the great extraordinary Custom Music Hack comes to your .. gits

2 files changed, 83 insertions, 66 deletions

diff --git a/src/music.S b/src/music.S
deleted file mode 100644
index 93c57dc..0000000
--- a/src/music.S
+++ /dev/null
@@ -1,66 +0,0 @@
-.text
-
-# An Epic Music Hack
-
-.extern SoundRelatedClass
-.extern sprintf
-.global HaxMusic
-
-# Without Drums: Type 0
-# Athletic, Castle(Siro)
-
-# With Drums: Type 1
-# Overworld(Chijou), ...
-
-HaxMusic:
-	cmpwi r3, 100
-	bltlr
-
-	li r4, 0 # Type: No Yoshi Drums
-	cmpwi r3, 200
-	blt Begin
-
-	li r4, 1
-Begin:
-
-	stwu r1, -0x10(r1)
-	mflr r0
-	stw r0, 0x14(r1)
-	stw r31, 0xC(r1)
-	stw r30, 0x8(r1)
-
-	mr r31, r3
-
-	lis r3, SoundRelatedClass@h
-	ori r3, r3, SoundRelatedClass@l
-	lwz r3, 0(r3)
-	lwz r30, 0x5CC(r3)
-	addis r30, r30, 3
-
-	subi r3, r30, 0x6A84
-	lis r4, RegularMusic@h
-	ori r4, r4, RegularMusic@l
-	mr r5, r31
-	bl sprintf
-
-	subi r3, r30, 0x6A0C
-	lis r4, FastMusic@h
-	ori r4, r4, FastMusic@l
-	mr r5, r31
-	bl sprintf
-
-	li r3, 1
-
-	lwz r0, 0x14(r1)
-	lwz r31, 0xC(r1)
-	lwz r30, 0x8(r1)
-	mtlr r0
-	addi r1, r1, 0x10
-	blr
-
-
-.data
-RegularMusic:	.string "stream/theme%03d.brstm"
-FastMusic:		.string "stream/theme%03d_fast.brstm"
-
-
diff --git a/src/music.cpp b/src/music.cpp
new file mode 100644
index 0000000..a687d35
--- /dev/null
+++ b/src/music.cpp
@@ -0,0 +1,83 @@
+#include <game.h>
+
+struct HijackedStream {
+	//const char *original;
+	//const char *originalFast;
+	u32 stringOffset;
+	u32 stringOffsetFast;
+	u8 originalID;
+};
+
+struct Hijacker {
+	HijackedStream stream[2];
+	u8 currentStream;
+	u8 currentCustomTheme;
+};
+
+
+// Offsets are from the start of the INFO block, not the start of the brsar.
+// INFO begins at 0x212C0, so that has to be subtracted from absolute offsets
+// within the brsar.
+
+#define _I(offs) ((offs)-0x212C0)
+
+Hijacker Hijackers[2] = {
+	{
+		{
+			{/*"athletic_lr.n.32.brstm", "athletic_fast_lr.n.32.brstm",*/ _I(0x4A8F8), _I(0x4A938), 4},
+			{/*"BGM_SIRO.32.brstm", "BGM_SIRO_fast.32.brstm",*/ _I(0x4B2E8), _I(0x4B320), 10}
+		},
+		0, 0
+	},
+
+	{
+		{
+			{/*"STRM_BGM_CHIJOU.brstm", "STRM_BGM_CHIJOU_FAST.brstm",*/ _I(0x4A83C), _I(0x4A8B4), 1},
+			{/*"STRM_BGM_CHIKA.brstm", "STRM_BGM_CHIKA_FAST.brstm",*/ _I(0x4A878), _I(0x4A780), 2},
+		},
+		0, 0
+	}
+};
+
+extern void *SoundRelatedClass;
+inline char *BrsarInfoOffset(u32 offset) {
+	return (char*)(*(u32*)(((u32)SoundRelatedClass) + 0x5CC)) + offset;
+}
+
+extern "C" u8 after_course_getMusicForZone(u8 realThemeID) {
+	if (realThemeID < 100)
+		return realThemeID;
+
+	// drums get to use type 1
+	int hjIndex = (realThemeID >= 200) ? 1 : 0;
+
+	Hijacker *hj = &Hijackers[hjIndex];
+
+	// do we already have this theme in this slot?
+	// if so, don't switch streams
+	// if we do, NSMBW will think it's a different song, and restart it ...
+	// but if it's just an area transition where both areas are using the same
+	// song, we don't want that
+	if (hj->currentCustomTheme == realThemeID)
+		return hj->stream[hj->currentStream].originalID;
+
+	// which one do we use this time...?
+	int toUse = (hj->currentStream + 1) & 1;
+
+	hj->currentStream = toUse;
+	hj->currentCustomTheme = realThemeID;
+
+	// write the stream's info
+	HijackedStream *stream = &hj->stream[hj->currentStream];
+
+	sprintf(BrsarInfoOffset(stream->stringOffset), "stream/theme%03d.brstm", realThemeID);
+	sprintf(BrsarInfoOffset(stream->stringOffsetFast), "stream/theme%03d_fast.brstm", realThemeID);
+
+	// done!
+
+	return stream->originalID;
+}
+
+
+
+