| 摘要 |
A digital data processing system uses variable length instructions grouped in routines and subroutines. One of the instructions in a routine is a subroutine calling instruction, Fig. 10A or 10B, which includes an operation code, FA or FB and two operand specifiers. One operand specifier represents an argument list address or argument count and thus enables determination of the arguments to be passed from the calling routine to the subroutine, and the other operand specifier specifies the initial address of the subroutine, which contains a subroutine mask designating those of a set of general registers which are to be used by the subroutine and the contents of which are therefore to be stored, at memory locations specified by a stack pointer register, for when return to the routine is made. The contents of argument pointer, frame pointer and program counter registers are always stored. <IMAGE> |
