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snookr10.cpp: Realigned the ASCII diagram about encryption,

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messed up some time ago for some bulk changes.
This commit is contained in:
Roberto Fresca 2022-04-30 05:24:06 +02:00
parent 90f166da8f
commit f65c56c6c7
1 changed files with 12 additions and 12 deletions
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24
src/mame/drivers/snookr10.cpp
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@ -206,15 +206,15 @@
To properly decrypt the thing 'on the fly' as the hardware does, I applied a bitswap into TILE_GET_INFO.
This method rearrange the tile number for each tile called to be drawn.
The final algorithm is:
digit #3
+-------+ swapped digits 1 & 2
| | +-------+------+
tile_offset = bitswap<16>((tile_offset & 0xfff),15,14,13,12, 8,9,10,11, 0,1,2,3, 4,5,6,7)
| | | | | | | | || | | |
inverted inverted|inverted
bitorder bitorder|bitorder
Colors are scrambled in the following way:
The final algorithm is: +---- swapped ----+
digit #3 digit #1 digit #2
+-------+ +-----+ +-----+
| | | | | |
tile_offset = bitswap<16>((tile_offset & 0xfff),15,14,13,12, 8,9,10,11, 0,1,2,3, 4,5,6,7 )
| | | | | | | | | | | |
inverted inverted inverted
bitorder bitorder bitorder
Colors are scrambled in the following way:
Normal | Scrambled
offset | offset
@ -244,10 +244,10 @@
1st nibble
inverted bitorder
| | | |
color_index = bitswap<8>(color_index,4,5,6,7,2,3,0,1)
color_index = bitswap<8>(color_index,4,5,6,7,2,3,0,1)
<-> <->
2nd nibble
swappeed pairs
swapped pairs
Scary, huh?... ;-)
@ -438,7 +438,7 @@
So, the algorithm to properly decrypt the color codes is the following one:
color_index = bitswap<8>(color_index,7,5,6,4,3,2,1,0)
color_index = bitswap<8>(color_index,7,5,6,4,3,2,1,0)
| |
swapped