HP Data Entry and Forms Management System (VPLUS) Reference Manual (32209-90024)

Chapter 6 259
USING VPLUS INTRINSICS
INTRINSIC DESCRIPTIONS
VBLOCKREAD
The VBLOCKREAD intrinsic reads a block of characters from a terminal in block mode. The
syntax and parameter descriptions for this intrinsic are provided below.
VBLOCKREAD {COMAREA,BUF,LEN,ACTLEN,TMODE,LOC,BC,TC}
COMAREA The following COMAREA fields must be set before calling VBLOCKREAD,ifnot
already set:
LANGUAGE Set to code identifying the programming language of the
calling program.
COMAREALEN Set to total number of 2-byte words in COMAREA.
VBLOCKREAD may set the following COMAREA fields:
CSTATUS Set to nonzero value if call is unsuccessful.
FILERRNUM Set to file error code if MPE file error.
BUF Byte array to receive data from the terminal.
LEN Maximum number of bytes to read from terminal (2-byte integer).
ACTLEN Actual number of bytes read from terminal (2-byte integer).
TMODE Terminal setting at the time of read (2-byte integer).
1 assume terminal is in format mode.
2 assume terminal is in unformatted mode.
LOC Start position of write (array of two 2-byte integers). Absolute cursor
addressing is not allowed in format mode. An error will be returned.
[0] [0] home cursor before read
[-1] [0] start from current cursor position
BC Buffer control (2-byte integer) -- not currently used. Must initialize to zero.
TC Terminal control (2-byte integer)--not currently used. Must initialize to
zero.
This intrinsic reads a block of data from the terminal with a number of options. There are
two major differences between VREADFIELDS and this procedure. First, it provides more
options for reading data from the terminal. Second, data read is returned directly to the
application buffer. There is no VPLUS form associated with the read.
Like the companion intrinsic, VBLOCKWRITE, this procedure is recommended only for
advanced programmers who are proficient with terminal input/output. VOPENTERM must be
called before using VBLOCKREAD. The keyboard must be unlocked before calling
VBLOCKREAD. (Refer to keyboard unlock options in VBLOCKWRITE.) VBLOCKREAD will lock the
keyboard immediately after
Enter or a function key is pressed to ensure data integrity.
This procedure is primarily designed for unformatted reads. For users who do not use
VREADFIELDS but use VBLOCKREAD to read data in format mode, the application data
interpretation algorithm should accommodate both MDT (Modified Data Tag) and
non-MDT inputs. When MDT is on, unmodified blanks and data are not transmitted from
the terminal. Refer to the appropriate terminal reference manuals for further explanation