PURPOSE: To realize easily a reentrant subroutine, by performing automatically the evacuation of the register group, the security of a working area and the setting of a static link respectively on a stack and by means of hardwares when the subroutine is called.
CONSTITUTION: The contents of a general-purpose register 3 is evacuated to a work register 5. The register 3 is shown by a static link address designating register number of an instruction which is read out by a main storage device 1. Then a program status word 4 is pushed down to a stack, and the contents of the head address of a subroutine is evacuated to a work register 6. The contents of the register 3 is pushed down to a stack in accordance with a register save pattern. The contents of a work register 9 is subtracted by an operator 10, and the contents of the register 6 and the static link address of the register 5 are pushed down to the stack. Finally the contents of the word 4 receives the addition of (1) through the operator 10, and the head address of the main body of the subroutine program is obtained for execution.
YAMADA SHIGEKI
SATOU NORIO
FUJISAWA MITSURU
IKUTA AKIRA
OCHIAI SHIGEO
NIPPON TELEGRAPH & TELEPHONE
NIPPON ELECTRIC CO
HITACHI LTD
FUJITSU LTD