The explanation I gave was a quick overview for you to check where fp12 gets its value, I kept digging myself and found out that it gets its value from memory, here's an overview of the process:
We now know that fp12 gets set in this instruction cvt.s.w f12,f00 this instruction means "Convert the integer in f00 to a float of the same value and store it in f12" well, now we need to find where in the world f00 gets set
Looking at the full asm we have:
; Some notes on asm: