The following functions make up the directed I/O library:
1. dioinit(&argc,argv) Make this the first thing you do in
your "main" function, to process
redirection commands on the CP/M
command line.
2. getchar() Gets a character from the keyboard,
or from a directed input file if one
was specified on the command line.
3. putchar(c) Puts a character out to the console,
or to a directed output file if one
was specified on the command line.
4. dioflush() Flushes directed output file, if open,
and closes all directed I/O files (if
any.) This must be called before your
program exits or returns to CP/M.
To activate redirection: Four special arguments may be given
on the command line to the generated COM file...
>foo causes "putchar" to place characters into the file
named "foo" instead of to the console.
+foo like >foo except that the characters are ALSO sent
to the console.
<foo causes "getchar" to return characters from the file
named "foo" instead of from the keyboard.
command |prog causes the standard output of the command specified in
"command" to be fed into the standard input of another
program, "prog". (BOTH "command" and "prog" must be
compiled with DIO)
(Note that there must never be any spaces between >,+,< or | and the
corresponding filename.)
Thus, a C program using redirection has the following form:
main(argc,argv)
char **argv;
{
... /* declarations */
dioinit(&argc,argv) /* initialize redirection */
... /* body of program */
dioflush();
}
NOTES:
0. Redirection and pipes work only for TEXT. This mechanism should
not be used for binary data.
1. The "getchar" and "putchar" functions should each be used EXPLICITLY
at least once in your main source file, so that the correct versions
are picked off from DIO.CRL instead of the incorrect ones from
DEFF2.CRL (because of the way the linker works.)
2. The "putc" library function should be modified so that an iobuf
value of 4 sends a character to the CP/M console via a "bdos"
call (as opposed to using "putchar"), and that a '\n' character
thus sent should be expanded into a CR-LF combination. This
is easily accomplished by adding the following clause to the "putc"
function, recompiling STDLIB1.C, and updating DEFF.CRL by
transferring in the new "putc" with CLIB.COM:
if (_iobuf == 4) {
if (c == '\n') bdos(2,'\r');
bdos(2,c);
}
(This may already have been done in the version you have.)
3. The "execv" function, used by this package, is available in the
file EXECV.ASM; it should be assembled, renamed EXECV.CRL, and
then transferred into DEFF2.CRL using CLIB.COM.
(This may already have been done in the version you have.)
*/
#include "bdscio.h"
#include "dio.h"
#define CON_INPUT 1 /* BDOS call to read console */
#define CON_OUTPUT 2 /* BDOS call to write to console */
#define CON_STATUS 11 /* BDOS call to interrogate status */
#define CONTROL_C 3 /* Quit character */
#define STDERR 4 /* Standard Error descriptor (sorry,
Unix fans, 2 was already used.) */
#define INPIPE 2 /* bit setting to indicate directed
input from a temp. pipe fil */
#define VERBOSE 2 /* bit setting to indicate output is to
go to console AND directed output */
/*
The "dioinit" function must be called at the beginning of the
"main" function:
*/
#define argc *argcp
dioinit(argcp,argv)
int *argcp;
char **argv;
{
int i,j, argcount;
_diflag = _doflag = _pipef = FALSE; /* No directed I/O by default */
_nullpos = &argv[argc];
argcount = 1;
for (i = 1; i < argc; i++) /* Scan the command line for > and < */
{
if (_pipef) break;
switch(*argv[i]) {
case '<': /* Check for directed input: */
if (!argv[i][1]) goto barf;
if (fopen(&argv[i][1], _dibuf) == ERROR)
{
fprintf(STDERR,"Can't open %s\n",&argv[i][1]);
exit();
}
_diflag = TRUE;
if (strcmp(argv[i],"<TEMPIN.$$$") == 0)
_diflag |= INPIPE;
goto movargv;
case '|': /* Check for pipe: */
_pipef++;
_pipedest = &argv[i][1]; /* save prog name for execl */
if (argv[i][1])
{
argv[i] = ".TEMPOUT.$$$"; /* temp. output */
_savei = &argv[i];
}
goto foo;
default: /* handle normal arguments: */
argcount++;
}
}
}
#undef argc
/*
The "dioflush" function must be called before exiting the program:
*/
dioflush()
{
if (_diflag)
{
fclose(_dibuf);
}
/* Cleanup unconditionally so rename below can't screw up */
unlink("tempin.$$$");
if (_doflag)
{
putc(CPMEOF,_dobuf);
fflush(_dobuf);
fclose(_dobuf);
rename("tempout.$$$","tempin.$$$");
if (_pipef)
{
*_savei = "<TEMPIN.$$$";
*_nullpos = NULL;
execv(_pipedest,_savei);
}
}
}
/*
This version of "getchar" replaces the regular version when using
directed I/O:
*/
getchar()
{
char c;
if (_diflag) {
if ((c = getc(_dibuf)) == '\r') c = getc(_dibuf);
} else
if ((c = bdos(CON_INPUT)) == CONTROL_C) exit();
if (c == CPMEOF) return EOF; /* Control-Z is EOF key */
if (c == '\r')
{
c = '\n';
if (!_diflag) bdos(2,'\n'); /* echo LF after CR to console */
}
return c;
}
/*
This version of "putchar" replaces the regular version when using
directed I/O:
*/
putchar(c)
char c;
{
if (_doflag)
{
if (c == '\n') putc('\r',_dobuf);
if(putc(c,_dobuf) == ERROR)
{
fprintf(STDERR,"File output error; disk full?\n");
exit();
}
if (!(_doflag & VERBOSE)) return;
}
if (bdos(CON_STATUS) && bdos(CON_INPUT) == CONTROL_C) exit();
if (c == '\n') bdos(CON_OUTPUT,'\r');
bdos(CON_OUTPUT,c);
}
