Add stubs for PSG.

src/gamegear.c

@@ -1,4 +1,4 @@
-/* Copyright (C) 2014-2015 Ben Kurtovic <ben.kurtovic@gmail.com>
+/* Copyright (C) 2014-2016 Ben Kurtovic <ben.kurtovic@gmail.com>
    Released under the terms of the MIT License. See LICENSE for details. */
 
 #include <stdlib.h>
@@ -24,7 +24,8 @@ GameGear* gamegear_create()
     GameGear *gg = cr_malloc(sizeof(GameGear));
     mmu_init(&gg->mmu);
     vdp_init(&gg->vdp);
-    io_init(&gg->io, &gg->vdp);
+    psg_init(&gg->psg);
+    io_init(&gg->io, &gg->vdp, &gg->psg);
     z80_init(&gg->cpu, &gg->mmu, &gg->io);
 
     gg->powered = false;
@@ -42,6 +43,7 @@ void gamegear_destroy(GameGear *gg)
 {
     mmu_free(&gg->mmu);
     vdp_free(&gg->vdp);
+    psg_free(&gg->psg);
     free(gg);
 }
 

src/gamegear.h

@@ -1,4 +1,4 @@
-/* Copyright (C) 2014-2015 Ben Kurtovic <ben.kurtovic@gmail.com>
+/* Copyright (C) 2014-2016 Ben Kurtovic <ben.kurtovic@gmail.com>
    Released under the terms of the MIT License. See LICENSE for details. */
 
 #pragma once
@@ -8,6 +8,7 @@
 
 #include "io.h"
 #include "mmu.h"
+#include "psg.h"
 #include "rom.h"
 #include "z80.h"
 
@@ -23,6 +24,7 @@ typedef struct GameGear {
     Z80 cpu;
     MMU mmu;
     VDP vdp;
+    PSG psg;
     IO io;
     bool powered;
     GGFrameCallback callback;

src/io.c

@@ -6,9 +6,10 @@
 /*
     Initialize an IO object.
 */
-void io_init(IO *io, VDP *vdp)
+void io_init(IO *io, VDP *vdp, PSG *psg)
 {
     io->vdp = vdp;
+    io->psg = psg;
 }
 
 /*
@@ -72,8 +73,7 @@ void io_port_write(IO *io, uint8_t port, uint8_t value)
         // TODO: Write to I/O control register
         goto except;
     } else if (port <= 0x7F) {
-        // TODO: Write to the SN76489 PSG
-        goto except;
+        psg_write(io->psg, value);
     } else if (port <= 0xBF && !(port % 2)) {
         vdp_write_data(io->vdp, value);
     } else if (port <= 0xBF) {

src/io.h

@@ -6,19 +6,21 @@
 #include <stdbool.h>
 #include <stdint.h>
 
+#include "psg.h"
 #include "vdp.h"
 
 /* Structs */
 
 typedef struct {
     VDP *vdp;
+    PSG *psg;
     bool except;
     uint8_t exc_port;
 } IO;
 
 /* Functions */
 
-void io_init(IO*, VDP*);
+void io_init(IO*, VDP*, PSG*);
 void io_power(IO*);
 bool io_check_irq(IO*);
 uint8_t io_port_read(IO*, uint8_t);

src/psg.c

@@ -0,0 +1,43 @@
+/* Copyright (C) 2014-2016 Ben Kurtovic <ben.kurtovic@gmail.com>
+   Released under the terms of the MIT License. See LICENSE for details. */
+
+#include "psg.h"
+#include "util.h"
+
+/*
+    Initialize the SN76489 Programmable Sound Generator (PSG).
+*/
+void psg_init(PSG *psg)
+{
+    // TODO
+    (void) psg;
+}
+
+/*
+    Free memory previously allocated by the PSG.
+*/
+void psg_free(PSG *psg)
+{
+    // TODO
+    (void) psg;
+}
+
+/*
+    Power on the PSG, setting up initial state.
+*/
+void psg_power(PSG *psg)
+{
+    psg->tone1 = psg->tone2 = psg->tone3 = 0x0000;
+    psg->vol1 = psg->vol2 = psg->vol3 = 0x0F;
+    psg->noise = 0x00;
+}
+
+/*
+    Write a byte of input to the PSG.
+*/
+void psg_write(PSG *psg, uint8_t byte)
+{
+    // TODO
+    (void) psg;
+    TRACE("PSG ignoring write: 0x%02X", byte)
+}

src/psg.h

@@ -0,0 +1,21 @@
+/* Copyright (C) 2014-2016 Ben Kurtovic <ben.kurtovic@gmail.com>
+   Released under the terms of the MIT License. See LICENSE for details. */
+
+#pragma once
+
+#include <stdint.h>
+
+/* Structs */
+
+typedef struct {
+    uint16_t tone1, tone2, tone3;
+    uint8_t vol1, vol2, vol3;
+    uint8_t noise;
+} PSG;
+
+/* Functions */
+
+void psg_init(PSG*);
+void psg_free(PSG*);
+void psg_power(PSG*);
+void psg_write(PSG*, uint8_t);