IBM 5280 Distributed Data System - Index of

Subroutine CaU (CALL/CALL TB)CALL BRnBh)Source: CALL BRn instruction labelCALLTBtable labelIObject:OB0 8 I 2931~ I ~ I0 fJ II IID Index register address: The address of the register that contains the index.fJ Bit15:a = CALL1 = CALL TBII Branch address for CALL: Branch to the instruction at this address.Note: This address is all zeros if no instruction is specified.Table address for CALL TB: The address of the table.a Bits 30 and 31 for CALL:00 = Current area01 = Common function area 110 = Base area11 = Common function area 2Bits 30 and 31 for CALL TB: The last 2 bits of the table address.Note: Bits 0-15 of the table entry correspond to bits 16-31 of the CALL instruction.Bits 14 and 15 of the table entry may contain the common function flagsdescribed for bits 30 and 31 of the CALL instruction.If bit 15 is 0, the microprocessor adds the contents of the index register to thebranch address and branches to the resulting address. If bit 15 is 1, the microprocessorbranches to the address in the table entry indicated by the indexregister, using the table indicated by II. If the index is 0, the first address in thetable is used.148