memory-values

name	memory-values
description	How to add or modify a DuckStation game-memory reader in the MemoryAccess project of this Digimon World app (MemoryValueSyncBase subclasses, the Empty Null Object requirement, LiveMemoryReader wiring, read-on-poll/write-on-set, EventHub signalling, bit flags). Use when exposing a new game stat/value or changing how memory is read or written.

Memory access (MemoryAccess project)

LiveMemoryReader.Instance monitors for the emulator process; PsxRam locates the PSX RAM base by byte-signature scan; ProcessMemory wraps ReadProcessMemory/WriteProcessMemory. Reads happen on the 1-second poll; writes happen when a value property's setter is assigned (e.g. a cheat-sheet edit persists straight into game RAM).

Adding a reader

1. Create a class extending MemoryValueSyncBase (auto-polls every 1s while connected). Offsets as UPPER_SNAKE_CASE consts.
2. Each value = a property whose getter returns the cached field and whose setter writes to RAM via mem.WriteInt16/Int32/Byte(ram.A(OFFSET), value).
3. Override OnUpdateData() to read all fields, then signal the relevant EventHub (EmulatorLinkEventHub.SignalDigimon…Synchronized()).
4. Required: provide an Empty Null Object — a private parameterless ctor chaining this(ProcessMemory.Empty, PsxRam.Empty) and a public static X Empty { get; } = new(); — and add a default for it in LiveMemoryReader. This is what makes reads/writes safe no-ops while disconnected.

Bit flags

For a packed flag byte, cache the byte and expose bool properties via helpers:

private bool HasBit(int bit) => (_flags & (1 << bit)) != 0;
private void SetFlag(int bit, bool value)
{
    _flags = (byte)(value ? _flags | (1 << bit) : _flags & ~(1 << bit));
    mem.WriteByte(ram.A(FLAGS_OFFSET), _flags);
}

Read-modify-write preserves the other bits. (Cheat Engine BitStart N = bit index N, i.e. mask 1 << N.)

Reference

DW1_NTSC.CT (bundled Cheat Engine table) is the source of addresses/bit positions — grep it for a value before assuming one doesn't exist.