From 466c77362ebffa6d5f871b0a1a6488a07af936d3 Mon Sep 17 00:00:00 2001
From: fgsfds <derp.primus@gmail.com>
Date: Thu, 28 Sep 2023 00:55:14 +0200
Subject: [PATCH] port: mod: add support for sequence replacements

---
 port/include/mod.h |  2 ++
 port/src/mod.c     | 25 +++++++++++++++++++
 src/lib/snd.c      | 61 ++++++++++++++++++++++++++++++++++++----------
 3 files changed, 75 insertions(+), 13 deletions(-)

diff --git a/port/include/mod.h b/port/include/mod.h
index 5ebac5615..7d33b82ce 100644
--- a/port/include/mod.h
+++ b/port/include/mod.h
@@ -14,4 +14,6 @@ s32 modTextureLoad(u16 num, void *dst, u32 dstSize);
 s32 modAnimationLoadDescriptor(u16 num, struct animtableentry *anim);
 void *modAnimationLoadData(u16 num);
 
+void *modSequenceLoad(u16 num, u32 *outSize);
+
 #endif
diff --git a/port/src/mod.c b/port/src/mod.c
index 0cfeb19d2..681fb7503 100644
--- a/port/src/mod.c
+++ b/port/src/mod.c
@@ -12,6 +12,7 @@
 
 #define MOD_TEXTURES_DIR "textures"
 #define MOD_ANIMATIONS_DIR "animations"
+#define MOD_SEQUENCES_DIR "sequences"
 
 extern struct stagemusic g_StageTracks[];
 extern struct stageallocation g_StageAllocations8Mb[];
@@ -437,6 +438,30 @@ s32 modTextureLoad(u16 num, void *dst, u32 dstSize)
 	return ret;
 }
 
+void *modSequenceLoad(u16 num, u32 *outSize)
+{
+	static s32 dirExists = -1;
+	if (dirExists < 0) {
+		dirExists = (fsFileSize(MOD_SEQUENCES_DIR "/") >= 0);
+	}
+
+	if (!dirExists) {
+		return NULL;
+	}
+
+	char path[FS_MAXPATH + 1];
+	snprintf(path, sizeof(path), MOD_SEQUENCES_DIR "/%04x.bin", num);
+	if (fsFileSize(path) > 0) {
+		void *ret = fsFileLoad(path, outSize);
+		if (ret) {
+			sysLogPrintf(LOG_NOTE, "mod: loaded external sequence %04x", num);
+			return ret;
+		}
+	}
+
+	return NULL;
+}
+
 void *modAnimationLoadData(u16 num)
 {
 	char path[FS_MAXPATH + 1];
diff --git a/src/lib/snd.c b/src/lib/snd.c
index 908859d54..997f868b5 100644
--- a/src/lib/snd.c
+++ b/src/lib/snd.c
@@ -23,7 +23,9 @@
 #include "data.h"
 #include "types.h"
 #ifndef PLATFORM_N64
+#include "system.h"
 #include "preprocess.h"
+#include "mod.h"
 #endif
 
 #define MAX_SEQ_SIZE_4MB 1024 * 14
@@ -1637,22 +1639,55 @@ bool seqPlay(struct seqinstance *seq, s32 tracknum)
 		return false;
 	}
 
-	binlen = ALIGN16(g_SeqTable->entries[seq->tracknum].binlen) + 0x40;
+#ifndef PLATFORM_N64
+	// try to load external replacement, which can be either compressed or not
+	u32 extlen = 0;
+	u8 *extseq = modSequenceLoad(seq->tracknum, &extlen);
+	if (extseq) {
+		if (extlen > 2 && rzipIs1173(extseq)) {
+			// sequence is compressed; uncompress
+			binlen = ((u32)extseq[2] << 16) | ((u32)extseq[3] << 8) | (u32)extseq[4];
+			binlen = ALIGN16(binlen) + 0x40;
+			if (binlen >= g_SeqBufferSize) {
+				return false;
+			}
+			ziplen = ALIGN16(extlen);
+			binstart = seq->data;
+			zipstart = binstart + binlen - ziplen;
+			ziplen = rzipInflate(zipstart, binstart, scratch);
+		} else {
+			// sequence is uncompressed; just load as is
+			binlen = ALIGN16(extlen) + 0x40;
+			if (binlen >= g_SeqBufferSize) {
+				return false;
+			}
+			ziplen = extlen;
+			binstart = seq->data;
+			zipstart = NULL;
+			dmaExec(binstart, (romptr_t)extseq, extlen);
+		}
+		sysMemFree(extseq);
+	} else
+#endif
+	{
+		binlen = ALIGN16(g_SeqTable->entries[seq->tracknum].binlen) + 0x40;
 
-	if (binlen >= g_SeqBufferSize) {
-		return false;
+		if (binlen >= g_SeqBufferSize) {
+			return false;
+		}
+
+		ziplen = ALIGN16(g_SeqTable->entries[seq->tracknum].ziplen);
+#if VERSION < VERSION_NTSC_1_0
+		if (seq->data);
+#endif
+
+		binstart = seq->data;
+		zipstart = binstart + binlen - ziplen;
+	
+		dmaExec(zipstart, g_SeqTable->entries[seq->tracknum].romaddr, ziplen);
+		ziplen = rzipInflate(zipstart, binstart, scratch);
 	}
 
-	ziplen = ALIGN16(g_SeqTable->entries[seq->tracknum].ziplen);
-#if VERSION < VERSION_NTSC_1_0
-	if (seq->data);
-#endif
-	binstart = seq->data;
-	zipstart = binstart + binlen - ziplen;
-
-	dmaExec(zipstart, g_SeqTable->entries[seq->tracknum].romaddr, ziplen);
-
-	ziplen = rzipInflate(zipstart, binstart, scratch);
 #ifndef PLATFORM_N64
 	preprocessALCMidiHdr(binstart, ziplen);
 #endif