Y8950Adpcm.cc

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// The actual sample playing part is duplicated for the 'emu' domain and the
// 'audio' domain. The emu part is responsible for cycle accurate sample
// read back (see peekReg() register 0x13 and 0x14) and for cycle accurate
// status register updates (the status bits related to playback, e.g.
// end-of-sample). The audio part is responsible for the actual sound
// generation. This split up allows for the two parts to be out-of-sync. So for
// example when emulation is running faster or slower than 100% realtime speed,
// we both get cycle accurate emulation behaviour and still sound generation at
// 100% realtime speed (which is most of the time better for sound quality).
 
#include "Y8950Adpcm.hh"
#include "Y8950.hh"
#include "Clock.hh"
#include "DeviceConfig.hh"
#include "MSXMotherBoard.hh"
#include "Math.hh"
#include "narrow.hh"
#include "serialize.hh"
#include <algorithm>
#include <array>
 
namespace openmsx {
 
// Bitmask for register 0x07
static constexpr int R07_RESET       = 0x01;
static constexpr int R07_SP_OFF      = 0x08;
static constexpr int R07_REPEAT      = 0x10;
static constexpr int R07_MEMORY_DATA = 0x20;
static constexpr int R07_REC         = 0x40;
static constexpr int R07_START       = 0x80;
static constexpr int R07_MODE        = 0xE0;
 
// Bitmask for register 0x08
static constexpr int R08_ROM         = 0x01;
static constexpr int R08_64K         = 0x02;
static constexpr int R08_DA_AD       = 0x04;
static constexpr int R08_SAMPL       = 0x08;
static constexpr int R08_NOTE_SET    = 0x40;
static constexpr int R08_CSM         = 0x80;
 
static constexpr int DIFF_MAX     = 0x6000;
static constexpr int DIFF_MIN     = 0x7F;
static constexpr int DIFF_DEFAULT = 0x7F;
 
static constexpr int STEP_BITS = 16;
static constexpr int STEP_MASK = (1 << STEP_BITS) -1;
 
 
Y8950Adpcm::Y8950Adpcm(Y8950& y8950_, const DeviceConfig& config,
                       const std::string& name, unsigned sampleRam)
        : Schedulable(config.getScheduler())
        , y8950(y8950_)
        , ram(config, name + " RAM", "Y8950 sample RAM", sampleRam)
        , clock(config.getMotherBoard().getCurrentTime())
{
        clearRam();
}
 
void Y8950Adpcm::clearRam()
{
        ram.clear(0xFF);
}
 
void Y8950Adpcm::reset(EmuTime::param time)
{
        removeSyncPoint();
 
        clock.reset(time);
 
        startAddr = 0;
        stopAddr = 7;
        delta = 0;
        addrMask = (1 << 18) - 1;
        reg7 = 0;
        reg15 = 0;
        readDelay = 0;
        romBank = false;
        writeReg(0x12, 255, time); // volume
 
        restart(emu);
        restart(aud);
 
        y8950.setStatus(Y8950::STATUS_BUF_RDY);
}
 
bool Y8950Adpcm::isPlaying() const
{
        return (reg7 & 0xC0) == 0x80;
}
bool Y8950Adpcm::isMuted() const
{
        return !isPlaying() || (reg7 & R07_SP_OFF);
}
 
void Y8950Adpcm::restart(PlayData& pd)
{
        pd.memPtr = startAddr;
        pd.nowStep = (1 << STEP_BITS) - delta;
        pd.out = 0;
        pd.output = 0;
        pd.diff = DIFF_DEFAULT;
        pd.nextLeveling = 0;
        pd.sampleStep = 0;
        pd.adpcm_data = 0; // dummy, avoid UMR in serialize
}
 
void Y8950Adpcm::sync(EmuTime::param time)
{
        if (isPlaying()) { // optimization, also correct without this test
                unsigned ticks = clock.getTicksTill(time);
                for (unsigned i = 0; isPlaying() && (i < ticks); ++i) {
                        (void)calcSample(true); // ignore result
                }
        }
        clock.advance(time);
}
 
void Y8950Adpcm::schedule()
{
        assert(isPlaying());
        if ((stopAddr > startAddr) && (delta != 0)) {
                // TODO possible optimization, no need to set sync points if
                //      the corresponding bit is masked in the interrupt enable
                //      register
                if (reg7 & R07_MEMORY_DATA) {
                        // we already did a sync(time), so clock is up-to-date
                        Clock<Y8950::CLOCK_FREQ, Y8950::CLOCK_FREQ_DIV> stop(clock);
                        uint64_t samples = stopAddr - emu.memPtr + 1;
                        uint64_t length = (samples << STEP_BITS) +
                                        ((1 << STEP_BITS) - emu.nowStep) +
                                        (delta - 1);
                        stop += unsigned(length / delta);
                        setSyncPoint(stop.getTime());
                } else {
                        // TODO we should also set a sync-point in this case
                        //      because this mode sets the STATUS_BUF_RDY bit
                        //      which also triggers an IRQ
                }
        }
}
 
void Y8950Adpcm::executeUntil(EmuTime::param time)
{
        assert(isPlaying());
        sync(time); // should set STATUS_EOS
        assert(y8950.peekRawStatus() & Y8950::STATUS_EOS);
        if (isPlaying() && (reg7 & R07_REPEAT)) {
                schedule();
        }
}
 
void Y8950Adpcm::writeReg(byte rg, byte data, EmuTime::param time)
{
        sync(time); // TODO only when needed
        switch (rg) {
        case 0x07: // START/REC/MEM DATA/REPEAT/SP-OFF/-/-/RESET
                reg7 = data;
                if (reg7 & R07_START) {
                        y8950.setStatus(Y8950::STATUS_PCM_BSY);
                } else {
                        y8950.resetStatus(Y8950::STATUS_PCM_BSY);
                }
                if (reg7 & R07_RESET) {
                        reg7 = 0;
                }
                if (reg7 & R07_START) {
                        // start ADPCM
                        restart(emu);
                        restart(aud);
                }
                if (reg7 & R07_MEMORY_DATA) {
                        // access external memory?
                        emu.memPtr = startAddr;
                        aud.memPtr = startAddr;
                        readDelay = 2; // two dummy reads
                        if ((reg7 & 0xA0) == 0x20) {
                                // Memory read or write
                                y8950.setStatus(Y8950::STATUS_BUF_RDY);
                        }
                } else {
                        // access via CPU
                        emu.memPtr = 0;
                        aud.memPtr = 0;
                }
                removeSyncPoint();
                if (isPlaying()) {
                        schedule();
                }
                break;
 
        case 0x08: // CSM/KEY BOARD SPLIT/-/-/SAMPLE/DA AD/64K/ROM
                romBank = data & R08_ROM;
                addrMask = data & R08_64K ? (1 << 16) - 1 : (1 << 18) - 1;
                break;
 
        case 0x09: // START ADDRESS (L)
                startAddr = (startAddr & 0x7F807) | (data << 3);
                break;
        case 0x0A: // START ADDRESS (H)
                startAddr = (startAddr & 0x007FF) | (data << 11);
                break;
 
        case 0x0B: // STOP ADDRESS (L)
                stopAddr = (stopAddr & 0x7F807) | (data << 3);
                if (isPlaying()) {
                        removeSyncPoint();
                        schedule();
                }
                break;
        case 0x0C: // STOP ADDRESS (H)
                stopAddr = (stopAddr & 0x007FF) | (data << 11);
                if (isPlaying()) {
                        removeSyncPoint();
                        schedule();
                }
                break;
 
        case 0x0F: // ADPCM-DATA
                writeData(data);
                break;
 
        case 0x10: // DELTA-N (L)
                delta = (delta & 0xFF00) | data;
                volumeWStep = (volume * delta) >> STEP_BITS;
                if (isPlaying()) {
                        removeSyncPoint();
                        schedule();
                }
                break;
        case 0x11: // DELTA-N (H)
                delta = (delta & 0x00FF) | (data << 8);
                volumeWStep = (volume * delta) >> STEP_BITS;
                if (isPlaying()) {
                        removeSyncPoint();
                        schedule();
                }
                break;
 
        case 0x12: { // ENVELOP CONTROL
                volume = data;
                volumeWStep = (volume * delta) >> STEP_BITS;
                break;
        }
        case 0x0D: // PRESCALE (L)
        case 0x0E: // PRESCALE (H)
        case 0x15: // DAC-DATA  (bit9-2)
        case 0x16: //           (bit1-0)
        case 0x17: //           (exponent)
        case 0x1A: // PCM-DATA
                // not implemented
                break;
        }
}
 
void Y8950Adpcm::writeData(byte data)
{
        reg15 = data;
        if ((reg7 & R07_MODE) == 0x60) {
                // external memory write
                assert(!isPlaying()); // no need to update the 'aud' data
                if (readDelay) {
                        emu.memPtr = startAddr;
                        readDelay = 0;
                }
                if (emu.memPtr <= stopAddr) {
                        writeMemory(emu.memPtr, data);
                        emu.memPtr += 2; // two nibbles at a time
 
                        // reset BRDY bit in status register,
                        // which means we are processing the write
                        y8950.resetStatus(Y8950::STATUS_BUF_RDY);
 
                        // setup a timer that will callback us in 10
                        // master clock cycles for Y8950. In the
                        // callback set the BRDY flag to 1, which
                        // means we have written the data. For now, we
                        // don't really do this; we simply reset and
                        // set the flag in zero time, so that the IRQ
                        // will work.
                        y8950.setStatus(Y8950::STATUS_BUF_RDY);
 
                        if (emu.memPtr > stopAddr) {
                                // we just received the last byte: set EOS
                                // verified on real HW:
                                //  in case of EOS, BUF_RDY is set as well
                                y8950.setStatus(Y8950::STATUS_EOS);
                                // Eugeny tested that pointer wraps when
                                // continue writing after EOS
                                emu.memPtr = startAddr;
                        }
                }
 
        } else if ((reg7 & R07_MODE) == 0x80) {
                // ADPCM synthesis from CPU
 
                // Reset BRDY bit in status register, which means we
                // are full of data
                y8950.resetStatus(Y8950::STATUS_BUF_RDY);
        }
}
 
byte Y8950Adpcm::readReg(byte rg, EmuTime::param time)
{
        sync(time); // TODO only when needed
        byte result = (rg == 0x0F)
                    ? readData()   // ADPCM-DATA
                    : peekReg(rg); // other
        return result;
}
 
byte Y8950Adpcm::peekReg(byte rg, EmuTime::param time) const
{
        const_cast<Y8950Adpcm*>(this)->sync(time); // TODO only when needed
        return peekReg(rg);
}
 
byte Y8950Adpcm::peekReg(byte rg) const
{
        switch (rg) {
        case 0x0F: // ADPCM-DATA
                return peekData();
        case 0x13:
                // TODO check: is this before or after
                //   volume is applied
                //   filtering is performed
                return narrow_cast<byte>((emu.output >>  8) & 0xFF);
        case 0x14:
                return narrow_cast<byte>((emu.output >> 16) & 0xFF);
        default:
                return 255;
        }
}
 
void Y8950Adpcm::resetStatus()
{
        // If the BUF_RDY mask is cleared (e.g. by writing the value 0x80 to
        // register R#4). Reading the status register still has the BUF_RDY
        // bit set. Without this behavior demos like 'NOP Unknown reality'
        // hang when testing the amount of sample ram or when uploading data
        // to the sample ram.
        //
        // Before this code was added, those demos also worked but only
        // because we had a hack that always kept bit BUF_RDY set.
        //
        // When the ADPCM unit is not performing any function (e.g. after a
        // reset), the BUF_RDY bit should still be set. The AUDIO detection
        // routine in 'MSX-Audio BIOS v1.3' depends on this. See
        //   [3533002] Y8950 not being detected by MSX-Audio v1.3
        //   https://sourceforge.net/tracker/?func=detail&aid=3533002&group_id=38274&atid=421861
        // TODO I've implemented this as '(reg7 & R07_MODE) == 0', is this
        //      correct/complete?
        if (((reg7 & R07_MODE & ~R07_REC) == R07_MEMORY_DATA) ||
            ((reg7 & R07_MODE) == 0)){
                // transfer to or from sample ram, or no function
                y8950.setStatus(Y8950::STATUS_BUF_RDY);
        }
}
 
byte Y8950Adpcm::readData()
{
        if ((reg7 & R07_MODE) == R07_MEMORY_DATA) {
                // external memory read
                assert(!isPlaying()); // no need to update the 'aud' data
                if (readDelay) {
                        emu.memPtr = startAddr;
                }
        }
        byte result = peekData();
        if ((reg7 & R07_MODE) == R07_MEMORY_DATA) {
                assert(!isPlaying()); // no need to update the 'aud' data
                if (readDelay) {
                        // two dummy reads
                        --readDelay;
                        y8950.setStatus(Y8950::STATUS_BUF_RDY);
                } else if (emu.memPtr > stopAddr) {
                        // set EOS bit in status register
                        y8950.setStatus(Y8950::STATUS_EOS);
                } else {
                        emu.memPtr += 2; // two nibbles at a time
 
                        // reset BRDY bit in status register, which means we
                        // are reading the memory now
                        y8950.resetStatus(Y8950::STATUS_BUF_RDY);
 
                        // setup a timer that will callback us in 10 master
                        // clock cycles for Y8950. In the callback set the BRDY
                        // flag to 1, which means we have another data ready.
                        // For now, we don't really do this; we simply reset and
                        // set the flag in zero time, so that the IRQ will work.
 
                        // set BRDY bit in status register
                        y8950.setStatus(Y8950::STATUS_BUF_RDY);
                }
        }
        return result;
}
 
byte Y8950Adpcm::peekData() const
{
        if ((reg7 & R07_MODE) == R07_MEMORY_DATA) {
                // external memory read
                assert(!isPlaying()); // no need to update the 'aud' data
                if (readDelay) {
                        return reg15;
                } else if (emu.memPtr > stopAddr) {
                        return 0;
                } else {
                        return readMemory(emu.memPtr);
                }
        } else {
                return 0; // TODO check
        }
}
 
void Y8950Adpcm::writeMemory(unsigned memPtr, byte value)
{
        unsigned addr = (memPtr / 2) & addrMask;
        if ((addr < ram.size()) && !romBank) {
                ram.write(addr, value);
        }
}
byte Y8950Adpcm::readMemory(unsigned memPtr) const
{
        unsigned addr = (memPtr / 2) & addrMask;
        if (romBank || (addr >= ram.size())) {
                return 0; // checked on a real machine
        } else {
                return ram[addr];
        }
}
 
int Y8950Adpcm::calcSample()
{
        // called by audio thread
        if (!isPlaying()) return 0;
        int output = calcSample(false);
        return (reg7 & R07_SP_OFF) ? 0 : output;
}
 
int Y8950Adpcm::calcSample(bool doEmu)
{
        // values taken from ymdelta.c by Tatsuyuki Satoh.
        static constexpr std::array<int, 16> F1 = {
                 1,   3,   5,   7,   9,  11,  13,  15,
                -1,  -3,  -5,  -7,  -9, -11, -13, -15
        };
        static constexpr std::array<int, 16> F2 = {
                57,  57,  57,  57,  77, 102, 128, 153,
                57,  57,  57,  57,  77, 102, 128, 153
        };
 
        assert(isPlaying());
 
        PlayData& pd = doEmu ? emu : aud;
        pd.nowStep += delta;
        if (pd.nowStep & ~STEP_MASK) {
                pd.nowStep &= STEP_MASK;
                byte val = [&] {
                        if (!(pd.memPtr & 1)) {
                                // even nibble
                                if (reg7 & R07_MEMORY_DATA) {
                                        pd.adpcm_data = readMemory(pd.memPtr);
                                } else {
                                        pd.adpcm_data = reg15;
                                        // set BRDY bit, ready to accept new data
                                        if (doEmu) {
                                                y8950.setStatus(Y8950::STATUS_BUF_RDY);
                                        }
                                }
                                return byte(pd.adpcm_data >> 4);
                        } else {
                                // odd nibble
                                return byte(pd.adpcm_data & 0x0F);
                        }
                }();
                int prevOut = pd.out;
                pd.out = Math::clipToInt16(pd.out + (pd.diff * F1[val]) / 8);
                pd.diff = std::clamp((pd.diff * F2[val]) / 64, DIFF_MIN, DIFF_MAX);
 
                int prevLeveling = pd.nextLeveling;
                pd.nextLeveling = (prevOut + pd.out) / 2;
                int deltaLeveling = pd.nextLeveling - prevLeveling;
                pd.sampleStep = deltaLeveling * volumeWStep;
                int tmp = deltaLeveling * ((volume * narrow<int>(pd.nowStep)) >> STEP_BITS);
                pd.output = prevLeveling * volume + tmp;
 
                ++pd.memPtr;
                if ((reg7 & R07_MEMORY_DATA) &&
                    (pd.memPtr > stopAddr)) {
                        // On 2003/06/21 I commited a patch with comment:
                        //   generate end-of-sample interrupt at every sample
                        //   end, including loops
                        // Unfortunately it doesn't give any reason why and now
                        // I can't remember it :-(
                        // This is different from e.g. the MAME implementation.
                        if (doEmu) {
                                y8950.setStatus(Y8950::STATUS_EOS);
                        }
                        if (reg7 & R07_REPEAT) {
                                restart(pd);
                        } else {
                                if (doEmu) {
                                        removeSyncPoint();
                                        reg7 = 0;
                                }
                        }
                }
        } else {
                pd.output += pd.sampleStep;
        }
        return pd.output >> 12;
}
 
 
// version 1:
//  Initial version
// version 2:
//  - Split PlayData in emu and audio part (though this doesn't add new state
//    to the savestate).
//  - Added clock object.
template<typename Archive>
void Y8950Adpcm::serialize(Archive& ar, unsigned version)
{
        ar.template serializeBase<Schedulable>(*this);
        ar.serialize("ram",          ram,
                     "startAddr",    startAddr,
                     "stopAddr",     stopAddr,
                     "addrMask",     addrMask,
                     "volume",       volume,
                     "volumeWStep",  volumeWStep,
                     "readDelay",    readDelay,
                     "delta",        delta,
                     "reg7",         reg7,
                     "reg15",        reg15,
                     "romBank",      romBank,
 
                     "memPntr",      emu.memPtr, // keep 'memPntr' for bw compat
                     "nowStep",      emu.nowStep,
                     "out",          emu.out,
                     "output",       emu.output,
                     "diff",         emu.diff,
                     "nextLeveling", emu.nextLeveling,
                     "sampleStep",   emu.sampleStep,
                     "adpcm_data",   emu.adpcm_data);
        if constexpr (Archive::IS_LOADER) {
                // ignore aud part for saving,
                // for loading we make it the same as the emu part
                aud = emu;
        }
 
        if (ar.versionBelow(version, 2)) {
                clock.reset(getCurrentTime());
 
                // reschedule, because automatically deserialized sync-point
                // can be off, because clock.getTime() != getCurrentTime()
                removeSyncPoint();
                if (isPlaying()) {
                        schedule();
                }
        } else {
                ar.serialize("clock", clock);
        }
}
INSTANTIATE_SERIALIZE_METHODS(Y8950Adpcm);
 
} // namespace openmsx