Nissan ECU ROM reverse-engineering. 2: tables & axis data

Looking at typical 2D table lookup code and how to confirm axis locations (i.e. row / column values), and input value sources.
Nissan ROMs usually do a standard bilinear interpolation ( en.wikipedia.o... ), by locating each input value in its respective axis table, and computing a "fraction" when it inevitably falls between rows/columns. At the last step it uses those fractions and the 2D table to produce the final value.
Not mentioned in the video : the final value computed by tbl_lookup() is returned in register R0, as is almost always the case. That output is sometimes then copied to a RAM location which can be logged ; this, in conjunction with the two RAM locations of the input values, can confirm that the storage order of the table was correct.

[@justinwademckinney6032]

Hey! Awesome to see you on RUclips Sharing this stuff. Can't wait to dive in!

[@brandonlittle6444]

Excellent video.

[@hex_surfer4588]

Seems like IDAPro is much more user friendly than Ghidra. Great video!