Improve multiple accessing pxCurrentTCB in a function

[chinglee-iot]

Description

Address Richard's feedback to update the usage of pxCurrentTCB in a function. Since pxCurrentTCB is a volatile variable, accessing it multiple times can be slow if this pointer is not changed.

In this PR:

• Use a const pointer variable to access pxCurrentTCB in a function to prevent multiple accessing a volatile variable.
• The prvGetCurrentTaskTCB() and prvGetCurrentTaskTCBUnsafe() functions are provided. prvGetCurrentTaskTCBUnsafe() can improve performance in SMP environments as it does not disable/enable interrupts. However, it should only be called in contexts where race conditions cannot occur.

Test Steps

Performance comparison test.

Checklist:

• [ ] I have tested my changes. No regression in existing tests.
• [ ] I have modified and/or added unit-tests to cover the code changes in this Pull Request.

Related Issue

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[sonarcloud[bot]]

Quality Gate failed

Failed conditions
3.3% Duplication on New Code (required ≤ 3%)

See analysis details on SonarCloud