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US 2015/0317152 A1Published application
Patching of Program Code Executed from One Time Programmable Memory
AssigneeDialog Semiconductor GmbH
InventorPhilip Todd
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Abstract
Patching of program code stored in and directly executed from an OTP is supported by a patch mechanism that does not rely on additional hardware, external intervention or RAM. The features of the disclosure include using a patch daisy chain, delay considerations, non-destructive patching and nested subroutine calls. The techniques disclosed are equally applicable for OTP with an unprogrammed value of “1” as for unprogrammed values of “0”.
Claims25
A method to support patching of program code executed from OTP memory at a subroutine level, the method comprising the steps of:
- (1) providing an one-time programmable (OTP) memory and a means to convert bits of the OTP memory, wherein one or more hooks comprising jump instructions are inserted into an original code on the OTP memory such that subroutine calls can be made from the hook to a subroutine hook rather than directly to the subroutine start address itself;
- (2) programming a new subroutine in the formerly unprogrammed OTP memory area;
- and
- (3) patching an existing hook jumping to a subroutine to be retired, wherein the modified hook is capable to jump to the new subroutine.
1 more element
Dependencies are inferred from the claim text.