// license:BSD-3-Clause // copyright-holders:Devin Acker /*************************************************************************** Casio GT913 sound (HLE) This is the sound portion of the GT913. Up to 24 voices can be mixed into a 16-bit stereo serial bitstream, which is then input to either a serial DAC or a HG51B-based DSP, depending on the model of keyboard. The sample format, as well as other details such as the linear interpolation, are covered in these two Japanese patents: https://patents.google.com/patent/JP3603343B2/en https://patents.google.com/patent/JPH07199996A/en TODO: Volume envelope rates still need adjusting. (See comment in gt913_sound_device::command_w regarding command 6007) ***************************************************************************/ #include "emu.h" #include "gt913_snd.h" //************************************************************************** // DEVICE DEFINITIONS //************************************************************************** DEFINE_DEVICE_TYPE(GT913_SOUND, gt913_sound_device, "gt913_sound_hle", "Casio GT913F sound") // expand 2-bit exponent deltas const u8 gt913_sound_device::exp_2_to_3[4] = { 0, 1, 2, 7 }; // sign-extend 7-bit sample deltas const s8 gt913_sound_device::sample_7_to_8[128] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, -64, -63, -62, -61, -60, -59, -58, -57, -56, -55, -54, -53, -52, -51, -50, -49, -48, -47, -46, -45, -44, -43, -42, -41, -40, -39, -38, -37, -36, -35, -34, -33, -32, -31, -30, -29, -28, -27, -26, -25, -24, -23, -22, -21, -20, -19, -18, -17, -16, -15, -14, -13, -12, -11, -10, -9, -8, -7, -6, -5, -4, -3, -2, -1 }; // based on SW-10 softsynth const u16 gt913_sound_device::volume_ramp[17] = { 0x0000, 0x00fa, 0x0231, 0x03b5, 0x0596, 0x07ee, 0x0ad8, 0x0e78, 0x12fa, 0x1897, 0x1f93, 0x2843, 0x3313, 0x4087, 0x5143, 0x6617, 0x8000 }; gt913_sound_device::gt913_sound_device(const machine_config &mconfig, const char *tag, device_t *owner, const XTAL &clock) : device_t(mconfig, GT913_SOUND, tag, owner, clock) , device_sound_interface(mconfig, *this) , device_rom_interface(mconfig, *this) { } void gt913_sound_device::device_start() { /* generate sound at 104 cycles per sample (~= 144.231 kHz sample clock to the DAC) on keyboard models that include a DSP, this also results in a multiple of the 36.058 kHz CPU->DSP sync signal shown in some schematics (WK-1200 and others) */ m_stream = stream_alloc(0, 2, clock() / 104); save_item(NAME(m_gain)); save_item(NAME(m_data)); save_item(STRUCT_MEMBER(m_voices, m_enable)); save_item(STRUCT_MEMBER(m_voices, m_addr_start)); save_item(STRUCT_MEMBER(m_voices, m_addr_end)); save_item(STRUCT_MEMBER(m_voices, m_addr_loop)); save_item(STRUCT_MEMBER(m_voices, m_addr_current)); save_item(STRUCT_MEMBER(m_voices, m_addr_frac)); save_item(STRUCT_MEMBER(m_voices, m_pitch)); save_item(STRUCT_MEMBER(m_voices, m_sample)); save_item(STRUCT_MEMBER(m_voices, m_sample_next)); save_item(STRUCT_MEMBER(m_voices, m_exp)); save_item(STRUCT_MEMBER(m_voices, m_volume_data)); save_item(STRUCT_MEMBER(m_voices, m_volume_current)); save_item(STRUCT_MEMBER(m_voices, m_volume_target)); save_item(STRUCT_MEMBER(m_voices, m_volume_rate)); save_item(STRUCT_MEMBER(m_voices, m_balance)); save_item(STRUCT_MEMBER(m_voices, m_gain)); } void gt913_sound_device::device_reset() { m_gain = 0; std::memset(m_data, 0, sizeof(m_data)); std::memset(m_voices, 0, sizeof(m_voices)); } void gt913_sound_device::sound_stream_update(sound_stream& stream, std::vector const& inputs, std::vector& outputs) { for (int i = 0; i < outputs[0].samples(); i++) { s64 left = 0, right = 0; for (auto& voice : m_voices) { update_envelope(voice); if (voice.m_enable) mix_sample(voice, left, right); } outputs[0].put_int_clamp(i, (left * m_gain) >> 27, 32678); outputs[1].put_int_clamp(i, (right * m_gain) >> 27, 32768); } } void gt913_sound_device::rom_bank_pre_change() { m_stream->update(); } void gt913_sound_device::mix_sample(voice_t& voice, s64& left, s64& right) { // update sample position voice.m_addr_frac += voice.m_pitch; while (voice.m_enable && voice.m_addr_frac >= (1 << 25)) { voice.m_addr_frac -= (1 << 25); update_sample(voice); } // interpolate, apply envelope + channel gain, and mix into output const u8 step = (voice.m_addr_frac >> 22) & 7; const u8 env = (voice.m_volume_current >> 27); const u16 env_step = (voice.m_volume_current >> 16) & 0x7ff; const u32 env_level = (u32)volume_ramp[env] + (((volume_ramp[env + 1] - volume_ramp[env]) * env_step) >> 11); const s64 sample = ((s64)voice.m_sample + (voice.m_sample_next * step / 8)) * voice.m_gain * env_level; left += sample * voice.m_balance[0]; right += sample * voice.m_balance[1]; } void gt913_sound_device::update_envelope(voice_t& voice) { if (voice.m_volume_target > voice.m_volume_current && (voice.m_volume_target - voice.m_volume_current) > voice.m_volume_rate) { voice.m_volume_current += voice.m_volume_rate; } else if (voice.m_volume_target < voice.m_volume_current && (voice.m_volume_current - voice.m_volume_target) > voice.m_volume_rate) { voice.m_volume_current -= voice.m_volume_rate; } else { voice.m_volume_current = voice.m_volume_target; } } void gt913_sound_device::update_sample(voice_t& voice) { voice.m_sample += voice.m_sample_next; if (voice.m_addr_current >= voice.m_addr_end) { if (voice.m_addr_loop == voice.m_addr_end) { voice.m_enable = false; return; } voice.m_addr_current = voice.m_addr_loop; /* The last 12 bytes of each sample are a table containing five sample and exponent value pairs for the data words immediately after the loop point. The first pair corresponds to what the sample and exponent value will be _after_ processing the first 16-bit word after the loop, so once we've reached that point, use those values to reload the current sample and exponent */ const u32 addr_loop_data = (voice.m_addr_end + 1) & ~1; voice.m_sample_next = read_word(addr_loop_data) - voice.m_sample; voice.m_exp = read_word(addr_loop_data + 10) & 7; if (!BIT(voice.m_addr_current, 0)) { /* the loop data represents the state after applying both samples in a 16-bit word, so if we're looping to the first of the two samples, compensate for the second one */ const u16 word = read_word(voice.m_addr_current); const s16 delta = sample_7_to_8[word >> 9]; voice.m_sample_next -= delta * (1 << voice.m_exp); } } else { /* For all other samples, just get the next sample delta value. For even-numbered samples, also update the exponent/shift value. */ const u16 word = read_word(voice.m_addr_current & ~1); s16 delta = 0; if (!BIT(voice.m_addr_current, 0)) { voice.m_exp += exp_2_to_3[word & 3]; voice.m_exp &= 7; delta = sample_7_to_8[(word >> 2) & 0x7f]; } else { delta = sample_7_to_8[word >> 9]; } voice.m_sample_next = delta * (1 << voice.m_exp); } voice.m_addr_current++; } void gt913_sound_device::data_w(offs_t offset, u16 data) { assert(offset < 3); m_data[offset] = data; } u16 gt913_sound_device::data_r(offs_t offset) { assert(offset < 3); return m_data[offset]; } void gt913_sound_device::command_w(u16 data) { m_stream->update(); const uint8_t voicenum = (data & 0x1f00) >> 8; const uint16_t voicecmd = data & 0x60ff; if (data == 0x0012) { m_gain = m_data[0] & 0x3f; return; } else if (voicenum >= 24) { return; } auto& voice = m_voices[voicenum]; if (voicecmd == 0x0008) // voice data write commands { /* sample start addresses seem to need to be word-aligned to decode properly (see: ctk551 "Trumpet" patch, which will have a bad exponent value otherwise) this apparently doesn't apply to end/loop addresses, though, or else samples may loop badly or even become noticeably detuned TODO: is the LSB of start addresses supposed to indicate something else, then? */ voice.m_addr_start = (m_data[1] | (m_data[2] << 16)) & 0x3ffffe; } else if (voicecmd == 0x0000) { voice.m_addr_end = (m_data[0] | (m_data[1] << 16)) & 0x3fffff; } else if (voicecmd == 0x2000) { voice.m_addr_loop = (m_data[0] | (m_data[1] << 16)) & 0x3fffff; } else if (voicecmd == 0x200a) { /* TODO: what does bit 3 of data[2] do? ctk551 sets it unconditionally */ voice.m_exp = m_data[2] & 7; } else if (voicecmd == 0x200b) { bool enable = BIT(m_data[2], 7); if (enable && !m_voices[voicenum].m_enable) { voice.m_addr_current = voice.m_addr_start; voice.m_addr_frac = 0; voice.m_volume_current = 0; voice.m_sample = voice.m_sample_next = 0; } voice.m_enable = enable; } else if (voicecmd == 0x4004) { voice.m_balance[0] = (m_data[1] & 0xe0) >> 5; voice.m_balance[1] = (m_data[1] & 0x1c) >> 2; } else if (voicecmd == 0x4005) { /* for pitch, data[1] apparently contains both the most and least significant of 4 bytes, with data0 in the middle. strange, but apparently correct (see higher octaves of ctk551 E.Piano2) */ voice.m_pitch = (m_data[1] << 24) | (m_data[0] << 8) | (m_data[1] >> 8); } else if (voicecmd == 0x6006) { /* per-voice gain used for normalizing samples currently treated such that the lower 3 bits are fractional */ voice.m_gain = m_data[1] & 0xff; } else if (voicecmd == 0x6007) { // logerror("voice %u volume %u rate %u\n", voicenum, (m_data[0] >> 8), m_data[0] & 0xff); voice.m_volume_data = m_data[0]; voice.m_volume_target = (m_data[0] & 0x7f00) << 16; // referenced from the SW-10 softsynth u8 base = m_data[0] & 0xff; u8 shift = base >> 5; switch (shift) { case 0: shift = base >> 2; base &= 3; break; case 1: shift = 8; base &= 0x1f; break; default: shift += 6; base = (base & 0x1f) | 0x20; break; } /* this part is less certain - the overall rate needs adjusting based on the sample rate difference between this and the softsynth. it's probably not exact, but it sounds okay */ voice.m_volume_rate = (base * 3) << (shift + 5); } else if (voicecmd == 0x2028) // voice data read commands { /* data0 is used to determine if it's time to start the next part of the volume envelope or not */ m_data[0] = voice.m_volume_current >> 16; /* data1 is used to read consecutive output samples and detect zero crossings when applying volume or expression changes to a MIDI channel */ m_data[1] = voice.m_sample; } else if (voicecmd == 0x6020) { /* AP-10 sometimes issues this command, then clears the low byte of data0, and then issues command 0x6007 with the result (to pause an envelope?) */ m_data[0] = voice.m_volume_data; } else { logerror("unknown sound write %04x (data: %04x %04x %04x)\n", data, m_data[0], m_data[1], m_data[2]); } } u16 gt913_sound_device::status_r() { /* ctk551 reads the current gain level out of the lower 6 bits and ignores the rest it's unknown what, if anything, the other bits are supposed to contain */ return m_gain & 0x3f; }