WARNING! Version 1.5 of the BDS C Compiler will not work under
pre-2.x versions of the CP/M operating system. In order to take
full advantage of CP/M 2.x I/O mechanisms without introducing
really painful configuration complications, compatibility with
CP/M 1.4 (or earlier versions) has been sacrificed. Users who
cannot upgrade their CP/M's to version 2.x must go on using v1.46
of the compiler. Sorry about that.)
You Can Now Get BDS C From Vendors Other Than Lifeboat
So far, the only definite alternative distributor is the BDS C User's
Group. I am at a very flexible position right now regarding dealer
distribution arrangements, and welcome inquiries from potential
distributors. I'm not going to go running to every outfit that advertises
in BYTE and beg them to sell the compiler, simply because I'm not sure how
much of a hassle I'd be signing up for by that behavior. Rather, I'd like
to see small-scale hacker types involved in distribution, so that end-users
can have a prayer of receiving INTELLIGENT customer service. Gads, anytime
I get to rambling about something interesting I begin to wonder if it is
bordering on a commercialistic exploitation of the ARPA net!???? To play it
safe: if anyone reading this paragraph objects to the content, feel free to
delete it from this file.
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New Command Line Options
CLINK now takes a new option, -n, which causes the resulting COM file to
not perform a warm-boot after it is finished executing. This option
performs the function that v1.46's NOBOOT.C program had been doing. Note
that when -n is used, there is approximately 2K less user memory available
because the CCP is not overwritten.
CC (formerly named CC1) now takes the option -k, to activate the Kirkland
debugger mechanism. This causes a special symbol table file (having
extension .CDB) to be written to disk, and causes the compiler to generate
special restart instructions at the start of every statement to interact
with David Kirkland's C debugger package. The debugger may not be included
on the distribution disk for space limitation reasons, but is available for
nominal cost-of-media cost from the BDS C User's Group or from BD Software
(on 8" disk) via special arrangement.
Functional Changes to Major Commands
CLINK now automatically loads all functions, by default, from each CRL
given on the command line in a linkage. The -f option is now reversed in
sense from previous versions, and operates exactly the same as L2's -l
option...i.e., -f appearing on a CLINK command line causes all CRL files
named after it to be scanned instead of loaded, while all CRL files named
before the -f flag are loaded. This makes the general format of a CLINK
command line be:
Other options may be interspersed in the command line, of course.
New Low-Level File I/O Features
- All the low-level file I/O now uses the CP/M 2.2x random-record read
and write calls. Therefore, files may be up to 8 megabytes in length
instead of only up to 256K bytes.
- The "seek" function may be given an origin code of 2, meaning to seek
relative to the end of the file. Note that the offset must be negative
in this case to make sense, since it is always added to the base, which
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in this case is the end of the file. For example, the following call
seeks to the next-to-last sector in the file:
seek(fd, -2, 2); /* seek to 2nd sector from end of file */
- User number prefixes are now accepted wherever a filename argument is
called for. Such a prefix consists of a decimal number between 0 and
31, followed immediately by a slash (/) character and then the filename
(with or without an optional disk designator). This causes the file
I/O mechanism to switch into the user area associated with each file
for the duration of any I/O operation involving that file, then switch
back to the current user area when done. Any filename may now take
either an explicit disk designator, an explicit user area, or both. If
both are given, then the user area specification must precede the disk
designator. Here is an example:
if (open("0/A:DATABASE.DAT",2) == ERROR)
exit(puts("Can't open the database, turkey. \n"));
Note that this allows programs in separate user areas to manipulate a
common data file kept on one particular drive and user area,
eliminating the need to have a separate copy of the data file in each
user area needing it. If you are running the "ZCPR" public-domain CCP
replacement program for CP/M, or any shell (such as "MicroShell") that
searches special drives and user areas for command files, then that
feature combined with the user-area enhancements to the file I/O
library allow a very efficient utilization of the CP/M filesystem.
- There are some new functions that provide better diagnosis of errors
caused by low-level file I/O calls. Whenever a call such as open, read
or write returns a value of -1 (ERROR), the errno function may be
called to return a more detailed error description code explaining
exactly what went wrong. The errmsg function may be used to return a
pointer to a string corresponding to the error value returned by errno.
A typical usage of these functions is as follows:
i = read(fd, buffer, 20); /* try to read 20 sectors */
if (i == ERROR) { /* if an error occurred...*/
printf("\n%s -- ABORTING THIS PROGRAM.",
errmsg(errno));
exit();
}
New Library File Searching Capabilities
Both the compiler and linker (CC and CLINK) now have the ability to search
for library files in a default CP/M drive and user area, sometimes in
addition to the currently-logged drive and user area. If the user
configures CC and CLINK as described in the configuration section below,
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then CC will know to search a default directory for included files named in
angle brackets, and CLINK will know to search a default directory for
library files. Also, if a CRL file is named on the CLINK command line and
CLINK cannot find that file in the current drive and user area, then the
default area (as configured) will be searched for that file.
CLINK now accepts user area prefixes on CRL filenames given on the command
line (except for the main CRL file, which must be in the current user
area.) If an explicit disk drive and/or user area specification is given on
the CRL filename to CLINK, then the default area will not be searched
automatically. This is so that if an explicit user area is given for a new
test version of a CRL file, and a similarly named CRL file exists in the
default library area, then the one in the default area will not be used if
the explicitly named one is not found.
Configuration
BDS C commands should simply come up running under any CP/M system,
without any special configuration procedure necessary. There are several
optional features of the compiler and linker that may be configured by the
user to increase the flexibility of the package. This subsection explains
each of those options and how to select them.
If Running MPM II:
If you are running BDS C under MP/M II, you must re-assemble the run-time
package with the "MPM2" symbol equated to 1 (it comes configured to 0).
Simply edit the CCC.ASM file, assemble it using ASM, use LOAD to create
CCC.COM, then rename that to C.CCC.
CC and CLINK configuration
There are several user-configurable features in CC.COM and CLINK.COM
controlled by a specific bytes of memory very close to the beginning of each
command file. In order to change these features, use DDT or SID to read
CC.COM or CLINK.COM into memory (noting the length of the file printed upon
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successful loading 1), make the changes using the s command, hit control-C,
and use the CP/M SAVE command to write the modified command back to disk.
Make sure to have your master distribution disk safely tucked away somewhere
before attempting these modifications!
Both CC.COM and CLINK.COM contain an identically structured four-byte
configuration block. The base address of the block for CC.COM is 0155h, and
for CLINK it is 0103h. The contents of the block are as follows:
Addr. Function Default value
base+0 Default library disk FF (current)
base+1 Default library user area FF (current)
base+2 Disk where SUBMIT files are processed 00 (disk A)
base+3 Poll console for interrupts (0 or 1) 01 (enabled)
Note that each item in the block is exactly one byte in length. The first
two items specify a default disk and user area to be treated as a "library
directory" by CC and CLINK. For CC, the library directory specifies where to
find the files named in #include directives when the filename is enclosed in
angle brackets 2, and also where to find CC2.COM for the second phase of
compilation. For CLINK, this says where to find the files DEFF.CRL,
DEFF2.CRL, DEFF3.CRL (if present) and C.CCC.
For the default library disk, a value of 0 specifies drive A, 1 specifies
drive B, etc., and a value of FFh (255 decimal) specifies that the
currently-logged disk is to be used as the default library disk. For the
default library user area, the values 0-15 denote the corresponding user
area, and a value of FFh (255 decimal) specifies that the current user area
is to be the default library user area. Both the library disk and user area
come configured to FFh; thus, the distribution version of the v1.50 compiler
and linker behave the same as earlier versions, in which the current drive
and user area were always assumed to contain the library files by default.
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1. To convert the hex address printed by DDT or SID for the last address of
the file into the decimal number you must give to the SAVE command, use the
following algorithm: take the leftmost two hex digits, and compute their
decimal equivalent (e.g., 3C80 yields 3C, which is 60 decimal). Then,
subtract 1 from that if the rightmost two digits are 00. The final result is
the number to give SAVE.
2. Filenames enclosed in double quotes always cause the #include directive
to search the current directory for the named file, regardless of
configuration
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The third location designates which CP/M drive contains the $$$.SUB file
that exists during "Submit File" processing. CLINK always tries to erase
pending submit files when an error occurs, while CC only tries to do so when
the -x option is given. Since most systems always place the $$$.SUB file on
drive A, that is the way CC and CLINK come configured by default. But, if
the user has customized his system to put the $$$.SUB file on the current
drive instead of always on A:, then the byte pointed to by the address in
these locations should be changed from 01 to 00.
The fourth and final location in the configuration block is a simple flag
telling CC or CLINK whether or not the system console should be polled for
the interrupt character (^C) during execution of the command. If enabled
(non-zero), then any input typed on the console by the user during execution
of the command will be ignored unless ^C is typed, in which case the command
will be immediately aborted and control will return to command level. If
disabled (zero), then the console will never be polled. This is useful for
certain interrupt driven systems that need to recognize type-ahead and can
handle interruption on their own without needing to be polled by the
currently executing transient command.
This configuration scheme allows users with large-capacity disks to pick
some particular drive and user area in which to keep all standard header and
library files. The library disk and user area bytes should be considered
together as a unit; if you change one, you'll probably want to change the
other also.
Note that CC2.COM does not need to be configured; CC.COM passes it all the
relevant information upon transfer of control.
