Sprinter/mame
2
0
Fork 0
mirror of https://github.com/holub/mame synced 2025-04-22 08:22:15 +03:00
Code Issues Actions Packages Projects Releases Wiki Activity

ay8910.cpp: Improve AY8930 noise algorithm, simplify some logic (#8729)

Browse Source
This commit is contained in:
cam900 2021-10-21 22:07:10 +09:00 committed by GitHub
parent e241a3ad92
commit 4e1fce0d2a
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 85 additions and 64 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

101
src/devices/sound/ay8910.cpp
View File

@ -590,7 +590,7 @@ YM2203 Japanese datasheet contents, translated: http://www.larwe.com/technical/c
*
*************************************/
#define ENABLE_REGISTER_TEST (0) /* Enable preprogrammed registers */
#define ENABLE_REGISTER_TEST (0) // Enable preprogrammed registers
#define LOG_IGNORED_WRITES (0)
static constexpr stream_buffer::sample_t MAX_OUTPUT = 1.0;
@ -641,7 +641,7 @@ static const ay8910_device::ay_ym_param ym2149_param_env =
};
#if 0
/* RL = 1000, Hacker Kay normalized, 2.1V to 3.2V */
// RL = 1000, Hacker Kay normalized, 2.1V to 3.2V
static const ay8910_device::ay_ym_param ay8910_param =
{
664, 913,
@ -826,7 +826,7 @@ static inline void build_3D_table(double rl, const ay8910_device::ay_ym_param *p
tab[j] = MAX_OUTPUT * temp[j];
}
/* for (e = 0;e<16;e++) printf("%d %d\n",e << 10, tab[e << 10]); */
// for (e = 0;e<16;e++) printf("%d %d\n",e << 10, tab[e << 10]);
}
static inline void build_single_table(double rl, const ay8910_device::ay_ym_param *par, int normalize, stream_buffer::sample_t *tab, int zero_is_off)
@ -906,13 +906,9 @@ stream_buffer::sample_t ay8910_device::mix_3D()
}
}
if (m_feature & PSG_EXTENDED_ENVELOPE) // AY8914 Has a two bit tone_envelope field
{
indx |= env_mask | (m_vol_enabled[chan] ? ((env_volume >> (3-tone_envelope(tone))) << (chan*5)) : 0);
}
else
{
indx |= env_mask | (m_vol_enabled[chan] ? env_volume << (chan*5) : 0);
}
}
else
{
@ -956,7 +952,7 @@ void ay8910_device::ay8910_write_reg(int r, int v)
m_tone[2].set_period(m_regs[AY_CFINE], coarse);
break;
case AY_NOISEPER:
/* No action required */
// No action required
break;
case AY_AVOL:
m_tone[0].set_volume(m_regs[AY_AVOL]);
@ -975,7 +971,7 @@ void ay8910_device::ay8910_write_reg(int r, int v)
if ((m_last_enable == -1) ||
((m_last_enable & 0x40) != (m_regs[AY_ENABLE] & 0x40)))
{
/* write out 0xff if port set to input */
// write out 0xff if port set to input
if (!m_port_a_write_cb.isnull())
m_port_a_write_cb((offs_t)0, (m_regs[AY_ENABLE] & 0x40) ? m_regs[AY_PORTA] : 0xff);
}
@ -983,7 +979,7 @@ void ay8910_device::ay8910_write_reg(int r, int v)
if ((m_last_enable == -1) ||
((m_last_enable & 0x80) != (m_regs[AY_ENABLE] & 0x80)))
{
/* write out 0xff if port set to input */
// write out 0xff if port set to input
if (!m_port_b_write_cb.isnull())
m_port_b_write_cb((offs_t)0, (m_regs[AY_ENABLE] & 0x80) ? m_regs[AY_PORTB] : 0xff);
}
@ -1065,7 +1061,7 @@ void ay8910_device::ay8910_write_reg(int r, int v)
break;
case AY_NOISEAND:
case AY_NOISEOR:
// not implemented
// No action required
break;
default:
m_regs[r] = 0; // reserved, set as 0
@ -1084,21 +1080,21 @@ void ay8910_device::sound_stream_update(sound_stream &stream, std::vector<read_s
int samples = outputs[0].samples();
/* hack to prevent us from hanging when starting filtered outputs */
// hack to prevent us from hanging when starting filtered outputs
if (!m_ready)
{
for (int chan = 0; chan < m_streams; chan++)
outputs[chan].fill(0);
}
/* The 8910 has three outputs, each output is the mix of one of the three */
/* tone generators and of the (single) noise generator. The two are mixed */
/* BEFORE going into the DAC. The formula to mix each channel is: */
/* (ToneOn | ToneDisable) & (NoiseOn | NoiseDisable). */
/* Note that this means that if both tone and noise are disabled, the output */
/* is 1, not 0, and can be modulated changing the volume. */
// The 8910 has three outputs, each output is the mix of one of the three
// tone generators and of the (single) noise generator. The two are mixed
// BEFORE going into the DAC. The formula to mix each channel is:
// (ToneOn | ToneDisable) & (NoiseOn | NoiseDisable).
// Note that this means that if both tone and noise are disabled, the output
// is 1, not 0, and can be modulated changing the volume.
/* buffering loop */
// buffering loop
for (int sampindex = 0; sampindex < samples; sampindex++)
{
for (int chan = 0; chan < NUM_CHANNELS; chan++)
@ -1114,25 +1110,25 @@ void ay8910_device::sound_stream_update(sound_stream &stream, std::vector<read_s
}
}
m_count_noise++;
if (m_count_noise >= noise_period())
if ((++m_count_noise) >= noise_period())
{
/* toggle the prescaler output. Noise is no different to
* channels.
*/
// toggle the prescaler output. Noise is no different to
// channels.
m_count_noise = 0;
m_prescale_noise ^= 1;
if (!m_prescale_noise || is_expanded_mode()) // AY8930 noise generator rate is twice compares as compatibility mode
// TODO : verify algorithm for AY8930
if (is_expanded_mode()) // AY8930 noise generator rate is twice compares as compatibility mode
{
/* The Random Number Generator of the 8910 is a 17-bit shift */
/* register. The input to the shift register is bit0 XOR bit3 */
/* (bit0 is the output). This was verified on AY-3-8910 and YM2149 chips. */
// TODO : get actually algorithm for AY8930
m_rng ^= (((m_rng & 1) ^ ((m_rng >> 3) & 1)) << 17);
m_rng >>= 1;
if ((++m_noise_value) >= ((u8(m_rng) & noise_and()) | noise_or()))
{
m_noise_value = 0;
m_noise_out ^= 1;
noise_rng_tick();
}
}
else if (!m_prescale_noise)
noise_rng_tick();
}
for (int chan = 0; chan < NUM_CHANNELS; chan++)
@ -1141,20 +1137,19 @@ void ay8910_device::sound_stream_update(sound_stream &stream, std::vector<read_s
m_vol_enabled[chan] = (tone->output | tone_enable(chan)) & (noise_output() | noise_enable(chan));
}
/* update envelope */
// update envelope
for (int chan = 0; chan < NUM_CHANNELS; chan++)
{
envelope = &m_envelope[chan];
if (envelope->holding == 0)
{
const u32 period = envelope->period * m_step;
envelope->count++;
if (envelope->count >= period)
if ((++envelope->count) >= period)
{
envelope->count = 0;
envelope->step--;
/* check envelope current position */
// check envelope current position
if (envelope->step < 0)
{
if (envelope->hold)
@ -1166,8 +1161,8 @@ void ay8910_device::sound_stream_update(sound_stream &stream, std::vector<read_s
}
else
{
/* if CountEnv has looped an odd number of times (usually 1), */
/* invert the output. */
// if CountEnv has looped an odd number of times (usually 1),
// invert the output.
if (envelope->alternate && (envelope->step & (m_env_step_mask + 1)))
envelope->attack ^= m_env_step_mask;
@ -1260,10 +1255,8 @@ void ay8910_device::build_mixer_table()
build_single_table(m_res_load[chan], m_par_env, normalize, m_env_table[chan], 0);
}
}
/*
* The previous implementation added all three channels up instead of averaging them.
* The factor of 3 will force the same levels if normalizing is used.
*/
// The previous implementation added all three channels up instead of averaging them.
// The factor of 3 will force the same levels if normalizing is used.
else
{
build_3D_table(m_res_load[0], m_par, m_par_env, normalize, 3, m_zero_is_off, m_vol3d_table.get());
@ -1293,10 +1286,12 @@ void ay8910_device::ay8910_statesave()
save_item(NAME(m_regs));
save_item(NAME(m_last_enable));
save_item(NAME(m_noise_value));
save_item(NAME(m_count_noise));
save_item(NAME(m_prescale_noise));
save_item(NAME(m_rng));
save_item(NAME(m_noise_out));
save_item(NAME(m_mode));
save_item(NAME(m_flags));
}
@ -1330,8 +1325,8 @@ void ay8910_device::device_start()
build_mixer_table();
/* The envelope is pacing twice as fast for the YM2149 as for the AY-3-8910, */
/* This handled by the step parameter. Consequently we use a multipler of 2 here. */
// The envelope is pacing twice as fast for the YM2149 as for the AY-3-8910,
// This handled by the step parameter. Consequently we use a multipler of 2 here.
m_channel = stream_alloc(0, m_streams, master_clock / 8);
ay_set_clock(master_clock);
@ -1344,15 +1339,17 @@ void ay8910_device::ay8910_reset_ym()
m_active = false;
m_register_latch = 0;
m_rng = 1;
m_noise_out = 0;
m_mode = 0; // ay-3-8910 compatible mode
for (int chan = 0; chan < NUM_CHANNELS; chan++)
{
m_tone[chan].reset();
m_envelope[chan].reset();
}
m_noise_value = 0;
m_count_noise = 0;
m_prescale_noise = 0;
m_last_enable = -1; /* force a write */
m_last_enable = -1; // force a write
for (int i = 0; i < AY_PORTA; i++)
ay8910_write_reg(i,0);
m_ready = 1;
@ -1402,10 +1399,10 @@ void ay8910_device::ay8910_write_ym(int addr, u8 data)
if (m_active)
{
const u8 register_latch = m_register_latch + get_register_bank();
/* Data port */
// Data port
if (m_register_latch == AY_EASHAPE || m_regs[register_latch] != data)
{
/* update the output buffer before changing the register */
// update the output buffer before changing the register
m_channel->update();
}
@ -1417,7 +1414,7 @@ void ay8910_device::ay8910_write_ym(int addr, u8 data)
m_active = (data >> 4) == 0; // mask programmed 4-bit code
if (m_active)
{
/* Register port */
// Register port
m_register_latch = data & 0x0f;
}
else
@ -1430,15 +1427,15 @@ void ay8910_device::ay8910_write_ym(int addr, u8 data)
u8 ay8910_device::ay8910_read_ym()
{
device_type chip_type = type();
int r = m_register_latch + get_register_bank();
u8 r = m_register_latch + get_register_bank();
if (!m_active) return 0xff; // high impedance
if ((r & 0xf) == AY_EASHAPE) // shared register
r &= 0xf;
/* There are no state dependent register in the AY8910! */
/* m_channel->update(); */
// There are no state dependent register in the AY8910!
// m_channel->update();
switch (r)
{
@ -1609,8 +1606,10 @@ ay8910_device::ay8910_device(const machine_config &mconfig, device_type type, co
m_register_latch(0),
m_last_enable(0),
m_prescale_noise(0),
m_noise_value(0),
m_count_noise(0),
m_rng(0),
m_noise_out(0),
m_mode(0),
m_env_step_mask((!(feature & PSG_HAS_EXPANDED_MODE)) && (psg_type == PSG_TYPE_AY) ? 0x0f : 0x1f),
m_step( (!(feature & PSG_HAS_EXPANDED_MODE)) && (psg_type == PSG_TYPE_AY) ? 2 : 1),

48
src/devices/sound/ay8910.h
View File

@ -76,7 +76,12 @@ public:
// configuration helpers
void set_flags(int flags) { m_flags = flags; }
void set_psg_type(psg_type_t psg_type) { set_type(psg_type); }
void set_psg_type(psg_type_t psg_type)
{
// Ignore when AY8930 for now
if (!(m_feature & PSG_HAS_EXPANDED_MODE))
set_type(psg_type);
}
void set_resistors_load(int res_load0, int res_load1, int res_load2) { m_res_load[0] = res_load0; m_res_load[1] = res_load1; m_res_load[2] = res_load2; }
auto port_a_read_callback() { return m_port_a_read_cb.bind(); }
auto port_b_read_callback() { return m_port_b_read_cb.bind(); }
@ -144,7 +149,7 @@ protected:
private:
static constexpr unsigned NUM_CHANNELS = 3;
/* register id's */
// register id's
enum
{
AY_AFINE = 0x00,
@ -243,7 +248,7 @@ private:
attack = (shape & 0x04) ? mask : 0x00;
if ((shape & 0x08) == 0)
{
/* if Continue = 0, map the shape to the equivalent one which has Continue = 1 */
// if Continue = 0, map the shape to the equivalent one which has Continue = 1
hold = 1;
alternate = attack;
}
@ -258,6 +263,18 @@ private:
}
};
inline void noise_rng_tick()
{
// The Random Number Generator of the 8910 is a 17-bit shift
// register. The input to the shift register is bit0 XOR bit3
// (bit0 is the output). This was verified on AY-3-8910 and YM2149 chips.
if (m_feature & PSG_HAS_EXPANDED_MODE) // AY8930 LFSR algorithm is slightly different, verified from manual
m_rng = (m_rng >> 1) | ((BIT(m_rng, 0) ^ BIT(m_rng, 2)) << 16);
else
m_rng = (m_rng >> 1) | ((BIT(m_rng, 0) ^ BIT(m_rng, 3)) << 16);
}
// inlines
inline bool tone_enable(int chan) { return BIT(m_regs[AY_ENABLE], chan); }
inline u8 tone_volume(tone_t *tone) { return tone->volume & (is_expanded_mode() ? 0x1f : 0x0f); }
@ -267,11 +284,14 @@ private:
inline bool noise_enable(int chan) { return BIT(m_regs[AY_ENABLE], 3 + chan); }
inline u8 noise_period() { return is_expanded_mode() ? m_regs[AY_NOISEPER] & 0xff : m_regs[AY_NOISEPER] & 0x1f; }
inline u8 noise_output() { return m_rng & 1; }
inline u8 noise_output() { return is_expanded_mode() ? m_noise_out & 1 : m_rng & 1; }
inline bool is_expanded_mode() { return ((m_feature & PSG_HAS_EXPANDED_MODE) && ((m_mode & 0xe) == 0xa)); }
inline u8 get_register_bank() { return is_expanded_mode() ? (m_mode & 0x1) << 4 : 0; }
inline u8 noise_and() { return m_regs[AY_NOISEAND] & 0xff; }
inline u8 noise_or() { return m_regs[AY_NOISEOR] & 0xff; }
// internal helpers
void set_type(psg_type_t psg_type);
inline stream_buffer::sample_t mix_3D();
@ -286,17 +306,19 @@ private:
int m_ready;
sound_stream *m_channel;
bool m_active;
s32 m_register_latch;
u8 m_register_latch;
u8 m_regs[16 * 2];
s32 m_last_enable;
s16 m_last_enable;
tone_t m_tone[NUM_CHANNELS];
envelope_t m_envelope[NUM_CHANNELS];
u8 m_prescale_noise;
s32 m_count_noise;
s32 m_rng;
s16 m_noise_value;
s16 m_count_noise;
u32 m_rng;
u8 m_noise_out;
u8 m_mode;
u8 m_env_step_mask;
/* init parameters ... */
// init parameters ...
int m_step;
int m_zero_is_off;
u8 m_vol_enabled[NUM_CHANNELS];
@ -305,9 +327,9 @@ private:
stream_buffer::sample_t m_vol_table[NUM_CHANNELS][16];
stream_buffer::sample_t m_env_table[NUM_CHANNELS][32];
std::unique_ptr<stream_buffer::sample_t[]> m_vol3d_table;
int m_flags; /* Flags */
int m_feature; /* Chip specific features */
int m_res_load[3]; /* Load on channel in ohms */
int m_flags; // Flags
int m_feature; // Chip specific features
int m_res_load[3]; // Load on channel in ohms
devcb_read8 m_port_a_read_cb;
devcb_read8 m_port_b_read_cb;
devcb_write8 m_port_a_write_cb;
@ -337,7 +359,7 @@ class ay8914_device : public ay8910_device
public:
ay8914_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock);
/* AY8914 handlers needed due to different register map */
// AY8914 handlers needed due to different register map
u8 read(offs_t offset);
void write(offs_t offset, u8 data);
};