Method and related device for use in decoding executable code
The invention provides for a method and related device and control program for use in decoding executable code in a processing system, for example run-time operating system, including bit-shuffling code at run-time, and including the steps of dividing the code into a plurality of sub-portions, identifying sub-portions of the code that can be bit-shuffled prior to the said run-time and bit-shuffling the said identified sub-portions prior to run-time so as to reduce the bit-shuffling required at run-time.
1. A method for use in decoding executable code in a processor system including bit-shuffling code, and including the steps of:
dividing the code into a plurality of sub-portions;
identifying sub-portions of the code that can be bit-shuffled prior to processing; and
bit-shuffling the said identified sub-portions prior to processing so as to reduce the processing bit-shuffling required.
2. A method as claimed in claim 1 wherein the said system comprises a run-time operating system and the said identified sub-portions are bit-shuffled prior to run-time.
3. A method as claimed in claim 2 , and including the step of, at link time, generating a relocation patch-up table for the loading and relocation of the code.
4. A method as claimed in claim 3 , and including the step of examining the relocation patch-up table at the end of the aforesaid linking so as, to determine which addresses in the code are patched.
5. A method as claimed in claim 2 , wherein the said identified subportions are bit-shuffled at link time.
6. A method as claimed in claim 2 , and including the step of generating a record of the sub-portions to be patched and shuffled at run-time in the form of a bitmap.
7. A method as claimed in claim 6 , and including the step of adding the said bitmap to the executable code.
8. A method as claimed in claim 2 , and including the steps of identifying sub-portions of the code that do not require patching at run-time in order to identify the sub-portions for pre-shuffling.
9. A method as claimed in claim 2 , and including the step of reading code elements within a program loader for the execution of the program.
10. A method as claimed in claim 9 , wherein the program loader is arranged to read the relocation patch-up table and the executable code and writes the result back within the executable code.
11. A method as claimed in claim 2 , wherein the executable code comprises a TriMedia program having a text segment containing TriMedia executable code.
12. A method as claimed in claim 2 , wherein each sub-portion of code comprises a cache-sized block.
13. A method as claimed in claim 12 , wherein each cache-sized block comprises a 64 byte block.
14. A method as claimed in claim 2 and for use with any form of TriMedia executable image requiring loading and relocation before execution.
15. A method as claimed in claim 1 , and including the linking of pre-shuffled code during a later link time phase.
16. Decoding apparatus for decoding executable code in a processor and including means for bit-shuffling code, the apparatus further comprising:
means for dividing the code into a plurality of sub-portions;
means for identifying sub-portions of the code that can be bit-shuffled prior to processing; and
means for bit-shuffling the said identified sub-portions prior to processing so as to reduce the processing bit-shuffling required.
17. Apparatus as claimed in claim 16 wherein the said system comprises a run-time operating system and the sub portions identified are those that can be bit-shuffled prior to run time.
18. Apparatus as claimed in claim 17 , and including means for generating a relocation patch-up table for the loading and relocation of the code at link time.
19. Apparatus as claimed in claim 17 , and including means for bitshuffling the identified sub-portions at link time.
20. Apparatus as claimed in claim 17 , and including means for generating a record of the sub-portions to be patched and shuffled at run-time in the form of a bitmap.
21. Apparatus as claimed in claim 17 , and including a program loader into which code elements are read for program execution.
22. Apparatus as claimed in claim 21 , wherein the program loader is arranged to read the relocation patch-up table and the executable code and to write the result back within the executable code.
23. Apparatus as claimed in claim 17 , wherein each sub-portion of code comprises a cache-sized block.
24. Apparatus as claimed in claim 17 , wherein each cache-sized block comprises a 64 byte block.
25. Apparatus as claimed in claim 16 and arranged for linking pre-shuffled code during a later link time phase.
26. A computer readable medium including a computer program element comprising computer program code means to make a computer execute procedure to decode executable code in a processor including bit-shuffling code, and to:
divide the code into a plurality of sub-portions;
identify sub-portions of the code that can be bit-shuffled prior to processing; and
bit-shuffle the said identified sub-portions prior to processing so as to reduce the processing bit-shuffling required.
27. A complete program element as claimed in claim 26 and arranged to control decoding in a run-time operating system.
28. A computer program element as claimed in claim 26 and arranged to control the linking of pre-shuffled code during a later link time phase.
29. A computer program product comprising a computer readable medium and including a program element as claimed in claim 26 .