From a92c29bbdb27aee2d7989e5ddf115afc9f5c7698 Mon Sep 17 00:00:00 2001
From: Ian Karlsson <themvrules@gmail.com>
Date: Wed, 23 Feb 2022 23:51:34 +0100
Subject: [PATCH] qsound clipping fix from MAME

---
 src/engine/platform/sound/qsound.c | 14 ++++++++------
 src/engine/platform/sound/qsound.h |  4 ++--
 2 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/src/engine/platform/sound/qsound.c b/src/engine/platform/sound/qsound.c
index 838ece1aa..b52475b36 100644
--- a/src/engine/platform/sound/qsound.c
+++ b/src/engine/platform/sound/qsound.c
@@ -162,7 +162,7 @@ void qsound_reset(struct qsound_chip *chip)
 	chip->state_counter = 0;
 }
 
-uint8_t qsound_stream_update(struct qsound_chip *chip, int16_t **outputs, int samples)
+void qsound_stream_update(struct qsound_chip *chip, int16_t **outputs, int samples)
 {
 	// Clear the buffers
 	memset(outputs[0], 0, samples * sizeof(*outputs[0]));
@@ -174,10 +174,9 @@ uint8_t qsound_stream_update(struct qsound_chip *chip, int16_t **outputs, int sa
 		outputs[0][i] = chip->out[0];
 		outputs[1][i] = chip->out[1];
 	}
-  return 0;
 }
 
-uint8_t qsound_w(struct qsound_chip *chip, uint8_t offset, uint8_t data)
+void qsound_w(struct qsound_chip *chip, uint8_t offset, uint8_t data)
 {
 	switch (offset)
 	{
@@ -193,7 +192,6 @@ uint8_t qsound_w(struct qsound_chip *chip, uint8_t offset, uint8_t data)
 		default:
 			break;
 	}
-  return 0;
 }
 
 uint8_t qsound_r(struct qsound_chip *chip)
@@ -614,10 +612,14 @@ static void state_normal_update(struct qsound_chip *chip)
 				pan_index = 97;
 
 			// Apply different volume tables on the dry and wet inputs.
-			dry -= (chip->voice_output[v] * chip->pan_tables[ch][PANTBL_DRY][pan_index])<<2;
-			wet -= (chip->voice_output[v] * chip->pan_tables[ch][PANTBL_WET][pan_index])<<2;
+			dry -= (chip->voice_output[v] * chip->pan_tables[ch][PANTBL_DRY][pan_index]);
+			wet -= (chip->voice_output[v] * chip->pan_tables[ch][PANTBL_WET][pan_index]);
 		}
 
+		// Saturate accumulated voices
+		dry = CLAMP(dry, -0x1fffffff, 0x1fffffff) << 2;
+		wet = CLAMP(wet, -0x1fffffff, 0x1fffffff) << 2;
+
 		// Apply FIR filter on 'wet' input
 		wet = fir(&chip->filter[ch], wet >> 16);
 
diff --git a/src/engine/platform/sound/qsound.h b/src/engine/platform/sound/qsound.h
index 7c04850ae..ed05dd65a 100644
--- a/src/engine/platform/sound/qsound.h
+++ b/src/engine/platform/sound/qsound.h
@@ -109,8 +109,8 @@ long qsound_start(struct qsound_chip *chip, int clock);
 void qsound_reset(struct qsound_chip *chip);
 void qsound_update(struct qsound_chip *chip);
 
-uint8_t qsound_stream_update(struct qsound_chip *chip, int16_t **outputs, int samples);
-uint8_t qsound_w(struct qsound_chip *chip, uint8_t offset, uint8_t data);
+void qsound_stream_update(struct qsound_chip *chip, int16_t **outputs, int samples);
+void qsound_w(struct qsound_chip *chip, uint8_t offset, uint8_t data);
 uint8_t qsound_r(struct qsound_chip *chip);
 void qsound_write_data(struct qsound_chip *chip, uint8_t address, uint16_t data);
 uint16_t qsound_read_data(struct qsound_chip *chip, uint8_t address);