Matamagicians gather round for a game of guess that function

Matamagicians gather round for a game of guess that function
Some of you may spot a pattern sooner than I and you will win the prestige that goes with having discovered what one of the functions in the pv2 firmware does. Your contribution will eventually also make it easier to do more cool things with the pv2 still cameras. Here is a snippet of input and output to and from the function

 
       R0    R1
 INPUT FB    00
OUTPUT 00    00
 INPUT FC    00
OUTPUT 00    00
 INPUT FD    00
OUTPUT 00    00
 INPUT FE    00
OUTPUT 00    00
 INPUT FF    00
OUTPUT 00    00
 INPUT 00    01
OUTPUT 00    02
 INPUT 01    01
OUTPUT 01    02
 INPUT 02    01
OUTPUT 02    04
 INPUT 03    01
OUTPUT 03    04
 INPUT 04    01
OUTPUT 04    08
 INPUT 05    01
OUTPUT 05    08
 INPUT 06    01
OUTPUT 06    08
 INPUT 07    01
OUTPUT 07    08
 INPUT 08    01
OUTPUT 08    10
 INPUT 09    01
OUTPUT 09    10
 INPUT 0A    01
OUTPUT 0A    10
 INPUT 0B    01
OUTPUT 0B    10
 INPUT 0C    01
OUTPUT 0C    10
 INPUT 0D    01
OUTPUT 0D    10
 INPUT 0E    01
OUTPUT 0E    10

anyone wanting the entire input/output file PM me your email address and I'll send it along....once it finishes running in the v8 simulator that is.

The OUTPUT_R0:R1=0 when the input R0=0, but when R0=1 then OUTPUT_R0:R1 ~= INPUT_R0:R1. I'm guessing that the output is actually 8-bit, just in R0, with R1 being filled from incidental work in the function. It could be a division function, but there's not enough sample data to say anything for sure. Care to post more data, preferably with input R1>1?

sure, here is some from the end

 INPUT F8    FF
OUTPUT 08    00
 INPUT F9    FF
OUTPUT 07    00
 INPUT FA    FF
OUTPUT 06    00
 INPUT FB    FF
OUTPUT 05    00
 INPUT FC    FF
OUTPUT 04    00
 INPUT FD    FF
OUTPUT 03    00
 INPUT FE    FF
OUTPUT 02    00
 INPUT FF    FF
OUTPUT 01    0

and a middle section


 INPUT 01    F7
OUTPUT F7    EE
 INPUT 02    F7
OUTPUT EE    DC
 INPUT 03    F7
OUTPUT E5    DC
 INPUT 04    F7
OUTPUT DC    B8
 INPUT 05    F7
OUTPUT D3    B8
 INPUT 06    F7
OUTPUT CA    B

and another


 INPUT 03    6C
OUTPUT 44    B0
 INPUT 04    6C
OUTPUT B0    60
 INPUT 05    6C
OUTPUT 1C    60
 INPUT 06    6C
OUTPUT 88    60
 INPUT 07    6C
OUTPUT F4    60
 INPUT 08    6C
OUTPUT 60    C0

I'd gladly post the entire 2,177k file, but it is probably too long for a post :)

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