ADPCM4 decode impl

CMakeLists.txt

@@ -87,7 +87,9 @@ add_library(game_debug STATIC ${JSYSTEM_DEBUG_FILES} ${SSYSTEM_FILES}
         src/dusk/audio/DuskAudioSystem.cpp
         src/dusk/audio/JASCriticalSection.cpp
         src/dusk/audio/DuskDsp.hpp
-        src/dusk/audio/DuskDsp.cpp)
+        src/dusk/audio/DuskDsp.cpp
+        src/dusk/audio/Adpcm.cpp
+        src/dusk/audio/Adpcm.hpp)
 target_compile_definitions(game_debug PRIVATE TARGET_PC AVOID_UB=1 VERSION=0 $<$<CONFIG:Debug>:DEBUG=1>)
 
 # Make these properties PUBLIC so that the regular game target also sees them.

src/dusk/audio/Adpcm.cpp

@@ -0,0 +1,60 @@
+#include "Adpcm.hpp"
+
+#include <cassert>
+#include <fstream>
+
+#include "JSystem/JAudio2/JASAramStream.h"
+
+// https://github.com/magcius/vgmtrans/blob/8e34ddc2fb43948dc1e1a8759c739a0c1c7b62d7/src/main/formats/JaiSeqScanner.cpp#L489-L531
+// https://github.com/XAYRGA/JaiSeqX/blob/f29c024ec3663503f506aa02bcd503ada6e7d8aa/JaiSeqXLJA/DSP/JAIDSPADPCM4.cs#L86-L87
+
+static constexpr u16 Coefficient0[] = {
+    0,0x0800,0,0x0400,
+    0x1000,0x0e00,0x0c00,0x1200,
+    0x1068,0x12c0,0x1400,0x0800,
+    0x0400,0xfc00,0xfc00,0xf800
+};
+
+static constexpr u16 Coefficient1[] = {
+    0,0,0x0800,0x0400,0xf800,
+    0xfa00,0xfc00,0xf600,0xf738,
+    0xf704,0xf400,0xf800,0xfc00,
+    0x0400,0,0,
+};
+
+constexpr int AdpcmFrameSize = 9;
+
+static s16 Clamp16(s32 value) {
+    if (value > 0x7FFF) return 0x7FFF;
+    if (value < -0x8000) return -0x8000;
+    return value;
+}
+
+void dusk::audio::Adpcm4ToPcm16(const u8* adpcm, size_t adpcmLength, s16* pcm, size_t pcmLength, s16& hist2, s16& hist1) {
+    assert (adpcmLength % AdpcmFrameSize == 0 && "ADPCM must be divisible by frame size");
+
+    const auto expectedPcmLength = (adpcmLength / AdpcmFrameSize) * 16;
+    assert (expectedPcmLength <= pcmLength && "PCM output buffer is too small!");
+
+    for (int i = 0; i < adpcmLength; i += AdpcmFrameSize) {
+        u8 header = adpcm[i];
+
+        s32 scale = 1 << (header >> 4);
+        u8 coefIndex = header & 0xF;
+
+        s16 coef0 = (s16)Coefficient0[coefIndex];
+        s16 coef1 = (s16)Coefficient1[coefIndex];
+
+        for (int sampleIdx = 0; sampleIdx < 16; sampleIdx++) {
+            u8 adpcmValue = adpcm[i + 1 + sampleIdx / 2];
+            u8 unsignedNibble = sampleIdx % 2 == 0 ? adpcmValue >> 4 : adpcmValue & 0xF;
+            s8 signedNibble = ((s8)(unsignedNibble << 4)) >> 4;
+            s16 sample = Clamp16((((signedNibble * scale) << 11) + (coef0 * hist1 + coef1 * hist2)) >> 11);
+
+            hist2 = hist1;
+            hist1 = sample;
+
+            *pcm++ = sample;
+        }
+    }
+}

src/dusk/audio/Adpcm.hpp

@@ -0,0 +1,14 @@
+#ifndef DUSK_ADPCM_HPP
+#define DUSK_ADPCM_HPP
+
+#include <dolphin/types.h>
+
+namespace dusk::audio {
+    constexpr u32 Adpcm4FrameSize = 9;
+    constexpr u32 AdpcmSampleCount = 16;
+    constexpr u32 Adpcm2FrameSize = 5;
+
+    void Adpcm4ToPcm16(const u8* adpcm, size_t adpcmLength, s16* pcm, size_t pcmLength, s16& hist1, s16& hist0);
+}
+
+#endif  // DUSK_ADPCM_HPP