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Diffstat (limited to '3rdparty/ymfm/src/ymfm_ssg.h')
-rw-r--r-- | 3rdparty/ymfm/src/ymfm_ssg.h | 206 |
1 files changed, 206 insertions, 0 deletions
diff --git a/3rdparty/ymfm/src/ymfm_ssg.h b/3rdparty/ymfm/src/ymfm_ssg.h new file mode 100644 index 00000000000..da689e42f7a --- /dev/null +++ b/3rdparty/ymfm/src/ymfm_ssg.h @@ -0,0 +1,206 @@ +// BSD 3-Clause License +// +// Copyright (c) 2021, Aaron Giles +// All rights reserved. +// +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions are met: +// +// 1. Redistributions of source code must retain the above copyright notice, this +// list of conditions and the following disclaimer. +// +// 2. Redistributions in binary form must reproduce the above copyright notice, +// this list of conditions and the following disclaimer in the documentation +// and/or other materials provided with the distribution. +// +// 3. Neither the name of the copyright holder nor the names of its +// contributors may be used to endorse or promote products derived from +// this software without specific prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" +// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE +// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE +// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR +// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER +// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, +// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +#ifndef YMFM_SSG_H +#define YMFM_SSG_H + +#pragma once + +#include "ymfm.h" + +namespace ymfm +{ + +//********************************************************* +// OVERRIDE INTERFACE +//********************************************************* + +// ======================> ssg_override + +// this class represents a built-in overridable SSG implementation; at this +// time it is not implemented, so you will have to add your own, or else live +// with no SSG audio +class ssg_override +{ +public: + // reset our status + virtual void ssg_reset() = 0; + + // read/write to the SSG registers + virtual uint8_t ssg_read(uint32_t regnum) = 0; + virtual void ssg_write(uint32_t regnum, uint8_t data) = 0; + + // notification when the prescale has changed + virtual void ssg_prescale_changed() = 0; +}; + + +//********************************************************* +// REGISTER CLASS +//********************************************************* + +// ======================> ssg_registers + +// +// SSG register map: +// +// System-wide registers: +// 06 ---xxxxx Noise period +// 07 x------- I/O B in(0) or out(1) +// -x------ I/O A in(0) or out(1) +// --x----- Noise enable(0) or disable(1) for channel C +// ---x---- Noise enable(0) or disable(1) for channel B +// ----x--- Noise enable(0) or disable(1) for channel A +// -----x-- Tone enable(0) or disable(1) for channel C +// ------x- Tone enable(0) or disable(1) for channel B +// -------x Tone enable(0) or disable(1) for channel A +// 0B xxxxxxxx Envelope period fine +// 0C xxxxxxxx Envelope period coarse +// 0D ----x--- Envelope shape: continue +// -----x-- Envelope shape: attack/decay +// ------x- Envelope shape: alternate +// -------x Envelope shape: hold +// 0E xxxxxxxx 8-bit parallel I/O port A +// 0F xxxxxxxx 8-bit parallel I/O port B +// +// Per-channel registers: +// 00,02,04 xxxxxxxx Tone period (fine) for channel A,B,C +// 01,03,05 ----xxxx Tone period (coarse) for channel A,B,C +// 08,09,0A ---x---- Mode: fixed(0) or variable(1) for channel A,B,C +// ----xxxx Amplitude for channel A,B,C +// +class ssg_registers +{ +public: + // constants + static constexpr uint32_t OUTPUTS = 3; + static constexpr uint32_t CHANNELS = 3; + static constexpr uint32_t REGISTERS = 0x10; + static constexpr uint32_t ALL_CHANNELS = (1 << CHANNELS) - 1; + + // constructor + ssg_registers() { } + + // reset to initial state + void reset(); + + // save/restore + void save_restore(ymfm_saved_state &state); + + // direct read/write access + uint8_t read(uint32_t index) { return m_regdata[index]; } + void write(uint32_t index, uint8_t data) { m_regdata[index] = data; } + + // system-wide registers + uint32_t noise_period() const { return bitfield(m_regdata[0x06], 0, 5); } + uint32_t io_b_out() const { return bitfield(m_regdata[0x07], 7); } + uint32_t io_a_out() const { return bitfield(m_regdata[0x07], 6); } + uint32_t envelope_period() const { return m_regdata[0x0b] | (m_regdata[0x0c] << 8); } + uint32_t envelope_continue() const { return bitfield(m_regdata[0x0d], 3); } + uint32_t envelope_attack() const { return bitfield(m_regdata[0x0d], 2); } + uint32_t envelope_alternate() const { return bitfield(m_regdata[0x0d], 1); } + uint32_t envelope_hold() const { return bitfield(m_regdata[0x0d], 0); } + uint32_t io_a_data() const { return m_regdata[0x0e]; } + uint32_t io_b_data() const { return m_regdata[0x0f]; } + + // per-channel registers + uint32_t ch_noise_enable(uint32_t choffs) const { return bitfield(~m_regdata[0x07], 3 + choffs); } + uint32_t ch_tone_enable(uint32_t choffs) const { return bitfield(~m_regdata[0x07], 0 + choffs); } + uint32_t ch_tone_period(uint32_t choffs) const { return m_regdata[0x00 + 2 * choffs] | (bitfield(m_regdata[0x01 + 2 * choffs], 0, 4) << 8); } + uint32_t ch_envelope_enable(uint32_t choffs) const { return bitfield(m_regdata[0x08 + choffs], 4); } + uint32_t ch_amplitude(uint32_t choffs) const { return bitfield(m_regdata[0x08 + choffs], 0, 4); } + +private: + // internal state + uint8_t m_regdata[REGISTERS]; // register data +}; + + +// ======================> ssg_engine + +class ssg_engine +{ +public: + static constexpr int OUTPUTS = ssg_registers::OUTPUTS; + static constexpr int CHANNELS = ssg_registers::CHANNELS; + static constexpr int CLOCK_DIVIDER = 8; + + using output_data = ymfm_output<OUTPUTS>; + + // constructor + ssg_engine(ymfm_interface &intf); + + // configure an override + void override(ssg_override &override) { m_override = &override; } + + // reset our status + void reset(); + + // save/restore + void save_restore(ymfm_saved_state &state); + + // master clocking function + void clock(); + + // compute sum of channel outputs + void output(output_data &output); + + // read/write to the SSG registers + uint8_t read(uint32_t regnum); + void write(uint32_t regnum, uint8_t data); + + // return a reference to our interface + ymfm_interface &intf() { return m_intf; } + + // return a reference to our registers + ssg_registers ®s() { return m_regs; } + + // true if we are overridden + bool overridden() const { return (m_override != nullptr); } + + // indicate the prescale has changed + void prescale_changed() { if (m_override != nullptr) m_override->ssg_prescale_changed(); } + +private: + // internal state + ymfm_interface &m_intf; // reference to the interface + uint32_t m_tone_count[3]; // current tone counter + uint32_t m_tone_state[3]; // current tone state + uint32_t m_envelope_count; // envelope counter + uint32_t m_envelope_state; // envelope state + uint32_t m_noise_count; // current noise counter + uint32_t m_noise_state; // current noise state + ssg_registers m_regs; // registers + ssg_override *m_override; // override interface +}; + +} + +#endif // YMFM_SSG_H |