mixer: implement panning settings

fpga/rtl/magic.sv

@@ -21,8 +21,8 @@ module magic(
     output reg joy_sinclair,
     output reg rom_plus3,
     output reg rom_alt48,
-    output reg ay_abc,
-    output reg ay_mono,
+    output reg mix_abc,
+    output reg mix_mono,
     output reg divmmc_en
 );
 
@@ -72,8 +72,8 @@ always @(posedge clk28 or negedge rst_n) begin
         magic_beeper <= 0;
         timings <= TIMINGS_PENT;
         turbo <= TURBO_NONE;
-        ay_abc <= 1'b1;
-        ay_mono <= 0;
+        mix_abc <= 1'b1;
+        mix_mono <= 0;
         ram_mode <= RAM_512;
         rom_plus3 <= 0;
         rom_alt48 <= 0;
@@ -85,7 +85,7 @@ always @(posedge clk28 or negedge rst_n) begin
         8'h01: magic_beeper <= bus.d_reg[0];
         8'h02: timings <= timings_t'(bus.d_reg[1:0]);
         8'h03: turbo <= turbo_t'(bus.d_reg[1:0]);
-        8'h04: {ay_mono, ay_abc} <= bus.d_reg[1:0];
+        8'h04: {mix_mono, mix_abc} <= bus.d_reg[1:0];
         8'h05: rom_plus3 <= bus.d_reg[0];
         8'h06: rom_alt48 <= bus.d_reg[0];
         8'h07: joy_sinclair <= bus.d_reg[0];

fpga/rtl/mixer.sv

@@ -17,29 +17,48 @@ module mixer(
     input [7:0] sd_r1,
 
     input ay_abc,
-    input ay_mono,
+    input mono,
 
     output dac_l,
     output dac_r
 );
 
-localparam WIDTH = 11;
+localparam WIDTH = 13;
 
 reg [WIDTH:0] dac_l_cnt, dac_r_cnt;
 assign dac_l = dac_l_cnt[WIDTH];
 assign dac_r = dac_r_cnt[WIDTH];
 
 wire [WIDTH-1:0] dac_next_l =
-    sd_l0 + sd_l1 +
-    ay_a0 + ay_b0 +
-    ay_a1 + ay_b1 +
-    {beeper, tape_out, tape_in, 6'b000000}
+    {sd_l0, 1'b0} +
+    {sd_l1, 1'b0} +
+    {ay_a0, 1'b0} +
+    {ay_a1, 1'b0} +
+    (ay_abc? ay_b0 : ay_c0) +
+    (ay_abc? ay_b1 : ay_c1) +
+    {beeper, tape_out, tape_in, 7'b000000}
     ;
 wire [WIDTH-1:0] dac_next_r =
-    sd_r0 + sd_r1 +
-    ay_b0 + ay_c0 +
-    ay_b1 + ay_c1 +
-    {beeper, tape_out, tape_in, 6'b000000}
+    {sd_r0, 1'b0} +
+    {sd_r1, 1'b0} +
+    (ay_abc? {ay_c0, 1'b0} : {ay_b0, 1'b0}) +
+    (ay_abc? {ay_c1, 1'b0} : {ay_b1, 1'b0}) +
+    (ay_abc? ay_b0 : ay_c0) +
+    (ay_abc? ay_b1 : ay_c1) +
+    {beeper, tape_out, tape_in, 7'b000000}
+    ;
+wire [WIDTH-1:0] dac_next_mono =
+    sd_r0 +
+    sd_r1 +
+    sd_l0 +
+    sd_l1 +
+    ay_a0 +
+    ay_a1 +
+    ay_b0 +
+    ay_b1 +
+    ay_c0 +
+    ay_c1 +
+    {beeper, tape_out, tape_in, 7'b000000}
     ;
 
 always @(posedge clk28 or negedge rst_n) begin
@@ -48,8 +67,8 @@ always @(posedge clk28 or negedge rst_n) begin
         dac_r_cnt <= 0;
     end
     else begin
-        dac_l_cnt <= dac_l_cnt[WIDTH-1:0] + dac_next_l;
-        dac_r_cnt <= dac_r_cnt[WIDTH-1:0] + dac_next_r;
+        dac_l_cnt <= dac_l_cnt[WIDTH-1:0] + (mono? dac_next_mono : dac_next_l);
+        dac_r_cnt <= dac_r_cnt[WIDTH-1:0] + (mono? dac_next_mono : dac_next_r);
     end
 end
 

fpga/rtl/top.sv

@@ -229,7 +229,7 @@ cpucontrol cpucontrol0(
 
 /* MAGIC */
 wire magic_mode, magic_map;
-wire divmmc_en, joy_sinclair, rom_plus3, rom_alt48, ay_abc, ay_mono;
+wire divmmc_en, joy_sinclair, rom_plus3, rom_alt48, mix_abc, mix_mono;
 magic magic0(
     .rst_n(usrrst_n),
     .clk28(clk28),
@@ -252,8 +252,8 @@ magic magic0(
     .joy_sinclair(joy_sinclair),
     .rom_plus3(rom_plus3),
     .rom_alt48(rom_alt48),
-    .ay_abc(ay_abc),
-    .ay_mono(ay_mono),
+    .mix_abc(mix_abc),
+    .mix_mono(mix_mono),
     .divmmc_en(divmmc_en)
 );
 
@@ -365,8 +365,8 @@ mixer mixer0(
     .sd_r0(soundrive_r0),
     .sd_r1(soundrive_r1),
 
-    .ay_abc(ay_abc),
-    .ay_mono(ay_mono),
+    .ay_abc(mix_abc),
+    .mono(mix_mono),
 
     .dac_l(snd_l),
     .dac_r(snd_r)