HP Fortran Programmer's Guide (B3908-90031; September 2011)

Glossary
HP WDB
Glossary 263
stream I/O A type of I/O that is based on the
concept of a stream—a flow of data to or from a file
or I/O device. Streams are managed by the HP-UX
operating system. Access to a stream is provided by
a stream pointer, which is the address of a C-like
structure that contains information about a stream.
When the Fortran 90 intrinsic FSTREAM is given a
logical unit number, it returns a stream pointer,
providing Fortran programs with access to
stream-based system routines.
symbol table A table of names of procedures and
data, including their offset addresses. The compiler
inserts a symbol table in the object file for use by
the debugger and profiler.
T-Z
thread An independent flow of control within a
single process, having its own register set and
program counter. The HP-UX operating system
supports multiple-executing threads within the
same process.
Thread Trace Visualizer See ttv.
trap A change in system state that is caused by an
exception and that may be detected by the
executing program that took the exception. Traps
are hardware features that may be enabled or
disabled. If traps are enabled, they can change the
flow of control in the program that took the
exception. In response to a trap, the system may
generate a signal (for example, SIGFPE), which the
program can detect. Such a program can be
designed to handle traps. HP Fortran 90 provides
the ON statement to handle traps.
ttv A tool for analyzing parallel-executing
programs.
tty buffering A method for efficiently processing
data that is directed to standard output by capturing
it in a buffer before sending it to the screen.
underflow An exception condition that occurs
when the result of a floating-point operation is
smaller than the smallest normalized number. On
systems that support it, fast underflow is an
efficient method of handling this exception.
vectorization An optimization technique that
replaces eligible program loops that operate on
arrays with calls to specially tuned routines that
perform the same operation.
wall-clock time Time spent by an executing
program that includes system time as well as
process time. In contrast, virtual time takes into
account process time only. Profilers (such as
CXperf) that track both virtual time and wall-clock
time provide information about when a program is
blocked as well as when it is running.
HP WDB The HP Wildebeest Debugger (WDB) is
an HP-supported implementation of the Open
Source GNU debugger (GDB).