MPE/iX Intrinsics Reference Manual (32650-90875)

252 Chapter6
Command Definitions (FLUSHLOG-GETUSERMODE)
FREAD
FREAD
NM and CM callable.
Reads a logical record or portion of a record from a file to the stack.
Syntax
I16 I16V UDS I16V
transfercount :=FREAD( filenum,buffer,length );
Functional Return
transfercount 16-bit signed integer (assigned functional return)
Returns the length of the data transferred to
buffer :
• If a negative value is passed in the
length parameter,
transfercount is a positive value indicating the number of bytes
transferred.
• If a positive value is passed in the
length parameter, transfercount
is a positive value indicating the number of half words transferred.
• If nowait I/O is specified in FOPEN/HPFOPEN, a zero is returned. The
record length is returned in the
length parameter of the IOWAIT or
IODONTWAIT intrinsic.
NOTE If the file was opened with the nowait I/O option enabled, transfercount is
zero. The IOWAIT intrinsic can be used to determine the length of the data
transferred.
Parameters
filenum 16-bit signed integer by value (required)
Passes the file number of the file to be read. If
filenum references a
directory node, FREAD fails with a CCL file code.
buffer user-defined structure (required)
Returns the record that was read. This structure must be large enough to
hold all of the information to be transferred.
length 16-bit signed integer by value (required)
Passes the length of the data to be transferred to
buffer :
Value Meaning
<0 Length in bytes
=0
No transfer occurs