From 01878f5fdca9d08e4cf7ceed7f5a39f4df602de4 Mon Sep 17 00:00:00 2001
From: Joshua Wise <joshua@nyus.joshuawise.com>
Date: Mon, 28 Apr 2008 06:41:24 -0400
Subject: [PATCH] Sound: Leave it to Dennis.

---
 Sound1.v    | 15 +++++----------
 Sound2.v    |  2 +-
 Soundcore.v | 23 +++++++++++++++--------
 bootrom.asm |  4 ++++
 4 files changed, 25 insertions(+), 19 deletions(-)

diff --git a/Sound1.v b/Sound1.v
index 9444dbf..41abaa5 100644
--- a/Sound1.v
+++ b/Sound1.v
@@ -17,11 +17,11 @@ module Sound1(
 	);
 
 	/* can be optimized as register file */
-	reg [7:0] nr10, nr11, nr12, nr13, nr14;
+	reg [7:0] nr10 = 0, nr11 = 0, nr12 = 0, nr13 = 0, nr14 = 0;
 	reg [10:0] counter = 0;
 	reg [4:0] lencnt = 0;
 	reg [3:0] delta = 4'b1111;
-	reg [2:0] dutycnt;
+	reg toggle = 0;
 	reg [3:0] snd_out = 0;
 
 	assign snd_data = en ? snd_out : 0;
@@ -58,15 +58,10 @@ module Sound1(
 			counter <= counter - 1;
 		else begin
 			counter <= ~{nr14[2:0],nr13} + 1;  /* possible A */
-			dutycnt <= dutycnt + 1;
+			toggle <= ~toggle;
 		end
-
-		case (nr11[7:6])
-		2'b00: snd_out <= dutycnt ? 0 : delta;   /* probable A */
-		2'b01: snd_out <= (dutycnt[2:1] == 2'b0) ? delta : 0;
-		2'b10: snd_out <= dutycnt[2] ? delta : 0;
-		2'b11: snd_out <= (dutycnt[2:1] == 2'b0) ? 0 : delta;
-		endcase
+		
+		snd_out <= toggle ? delta : 0;	/* Leave it to Dennis. */
 	end
 
 	always @ (posedge lenclk) begin
diff --git a/Sound2.v b/Sound2.v
index fa5e5e7..2bb9598 100644
--- a/Sound2.v
+++ b/Sound2.v
@@ -16,7 +16,7 @@ module Sound2(
 	);
 
 	/* can be optimized as register file */
-	reg [7:0] nr21, nr22, nr23, nr24;
+	reg [7:0] nr21 = 0, nr22 = 0, nr23 = 0, nr24 = 0;
 	reg [10:0] counter = 0;
 	reg [4:0] lencnt = 0;
 	reg [3:0] delta = 4'b1111;
diff --git a/Soundcore.v b/Soundcore.v
index 16d6067..b2c4d35 100644
--- a/Soundcore.v
+++ b/Soundcore.v
@@ -17,9 +17,16 @@ module Soundcore(
 	reg [4:0] cntclk;
 	reg [13:0] lenclk;
 	wire [3:0] sndout1,sndout2,sndout3,sndout4;
-	wire [3:0] right_snd = nr51[0] ? sndout1 : 4'b0;
-	wire [3:0] left_snd = nr51[4] ? sndout1 : 4'b0;
-
+	wire [3:0] right_snd =
+		(nr51[0] ? sndout1 : 4'b0) +
+		(nr51[1] ? sndout2 : 4'b0) +
+		(nr51[2] ? sndout3 : 4'b0) +
+		(nr51[3] ? sndout4 : 4'b0);
+	wire [3:0] left_snd =
+		(nr51[4] ? sndout1 : 4'b0) +
+		(nr51[5] ? sndout2 : 4'b0) +
+		(nr51[6] ? sndout3 : 4'b0) +
+		(nr51[7] ? sndout4 : 4'b0);
 	assign sndout3 = 0;
 	assign sndout4 = 0;
 
@@ -34,14 +41,14 @@ module Soundcore(
 			case(addr)
 			`ADDR_NR50: nr50 <= data;
 			`ADDR_NR51: nr51 <= data;
-			`ADDR_NR52: nr52 <= {data[7],3'b1,data[3:0]};
+			`ADDR_NR52: nr52 <= {data[7],7'b1111111};
 			endcase
 		end
 		cntclk <= cntclk + 1;
 		lenclk <= lenclk + 1;
 		pwmcnt <= pwmcnt + 1; 
-		snd_data_l <= (pwmcnt <= left_snd) ? 1 : 0;
-		snd_data_r <= (pwmcnt <= right_snd) ? 1 : 0;
+		snd_data_l <= (pwmcnt <= left_snd) ? nr50[7] : 0;
+		snd_data_r <= (pwmcnt <= right_snd) ? nr50[3] : 0;
 	end
 
 	Sound1 s1(
@@ -52,7 +59,7 @@ module Soundcore(
 		.data(data),
 		.cntclk(cntclk[4]),
 		.lenclk(lenclk[13]),
-		.en(nr52[7] & nr52[0]),
+		.en(nr52[7]),
 		.snd_data(sndout1)
 	);
 	
@@ -64,7 +71,7 @@ module Soundcore(
 		.data(data),
 		.cntclk(cntclk[4]),
 		.lenclk(lenclk[13]),
-		.en(nr52[7] & nr52[0]),
+		.en(nr52[7]),
 		.snd_data(sndout2)
 	);
 
diff --git a/bootrom.asm b/bootrom.asm
index cd76097..4e780bf 100644
--- a/bootrom.asm
+++ b/bootrom.asm
@@ -185,8 +185,12 @@ boot:	jr .running	; $0100
 .running:
 	ld a, $FF
 	ld [$FF51], A
+	ld a, $00
+	ld [$FF25], a
 .diq:	ld A, [$FF51]
 	cp 0
 	jr z, .diq
+	ld a, 0
+	LD [$FF40],A
 	jp $0000
 
-- 
2.43.0