Reads the contents of a file into a buffer.
The file position is specified either:
The file position is at the start of the file when it is opened, and is lost when the file
is closed. Perform the file operation as a single action whenever possible. For example, do
not split a read of 16KB into four 4KB chunks unless there is no alternative.
R1 contains a pointer to a four-word
contains a handle for a file previously opened with
- word 2
points to a buffer
- word 3
contains the number of bytes to read to the buffer
from the file.
zero if the call is successful.
R0 contains the same value
as word 3, the call has failed and EOF is assumed.
R0 contains a smaller value
than word 3, the call was partially successful. No error is assumed,
but the buffer has not been filled.
If the handle is for an interactive device, that is,
–1. A nonzero return from
that the line read did not fill the buffer.