From b1c44cafc4bb624355c66702d6278a2ffeb894a1 Mon Sep 17 00:00:00 2001
From: revelj <david@revelj.se>
Date: Sun, 16 Aug 2020 09:34:00 +0200
Subject: [PATCH] Made frequency table lookups work across 256 byte boundaries
 Fixes https://github.com/trash80/mGB/issues/3

---
 Source/mGBASMSynthFunctions.s | 89 ++++++++++++++++++-----------------
 1 file changed, 46 insertions(+), 43 deletions(-)

diff --git a/Source/mGBASMSynthFunctions.s b/Source/mGBASMSynthFunctions.s
index 364bbb7..a67a130 100644
--- a/Source/mGBASMSynthFunctions.s
+++ b/Source/mGBASMSynthFunctions.s
@@ -60,12 +60,13 @@ _asmUpdatePu1PbWheelReset$::
 	ld	A,(hl)
 	ld	B,A
 
-	ld	A,#<_freq
-    add	A,B
-    add	A,B
-	ld	E,A
-    ld	A,#>_freq
-	ld	D,A
+	ld  A,B
+	add A,A
+	add A,#<_freq
+	ld  E,A
+	adc #>_freq
+	sub E
+	ld  D,A
 
 	ld  A,(DE)
 	ld	(#0xFF13),A
@@ -144,15 +145,13 @@ _asmUpdatePu2PbWheelReset$::
 
 	ld	hl, #_noteStatus + 3
 	ld	A,(hl)
-	ld	B,A
 
-
-	ld	A,#<_freq
-    add	A,B
-    add	A,B
-	ld	E,A
-    ld	A,#>_freq
-	ld	D,A
+	add A,A
+	add A,#<_freq
+	ld  E,A
+	adc #>_freq
+	sub E
+	ld  D,A
 
 	ld  A,(DE)
 	ld	(#0xFF18),A
@@ -254,14 +253,13 @@ _asmUpdateWavPbWheelReset$::
 
 	ld	hl, #_noteStatus + 5
 	ld	A,(hl)
-	ld	B,A
 
-	ld	A,#<_freq
-    add	A,B
-    add	A,B
-	ld	E,A
-    ld	A,#>_freq
-	ld	D,A
+	add A,A
+	add A,#<_freq
+	ld  E,A
+	adc #>_freq
+	sub E
+	ld  D,A
 
 	ld  A,(DE)
 
@@ -342,7 +340,8 @@ _asmUpdateNoiPbWheelReset$::
 	ld	A,#<_noiFreq
     add	A,B
 	ld	E,A
-    ld	A,#>_noiFreq
+    adc	A,#>_noiFreq
+	sub	E
 	ld	D,A
 
 	ld  A,(DE)
@@ -380,7 +379,7 @@ _asmPlayNotePu1::
 
 	cp #0x00
 	jr	nz,_asmPlayNotePu1OnSet$
-	jr	_asmPlayNotePu1Off$
+	jp	_asmPlayNotePu1Off$
 
 _asmPlayNotePu1OnSet$::
 	ld	A, (#0xFF12)
@@ -426,12 +425,13 @@ _asmPlayNotePu1On$::
 	ld	hl, #_noteStatus + 1
 	ld	(hl),B
 
-	ld	A,#<_freq
-    add	A,B
-    add	A,B
-	ld	E,A
-    ld	A,#>_freq
-	ld	D,A
+	ld  A,B
+	add A,A
+	add A,#<_freq
+	ld  E,A
+	adc #>_freq
+	sub E
+	ld  D,A
 
 	ld  A,(DE)
 	ld	(#0xFF13),A
@@ -522,7 +522,7 @@ _asmPlayNotePu2$::
 
 	cp #0x00
 	jr	nz,_asmPlayNotePu2OnSet$
-	jr	_asmPlayNotePu2Off$
+	jp	_asmPlayNotePu2Off$
 
 _asmPlayNotePu2OnSet$::
 	ld	A, (#0xFF17)
@@ -566,12 +566,13 @@ _asmPlayNotePu2On$::
 	ld	hl, #_noteStatus + 3
 	ld	(hl),B
 
-	ld	A,#<_freq
-    add	A,B
-    add	A,B
-	ld	E,A
-    ld	A,#>_freq
-	ld	D,A
+	ld  A,B
+	add A,A
+	add A,#<_freq
+	ld  E,A
+	adc #>_freq
+	sub E
+	ld  D,A
 
 	ld  A,(DE)
 	ld	(#0xFF18),A
@@ -689,12 +690,13 @@ pop bc
 ret
 
 _asmPlayNoteWavSet$::
-	ld	A,#<_freq
-    add	A,B
-    add	A,B
-	ld	E,A
-    ld	A,#>_freq
-	ld	D,A
+	ld  A,B
+	add A,A
+	add A,#<_freq
+	ld  E,A
+	adc #>_freq
+	sub E
+	ld  D,A
 
 	ld  A,(DE)
 
@@ -821,7 +823,8 @@ _asmPlayNoteNoiOn$::
 	ld	A,#<_noiFreq
     add	A,B
 	ld	E,A
-    ld	A,#>_noiFreq
+    adc	A,#>_noiFreq
+	sub	E
 	ld	D,A
 
 	ld  A,(DE)