The READV macro reads data on a socket and stores it in a set of buffers. If a datagram packet is too long to fit in the supplied buffer, datagram sockets discard extra bytes.
The following requirements apply to this call:
| Authorization: | Supervisor state or problem state, any PSW key. |
| Dispatchable unit mode: | Task. |
| Cross memory mode: | PASN = HASN. |
| Amode: | 31-bit or 24-bit. Note: See "Addressability
mode (Amode) considerations" under CALL instruction API environmental restrictions and programming requirements.
|
| ASC mode: | Primary address space control (ASC) mode. |
| Interrupt status: | Enabled for interrupts. |
| Locks: | Unlocked. |
| Control parameters: | All parameters must be addressable by the caller and in the primary address space. |
>>-EZASMI--TYPE=READV--,S--=--+-number---+----------------------> +-address--+ +-*indaddr-+ '-(reg)----' >--,IOV--=--+-address--+--,IOVCNT--=--+-address--+--------------> +-*indaddr-+ +-*indaddr-+ '-(reg)----' '-(reg)----' >--,ERRNO--=--+-address--+--,RETCODE--=--+-address--+-----------> +-*indaddr-+ +-*indaddr-+ '-(reg)----' '-(reg)----' >--+---------------------------+--+-------------------------+---> +-,ECB--=--+-address--+-----+ '-,ERROR--=--+-address--+-' | +-*indaddr-+ | +-*indaddr-+ | '-(reg)----' | '-(reg)----' '-,REQAREA--=--+-address--+-' +-*indaddr-+ '-(reg)----' >--+------------------------+---------------------------------->< '-,TASK--=--+-address--+-' +-*indaddr-+ '-(reg)----'
- Keyword
- Description
- S
- Input parameter. A value or the address of a halfword binary number specifying the descriptor of the socket into which the data is to be read.
- IOV
- An array of three fullword structures with the number of structures
equal to the value in IOVCNT and the format
of the structures as follows:
- Fullword 1
- Input parameter. A buffer to be filled by the completion of the call.
- Fullword 2
- Input parameter. The ALET for this buffer.
If the buffer is in the primary address space, this should be zeros.
If a nonzero ALET is specified, the ALET must represent a valid entry in the dispatchable unit access list (DU-AL) for the task issuing this call. Note that ALETs can be specified only for synchronous socket calls (for example, ECB/REQAREA cannot be specified). An exception to this is an ALET representing a SCOPE=COMMON data space.
- Fullword 3
- Input parameter. The length of the data buffer referred to in Fullword 1.
- IOVCNT
- Input parameter. A fullword binary field specifying the number of data buffers provided for this call. The limit is 120.
- ERRNO
- Output parameter. A fullword binary field. If RETCODE is negative, this contains an error number.
- RETCODE
- A fullword binary field that returns
one of the following values:
- Value
- Description
- 0
- A 0 return code indicates that the connection is closed and no data is available.
- >0
- A positive value indicates the number of bytes copied into the buffer.
- -1
- Check ERRNO for an error code.
- ECB or REQAREA
- Input parameter. This parameter is required if you are
using APITYPE=3. It points to a 104-byte field containing:
- For ECB
- A 4-byte ECB posted by TCP/IP when the macro completes.
- For REQAREA
- A 4-byte user token (set by you) that is presented to your exit when the response to this function request is complete.
- For ECB/REQAREA
- The last 100 bytes is a storage field used by the interface to save the state information.
Note: This storage must not be modified until the macro function has completed and the ECB has been posted, or the asynchronous exit has been driven. - ERROR
- Input parameter. The location in your program to receive control when the application programming interface (API) processing module cannot be loaded.
- TASK
- Input parameter. The location of the task storage area in your program.