linux, audio: add hooks acmFormatSuggest (#455)

## Link to GitHub Issue, if one exists
n/a

## Description of change

`acmFormatSuggest` is known to cause significant perf issues on Linux;
add a hook to return cached results.

The fix is only active in the Linux variant.

For discussion, see
* https://codeberg.org/nixac/spicetools/issues/2
* https://codeberg.org/nixac/spicetools/issues/4

## Testing
I've only tested this on Windows, checking if iidx and popn can boot,
play songs without audio issues.

src/spice2x/hooks/audio/acm.cpp

@@ -0,0 +1,230 @@
+#include "audio.h"
+
+#include <mutex>
+
+#include <external/robin_hood.h>
+
+#include <windows.h>
+#include <mmsystem.h>
+#include <msacm.h>
+
+#include "avs/game.h"
+#include "util/detour.h"
+#include "util/libutils.h"
+#include "util/logging.h"
+#include "util/memutils.h"
+#include "util/time.h"
+#include "util/unique_plain_ptr.h"
+
+#define ACM_CACHE_ENABLED 1
+#define ACM_DEBUG_PERF 0
+#define ACM_DEBUG_VERBOSE 0
+
+#if ACM_DEBUG_VERBOSE
+#define log_debug(module, format_str, ...) logger::push( \
+    LOG_FORMAT("M", module, format_str, ## __VA_ARGS__), logger::Style::GREY)
+#else
+#define log_debug(module, format_str, ...)
+#endif
+
+namespace hooks::audio::acm {
+    struct WAVE_FORMAT {
+        uint32_t suggest;
+        // for WAVEFORMATEX
+        std::vector<uint8_t> wave_format_ex;
+
+        bool operator==(const WAVE_FORMAT& other) const {
+            return (this->suggest == other.suggest &&
+                this->wave_format_ex == other.wave_format_ex);
+        }
+    };
+}
+
+namespace robin_hood {
+    template <>
+    struct hash<hooks::audio::acm::WAVE_FORMAT> {
+        std::size_t operator()(const hooks::audio::acm::WAVE_FORMAT& k) const noexcept {
+            std::size_t h = robin_hood::hash_bytes(
+                k.wave_format_ex.data(), k.wave_format_ex.size());
+
+            h = h ^ robin_hood::hash<uint32_t>{}(k.suggest) << 1;
+            return h;
+        }
+    };
+}
+
+namespace hooks::audio::acm {
+
+    static decltype(acmFormatSuggest) *acmFormatSuggest_orig = nullptr;
+    static std::mutex acm_formats_mutex;
+    static robin_hood::unordered_map<WAVE_FORMAT, std::vector<uint8_t>> acm_formats;
+
+    // hooks calls to acmFormatSuggest and returns cached results from previous calls
+    //
+    // iidx calls this many times during song load and reload (function of # of keysounds)
+    // - with near-identical arguments over and over again
+    // (when hovering over song in song select, selecting a song, and exiting result screen)
+    //
+    // on Linux this results in ACM module load/unload which is very expensive,
+    // resulting in significant perf improvement (seconds per song load);
+    // on Windows this saves milliseconds per song, at best
+    //
+    // https://codeberg.org/nixac/spicetools/issues/2
+    // https://codeberg.org/nixac/spicetools/issues/4
+    MMRESULT
+    acmFormatSuggest_cached (
+        HACMDRIVER had,
+        LPWAVEFORMATEX pwfxSrc,
+        LPWAVEFORMATEX pwfxDst,
+        DWORD cbwfxDst,
+        DWORD fdwSuggest) {
+
+        if (had != 0 || cbwfxDst == 0) {
+            return acmFormatSuggest_orig(had, pwfxSrc, pwfxDst, cbwfxDst, fdwSuggest);
+        }
+
+        WAVE_FORMAT key;
+        key.suggest = fdwSuggest;
+        const size_t src_size = sizeof(*pwfxSrc) + pwfxSrc->cbSize;
+        key.wave_format_ex.insert(
+            key.wave_format_ex.end(),
+            reinterpret_cast<uint8_t *>(pwfxSrc),
+            reinterpret_cast<uint8_t *>(pwfxSrc) + src_size);
+
+        std::lock_guard<std::mutex> lock(acm_formats_mutex);
+
+        MMRESULT mmresult = 0;
+
+        if (acm_formats.contains(key)) {
+            // found in cache
+            const auto &result = acm_formats.at(key);
+
+            if (cbwfxDst >= result.size()) {
+                // dest buffer big enough, return cached result
+                log_debug("audio::acm", "acmFormatSuggest cache hit, copying {} bytes", result.size());
+                std::memcpy(reinterpret_cast<uint8_t *>(pwfxDst), result.data(), result.size());
+                mmresult = 0;
+            } else {
+                // dest buffer not big enough, call original
+                log_debug("audio::acm", "acmFormatSuggest cache fail; cbwfxDst too small ({})", cbwfxDst);
+                mmresult = acmFormatSuggest_orig(had, pwfxSrc, pwfxDst, cbwfxDst, fdwSuggest);
+            }
+
+        } else {
+            log_debug("audio::acm", "acmFormatSuggest cache miss; calling original");
+            mmresult = acmFormatSuggest_orig(had, pwfxSrc, pwfxDst, cbwfxDst, fdwSuggest);
+
+            // cache the result, but don't allow unconstrained growth
+            if (mmresult == 0 && acm_formats.size() < 128) {
+                const size_t dest_size = sizeof(*pwfxDst) + pwfxDst->cbSize;
+                log_debug(
+                    "audio::acm",
+                    "acmFormatSuggest cache add; current cache size {}, new data {} bytes",
+                    acm_formats.size(),
+                    dest_size);
+
+                acm_formats[key] = std::vector<uint8_t>();
+                acm_formats[key].reserve(dest_size);
+                acm_formats[key].insert(
+                    acm_formats[key].begin(),
+                    reinterpret_cast<uint8_t *>(pwfxDst),
+                    reinterpret_cast<uint8_t *>(pwfxDst) + dest_size);
+            }
+        }
+
+        return mmresult;
+    }
+
+    MMRESULT
+    ACMAPI
+    acmFormatSuggest_hook (
+        HACMDRIVER had,
+        LPWAVEFORMATEX pwfxSrc,
+        LPWAVEFORMATEX pwfxDst,
+        DWORD cbwfxDst,
+        DWORD fdwSuggest) {
+
+        log_debug(
+            "audio::acm",
+            "acmFormatSuggest called: had={}, "
+            "formattag={}, ch={}, samplespersec={}, bytespersec={}, blockalign={}, bits={}, extrasize={}",
+            fmt::ptr(had),
+            pwfxSrc->wFormatTag,
+            pwfxSrc->nChannels,
+            pwfxSrc->nSamplesPerSec,
+            pwfxSrc->nAvgBytesPerSec,
+            pwfxSrc->nBlockAlign,
+            pwfxSrc->wBitsPerSample,
+            pwfxSrc->cbSize);
+
+#if ACM_DEBUG_PERF
+        const auto start = get_performance_milliseconds();
+#endif
+
+        // make a call to acmFormatSuggest
+
+#if ACM_CACHE_ENABLED
+        const auto result = acmFormatSuggest_cached(had, pwfxSrc, pwfxDst, cbwfxDst, fdwSuggest);
+#else 
+        const auto result = acmFormatSuggest_orig(had, pwfxSrc, pwfxDst, cbwfxDst, fdwSuggest);
+#endif
+
+        // log result
+
+#if ACM_DEBUG_PERF
+        const auto delta = get_performance_milliseconds() - start;
+        static double delta_total = 0;
+        delta_total += delta;
+
+        log_info(
+            "audio::acm",
+            "acmFormatSuggest_hook returned {}, took {} us (running total {} ms)",
+            result,
+            delta * 1000,
+            delta_total);
+#else
+        log_debug("audio::acm", "acmFormatSuggest_hook returned {}", result);
+#endif
+
+        if (result == 0 && cbwfxDst > sizeof(WAVEFORMATEX)) {
+            log_debug(
+                "audio::acm",
+                "....formattag={}, ch={}, samplespersec={}, bytespersec={}, blockalign={}, bits={}, extrasize={}",
+                pwfxDst->wFormatTag,
+                pwfxDst->nChannels,
+                pwfxDst->nSamplesPerSec,
+                pwfxDst->nAvgBytesPerSec,
+                pwfxDst->nBlockAlign,
+                pwfxDst->wBitsPerSample,
+                pwfxDst->cbSize);
+        }
+
+        return result;
+    }
+
+    void init() {
+
+        // only enabled on Linux as the performance gains are negligible on Windows
+#if SPICE_LINUX
+
+        HMODULE msacm = libutils::try_library("msacm32.dll");
+        if (msacm == nullptr) {
+            log_info("audio::acm", "msacm32.dll failed to hook");
+            return;
+        }
+
+        acmFormatSuggest_orig = detour::iat_try(
+            "acmFormatSuggest", acmFormatSuggest_hook, avs::game::DLL_INSTANCE);
+        if (acmFormatSuggest_orig != nullptr) {
+            log_misc("audio::acm", "acmFormatSuggest hooked");
+
+#if !ACM_CACHE_ENABLED
+            log_warning("audio::acm", "acmFormatSuggest cache DISABLED");
+#endif
+
+        }
+
+#endif
+
+    }
+}

src/spice2x/hooks/audio/acm.h

@@ -0,0 +1,5 @@
+#pragma once
+
+namespace hooks::audio::acm {
+    void init();
+}

src/spice2x/hooks/audio/audio.cpp

@@ -13,6 +13,7 @@
 #include "util/memutils.h"
 
 #include "audio_private.h"
+#include "acm.h"
 
 #ifdef _MSC_VER
 DEFINE_GUID(CLSID_MMDeviceEnumerator,
@@ -101,6 +102,7 @@ namespace hooks::audio {
 
         log_info("audio", "initializing");
         init_low_latency();
+        hooks::audio::acm::init();
 
         // general hooks
         CoCreateInstance_orig = detour::iat_try("CoCreateInstance", CoCreateInstance_hook);