According to the MSP430 EABI [1] section 3.3,
Arguments are assigned, in declared order, to the first available
register single, pair, or quad from the following list into which it
fits (with the following special exceptions). For MSP430 and
MSP430X, the argument registers are: R12, R13, R14, R15
Therefore, pvParameters should be passed in R12, as it is the first
argument, not R15. Keep passing the parameter in R15 for the
MSP430 EABI, if anyone is still using it.
[1] https://www.ti.com/lit/an/slaa534a/slaa534a.pdf
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