Do not calculate audio specifics in the hot loop but only in the func…

…tion that generates samples.
coornio · Sep 13, 2024 · eb2b5d0 · eb2b5d0
1 parent c9f1cad
commit eb2b5d0
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Showing 4 changed files with 23 additions and 27 deletions.
diff --git a/src/Systems/CHIP8/Chip8_CoreInterface.cpp b/src/Systems/CHIP8/Chip8_CoreInterface.cpp
@@ -286,7 +286,7 @@ void Chip8_CoreInterface::copyFontToMemory(
 ) noexcept {
 	std::copy_n(
 		std::execution::unseq,
-		cFontData, size, dest + offset
+		cFontData.begin(), size, dest + offset
 	);
 }
 

diff --git a/src/Systems/CHIP8/Chip8_CoreInterface.hpp b/src/Systems/CHIP8/Chip8_CoreInterface.hpp
@@ -198,7 +198,7 @@ class Chip8_CoreInterface : public EmuInterface {
 	); }
 
 protected:
-	static constexpr u8 cFontData[]{
+	static constexpr std::array<u8, 240> cFontData{ {
 		0x60, 0xA0, 0xA0, 0xA0, 0xC0, // 0
 		0x40, 0xC0, 0x40, 0x40, 0xE0, // 1
 		0xC0, 0x20, 0x40, 0x80, 0xE0, // 2
@@ -233,8 +233,8 @@ class Chip8_CoreInterface : public EmuInterface {
 		0xF8, 0x6C, 0x66, 0x66, 0x66, 0x66, 0x66, 0x6C, 0xF8, 0x00, // D
 		0xFE, 0x62, 0x60, 0x64, 0x7C, 0x64, 0x60, 0x62, 0xFE, 0x00, // E
 		0xFE, 0x66, 0x62, 0x64, 0x7C, 0x64, 0x60, 0x60, 0xF0, 0x00, // F
-	};
-	static constexpr u8 cFontDataMega[]{
+	} };
+	static constexpr std::array<u8, 160> cFontDataMega{ {
 		0x3C, 0x7E, 0xC3, 0xC3, 0xC3, 0xC3, 0xC3, 0xC3, 0x7E, 0x3C, // 0
 		0x18, 0x38, 0x58, 0x18, 0x18, 0x18, 0x18, 0x18, 0x18, 0x3C, // 1
 		0x3E, 0x7F, 0xC3, 0x06, 0x0C, 0x18, 0x30, 0x60, 0xFF, 0xFF, // 2
@@ -251,19 +251,19 @@ class Chip8_CoreInterface : public EmuInterface {
 		0x3C, 0x7E, 0xC3, 0xC3, 0xC3, 0xC3, 0xC3, 0xC3, 0x7E, 0x3C, // 0
 		0x3C, 0x7E, 0xC3, 0xC3, 0xC3, 0xC3, 0xC3, 0xC3, 0x7E, 0x3C, // 0
 		0x3C, 0x7E, 0xC3, 0xC3, 0xC3, 0xC3, 0xC3, 0xC3, 0x7E, 0x3C  // 0
-	};
+	} };
 
-	static constexpr u32 cBitsColor[]{ // 0-1 monochrome, 0-15 palette color
+	static constexpr std::array<u32, 16> cBitsColor{ { // 0-1 monochrome, 0-15 palette color
 		0x0C1218, 0xE4DCD4, 0x8C8884, 0x403C38,
 		0xD82010, 0x40D020, 0x1040D0, 0xE0C818,
 		0x501010, 0x105010, 0x50B0C0, 0xF08010,
 		0xE06090, 0xE0F090, 0xB050F0, 0x704020,
-	};
-	static constexpr u32 cForeColor[]{ // CHIP-8X foreground colors
+	} };
+	static constexpr std::array<u32,  8> cForeColor{ { // CHIP-8X foreground colors
 		0x000000, 0xEE1111, 0x1111EE, 0xEE11EE,
 		0x11EE11, 0xEEEE11, 0x11EEEE, 0xEEEEEE,
-	};
-	static constexpr u32 cBackColor[]{ // CHIP-8X background colors
+	} };
+	static constexpr std::array<u32,  4> cBackColor{ { // CHIP-8X background colors
 		0x111133, 0x111111, 0x113311, 0x331111,
-	};
+	} };
 };
diff --git a/src/Systems/CHIP8/Cores/XOCHIP.cpp b/src/Systems/CHIP8/Cores/XOCHIP.cpp
@@ -13,10 +13,7 @@
 /*==================================================================*/
 
 XOCHIP::XOCHIP()
-
-	: mAudioStep{ 4'000.0f / 128.0f / ASB->getFrequency() }
-	, mAudioTone{ mAudioStep }
-	, mDisplayBuffer{
+	: mDisplayBuffer{
 		{cScreenSizeY, cScreenSizeX},
 		{cScreenSizeY, cScreenSizeX},
 		{cScreenSizeY, cScreenSizeX},
@@ -37,7 +34,7 @@ XOCHIP::XOCHIP()
 
 		std::copy_n(
 			std::execution::unseq,
-			cBitsColor, 16,
+			cBitsColor.data(), 16,
 			mBitsColor.data()
 		);
 
@@ -273,20 +270,22 @@ void XOCHIP::renderAudioData() {
 
 	static f32 wavePhase{};
 
-
 	if (mSoundTimer) {
 		if (isBuzzerEnabled()) {
 			for (auto& sample : samplesBuffer) {
-				sample = static_cast<s8>(wavePhase > 0.5f ? 16 : -16);
+				sample    = static_cast<s8>(wavePhase > 0.5f ? 16 : -16);
 				wavePhase = std::fmod(wavePhase + mBuzzerTone, 1.0f);
 			}
 			BVS->setFrameColor(cBitsColor[0], cBitsColor[1]);
 		} else {
+			const auto audioStep{ std::pow(2.0f, (mAudioPitch - 64.0f) / 48.0f) };
+			const auto audioTone{ 31.25f / ASB->getFrequency() * audioStep };
+
 			for (auto& sample : samplesBuffer) {
 				const auto step{ static_cast<s32>(std::clamp(wavePhase * 128.0f, 0.0f, 127.0f)) };
 				const auto mask{ 1 << (7 ^ step & 7) };
-				sample = mSamplePattern[step >> 3] & mask ? 16 : -16;
-				wavePhase = std::fmod(wavePhase + mAudioTone, 1.0f);
+				sample    = mPatternBuf[step >> 3] & mask ? 16 : -16;
+				wavePhase = std::fmod(wavePhase + audioTone, 1.0f);
 			}
 			BVS->setFrameColor(cBitsColor[0], cBitsColor[0]);
 		}
@@ -770,7 +769,7 @@ void XOCHIP::scrollDisplayRT(const s32) {
 	// F002 - load 16-byte audio pattern from RAM at I
 	void XOCHIP::instruction_F002() noexcept {
 		for (auto idx{ 0 }; idx < 16; ++idx) {
-			mSamplePattern[idx] = readMemoryI(idx);
+			mPatternBuf[idx] = readMemoryI(idx);
 		}
 		isBuzzerEnabled(false);
 	}
@@ -816,8 +815,7 @@ void XOCHIP::scrollDisplayRT(const s32) {
 	}
 	// FX3A - set sound pitch = VX
 	void XOCHIP::instruction_Fx3A(const s32 X) noexcept {
-		const auto stepValue{ (mRegisterV[X] - 64.0f) / 48.0f };
-		mAudioTone = mAudioStep * std::pow(2.0f, stepValue);
+		mAudioPitch = mRegisterV[X];
 		isBuzzerEnabled(false);
 	}
 	// FN55 - store V0..VX to RAM at I..I+N

diff --git a/src/Systems/CHIP8/Cores/XOCHIP.hpp b/src/Systems/CHIP8/Cores/XOCHIP.hpp
@@ -30,10 +30,8 @@ class XOCHIP final : public Chip8_CoreInterface {
 
 /*==================================================================*/
 
-	std::array<u8, 16> mSamplePattern{};
-
-	f32 mAudioStep{};
-	f32 mAudioTone{};
+	std::array<u8, 16> mPatternBuf{};
+	s32 mAudioPitch{ 64 };
 
 /*==================================================================*/