Input mapping

This phase of processing reformats native mode data streams emanating from the IBM® 3270 Information Display terminal. The native mode data, includes device dependent control characters (buffer address and buffer order characters) interspersed among the entered text. Input mapping deletes from the data stream the device dependent control characters inserted by the 3270 control unit and places the agent/operator entered text in specific areas of blocks of main storage; these areas coincide with a previously defined symbolic reference module (DSECT). In addition, a series of bit indicators, one for each possible input field, is used by the input mapping function to summarize, to the user application, the contents of each respective input field. When text is entered for a field, the corresponding bit is set on.

These bit indicators are stored in the field suffixed by IMF in the user DSECT.

The reformatted block is then returned to the user via the BACKC macro or passed to a user determined destination via the ROUTC macro.

The user written application program segment entry requirements to input mapping are summarized as follows:
  • The prime input message block must be on data level 0; overflow records, if any, are on file.
  • The mapping interface work area has been correctly initialized with the map sequence number and RCPL (Routing Control Parameter List), if the latter is required.
  • The appropriate ENTER type macro must be executed. When the user application segment is to regain control after the input data has been formatted, an ENTRC must be coded. When the user application does not want to be returned to after the input data stream has been mapped, an ENTNC must be coded.
It is the user application's responsibility to determine if the device has an associated RCB. If the device has an associated RCB, the user application codes an ENTRC ASFI to regain control or codes ENTNC ASFI if not. If the device does not have an associated RCB, the user application codes an ENTRC ASFJ to regain control or codes an ENTNC ASFJ if no return is desired.
  • Register 1 must contain the address of the start of the mapping interface work area, which is required to begin on a halfword boundary.