From 03ac0f01ad2359a7ba2bc1ba64f8b1b8cbacceaa Mon Sep 17 00:00:00 2001
From: Luis Michaelis <me@lmichaelis.de>
Date: Wed, 1 May 2024 21:25:45 +0200
Subject: [PATCH] fix(DmStyle): fix broken pattern selection

---
 src/Performance.c |  2 +-
 src/Style.c       | 45 ++++++++++++++++++++++++---------------------
 src/_Internal.h   |  2 +-
 3 files changed, 26 insertions(+), 23 deletions(-)

diff --git a/src/Performance.c b/src/Performance.c
index fd7ea11..e7e89e9 100644
--- a/src/Performance.c
+++ b/src/Performance.c
@@ -581,7 +581,7 @@ static void DmPerformance_handleCommandMessage(DmPerformance* slf, DmMessage_Com
 		Dm_report(DmLogLevel_WARN, "DmPerformance: Command message with command %d not implemented", msg->command);
 	}
 
-	DmPattern* pttn = DmStyle_getRandomPattern(slf, msg->command);
+	DmPattern* pttn = DmStyle_getRandomPattern(slf->style, slf->groove, msg->command);
 	if (pttn == NULL) {
 		Dm_report(DmLogLevel_WARN, "DmPerformance: No suitable pattern found. Silence ensues ...", msg->command);
 		return;
diff --git a/src/Style.c b/src/Style.c
index b05324f..1cdb5af 100644
--- a/src/Style.c
+++ b/src/Style.c
@@ -102,7 +102,7 @@ static uint32_t Dm_toEmbellishmentFlagset(DmCommandType cmd) {
 }
 
 // See: https://documentation.help/DirectMusic/howmusicvariesduringplayback.htm
-DmPattern* DmStyle_getRandomPattern(DmPerformance* slf, DmCommandType cmd) {
+DmPattern* DmStyle_getRandomPattern(DmStyle* slf, uint32_t groove, DmCommandType cmd) {
 	uint32_t embellishment = Dm_toEmbellishmentFlagset(cmd);
 
 	// Select a random pattern according to the current groove level.
@@ -110,31 +110,34 @@ DmPattern* DmStyle_getRandomPattern(DmPerformance* slf, DmCommandType cmd) {
 	//                   have some way of defining how to select the pattern if more than 1 choice is available
 	//                   but I couldn't find it.
 
-	uint32_t index = rand() % slf->style->patterns.length;
-	for (size_t i = 0; i < slf->style->patterns.length; ++i) {
-		DmPattern* pttn = &slf->style->patterns.data[i];
+	int32_t index = rand() % slf->patterns.length;
+	do {
+		for (size_t i = 0; i < slf->patterns.length; ++i) {
+			DmPattern* pttn = &slf->patterns.data[i];
 
-		// Ignore patterns outside the current groove level.
-		if (slf->groove < pttn->groove_bottom || slf->groove > pttn->groove_top) {
-			continue;
-		}
+			// Ignore patterns outside the current groove level.
+			if (groove < pttn->groove_bottom || groove > pttn->groove_top) {
+				continue;
+			}
 
-		// Patterns with a differing embellishment are not supported
-		if (pttn->embellishment != embellishment && !(pttn->embellishment & embellishment)) {
-			continue;
-		}
+			// Patterns with a differing embellishment are not supported
+			if (pttn->embellishment != embellishment && !(pttn->embellishment & embellishment)) {
+				continue;
+			}
 
-		// Fix for Gothic 2 in which some patterns are empty but have a groove range of 1-100 with no embellishment set.
-		if (pttn->embellishment == DmCommand_GROOVE && pttn->length_measures == 1) {
-			continue;
-		}
+			// Fix for Gothic 2 in which some patterns are empty but have a groove range of 1-100 with no embellishment
+			// set.
+			if (pttn->embellishment == DmCommand_GROOVE && pttn->length_measures == 1) {
+				continue;
+			}
 
-		if (index == 0) {
-			return pttn;
-		}
+			if (index == 0) {
+				return pttn;
+			}
 
-		index -= 1;
-	}
+			index -= 1;
+		}
+	} while (index >= 0);
 
 	return NULL;
 }
diff --git a/src/_Internal.h b/src/_Internal.h
index fe5d97c..2567bdb 100644
--- a/src/_Internal.h
+++ b/src/_Internal.h
@@ -606,7 +606,7 @@ DMINT void DmStyle_release(DmStyle* slf);
 DMINT DmResult DmStyle_parse(DmStyle* slf, void* buf, size_t len);
 DMINT DmResult DmStyle_download(DmStyle* slf, DmLoader* loader);
 DMINT DmPart* DmStyle_findPart(DmStyle* slf, DmPartReference* pref);
-DMINT DmPattern* DmStyle_getRandomPattern(DmPerformance* slf, DmCommandType cmd);
+DMINT DmPattern* DmStyle_getRandomPattern(DmStyle* slf, uint32_t groove, DmCommandType cmd);
 
 DMINT void DmPart_init(DmPart* slf);
 DMINT void DmPart_free(DmPart* slf);