Codechange: Template input buffer type in audio mixer.

This reduces code duplication.
OpenTTD · Nov 27, 2023 · cfa88e9 · cfa88e9
1 parent a856fbe
commit cfa88e9
Showing 1 changed file with 9 additions and 44 deletions.
diff --git a/src/mixer.cpp b/src/mixer.cpp
@@ -63,13 +63,14 @@ static int RateConversion(T *b, int frac_pos)
 	return ((b[0] * ((1 << 16) - frac_pos)) + (b[1] * frac_pos)) >> 16;
 }
 
+template <typename T, uint TShift>
 static void mix_int16(MixerChannel *sc, int16_t *buffer, uint samples, uint8_t effect_vol)
 {
 	if (samples > sc->samples_left) samples = sc->samples_left;
 	sc->samples_left -= samples;
 	assert(samples > 0);
 
-	const int16_t *b = (const int16_t *)sc->memory + sc->pos;
+	const T *b = (const T *)sc->memory + sc->pos;
 	uint32_t frac_pos = sc->frac_pos;
 	uint32_t frac_speed = sc->frac_speed;
 	int volume_left = sc->volume_left * effect_vol / 255;
@@ -78,16 +79,16 @@ static void mix_int16(MixerChannel *sc, int16_t *buffer, uint samples, uint8_t e
 	if (frac_speed == 0x10000) {
 		/* Special case when frac_speed is 0x10000 */
 		do {
-			buffer[0] = Clamp(buffer[0] + (*b * volume_left  >> 16), -MAX_VOLUME, MAX_VOLUME);
-			buffer[1] = Clamp(buffer[1] + (*b * volume_right >> 16), -MAX_VOLUME, MAX_VOLUME);
+			buffer[0] = Clamp(buffer[0] + (*b * volume_left  >> TShift), -MAX_VOLUME, MAX_VOLUME);
+			buffer[1] = Clamp(buffer[1] + (*b * volume_right >> TShift), -MAX_VOLUME, MAX_VOLUME);
 			b++;
 			buffer += 2;
 		} while (--samples > 0);
 	} else {
 		do {
 			int data = RateConversion(b, frac_pos);
-			buffer[0] = Clamp(buffer[0] + (data * volume_left  >> 16), -MAX_VOLUME, MAX_VOLUME);
-			buffer[1] = Clamp(buffer[1] + (data * volume_right >> 16), -MAX_VOLUME, MAX_VOLUME);
+			buffer[0] = Clamp(buffer[0] + (data * volume_left  >> TShift), -MAX_VOLUME, MAX_VOLUME);
+			buffer[1] = Clamp(buffer[1] + (data * volume_right >> TShift), -MAX_VOLUME, MAX_VOLUME);
 			buffer += 2;
 			frac_pos += frac_speed;
 			b += frac_pos >> 16;
@@ -96,43 +97,7 @@ static void mix_int16(MixerChannel *sc, int16_t *buffer, uint samples, uint8_t e
 	}
 
 	sc->frac_pos = frac_pos;
-	sc->pos = b - (const int16_t *)sc->memory;
-}
-
-static void mix_int8_to_int16(MixerChannel *sc, int16_t *buffer, uint samples, uint8_t effect_vol)
-{
-	if (samples > sc->samples_left) samples = sc->samples_left;
-	sc->samples_left -= samples;
-	assert(samples > 0);
-
-	const int8_t *b = sc->memory + sc->pos;
-	uint32_t frac_pos = sc->frac_pos;
-	uint32_t frac_speed = sc->frac_speed;
-	int volume_left = sc->volume_left * effect_vol / 255;
-	int volume_right = sc->volume_right * effect_vol / 255;
-
-	if (frac_speed == 0x10000) {
-		/* Special case when frac_speed is 0x10000 */
-		do {
-			buffer[0] = Clamp(buffer[0] + (*b * volume_left  >> 8), -MAX_VOLUME, MAX_VOLUME);
-			buffer[1] = Clamp(buffer[1] + (*b * volume_right >> 8), -MAX_VOLUME, MAX_VOLUME);
-			b++;
-			buffer += 2;
-		} while (--samples > 0);
-	} else {
-		do {
-			int data = RateConversion(b, frac_pos);
-			buffer[0] = Clamp(buffer[0] + (data * volume_left  >> 8), -MAX_VOLUME, MAX_VOLUME);
-			buffer[1] = Clamp(buffer[1] + (data * volume_right >> 8), -MAX_VOLUME, MAX_VOLUME);
-			buffer += 2;
-			frac_pos += frac_speed;
-			b += frac_pos >> 16;
-			frac_pos &= 0xffff;
-		} while (--samples > 0);
-	}
-
-	sc->frac_pos = frac_pos;
-	sc->pos = b - sc->memory;
+	sc->pos = b - (const T *)sc->memory;
 }
 
 static void MxCloseChannel(uint8_t channel_index)
@@ -172,9 +137,9 @@ void MxMixSamples(void *buffer, uint samples)
 	for (uint8_t idx : SetBitIterator(active)) {
 		MixerChannel *mc = &_channels[idx];
 		if (mc->is16bit) {
-			mix_int16(mc, (int16_t*)buffer, samples, effect_vol);
+			mix_int16<int16_t, 16>(mc, (int16_t*)buffer, samples, effect_vol);
 		} else {
-			mix_int8_to_int16(mc, (int16_t*)buffer, samples, effect_vol);
+			mix_int16<int8_t, 8>(mc, (int16_t*)buffer, samples, effect_vol);
 		}
 		if (mc->samples_left == 0) MxCloseChannel(idx);
 	}