From 79a3e32d5db55a2740ed76b7c6a8944e59cb73da Mon Sep 17 00:00:00 2001
From: bicarus <202771338+bicarus-dev@users.noreply.github.com>
Date: Sat, 2 May 2026 02:17:51 -0700
Subject: [PATCH] iidx: delay logic for iidx tt (#669)

## Link to GitHub Issue or related Pull Request, if one exists
Re-implements fix for #181 as it was removed by #668

## Description of change
Add two options to add artificial delay to turntable input. These
operate directly on the input logic (`get_tt`) which is called by I/O
emulation code.

Functionally, it's **identical** to the `Delay (experimental)` option we
had in the analog tab, just moved to Options tab.

## Testing
64 bit tdj: ok
64 bit ldj bi2a: ok
32 bit ldj ezusb: ok

Worth noting that TDJ bi2x_hook polls at 120Hz, bi2a at ~500Hz, and
ezusb at ~170Hz
---
 src/spice2x/games/iidx/iidx.cpp   | 23 ++++++++++++++++++++++-
 src/spice2x/games/iidx/iidx.h     |  2 ++
 src/spice2x/launcher/launcher.cpp |  6 ++++++
 src/spice2x/launcher/options.cpp  | 20 ++++++++++++++++++++
 src/spice2x/launcher/options.h    |  2 ++
 5 files changed, 52 insertions(+), 1 deletion(-)

diff --git a/src/spice2x/games/iidx/iidx.cpp b/src/spice2x/games/iidx/iidx.cpp
index 0bf0f09..a64179d 100644
--- a/src/spice2x/games/iidx/iidx.cpp
+++ b/src/spice2x/games/iidx/iidx.cpp
@@ -67,6 +67,8 @@ namespace games::iidx {
     std::optional<std::string> SOUND_OUTPUT_DEVICE = std::nullopt;
     std::optional<std::string> SOUND_OUTPUT_DEVICE_IN_EFFECT = std::nullopt;
     std::optional<std::string> ASIO_DRIVER = std::nullopt;
+    uint32_t TT_DELAY_P1 = 0;
+    uint32_t TT_DELAY_P2 = 0;
     uint8_t DIGITAL_TT_SENS = 4;
     std::optional<std::string> SUBSCREEN_OVERLAY_SIZE = std::nullopt;
     std::optional<std::string> SCREEN_MODE = std::nullopt;
@@ -781,7 +783,26 @@ namespace games::iidx {
         }
 
         // return higher 8 bit
-        return (uint8_t) (ret_value >> 2);
+        uint8_t result = (uint8_t) (ret_value >> 2);
+
+        // delay
+        if ((player == 0 && TT_DELAY_P1 > 0) ||
+            (player == 1 && TT_DELAY_P2 > 0)) {
+
+            static std::queue<uint8_t> delay_queue[2];
+            auto &queue = delay_queue[player];
+
+            const auto max_size =
+                static_cast<size_t>((player == 0) ? TT_DELAY_P1 : TT_DELAY_P2) + 1;
+
+            queue.push(result);
+            while (queue.size() > max_size) {
+                queue.pop();
+            }
+            result = queue.front();
+        }
+
+        return result;
     }
 
     unsigned char get_slider(uint8_t slider) {
diff --git a/src/spice2x/games/iidx/iidx.h b/src/spice2x/games/iidx/iidx.h
index 2178901..f5cadfe 100644
--- a/src/spice2x/games/iidx/iidx.h
+++ b/src/spice2x/games/iidx/iidx.h
@@ -31,6 +31,8 @@ namespace games::iidx {
     extern bool NATIVE_TOUCH;
     extern std::optional<std::string> SOUND_OUTPUT_DEVICE;
     extern std::optional<std::string> ASIO_DRIVER;
+    extern uint32_t TT_DELAY_P1;
+    extern uint32_t TT_DELAY_P2;
     extern uint8_t DIGITAL_TT_SENS;
     extern std::optional<std::string> SUBSCREEN_OVERLAY_SIZE;
     extern std::optional<std::string> SCREEN_MODE;
diff --git a/src/spice2x/launcher/launcher.cpp b/src/spice2x/launcher/launcher.cpp
index 32b032b..9be9e88 100644
--- a/src/spice2x/launcher/launcher.cpp
+++ b/src/spice2x/launcher/launcher.cpp
@@ -518,6 +518,12 @@ int main_implementation(int argc, char *argv[]) {
     if (options[launcher::Options::IIDXTDJMode].value_bool()) {
         games::iidx::TDJ_MODE = true;
     }
+    if (options[launcher::Options::IIDXTTDelayP1].is_active()) {
+        games::iidx::TT_DELAY_P1 = options[launcher::Options::IIDXTTDelayP1].value_uint32();
+    }
+    if (options[launcher::Options::IIDXTTDelayP2].is_active()) {
+        games::iidx::TT_DELAY_P2 = options[launcher::Options::IIDXTTDelayP2].value_uint32();
+    }
     if (options[launcher::Options::spice2x_IIDXDigitalTTSensitivity].is_active()) {
         games::iidx::DIGITAL_TT_SENS = (uint8_t)
             options[launcher::Options::spice2x_IIDXDigitalTTSensitivity].value_uint32();
diff --git a/src/spice2x/launcher/options.cpp b/src/spice2x/launcher/options.cpp
index 42944cf..c6f3dcc 100644
--- a/src/spice2x/launcher/options.cpp
+++ b/src/spice2x/launcher/options.cpp
@@ -655,6 +655,26 @@ static const std::vector<OptionDefinition> OPTION_DEFINITIONS = {
         .game_name = "Beatmania IIDX",
         .category = "Game Options",
     },
+    {
+        // IIDXTTDelayP1
+        .title = "IIDX TT Delay Frames (Player 1)",
+        .name = "iidxttdelayp1",
+        .desc = "Delays turntable input by number of poll frames. Heavily dependent on what I/O emulation is in use! "
+            "As usual, changing any option requires a restart. Default: 0 (no delay).",
+        .type = OptionType::Integer,
+        .game_name = "Beatmania IIDX",
+        .category = "Game Options (Advanced)",
+    },
+    {
+        // IIDXTTDelayP2
+        .title = "IIDX TT Delay Frames (Player 2)",
+        .name = "iidxttdelayp2",
+        .desc = "Delays turntable input by number of poll frames. Heavily dependent on what I/O emulation is in use! "
+            "As usual, changing any option requires a restart. Default: 0 (no delay).",
+        .type = OptionType::Integer,
+        .game_name = "Beatmania IIDX",
+        .category = "Game Options (Advanced)",
+    },
     {
         // spice2x_IIDXDigitalTTSensitivity
         .title = "IIDX Digital TT Sensitivity",
diff --git a/src/spice2x/launcher/options.h b/src/spice2x/launcher/options.h
index 49974c5..2b97a9f 100644
--- a/src/spice2x/launcher/options.h
+++ b/src/spice2x/launcher/options.h
@@ -69,6 +69,8 @@ namespace launcher {
             IIDXAsioDriver,
             IIDXBIO2FW,
             IIDXTDJMode,
+            IIDXTTDelayP1,
+            IIDXTTDelayP2,
             spice2x_IIDXDigitalTTSensitivity,
             IIDXDigitalTTSocd,
             spice2x_IIDXLDJForce720p,