strings.h"; if you have no

need for "index", "rindex", "streql", and "beql", just edit them  out.

On the 4.1bsd system I am using declaring all these functions 'extern'

does not mean that they will all be loaded; but only the ones you use.

When using lesser systems you may find it necessary to break strings.h

up, or you could get by with just adding "extern" declarations for the

functions you want as you need them.  Many of these functions have the

same names as functions in the "standard C library", by design as this

is a replacement/reimplementation of part of that library.  So you may

have to talk the loader into loading this library first.   Again, I've

found no problems on 4.1bsd.

    You may wonder at my failure to provide manual pages for this code.

For the things in V7, 4.?, or SIII, you should be able to use whichever

manual page came with that system,  and anything I might write would be

so like it as to raise suspicions of violating AT&T copyrights.  In the

sources you will find comments which provide far more documentation for

these routines than AT&T ever provided for their strings stuff,  I just

don't happen to have put it in nroff -man form.   Had I done so, the .3

files would have outbulked the .c files!

    These files are in the public domain.  This includes getopt.c, which

is the work of Henry Spencer, University of Toronto Zoology, who says of

it "None of this software is derived from Bell software. I had no access

to the source for Bell's versions at the time I wrote it.  This software

is hereby explicitly placed in the public domain.  It may  be  used  for

any purpose on any machine by anyone." I would greatly prefer it if *my*

material received no military use.