FreeRTOS and MSP430F5418

Hari said:

Replaced all "call #function_name" with "calla #function_name" in portext.s43 (Line 102,80,77)

Also, registers should be saved on stack using the PUSHA instruction, to maintain any possibly existing 20 bit values. This is usually only necessary if you're using data above 64k, but still...

First, the POPX can be grouped together using the POPM.A instruction. It pops up to all 16 registers (well, it makes no sense for all 16, since popping R1 will move stack for the pop of R0 and popping R3 is futile and R2 may not be popped as 20 bit at all )

Using POPM.A  #12, R15 will pop R15 to R4 from sthe stack, while PUSHM.A #12,R15 will push R4 to R15 to stack (automatically inversed order!)

The combination pop/move can be fouped as a single instruction, since push and pop, liek all other orthogonal operations, can as well push and pop from and to a memory location (even register indirect).

The last instruction to modify the saved status register may NOT be 20 bit. The status register is 16 bit (even including the 4 'additional' address bits. Also, the return address is 16 bit on the stack (the additional 4 bits are int eh upper bits of the status register, which are undefined for status purposes, but used on 430X devices).

So what your BIC effectively does is clearing the return address to y0000 to y000f (the upper 4 bit of the 20 bit return ar enot touched), since all .A instructions will implicitely clear the upper 12 bits of a 32 bit memory location.

Use a normal standard 16 bit BIC(.W) for the status on the stack. And since the stack is usually in the lower 64k (no ram above), not even a BICX(.W) is required.