# SA-1 Root: Contra III
Version 1.2, released 2022-09-19

Contra III: The Alien Wars is the third Contra game made by Konami and an amazing
cinematic shooting game.

This SA-1 Root removes all slowdown present on the original game and drastically
reduces the loading times. It also saves the high scores and settings.

Special thanks to Erivando_BR for sending me the SA-1 Collection trace log files
of Contra III, which made this optimization patch possible to happen.

## How to Patch

Download the latest Contra III .bps patch file available on the
[Releases](https://github.com/VitorVilela7/SA1-Root/releases) tab.

You can patch it using [beat](https://www.romhacking.net/utilities/893/)
or [FLIPS](https://sneslab.net/tools/floating.zip), both common .bps patchers.

You can also patch the .asm files directly using
[Asar](https://github.com/RPGHacker/asar).

For more information on how to apply ROM patches, see this SnesLab
article: https://sneslab.net/wiki/How_to_apply_ROM_patches

It works only on the american version of Contra III. Contra Spirits and Super
Probotector **does not** work because both games were recompiled and its codes are
different compared to the american version. Depending on the demand I might
do them eventually, but they will likely require the same amount of effort as
a new game conversion.

Expected checksums:

### USA Version:
#### Before patching:
* CRC32: 84DA7CFE
* SHA256: A93EA87FC835C530B5135C5294433D15EEF6DBF656144B387E89AC19CF864996

#### After patching
* CRC32: FF3EE176
* SHA256: 5D2A0ED336E2681D694395A2183D82BEDCAC93B612CBFB5F543DA80A001E861D

## Compatibility

It works on both real hardware (sd2snes or SA-1 cart) and emulators (Snes9x and bsnes/higan/ares).

## Technical details

* Remapping mode: Full
* Remapping strategy: Runtime
* SA-1 usage: Aggressive

This game has a very complex data structure. Even more compared compared to Gradius III.
Direct page, indirect addressing and shared ROM/RAM pointers are pretty common on this game.
For that, I had to remap the entire RAM memory to the BW-RAM and for the data structures
that referenced banks 7E/7F were most of the time remapped by runtime for not having
to mine over 950KB of data structures.

SA-1 was used for the maximum time possible and a callback system was used for the SA-1
CPU calling back the SNES CPU when running on routines that it can't handle (APU uploads
and PPU updates mostly).

Because of the strategy used,
**128 kB (1024 Kbit) of BW-RAM is required to the game run** correctly.

## RAM remap

* ``$0000-$1FFF`` -> ``$6000-$7FFF``
* ``$7E:0000-$7F:FFFF`` -> ``$40:0000-$41:FFFF``

## Credits

Contra III - SA-1 Root wouldn't be that awesome without help from these people:

* Erivando_BR (testing and trace logs)
* Jeffrey (testing)
* kccheng (testing)
* Rodzilla97 (bug report)
* Vitor Vilela (patch author)
* You (for using it :D)

## Contacting me

You can contact me though the following links:

* My Website: https://www.sneslab.net/
* My Github profile: https://github.com/VitorVilela7
* My Twitter profile: https://twitter.com/HackerVilela
* My Patreon: https://www.patreon.com/vitorvilela