Calling and returning with BASSM and BSM
In the following example, a module named BELOW has the attributes AMODE 24, RMODE 24. BELOW uses a LOAD macro to obtain the address of module ABOVE. The LOAD macro returns the address in register 0 with the addressing mode indicated in bit 0 (a pointer-defined value). BELOW stores this address in location EPABOVE. When BELOW is ready to branch to ABOVE, BELOW loads ABOVE's entry point address from EPABOVE into register 15 and branches using BASSM 14,15. BASSM places the address of the next instruction into register 14 and sets bit 0 in register 14 to 0 to correspond to BELOW's addressing mode. BASSM replaces the PSW A-mode bit with bit 0 of register 15 (a 1 in this example) and replaces the PSW instruction address with the branch address (bits 1-31 of register 15) causing the branch.
