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Saturn Decompilation

Internals

Overlays

File Name

Stage

STAGE_00.PRG

Final Stage: Bloodlines

STAGE_0X.PRG

Entrance (1st visit)

STAGE_01.PRG

Entrance (2nd visit)

STAGE_02.PRG

Alchemy Laboratory

STAGE_03.PRG

Marble Gallery

STAGE_04.PRG

Outer Wall

STAGE_14.PRG

Center / Maria Boss

STAGE_15.PRG

Underground Garden / Skeleton Leader

STAGE_16.PRG

Cursed Prison

BOSS_02.PRG

Slogra & Gaibon

LOGO.PRG

Intro copyright logo

TITLE.PRG

Title screen and main menu

Memory mapping (Alucard)

Address

End addr.

Memory Area

File name

Description

06004080

~060505df

High Work Ram

0.BIN

A mix of SEGA libraries and some DRA.BIN

06066000

~0608008b

High Work Ram

GAME.PRG

Similar to DRA.BIN

060A5000

High Work Ram

ALUCARD.PRG

Alucard code overlay

060CF000

~060d5fff

High Work Ram

T_BAT.PRG etc.

Familiar code overlay

Memory mapping (Richter/Maria)

Address

End addr.

Memory Area

File name

Description

00232000

Low Work Ram

RICHTER.CHR/MARIA.CHR

Secondary player sprite graphics

06004080

High Work Ram

0.BIN

Entry point, Sega libraries

06060000

High Work Ram

GAME.PRG

Probably the equivalent of DRA.BIN

060A5000

High Work Ram

RICHTER.PRG/MARIA.PRG

Secondary player code overlay

060DC000

High Work Ram

STAGE_XX.PRG

Stage code overlay

05C1D980

VDP1 Ram

RIC_W.CHR/MAR_W.CHR

Secondary player sprite graphics

05C2F820

VDP1 Ram

STAGE_XX.CHR

Stage sprite graphics

Scratches

0.BIN

Saturn Func

PSX Func

Scratch

Matched?

Note

f_0000ae08

ratan2

https://decomp.me/scratch/889Ky

GAME.PRG

Saturn Func

PSX Func

Scratch

Matched?

Note

f_0000921C

func_800FD4C0

https://decomp.me/scratch/1CORM

f_000092C0

func_800FD5BC

https://decomp.me/scratch/DFpq8

Probably matching

f_00009328

func_800FD664

https://decomp.me/scratch/WEMRF

f_000152f4

Random

https://decomp.me/scratch/F5nPH

f_000157b4

CheckCollision

https://decomp.me/scratch/GZerS

f_0606F798

LearnSpell

y

f_0606F800

func_800FDD44

y

f_0606FC60

IsRelicActive

y

f_060A80E0

func_8011203C

y

ALUCARD.PRG

Saturn Func

PSX Func

Scratch

Matched?

Note

f_060A7DE8

BatFormFinished

y

f_060AA23C

ControlBatForm

y

f_060AC574

y

Part of EntityAlucard

T_BAT.PRG

Saturn Func

PSX Func

Scratch

Matched?

Note

data_00000000

g_ServantDesc

https://decomp.me/scratch/Eex58

Y

func_00000294

func_801713C8

https://decomp.me/scratch/FeLXE

func_000021b8

func_80173E78

https://decomp.me/scratch/kMCmY

Y

func_00002224

func_80173F30

https://decomp.me/scratch/ccc2s

Should be equivalent

func_060D11DC

func_80173EB0

https://decomp.me/scratch/z4bWL

func_060D125C

func_80173F74

https://decomp.me/scratch/nVmi2

func_0000225C

func_80173F74

https://decomp.me/scratch/ha1kO

func_000022AC

func_80173FE8

https://decomp.me/scratch/vOfP4

Y

STAGE_02.PRG (Alchemy Lab)

Saturn Func

PSX Func

Scratch

Matched?

Note

func_060EAFAC

EntityBloodyZombie

https://decomp.me/scratch/ZvlTe

Compiler patterns

Function return values

If you have an issue like this with jsr @r1 vs jsr @r0, your function prototype generally needs to return void to get r1, and non-void to get r0.

void DestroyEntity(Entity*);

  10:    mov.l   50 ,r1           
  12:    jsr     @r1

s32 DestroyEntity(Entity*);

r 10:    mov.l   50 ,r0         
r 12:    jsr     @r0

Equivalent code that produces different asm

The following two functions produce different asm. https://decomp.me/scratch/oNzR9

bool func_06013320(void) {
    if (DAT_060644C0 == 2) {
        return 1;
    }
    return 0;
}

bool func_06013320(void) { return DAT_060644C0 == 2; }

Ghidra output patterns:

Struct pointer dereference:

*(undefined *)(param_1 + 0x11) = 10;

param_1->unk11 = 10;

Graphics Info

Tile graphics are loaded by func_6008588. NOPing this out shows that the tilemap is present but the graphics aren't:

image

WIP https://decomp.me/scratch/TXaHJ

Part of the Richter sprite graphics are loaded by func_600A490. I think there's two banks loaded to different RAM areas. NOPing this out removes one of the banks.

image

Tile maps and collision data seem to be loaded by func_606C774. NOPing this out gives the following showing that the tile graphics are loaded but the map is messed up.

image

These functions all call func_0600f96C which is responsible for writing to an area of Low WRAM around ~26a750.

This area gets read by instructions at 0x60088BC (func_0600871C) or 0x60099fe (func_060098F0) or 0x6009bee (func_06009AE8). which transfers it to a buffer starting at high WRAM 0x0605C120.

NOPing out func_060098F0 prevents part of the transfer to high WRAM and you get this:

image

NOPing out func_06009AE8 gets this:

image

Then 0x0605C120 is processed and transferred to VDP2 Ram by func_60098F0. The instruction that does the write is at 0x6009a04.