4. System Functions and Subroutines

Transcription

1 Chapter 4 4. System s and Subroutines This chapter describes extensions to Fortran 77 that are related to the IRIX compiler and operating system. Library s summarizes the Fortran run-time library functions. Extended Intrinsic Subroutines describes the extensions to the Fortran intrinsic subroutines. Extended Intrinsic s describes the extensions to the Fortran functions. Library s The Fortran library functions provide an interface from Fortran programs to the IRIX system functions. System functions are facilities that are provided by the IRIX system kernel directly, as opposed to functions that are supplied by library code linked with your program. System functions are documented in volume 2 of the reference pages, with an overview in the intro(2) reference page. Table 4-1 summarizes the functions in the Fortran run-time library. In general, the name of the interface routine is the same as the name of the system function that would be called from a C program. For details on a system interface routine use the command: man 2 name_of_function Note: You must declare the time function as EXTERNAL; if you do not, the compiler will assume you mean the VMS-compatible intrinsic time function rather than the IRIX system function. (In general it is a good idea to declare any library function in an EXTERNAL statement as documentation.) 51

2 Chapter 4: System s and Subroutines Table 4-1 abort(3f) access acct alarm(3f) barrier(3p) blockproc(2) brk(2) chdir chmod(3f) chown(2) chroot close creat ctime(3f) dtime(3f) dup etime(3f) exit(2) fcntl(2) fdate(3f) fgetc(3f) fork(2) fputc(3f) abnormal termination determine accessibility of a file enable/disable process accounting execute a subroutine after a specified time perform barrier operations block processes change data segment space allocation change default directory change mode of a file change owner change root directory for a command close a file descriptor create or rewrite a file return system time return elapsed execution time duplicate an open file descriptor return elapsed execution time terminate process with status file control return date and time in an ASCII string get a character from a logical unit create a copy of this process write a character to a Fortran logical unit 52

3 Library s Table 4-1 (continued) free_barrier(3p) fseek(3f) fseek64(3f) fstat(2) ftell(3f) ftell64(3f) gerror(3f) getarg(3f) getc(3f) getcwd getdents(2) getegid(2) gethostid(2) getenv(3f) geteuid(2) getgid(2) gethostname(2) getlog(3f) getpgrp getpid getppid getsockopt(2) getuid(2) gmtime(3f) free barrier reposition a file on a logical unit reposition a file on a logical unit for 64-bit architecture get file status reposition a file on a logical unit reposition a file on a logical unit for 64-bit architecture get system error messages return command line arguments get a character from a logical unit get pathname of current working directory read directory entries get effective group ID get unique identifier of current host get value of environment variables get effective user ID get user or group ID of the caller get current host ID get user s login name get process group ID get process ID get parent process ID get options on sockets get user or group ID of caller return system time 53

4 Chapter 4: System s and Subroutines Table 4-1 (continued) iargc(3f) idate(3f) ierrno(3f) ioctl(2) isatty(3f) itime(3f) kill(2) link(2) loc(3f) lseek(2) lseek64(2) lstat(2) ltime(3f) m_fork(3p) m_get_myid(3p) return command line arguments return date or time in numerical form get system error messages control device determine if unit is associated with tty return date or time in numerical form send a signal to a process make a link to an existing file return the address of an object move read/write file pointer move read/write file pointer for 64-bit architecture get file status return system time create parallel processes get task ID m_get_numprocs(3p) get number of subtasks m_kill_procs(3p) m_lock(3p) m_next(3p) m_park_procs(3p) m_rele_procs(3p) m_set_procs(3p) m_sync(3p) m_unlock(3p) kill process set global lock return value of counter suspend child processes resume child processes set number of subtasks synchronize all threads unset a global lock 54

5 Library s Table 4-1 (continued) mkdir(2) mknod(2) mount(2) new_barrier(3p) nice open(2) oserror(3f) pause(2) perror(3f) pipe(2) plock(2) prctl(2) profil(2) ptrace putc(3f) putenv(3f) qsort(3f) read readlink rename(3f) rmdir(2) sbrk(2) schedctl(2) send(2) make a directory make a directory/file mount a filesystem initialize a barrier structure lower priority of a process open a file get/set system error suspend process until signal get system error messages create an interprocess channel lock process, test, or data in memory control processes execution-time profile process trace write a character to a Fortran logical unit set environment variable quick sort read from a file descriptor read value of symbolic link change the name of a file remove a directory change data segment space allocation call to scheduler control send a message to a socket 55

6 Chapter 4: System s and Subroutines Table 4-1 (continued) setblockproccnt(2) setgid sethostid(2) setoserror(3f) setpgrp(2) setsockopt(2) setuid sginap(2) sginap64(2) shmat(2) shmdt(2) sighold(2) sigignore(2) signal(2) sigpause(2) sigrelse(2) sigset(2) sleep(3f) socket(2) sproc(2) stat(2) stime(2) symlink(2) sync set semaphore count set group ID set current host ID set system error set process group ID set options on sockets set user ID put process to sleep put process to sleep in 64-bit environment attach shared memory detach shared memory raise priority and hold signal ignore signal change the action for a signal suspend until receive signal release signal and lower priority specify system signal handling suspend execution for an interval create an endpoint for communication TCP create a new share group process get file status set time make symbolic link update superblock 56

7 Library s Table 4-1 (continued) sysmp(2) sysmp64(2) system(3f) taskblock(3p) taskcreate(3p) taskctl(3p) taskdestroy(3p) tasksetblockcnt(3p) taskunblock(3p) time(3f) ttynam(3f) uadmin ulimit(2) ulimit64(2) umask umount(2) unblockproc(2) unlink(2) uscalloc(3p) uscalloc64(3p) uscas(3p) usclosepollsema(3p) usconfig(3p) uscpsema(3p) control multiprocessing control multiprocessing in 64-bit environment issue a shell command block tasks create a new task control task kill task set task semaphore count unblock task return system time (must be declared EXTERNAL) find name of terminal port administrative control get and set user limits get and set user limits in 64-bit architecture get and set file creation mask dismount a file system unblock processes remove a directory entry shared memory allocator shared memory allocator in 64-bit environment compare and swap operator detach file descriptor from a pollable semaphore semaphore and lock configuration operations acquire a semaphore 57

8 Chapter 4: System s and Subroutines Table 4-1 (continued) uscsetlock(3p) usctlsema(3p) usdumplock(3p) usdumpsema(3p) usfree(3p) usfreelock(3p) usfreepollsema(3p) usfreesema(3p) usgetinfo(3p) usinit(3p) usinitlock(3p) usinitsema(3p) usmalloc(3p) usmalloc64(3p) usmallopt(3p) usnewlock(3p) usnewpollsema(3p) usnewsema(3p) usopenpollsema(3p) uspsema(3p) usputinfo(3p) usrealloc(3p) usrealloc64(3p) ussetlock(3p) unconditionally set lock semaphore control operations dump lock information dump semaphore information user shared memory allocation free a lock free a pollable semaphore free a semaphore exchange information through an arena semaphore and lock initialize routine initialize a lock initialize a semaphore allocate shared memory allocate shared memory in 64-bit environment control allocation algorithm allocate and initialize a lock allocate and initialize a pollable semaphore allocate and initialize a semaphore attach a file descriptor to a pollable semaphore acquire a semaphore exchange information through an arena user share memory allocation user share memory allocation in 64-bit environment set lock 58

9 Extended Intrinsic Subroutines Table 4-1 (continued) ustestlock(3p) ustestsema(3p) usunsetlock(3p) usvsema(3p) uswsetlock(3p) wait(2) write test lock return value of semaphore unset lock free a resource to a semaphore set lock wait for a process to terminate write to a file Extended Intrinsic Subroutines This section describes the intrinsic subroutines that are extensions to Fortran 77 (the intrinsic functions that are standard to Fortran 77 are documented in Appendix A of the MIPSpro Fortran 77 Language Reference Manual). The rules for using the names of intrinsic subroutines are also discussed in that appendix. Table 4-2 gives an overview of the intrinsic subroutines and their function; they are described in detail in the sections following the topics. Table 4-2 Subroutine DATE IDATE ERRSNS EXIT TIME MVBITS Overview of System Subroutines Information Returned Current date as nine-byte string in ASCII representation Current month, day, and year, each represented by a separate integer Description of the most recent error Terminates program execution Current time in hours, minutes, and seconds as an eight-byte string in ASCII representation Moves a bit field to a diferent storage location 59

10 Chapter 4: System s and Subroutines DATE 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. IDATE 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 ERRSNS The ERRSNS routine returns information about the most recent program error; the format is as follows: CALL ERRSNS (arg1, arg2, arg3, arg4, arg5) 60

11 Extended Intrinsic Subroutines 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 Argument arg1 arg2 arg3 arg4 arg5 Information Returned by ERRSNS Contents IRIX global variable errno, which is then reset to zero after the call Zero Zero Logical unit number of the file that was being processed when the error occurred Zero Although only arg1 and arg4 return relevant information, arg2, arg3, and arg5 are always required. EXIT 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. TIME 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. 61

12 Chapter 4: System s and Subroutines MVBITS 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, INTEGER*4, or INTEGER*8. 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. Extended Intrinsic s Table 4-5 gives an overview of the intrinsic functions added as extensions of Fortran 77. Table 4-5 SECNDS RAN Extensions Information Returned Elapsed time as a floating point value in seconds. This is an intrinsic routine. 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. 62

13 Extended Intrinsic s SECNDS SECNDS is an intrinsic routine that returns the number of seconds since midnight, minus the value of the passed argument; 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. RAN RAN generates a pseudo-random number. The format is as follows: v = RAN(s) The argument s is an INTEGER*4 variable or array element. This variable serves as a seed in determining the next random number. It should initially be set to a large, odd integer value. You can compute multiple random number series by supplying different variables or array elements as the seed argument to different calls of RAN. Note: Because RAN modifies the argument s, calling the function with a constant can cause a core dump. The algorithm used in RAN is the linear congruential method. The code is similar to the following fragment: S = S * L RAN = FLOAT(IAND(RSHIFT(S,16),32767))/ RAN is supplied for compatibility with VMS. For demanding applications, consider using the functions described in the random(3b) reference page. These can all be called using techniques described under Using %VAL on page

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