pt3: init zeroed vars with loop

switching songs, sometimes they'd start wrong due to vars not
being initialized.  Easier to just zero everything than try to
figure out which field we weren't getting.  Also makes code smaller.

pt3_player/OPTIMIZATION.txt

@@ -25,6 +25,7 @@ Code Optimization
 	Qkumba#1	2937	??	1D.18	29s	171s	17%
 	Qkumba#2	2879	??	1C.18	28s	171s	16%
 	Qkumba#3+vmw	2816	??	1C.22	28s	171s	16%
+	Fixes,zero init 2776	??	1C.10	28s	171s	16%
 
 Times:							Validated
 	BH.PT3:	10.0B	16	1:33	 93	17.2%	

pt3_player/hello.bas

@@ -1,2 +1,2 @@
-  10  PRINT "PT3 PLAYER V0.7"
+  10  PRINT "PT3 PLAYER V0.8"
  100  PRINT  CHR$ (4)"BRUN PT3_PLAYER"

pt3_player/pt3_lib.s

@@ -19,6 +19,8 @@
 ; + 2832 bytes -- combine $D0 and $E0 decode
 ; + 2816 bytes -- eliminate "decode_done" variable (2.75k)
 ; + 2817 bytes -- eliminate pt3_version.  Slighly faster but also bigger
+; + 2828 bytes -- fix some correctness issues
+; + 2776 bytes -- init vars with loop (slower, but more correct and smaller)
 
 ; TODO
 ;   move some of these flags to be bits rather than bytes?
@@ -84,16 +86,18 @@ NOTE_TONE_SLIDE_TO_STEP	=39
 
 NOTE_STRUCT_SIZE=40
 
-note_a:
-	.byte	$0	; NOTE_VOLUME				; 0
-	.byte	$0	; NOTE_TONE_SLIDING_L			; 1
-	.byte	$0	; NOTE_TONE_SLIDING_H			; 2
-	.byte	$0	; NOTE_ENABLED				; 3
-	.byte	$0	; NOTE_ENVELOPE_ENABLED			; 4
-	.byte	$0	; NOTE_SAMPLE_POINTER_L			; 5
-	.byte	$0	; NOTE_SAMPLE_POINTER_H			; 6
-	.byte	$0	; NOTE_SAMPLE_LOOP			; 7
-	.byte	$0	; NOTE_SAMPLE_LENGTH			; 8
+begin_vars:
+
+note_a:									; reset?
+	.byte	$0	; NOTE_VOLUME				; 0	; Y
+	.byte	$0	; NOTE_TONE_SLIDING_L			; 1	; Y
+	.byte	$0	; NOTE_TONE_SLIDING_H			; 2	; Y
+	.byte	$0	; NOTE_ENABLED				; 3	; Y
+	.byte	$0	; NOTE_ENVELOPE_ENABLED			; 4	; Y
+	.byte	$0	; NOTE_SAMPLE_POINTER_L			; 5	; Y
+	.byte	$0	; NOTE_SAMPLE_POINTER_H			; 6	; Y
+	.byte	$0	; NOTE_SAMPLE_LOOP			; 7	; Y
+	.byte	$0	; NOTE_SAMPLE_LENGTH			; 8	; Y
 	.byte	$0	; NOTE_TONE_L				; 9
 	.byte	$0	; NOTE_TONE_H				; 10
 	.byte	$0	; NOTE_AMPLITUDE			; 11
@@ -102,16 +106,16 @@ note_a:
 	.byte	$0	; NOTE_LEN_COUNT			; 14
 	.byte	$0	; NOTE_ADDR_L				; 15
 	.byte	$0	; NOTE_ADDR_H				; 16
-	.byte	$0	; NOTE_ORNAMENT_POINTER_L		; 17
-	.byte	$0	; NOTE_ORNAMENT_POINTER_H		; 18
-	.byte	$0	; NOTE_ORNAMENT_LOOP			; 19
-	.byte	$0	; NOTE_ORNAMENT_LENGTH			; 20
+	.byte	$0	; NOTE_ORNAMENT_POINTER_L		; 17	; Y
+	.byte	$0	; NOTE_ORNAMENT_POINTER_H		; 18	; Y
+	.byte	$0	; NOTE_ORNAMENT_LOOP			; 19	; Y
+	.byte	$0	; NOTE_ORNAMENT_LENGTH			; 20	; Y
 	.byte	$0	; NOTE_ONOFF				; 21
 	.byte	$0	; NOTE_TONE_ACCUMULATOR_L		; 22
 	.byte	$0	; NOTE_TONE_ACCUMULATOR_H		; 23
 	.byte	$0	; NOTE_TONE_SLIDE_COUNT			; 24
-	.byte	$0	; NOTE_ORNAMENT_POSITION		; 25
-	.byte	$0	; NOTE_SAMPLE_POSITION			; 26
+	.byte	$0	; NOTE_ORNAMENT_POSITION		; 25	; Y
+	.byte	$0	; NOTE_SAMPLE_POSITION			; 26	; Y
 	.byte	$0	; NOTE_ENVELOPE_SLIDING			; 27
 	.byte	$0	; NOTE_NOISE_SLIDING			; 28
 	.byte	$0	; NOTE_AMPLITUDE_SLIDING		; 29
@@ -219,23 +223,23 @@ current_line:		.byte	$0
 current_pattern:	.byte	$0
 pt3_pattern_done:	.byte	$0
 
-pt3_noise_period:	.byte	$0
-pt3_noise_add:		.byte	$0
+pt3_noise_period:	.byte	$0					; Y
+pt3_noise_add:		.byte	$0					; Y
 
-pt3_envelope_period_l:	.byte	$0
-pt3_envelope_period_h:	.byte	$0
+pt3_envelope_period_l:	.byte	$0					; Y
+pt3_envelope_period_h:	.byte	$0					; Y
 pt3_envelope_slide_l:	.byte	$0
 pt3_envelope_slide_h:	.byte	$0
 pt3_envelope_slide_add_l:.byte	$0
 pt3_envelope_slide_add_h:.byte	$0
 pt3_envelope_add:	.byte	$0
-pt3_envelope_type:	.byte	$0
+pt3_envelope_type:	.byte	$0					; Y
 pt3_envelope_type_old:	.byte	$0
 pt3_envelope_delay:	.byte	$0
 pt3_envelope_delay_orig:.byte	$0
 
 pt3_mixer_value:	.byte	$0
-
+end_vars:
 
 ;==========================
 ; local variables
@@ -423,13 +427,22 @@ load_sample:
 	;	it will save bytes only if the labels are adjacent
 	;	it will add a lot more cycles, though
 pt3_init_song:
+
+	lda	#$0
+	sta	DONE_SONG						; 3
+	ldx	#(end_vars-begin_vars)
+zero_song_structs_loop:
+	dex
+	sta	note_a,X
+	bne	zero_song_structs_loop
+
+
 	lda	#$f							; 2
 	sta	note_a+NOTE_VOLUME					; 4
 	sta	note_b+NOTE_VOLUME					; 4
 	sta	note_c+NOTE_VOLUME					; 4
-
+.if 0
 	lda	#$0							; 2
-	sta	DONE_SONG						; 3
 	sta	note_a+NOTE_TONE_SLIDING_L				; 4
 	sta	note_b+NOTE_TONE_SLIDING_L				; 4
 	sta	note_c+NOTE_TONE_SLIDING_L				; 4
@@ -442,12 +455,16 @@ pt3_init_song:
 	sta	note_a+NOTE_ENVELOPE_ENABLED				; 4
 	sta	note_b+NOTE_ENVELOPE_ENABLED				; 4
 	sta	note_c+NOTE_ENVELOPE_ENABLED				; 4
+	sta	note_a+NOTE_SAMPLE_POSITION				; 4
+	sta	note_b+NOTE_SAMPLE_POSITION				; 4
+	sta	note_c+NOTE_SAMPLE_POSITION				; 4
 
 	sta	pt3_noise_period					; 4
 	sta	pt3_noise_add						; 4
 	sta	pt3_envelope_period_l					; 4
 	sta	pt3_envelope_period_h					; 4
 	sta	pt3_envelope_type					; 4
+.endif
 
 	; default ornament/sample in A
 	ldx	#(NOTE_STRUCT_SIZE*0)					; 2