Program execution method for specific case processing and apparatus using the same

A program execution method for executing specific case processing, in addition to normal processing, according to a processing request, comprising steps of:

• receiving a request for specific case processing during execution of normal processing;
• upon receipt of a request for specific case processing, temporarily inhibiting further receipt of a request for specific case processing, and branching to a routine for the specific case processing and storing a return address for use in returning to the normal processing in address holding means;
• saving the return address stored in the address holding means in address saving means during the routine;
• executing the specific case processing while allowing further receipt of a request for specific case processing;
• and
• automatically inhibiting further receipt of a request for specific case processing when an instruction for preparing environment for returning to the normal processing is executed after completion of the specific case processing.

A program execution apparatus comprising:

• a setting section for setting allowance or rejection of receipt of a request for specific case processing;
• an address holding section for storing a return address when a process branches to specific case processing;
• and
• an address saving section for saving a return address stored in the address holding section;
• wherein
• the setting section automatically rejects further receipt irrespective of a current setting situation when a return address read from the address saving section is stored in the address holding section.

A program execution apparatus for executing specific case processing, in addition to normal processing, according to a processing request, comprising:

• a setting section for setting allowance or rejection of receipt of a request for specific case processing;
• an address holding section for storing a return address when a process branches to specific case processing;
• and
• an address saving section for saving a return address stored in the address holding section;
• wherein
• the setting section temporarily inhibits further receipt of a request for specific case processing when a request for specific case processing is received during execution of the normal processing,
• the process branches to a routine for the specific case processing and stores a return address in the address holding section,
• the address saving section saves the return address stored in a return address holding section during execution of the routine, and
• the setting section automatically allows further receipt of a request for specific case processing when an instruction for preparing the environment for allowing further receipt of a request is executed.

A program execution apparatus for executing specific case processing, in addition to normal processing, according to a processing request, comprising:

• a setting section for setting allowance or rejection of receipt of a request for specific case processing;
• an address holding section for storing a return address when a process branches to specific case processing;
• and
• an address saving section for saving a return address stored in the address holding section;
• wherein
• the setting section temporarily inhibits further receipt of a request for specific case processing when a request for specific case processing has been received during execution of the normal processing,
• the process branches to a routine for the specific case processing and stores a return address in the address holding section,
• the address saving section saves the return address stored in a return address holding section during execution of the routine,
• the specific case processing is executed while the setting section allows again the receipt of a request for specific case processing;
• and
• the setting section automatically rejects further receipt of a request for specific case processing when an instruction for preparing the environment for returning to the normal processing is executed after completion of the specific case processing.

A program execution apparatus for executing specific case processing, in addition to normal processing, according to a processing request, comprising:

• an address holding section for storing a return address when a process branches to specific case processing;
• an address saving section for saving a return address stored in the address holding section;
• and
• a status discrimination section for discriminating between an update allowed state where the contents of the address holding section are allowed to be updated and an update inhibited state where it is inhibited;
• wherein
• the program execution apparatus in the update inhibited state enters into the update allowed state when acceptable interrupt level setting instruction is executed.

A program execution apparatus for executing specific case processing, in addition to normal processing, according to a processing request, comprising:

• an address holding section for storing a return address when a process branches to specific case processing;
• an address saving section for saving a return address stored in the address holding section;
• and
• a status discrimination section for discriminating between an update allowed state where the contents of the address holding section are allowed to be updated and an update inhibited state where it is inhibited;
• wherein
• the program execution apparatus in the update allowed state enters into the update inhibited state when a return address is stored in the address holding section.