From 42689377e6e20b3ce5cebe94eab2e1d7aa6904df Mon Sep 17 00:00:00 2001
From: "[ ]" <[ ]>
Date: Sun, 14 Dec 2025 23:17:40 +0900
Subject: [PATCH] feat: Resolve long load times before get ready for IIDX

> see #4
> partial improvements for result screen hang, see #2
---
 hooks/wmischook.cpp | 64 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 64 insertions(+)

diff --git a/hooks/wmischook.cpp b/hooks/wmischook.cpp
index 14a3173..55addd3 100644
--- a/hooks/wmischook.cpp
+++ b/hooks/wmischook.cpp
@@ -2,8 +2,71 @@
 #include "util/logging.h"
 #include "util/detour.h"
 #include "util/sigscan.h"
+#include "util/libutils.h"
+#include <mmsystem.h>
 
 
+namespace hooks::wmisc::msacm
+{
+typedef MMRESULT (*acmFormatSuggest_t)(HANDLE had, LPWAVEFORMATEX pwfxSrc, LPWAVEFORMATEX pwfxDst, DWORD cbwfxDst, DWORD fdwSuggest);
+static acmFormatSuggest_t acmFormatSuggest;
+
+static uint64_t hash_waveformatex(const WAVEFORMATEX *pwfx, DWORD fdwSuggest)
+{
+    //_INFO: no clashes, likely faster than hashing sizeof(WAVEFORMATEX) buffer
+    uint64_t h = 0;
+    h ^= (uint64_t) pwfx->nSamplesPerSec << 0;
+    h ^= (uint64_t) pwfx->nAvgBytesPerSec << 1;
+    h ^= (uint64_t) pwfx->nBlockAlign << 2;
+    h ^= (uint64_t) pwfx->wBitsPerSample << 3;
+    h ^= (uint64_t) pwfx->cbSize << 4;
+    h ^= (uint64_t) fdwSuggest << 5;
+    h ^= (uint64_t) pwfx->wFormatTag << 6;
+    h ^= (uint64_t) pwfx->nChannels << 7;
+    return h;
+}
+MMRESULT __stdcall on_acmFormatSuggest(HANDLE had, LPWAVEFORMATEX pwfxSrc, LPWAVEFORMATEX pwfxDst, DWORD cbwfxDst, DWORD fdwSuggest)
+{
+    static std::unordered_map<uint64_t, std::vector<char>> acmformats;
+    static std::mutex mutex;
+
+    // Find cached formats
+    size_t hash = hash_waveformatex(pwfxSrc, fdwSuggest);
+    {
+        std::lock_guard lock(mutex);
+        auto it = acmformats.find(hash);
+        if (it != acmformats.end())
+        {
+            // Copy cached result
+            memcpy(pwfxDst, it->second.data(), std::min(cbwfxDst, (DWORD) (sizeof(WAVEFORMATEX) + ((WAVEFORMATEX *) it->second.data())->cbSize)));
+            return MMSYSERR_NOERROR;
+        }
+    }
+
+    // Cache unique formats
+    log_info("hooks::wmisc::msacm", "Forwarding acmFormatSuggest({}) request due to cache miss", reinterpret_cast<void *>(hash));
+    MMRESULT r = acmFormatSuggest(had, pwfxSrc, pwfxDst, cbwfxDst, fdwSuggest);
+    if (r == MMSYSERR_NOERROR)
+    {
+        std::lock_guard lock(mutex);
+        acmformats[hash].resize(sizeof(WAVEFORMATEX) + pwfxDst->cbSize);
+        memcpy(acmformats[hash].data(), pwfxDst, sizeof(WAVEFORMATEX) + pwfxDst->cbSize);
+    }
+    return r;
+}
+void run(HINSTANCE hmodule)
+{
+    // Override acmFormatSuggest
+    HMODULE msacm = nullptr;
+    if ((msacm = libutils::try_library("msacm32.dll")))
+    {
+        acmFormatSuggest = (acmFormatSuggest_t) GetProcAddress(msacm, "acmFormatSuggest");
+    }
+    log_info("hooks::wmisc::msacm", "Hooking acmFormatSuggest({})", reinterpret_cast<void *>(acmFormatSuggest));
+    detour::trampoline_try(reinterpret_cast<void *>(acmFormatSuggest), reinterpret_cast<void *>(on_acmFormatSuggest), reinterpret_cast<void **>(&acmFormatSuggest));
+}
+}
+
 namespace hooks::wmisc::thumbnail
 {
 typedef bool (*ThumExists_t)(void *titleUTF_getter, int32_t id, char flag);
@@ -60,6 +123,7 @@ void apply_performance_hacks(HINSTANCE hmodule, const char *model, const char *e
     {
     case by_model("LDJ"):
         thumbnail::run(hmodule);
+        msacm::run(hmodule);
         break;
     default:
         break;