This chapter describes extensions to Fortran 77 that are related to the IRIX compiler and operating system.
"Library Functions" summarizes the Fortran run-time library functions.
"Intrinsic Subroutine Extensions" describes the extensions to the Fortran intrinsic subroutines.
"Function Extensions" describes the extensions to the Fortran functions.
The Fortran library functions provide an interface from Fortran programs to the system in the same way that the C library provides for C programs. The compiler automatically loads an interface routine when it processes the associated call.
Table 4-1 summarizes the functions in the Fortran run-time library.
Table 4-1. Summary of System Interface Library Routines
Function | Purpose |
|---|---|
abort | abnormal termination |
access | determine accessibility of a file |
acct | enable/disable process accounting |
alarm | execute a subroutine after a specified time |
barrier | perform barrier operations |
blockproc | block processes |
brk | change data segment space allocation |
chdir | change default directory |
chmod | change mode of a file |
chown | change owner |
chroot | change root directory for a command |
close | close a file descriptor |
creat | create or rewrite a file |
ctime | return system time |
dtime | return elapsed execution time |
dup | duplicate an open file descriptor |
etime | return elapsed execution time |
exit | terminate process with status |
fcntl | file control |
fdate | return date and time in an ASCII string |
fgetc | get a character from a logical unit |
fork | create a copy of this process |
fputc | write a character to a Fortran logical unit |
free_barrier | free barrier |
fseek | reposition a file on a logical unit |
fstat | get file status |
ftell | reposition a file on a logical unit |
gerror | get system error messages |
getarg | return command line arguments |
getc | get a character from a logical unit |
getcwd | get pathname of current working directory |
getdents | read directory entries |
getegid | get effective group ID |
gethostid | get unique identifier of current host |
getenv | get value of environment variables |
geteuid | get effective user ID |
getgid | get user or group ID of the caller |
gethostname | get current host ID |
getlog | get user's login name |
getpgrp | get process group ID |
getpid | get process ID |
getppid | get parent process ID |
getsockopt | get options on sockets |
getuid | get user or group ID of caller |
gmtime | return system time |
iargc | return command line arguments |
idate | return date or time in numerical form |
ierrno | get system error messages |
ioctl | control device |
isatty | determine if unit is associated with tty |
itime | return date or time in numerical form |
kill | send a signal to a process |
link | make a link to an existing file |
loc | return the address of an object |
lseek | move read/write file pointer |
lstat | get file status |
ltime | return system time |
m_fork | create parallel processes |
m_get_myid | get task ID |
m_get_numprocs | get number of subtasks |
m_kill_procs | kill process |
m_lock | set global lock |
m_next | return value of counter |
m_park_procs | suspend child processes |
m_rcle_procs | resume child processes |
m_set_procs | set number of subtasks |
m_sync | synchronize all threads |
m_unlock | unset a global lock |
mkdir | make a directory |
mknod | make a directory/file |
mount | mount a filesystem |
new_barrier | initialize a barrier structure |
nice | lower priority of a process |
open | open a file |
oserror | get/set system error |
pause | suspend process until signal |
perror | get system error messages |
pipe | create an interprocess channel |
plock | lock process, test, or data in memory |
prctl | control processes |
profil | execution-time profile |
ptrace | process trace |
putc | write a character to a Fortran logical unit |
putenv | set environment variable |
qsort | quick sort |
read | read from a file descriptor |
readlink | read value of symbolic link |
rename | change the name of a file |
rmdir | remove a directory |
sbrk | change data segment space allocation |
schedctl | call to scheduler control |
send | send a message to a socket |
setblockproccnt | set semaphore count |
setgid | set group ID |
sethostid | set current host ID |
setoserror | set system error |
setpgrp | set process group ID |
setsockopt | set options on sockets |
setuid | set user ID |
sginap | put process to sleep |
shmat | attach shared memory |
shmdt | detach shared memory |
sighold | raise priority and hold signal |
sigignore | ignore signal |
signal | change the action for a signal |
sigpause | suspend until receive signal |
sigrelse | release signal and lower priority |
sigset | specify system signal handling |
sleep | suspend execution for an interval |
socket | create an endpoint for communication TCP |
sproc | create a new share group process |
stat | get file status |
stime | set time |
symlink | make symbolic link |
sync | update superblock |
sysmp | control multiprocessing |
system | issue a shell command |
taskblock | block tasks |
taskcreate | create a new task |
taskctl | control task |
taskdestroy | kill task |
tasksetblockcnt | set task semaphore count |
taskunblock | unblock task |
time[a] | return system time |
ttynam | find name of terminal port |
uadmin | administrative control |
ulimit | get and set user limits |
umask | get and set file creation mask |
umount | dismount a file system |
unblockproc | unblock processes |
unlink | remove a directory entry |
uscalloc | shared memory allocator |
uscas | compare and swap operator |
usclosepollsema | detach file descriptor from a pollable semaphore |
usconfig | semaphore and lock configuration operations |
uscpsema | acquire a semaphore |
uscsetlock | unconditionally set lock |
usctlsema | semaphore control operations |
usdumplock | dump lock information |
usdumpsema | dump semaphore information |
usfree | user shared memory allocation |
usfreelock | free a lock |
usfreepollsema | free a pollable semaphore |
usfreesema | free a semaphore |
usgetinfo | exchange information through an arena |
usinit | semaphore and lock initialize routine |
usinitlock | initialize a lock |
usinitsema | initialize a semaphore |
usmalloc | allocate shared memory |
usmallopt | control allocation algorithm |
usnewlock | allocate and initialize a lock |
usnewpollsema | allocate and initialize a pollable semaphore |
usnewsema | allocate and initialize a semaphore |
usopenpollsem | attach a file descriptor to a pollable semaphore |
uspsema | acquire a semaphore |
usputinfo | exchange information through an arena |
usrealloc | user share memory allocation |
ussetlock | set lock |
ustest lock | test lock |
ustestsema | return value of semaphore |
ustrace | trace |
usunsetlock | unset lock |
usvsema | free a resource to a semaphore |
uswsetlock | set lock |
wait | wait for a process to terminate |
write | write to a file |
[a] The library function time can be invoked only if it is declared in an external statement. | |
You can display information on a function with the man command:
% man function |
This section describes the intrinsic subroutines that are extensions to Fortran 77. The rules for using the intrinsic subroutines are
The subroutine names are specially recognized by the compiler. A user-written subroutine with the same name as a system subroutine must be declared in an EXTERNAL statement in the calling subprogram.
Using a user-written subroutine with the same name as a system subroutine in one subprogram does not preclude using the actual system subroutine in a different subprogram.
To pass the name of a system subroutine as an argument to another subprogram, the name of the system subroutine must be declared in an INTRINSIC statement in the calling subprogram.
When a system subroutine name is passed as an argument to another subprogram, the call to the system subroutine via the formal parameter name in the receiving subprogram must use the primary calling sequence for the subprogram (when there is more than one possible calling sequence).
Table 4-2 gives an overview of the system subroutines and their function; they are described in detail in the sections following the table.
Table 4-2. Overview of System Subroutines
Subroutine | Information Returned |
|---|---|
DATE | Current date as nine-byte string in ASCII representation |
IDATE | Current month, day, and year, each represented by a separate integer |
ERRSNS | Description of the most recent error |
EXIT | Terminates program execution |
TIME | Current time in hours, minutes, and seconds as an eight-byte string in ASCII representation |
MVBITS | Moves a bit field to a different storage location |
The DATE routine returns the current date as set by the system; the format is as follows:
CALL DATE (buf) |
where buf is a variable, array, array element, or character substring nine bytes long. After the call, buf contains an ASCII variable in the format dd-mmm-yy, where dd is the date in digits, mmm is the month in alphabetic characters, and yy is the year in digits.
The IDATE routine returns the current date as three integer values representing the month, date, and year; the format is as follows:
CALL IDATE (m, d, y) |
where m, d, and y are either INTEGER*4 or INTEGER*2 values representing the current month, day and year. For example, the values of m, d and y on August 10, 1989, are
m = 8 d = 10 y = 89 |
The ERRSNS routine returns information about the most recent program error; the format is as follows:
CALL ERRSNS (arg1, arg2, arg3, arg4, arg5) |
The arguments (arg1, arg2, and so on) can be either INTEGER*4 or INTEGER*2 variables. On return from ERRSNS, the arguments contain the information shown in Table 4-3.
Table 4-3. Information Returned by ERRSNS
Argument | Contents |
|---|---|
arg1 | IRIX global variable errno, which is then reset to zero after the call |
arg2 | Zero |
arg3 | Zero |
arg4 | Logical unit number of the file that was being processed when the error occurred |
arg5 | Zero |
Although only arg1 and agr4 return relevant information, arg2, arg3, and arg5 are always required.
The EXIT routine causes normal program termination and optionally returns an exit-status code; the format is as follows:
CALL EXIT (status) |
where status is an INTEGER*4 or INTEGER*2 argument containing a status code.
The TIME routine returns the current time in hours, minutes, and seconds; the format is as follows:
CALL TIME (clock) |
where clock is a variable, array, array element, or character substring; it must be eight bytes long. After execution, clock contains the time in the format hh:mm:ss, where hh, mm, and ss are numerical values representing the hour, the minute, and the second.
The MVBITS routine transfers a bit field from one storage location to another; the format is as follows:
CALL MVBITS (source,sbit,length,destination,dbit) |
Table 4-4 defines the arguments. Arguments can be declared as INTEGER*2 or INTEGER*4.
Table 4-4. Arguments to MVBITS
Argument | Type | Contents |
|---|---|---|
source | Integer variable or array element | Source location of bit field to be transferred |
sbit | Integer expression | First bit position in the field to be transferred from source.
|
length | Integer expression | Length of the field to be transferred from source.
|
destination | Integer variable or array element | Destination location of the bit field |
dbit | Integer expression | First bit in destination to which the field is transferred
|
Table 4-5 gives an overview of the functions added as extensions of Fortran 77.
Table 4-5. Function Extensions
Function | Information Returned |
|---|---|
SECNDS | Elapsed time as a floating point value in seconds. This is an intrinsic routine. |
RAN | The next number from a sequence of pseudo-random numbers. This is not an intrinsic routine. |
These functions are described in detail in the following sections.
SECNDS is an intrinsic routine that returns the number of seconds since midnight, minus the value of the passed arguments; the format is as follows:
s = SECNDS(n) |
After execution, s contains the number of seconds past midnight less the value specified by n. Both s and n are single-precision, floating point values.
The RAN routine generates a random number; the format is as follows:
v = RAN(s) |
The argument s is an INTEGER*4 variable or array element; s serves as a seed in determining the next random number and should initially be set to a large, odd integer value. This permits the computation of multiple random number series by supplying different variable names as the seed argument to RAN.
 | Note: Because RAN modifies the argument s, calling the function with a constant can cause a core dump. |