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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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18
src/mame/drivers/snookr10.cpp
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@ -206,14 +206,14 @@
To properly decrypt the thing 'on the fly' as the hardware does, I applied a bitswap into TILE_GET_INFO. 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. This method rearrange the tile number for each tile called to be drawn.
The final algorithm is: The final algorithm is: +---- swapped ----+
digit #3 digit #3 digit #1 digit #2
+-------+ 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) 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 inverted inverted inverted
bitorder bitorder|bitorder bitorder bitorder bitorder
Colors are scrambled in the following way: Colors are scrambled in the following way:
Normal | Scrambled Normal | Scrambled
@ -247,7 +247,7 @@
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 2nd nibble
swappeed pairs swapped pairs
Scary, huh?... ;-) Scary, huh?... ;-)