diff options
Diffstat (limited to 'src/devices/sound/ay8910.cpp')
-rw-r--r-- | src/devices/sound/ay8910.cpp | 101 |
1 files changed, 50 insertions, 51 deletions
diff --git a/src/devices/sound/ay8910.cpp b/src/devices/sound/ay8910.cpp index c5f22df7243..1f0acab67d7 100644 --- a/src/devices/sound/ay8910.cpp +++ b/src/devices/sound/ay8910.cpp @@ -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), |