Sun Microsystems, Inc.

Oracle America, Inc.

Judith E Schwabe

Zhiqun Chen

Joshua Susser

A method for arithmetic expression optimization comprises validating at least one input stack associated with a first instruction operable on at least one operand of a first type and optimizing the first instruction to a second instruction operable on at least one operand of a second type that is smaller than the first type based at least in part on the relative size of the first type and the second type. The method also comprises matching the second type with an operand type of at least one operand in the at least one input stack associated with the second instruction. The matching comprises changing the type of instructions in a chain of instructions to equal the second type if the operand type is less than the second type. The chain is bounded by the second instruction and a third instruction that is the source of the at least one operand.

Optimization of N-base typed arithmetic instructions via rework

Apparatus and processes, including computer implemented processes, for managing exceptions throwable during execution of methods in one or more classes by a machine. Each method includes an exception handler array defining exception handlers associated with the method. The method includes combining the exception handler arrays for all methods into a single exception handler table.

Zero overhead exception handling

A system links architecture neutral code downloaded to a resource constrained computer. The code may be separated into one or more packages having one or more referenceable items. The system maps the one or more referenceable items into corresponding one or more tokens; orders the tokens to correspond to a run-time mode; downloads the packages to the resource constrained computer; and links the packages into an executable code using the ordered tokens.

Token-based linking

A method for arithmetic expression optimization includes receiving a first instruction defined for a first processor having a first base, the first instruction including an operator and at least one operand, converting the first instruction to a second instruction optimized for a second processor having a second base when all operands do not carry potential overflow or when the operator is insensitive to overflow, the second base being smaller than the first base, and converting to a wider base a third instruction that is the source of the overflow when the at least one operand the potential for overflow and when the operator is sensitive to overflow. An apparatus for arithmetic expression optimization includes at least one memory having program instructions and at least one processor configured to use the program instructions to receive a first instruction defined for a first processor having a first base, convert the first instruction to a second instruction optimized for a second processor having a second base when every one of the at least one operand does not carry potential overflow or when the operator is insensitive to overflow, the second base being smaller than the first base, and convert to a wider base a third instruction that is the source of the overflow when the at least one operand the potential for overflow and when the operator is sensitive to overflow.

Optimization of n-base typed arithmetic expressions

A method of operating a computer system includes providing a program in memory, verifying the program prior to an installation of the program and generating a program fault signal when the verification fails. The program includes at least one program unit, and each program unit includes an Application Programming Interface (API) definition file and an implementation. Each API definition file defines items in its associated program unit that are made accessible to one or more other program units and each implementation includes executable code corresponding to the API definition file. The executable code includes type specific instructions and data. Verification includes determining whether a first program unit implementation is internally consistent, determining whether the first program unit implementation is consistent with a first program unit API definition file associated with the first program unit implementation and generating a program fault signal when the verifying fails. A resource-constrained device includes a memory for providing a remotely verified application software program that includes at least one program unit, each program unit comprising type specific instructions and data. The resource-constrained device also includes a virtual machine that is capable of executing instructions included within the application software program. The remote verification uses an API definition file for each implementation to determine whether a first program unit implementation is internally consistent and to determine whether the first program unit implementation is consistent with a first program unit API definition file associated with the first program unit implementation.

Remote incremental program verification using API definitions

A method for arithmetic expression optimization includes receiving an operator and at least one operand of a first instruction defined for a first processor having a first base. The method also includes converting the first instruction to a second instruction optimized for a second processor having a second base smaller than the first base when the at least one operand does not carry potential overflow beyond the second base or when the operator is insensitive to overflow. The method also includes converting instructions in an instruction chain to a wider base larger than the second base and smaller or equal to the first base when the at least one operand carries potential overflow beyond the second base and when the operator is sensitive to overflow. The chain is bounded by the second instruction and a third instruction that has been previously optimized and is the source of the potential overflow.

Overflow sensitive arithmetic instruction optimization using chaining

A resource-constrained device such as a smart card or the like includes memory for storing an application software program comprising an object-oriented, verifiable, platform-independent, type-safe and pointer-safe sequence of instructions. The device can also include a virtual machine implemented on a microprocessor where the virtual machine is capable of executing the sequence of instructions. Each instruction includes an operation code, and each data manipulation instruction is specific to a particular data type. The application program can be stored on a computer-readable medium prior to being received by the resource-constrained device. Methods of using such an application program, including accessing the program over the Internet and downloading it to a smart card, also are disclosed.

Object-oriented instruction set for resource-constrained devices

A method for representing an application programming interface (API) for an object-oriented library includes creating a list of public elements in the library and storing the list. Each public element in the list includes a sublist of all public related elements for the element. According to one aspect, the public elements include classes and interfaces, the public related elements include public superclasses and public superinterfaces, and the library is a Java&#x2122; package. According to one aspect, a method for determining a program hierarchy includes receiving an API definition file for an object-oriented library and indicating a first public element is a direct parent of a second public element when the first public element is represented in the sublist for the second public element and the first public element is not represented in the sublist for any other public element listed in the sublist for the second public element. According to another aspect, a method for detecting changes to a program hierarchy includes comparing a first program hierarchy reconstructed from a first API definition file with a second program hierarchy reconstructed form a second API definition file and indicating an error when the first program hierarchy is inconsistent with the second program hierarchy.

API representation enabling submerged hierarchy

A method for arithmetic expression optimization includes receiving an operator and at least one operand of a first instruction defined for a first processor having a first base. The method also includes converting the first instruction to a second instruction optimized for a second processor having a second base smaller than the first base when overflow is impossible based at least in part on the operator and the relationship between the operand type and the second base. The method also includes converting instructions in an instruction chain to a wider base larger than the second base and smaller or equal to the first base when the at least one operand carries potential overflow beyond the second base and when the operator is sensitive to overflow. The chain is bounded by the second instruction and a third instruction that has been previously optimized and is the source of the potential overflow.

Overflow predictive arithmetic instruction optimization using chaining

A method for arithmetic overflow detection includes receiving a first instruction defined for a first processor having a first base, where the instruction comprises an operator and at least one operand having an operand type. The method also includes indicating whether the at least one operand has potential overflow based at least in part on the operator and the relationship between the operand type and a result type associated with the operator.

Predictive arithmetic overflow detection

A method of operating a computer system includes providing a first version of a program in memory and verifying the program prior to program execution. Program verification includes indicating a verification error when a first version of a first program unit implementation is not internally consistent, indicating a verification error when the first version of the first program unit implementation is inconsistent with the version of the program unit API definition file associated with the first version of the first program unit implementation, receiving a second version of the first program unit implementation and a second version of the first program unit implementation is binary compatible with the first version of the first program unit implementation by comparing the first version of the first program unit API definition file and the second version of the first program unit API definition unit.

Remote incremental program binary compatibility verification using API definitions

Remote incremental program verification may be achieved by receiving content verified by at least one content provider, installing the content on a resource-constrained device, issuing the resource-constrained device to an end user, and allowing post-issuance installation of verified content on the resource-constrained device by a trusted post-issuance installer. The at least one content provider includes an applet provider, a device manufacturer, a device issuer, and a trusted post-issuance installer. The content includes at least one program unit, where each program unit comprises an Application Programming Interface (API) definition file and an implementation. Each API definition file defines items in its associated program unit that are made accessible to one or more other program units, and each implementation includes executable code corresponding to the API definition file. The executable code includes type-specific instructions and data. The verification includes determining binary compatibility of earlier program unit implementations with later program unit implementations.

Populating binary compatible resource-constrained devices with content verified using API definitions

Remote incremental program verification may be achieved by receiving content verified by at least one content provider, installing the content on a resource-constrained device, disabling subsequent installation of content on the resource-constrained device, and issuing the resource-constrained device to an end user. The at least one content provider includes an applet provider, a device manufacturer, and a device issuer. The content includes at least one program unit, where each program unit comprises an Application Programming Interface (API) definition file and an implementation. Each API definition file defines items in its associated program unit that are made accessible to one or more other program units, and each implementation includes executable code corresponding to the API definition file. The executable code includes type specific instructions and data.

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Palo Alto, CA, United States of America

Judith E Schwabe