Keeping only the bits you want
Masking throws away the bits you don't care about. AND a number with a mask and only the mask's set bits survive; everything else collapses to zero. When those set bits lie scattered rather than forming a single run, MWCC falls back to its immediate AND, andi..
Watch n get masked with 0x0A — decimal 10, bits 1 and 3 set:
andi. r3, r3, 10
blr
Only 16 bits fit in that immediate, which pins andi. to the low half-word and nothing above it. The dot marks the record form: cr0 gets LT, GT, or EQ from a signed comparison of the result with zero, plus SO copied from the summary-overflow flag. MWCC emits andi. even when these flags go unread, because PowerPC has no dotless immediate AND.
(A run of contiguous bits compiles another way — "Testing Whether a Bit Is Set" covers that. Because 0x0A splits its set bits apart, andi. is what you land on.)
Recover the target mask from its immediate, then write the C expression that reproduces it.
Your task
Write func_803564a0 to match the target.