Latch DAC data address for PCM driver when releasing Z80 bus

Prevents the PCM driver from sending junk to the data port of other YM2612 registers

src/synth.c

@@ -44,10 +44,11 @@ static u8 volumeAdjustedTotalLevel(u8 channel, u8 totalLevel);
 static void channelParameterUpdated(u8 channel);
 static void otherParameterUpdated(u8 channel, ParameterUpdated parameterUpdated);
 static void writeRegSafe(u8 part, u8 reg, u8 data);
+static void releaseZ80Bus(void);
 
 void synth_init(const FmChannel* initialPreset)
 {
-    // Z80_loadDriver(Z80_DRIVER_PCM, true);
+    Z80_loadDriver(Z80_DRIVER_PCM, true);
     Z80_requestBus(TRUE);
     writeSpecialModeReg();
     for (u8 chan = 0; chan < MAX_FM_CHANS; chan++) {
@@ -57,7 +58,7 @@ void synth_init(const FmChannel* initialPreset)
         updateChannel(chan);
     }
     writeGlobalLfo();
-    Z80_releaseBus();
+    releaseZ80Bus();
 }
 
 static void updateChannel(u8 chan)
@@ -454,6 +455,12 @@ static void writeRegSafe(u8 part, u8 reg, u8 data)
     bool takenAlready = Z80_getAndRequestBus(TRUE);
     YM2612_writeReg(part, reg, data);
     if (!takenAlready) {
-        Z80_releaseBus();
+        releaseZ80Bus();
     }
 }
+
+static void releaseZ80Bus(void)
+{
+    YM2612_write(0, 0x2A); // Latch reg address for PCM driver
+    Z80_releaseBus();
+}

tests/Makefile

@@ -107,6 +107,7 @@ MOCKS=midi_process \
 MD_MOCKS=SYS_setVIntCallback \
 	VDP_setTextPalette \
 	YM2612_writeReg \
+	YM2612_write \
 	VDP_drawText \
 	VDP_clearText \
 	VDP_setBackgroundColor \

tests/asserts.c

@@ -81,9 +81,14 @@ void _expect_ym2612_write_reg_any_data(u8 part, u8 reg, const char* const file,
 #endif
     expect_value_with_pos(__wrap_Z80_getAndRequestBus, wait, TRUE, file, line);
     will_return_with_pos(__wrap_Z80_getAndRequestBus, false, file, line);
+
     expect_any_with_pos(__wrap_YM2612_writeReg, part, file, line);
     expect_any_with_pos(__wrap_YM2612_writeReg, reg, file, line);
     expect_any_with_pos(__wrap_YM2612_writeReg, data, file, line);
+
+    expect_value_with_pos(__wrap_YM2612_write, port, 0, file, line);
+    expect_value_with_pos(__wrap_YM2612_write, data, 0x2A, file, line);
+
     expect_function_call(__wrap_Z80_releaseBus);
 }
 
@@ -96,6 +101,9 @@ void expect_ym2612_write_operator_any_data(u8 chan, u8 op, u8 baseReg)
     expect_value(__wrap_YM2612_writeReg, reg, baseReg + REG_OFFSET(chan) + (regOpIndex(op) * 4));
     expect_any(__wrap_YM2612_writeReg, data);
 
+    expect_value(__wrap_YM2612_write, port, 0);
+    expect_value(__wrap_YM2612_write, data, 0x2A);
+
     expect_function_call(__wrap_Z80_releaseBus);
 }
 
@@ -138,9 +146,14 @@ void _expect_ym2612_write_reg(u8 part, u8 reg, u8 data, const char* const file,
 #endif
     expect_value(__wrap_Z80_getAndRequestBus, wait, TRUE);
     will_return(__wrap_Z80_getAndRequestBus, false);
+
     expect_value_with_pos(__wrap_YM2612_writeReg, part, part, file, line);
     expect_value_with_pos(__wrap_YM2612_writeReg, reg, reg, file, line);
     expect_value_with_pos(__wrap_YM2612_writeReg, data, data, file, line);
+
+    expect_value_with_pos(__wrap_YM2612_write, port, 0, file, line);
+    expect_value_with_pos(__wrap_YM2612_write, data, 0x2A, file, line);
+
     expect_function_call(__wrap_Z80_releaseBus);
 }
 

tests/unit/test_synth.c

@@ -20,6 +20,8 @@ static void set_initial_registers(void)
         expect_any(__wrap_YM2612_writeReg, data);
     }
 
+    expect_value(__wrap_YM2612_write, port, 0);
+    expect_value(__wrap_YM2612_write, data, 0x2A);
     expect_function_call(__wrap_Z80_releaseBus);
 
     const FmChannel M_BANK_0_INST_0_GRANDPIANO = { 0, 0, 3, 0, 0, 0, 0,
@@ -37,14 +39,14 @@ static void loads_pcm_driver(void)
 static int test_synth_setup(UNUSED void** state)
 {
     updated = false;
-    // loads_pcm_driver();
+    loads_pcm_driver();
     set_initial_registers();
     return 0;
 }
 
 static void test_synth_init_sets_initial_registers(UNUSED void** state)
 {
-    // loads_pcm_driver();
+    loads_pcm_driver();
     set_initial_registers();
 }
 
@@ -744,6 +746,8 @@ static void test_requests_Z80_bus_if_not_already_taken(UNUSED void** state)
     expect_value(__wrap_YM2612_writeReg, reg, 0x2B);
     expect_value(__wrap_YM2612_writeReg, data, 0);
 
+    expect_value(__wrap_YM2612_write, port, 0);
+    expect_value(__wrap_YM2612_write, data, 0x2A);
     expect_function_call(__wrap_Z80_releaseBus);
 
     __real_synth_directWriteYm2612(0, 0x2B, 0);

tests/wraps.c

@@ -406,6 +406,14 @@ void __wrap_YM2612_writeReg(const u16 part, const u8 reg, const u8 data)
     check_expected(data);
 }
 
+void __wrap_YM2612_write(const u16 port, const u8 data)
+{
+    if (disableChecks)
+        return;
+    check_expected(port);
+    check_expected(data);
+}
+
 void __wrap_VDP_drawText(const char* str, u16 x, u16 y)
 {
 }

tests/wraps.h

@@ -179,6 +179,7 @@ extern void __real_scheduler_addFrameHandler(HandlerFunc* onFrame);
 
 /* SDGK wraps */
 void __wrap_YM2612_writeReg(const u16 part, const u8 reg, const u8 data);
+void __wrap_YM2612_write(const u16 port, const u8 data);
 void __wrap_VDP_drawText(const char* str, u16 x, u16 y);
 void __wrap_SYS_setVIntCallback(VoidCallback* CB);
 void __wrap_VDP_setTextPalette(u16 palette);