add pattern loading from table

main.usm

@@ -59,7 +59,7 @@
 ( speed - how many ticks we play a note every )
 #10 .Playback/speed STZ
 
-;pattern .Playback/pattern-addr STZ2
+#00 ;load-pattern JSR2
 
 ( display/audio init )
 ;on-frame .Screen/vector DEO2
@@ -84,6 +84,13 @@ BRK
 	.Playback/pattern-addr LDZ2 #00 .Edit/selection-x LDZ ADD2 #00 .Edit/selection-y LDZ PTN_WIDTH MUL2 ADD2
 RTN
 
+@load-pattern ( index -- ) ( loads a pattern from the table )
+	#02 MUL #00 SWP ( convert index to an actual index into the table )
+	;pattern_table ADD2 ( add to the table )
+	LDA2 ( load the address )
+	.Playback/pattern-addr STZ2 ( store in pattern index )
+RTN
+
 @handle-cursor ( controller -- ) ( handles moving the cursor around ) 
 	DUP #10 AND #00 NEQ ,&up JCN ( check the if the four directions are pressed )
 	DUP #20 AND ,&down JCN
@@ -367,6 +374,9 @@ BRK
 ( pattern format - each note has 3 bytes. Pitch, instrument, volume. patterns are 0x10 long.
   an ff in the note column of the pattern will kill the existing note without starting a new one (this is the tracker "box" note) )
 
+@data ( start of data )
+@pattern_table :pattern $fd ( pattern table. Contains the addresses of patterns )
+@pattern_pointer :pattern/end ( pattern pointer. Points to where the next pattern will be written in memory )
 @pattern [
 	48 12 66
 	49 34 66
@@ -383,5 +393,5 @@ BRK
 	54 00 66 
 	ff 00 66
 	56 00 ff
-	57 00 66
-]
+	57 00 66 &end
+]