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How much RAM my applet needs

JavaCard Applet Development Related Questions and Answers.
cprgolds
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How much RAM my applet needs

Post by cprgolds » Tue Jan 17, 2017 11:09 pm

I wonder how much RAM my applet will need. What consumes RAM in my applet? I can count the transient variables but how do I find out how much RAM for the stack I need?

Wardor
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Re: How much RAM my applet needs

Post by Wardor » Wed Jan 18, 2017 5:27 am

What consumes RAM in my applet?

transient variables, the stack,APDU buffer

I can count the transient variables but how do I find out how much RAM for the stack I need?

IMO, JCVM method stack is pre-allocated to a minimum size.
You can try to call the method JCSystem.getAvailableMemory(MEMORY_TYPE_TRANSIENT_RESET) within each method and save it to a shared byte array for output. But the method's parameters will also consume stack memory.

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mabel
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Re: How much RAM my applet needs

Post by mabel » Wed Jan 18, 2017 6:21 am

As far as I know, APDU buffer and stack consume pre-allocated RAM.

cprgolds
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Re: How much RAM my applet needs

Post by cprgolds » Thu Jan 19, 2017 12:06 am

Thanks for all the answers. I have tried to call JCSystem.getAvailableMemory(MEMORY_TYPE_TRANSIENT_RESET) to know the approximate memory.

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