11/3/71 SYS SEEK (II)





11/3/71                                             SYS SEEK (II)





NAME            seek  --  move read/write pointer



SYNOPSIS        (file descriptor in r0)

                sys     seek; offset; ptrname   / seek = 19.



DESCRIPTION     The file descriptor refers to a file open for

                reading or writing.  The read (or write) pointer

                for the file is set as follows:



                   if ptrname is 0, the pointer is set to offset.



                   if ptrname is 1, the pointer is set to its

                   current location plus offset.



                   if ptrname is 2, the pointer is set to the

                   size of the file plus offset.





FILES           --



SEE ALSO        tell



DIAGNOSTICS     The error bit (c-bit) is set for an undefined

                file descriptor.



BUGS            A file can conceptually be as large as 2**20

                bytes.  Clearly only 2**16 bytes can be addressed

                by seek.  The problem is most acute on the tape

                files and RK and RF.  Something is going to be

                done about this.



OWNER           ken, dmr
squoze.net
