MEGA65: audio mixer small code reorg. #272

Just some code clean-up to move the audio mixer register ("coeffs") R/W
into audio65.c

Author: lgblgblgb

targets/mega65/audio65.c

@@ -1,6 +1,6 @@
 /* A work-in-progess MEGA65 (Commodore 65 clone origins) emulator
    Part of the Xemu project, please visit: https://github.com/lgblgblgb/xemu
-   Copyright (C)2016-2024 LGB (Gábor Lénárt) <[email protected]>
+   Copyright (C)2016-2025 LGB (Gábor Lénárt) <[email protected]>
 
 This program is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
@@ -45,6 +45,8 @@ static int system_sound_mix_freq;		// playback sample rate (in Hz) of the emulat
 static int system_sid_cycles_per_sec;
 static double dma_audio_mixing_value;
 
+Uint8 mixer_register = 0x00;
+static Uint8 mixer_coeffs[0x100];
 
 #if NUMBER_OF_SIDS != 4
 #	error "Currently NUMBER_OF_SIDS macro must be set to 4!"
@@ -385,6 +387,28 @@ void audio65_start ( void )
 }
 
 
+Uint8 audio65_read_mixer_register ( void )
+{
+	return mixer_coeffs[mixer_register];
+}
+
+
+void audio65_write_mixer_register ( const Uint8 data )
+{
+	mixer_coeffs[mixer_register] = data;
+	if (mixer_register == 0x1E || mixer_register == 0x1F) {		// HDMI-LEFT?
+		int vol = (mixer_coeffs[0x1E] << 8) + mixer_coeffs[0x1F];
+		vol = vol * 100 / 65536;
+		audio_set_stereo_parameters(vol, AUDIO_UNCHANGED_SEPARATION);
+	}
+	if (mixer_register == 0x3E || mixer_register == 0x3F)   {	// HDMI-RIGHT?
+		int vol = (mixer_coeffs[0x3E] << 8) + mixer_coeffs[0x3F];
+		vol = vol * 100 / 65536;
+		audio_set_stereo_parameters(vol, AUDIO_UNCHANGED_SEPARATION);
+	}
+}
+
+
 void audio65_init ( int sid_cycles_per_sec, int sound_mix_freq, int volume, int separation, unsigned int buffer_size )
 {
 	static volatile int initialized = 0;

targets/mega65/audio65.h

@@ -1,6 +1,6 @@
 /* A work-in-progess MEGA65 (Commodore-65 clone origins) emulator
    Part of the Xemu project, please visit: https://github.com/lgblgblgb/xemu
-   Copyright (C)2016-2024 LGB (Gábor Lénárt) <[email protected]>
+   Copyright (C)2016-2025 LGB (Gábor Lénárt) <[email protected]>
 
 This program is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
@@ -40,6 +40,7 @@ extern struct SidEmulation sid[NUMBER_OF_SIDS];
 
 extern int stereo_separation;
 extern int audio_volume;
+extern Uint8 mixer_register;
 
 extern void audio65_init ( int sid_cycles_per_sec, int sound_mix_freq, int volume, int separation, unsigned int buffer_size );
 extern void audio65_reset ( void );
@@ -50,4 +51,7 @@ extern void audio65_sid_write ( const int addr, const Uint8 data );
 extern void audio65_sid_inc_framecount ( void );
 extern void audio_set_stereo_parameters ( int vol, int sep );
 
+extern Uint8 audio65_read_mixer_register  ( void );
+extern void  audio65_write_mixer_register ( const Uint8 data );
+
 #endif

targets/mega65/io_mapper.c

@@ -48,8 +48,6 @@ int    core_age_in_days;
 static const Uint8 fpga_firmware_version[] = { 'X','e','m','u' };
 static const Uint8 cpld_firmware_version[] = { 'N','o','w','!' };
 
-static Uint8 coeff_addr = 0x00;
-static Uint8 mixer_coeffs[0x100];
 
 #define RETURN_ON_IO_READ_NOT_IMPLEMENTED(func, fb) \
 	do { DEBUG("IO: NOT IMPLEMENTED read (emulator lacks feature), %s $%04X fallback to answer $%02X" NL, func, addr, fb); \
@@ -261,6 +259,10 @@ Uint8 io_read ( unsigned int addr )
 					return rand() & 0xF;
 				case 0xDF: // D6DF: FPGA die temperature, high byte: assuming to be 164 (just because I see that on a real MEGA65 currently at my room's temperature ...)
 					return 164;
+				case 0xF4:
+					return mixer_register;
+				case 0xF5:
+					return audio65_read_mixer_register();
 				default:
 					DEBUG("MEGA65: reading MEGA65 specific I/O @ $D6%02X result is $%02X" NL, addr, D6XX_registers[addr]);
 					return D6XX_registers[addr];
@@ -344,22 +346,6 @@ Uint8 io_read ( unsigned int addr )
 	}
 }
 
-void update_mixer_coeffs(Uint8 data)
-{
-	mixer_coeffs[coeff_addr] = data;
-
-	if (coeff_addr == 0x1E || coeff_addr == 0x1F) {	// HDMI-LEFT?
-		int vol = (mixer_coeffs[0x1E] << 8) + mixer_coeffs[0x1F];
-		vol = vol * 100 / 65536;
-		audio_set_stereo_parameters(vol, AUDIO_UNCHANGED_SEPARATION);
-	}
-
-	if (coeff_addr == 0x3E || coeff_addr == 0x3F)	{ // HDMI-RIGHT?
-		int vol = (mixer_coeffs[0x3E] << 8) + mixer_coeffs[0x3F];
-		vol = vol * 100 / 65536;
-		audio_set_stereo_parameters(vol, AUDIO_UNCHANGED_SEPARATION);
-	}
-}
 
 
 /* Please read comments at io_read() above, those apply here too.
@@ -481,14 +467,14 @@ void io_write ( unsigned int addr, Uint8 data )
 				eth65_write_reg(addr, data);
 				return;
 			}
-
 			if (addr == 0xF4) {		// audio mixer co-efficient address
-				coeff_addr = data;
+				mixer_register = data;
+				return;
 			}
-			if (addr == 0XF5) {		// audio mixer co-efficient value
-				update_mixer_coeffs(data);
+			if (addr == 0xF5) {		// audio mixer co-efficient value
+				audio65_write_mixer_register(data);
+				return;
 			}
-
 			static int d6cf_exit_status = 0x42;
 			switch (addr) {
 				case 0x0A:	// write bit 7 is zero -> flush the queue