diff options
Diffstat (limited to 'src/emu/sound/saa1099.c')
-rw-r--r-- | src/emu/sound/saa1099.c | 32 |
1 files changed, 19 insertions, 13 deletions
diff --git a/src/emu/sound/saa1099.c b/src/emu/sound/saa1099.c index fc08f5dc58b..a915fa6ed38 100644 --- a/src/emu/sound/saa1099.c +++ b/src/emu/sound/saa1099.c @@ -63,6 +63,13 @@ 0x1c | ---- ---x | All channels enable (0 = off, 1 = on) 0x1c | ---- --x- | Synch & Reset generators + Version History: + ================ + ??-??-200? - First version of the driver submitted for MESS (GPL/MESS license) + ??-??-200? - Submitted to DOSBOX for Creative Music System/Game Blaster emulation + ??-??-201? - Driver relicensed to BSD 3 Clause (GPL+ compatible) + 06-27-2015 - Applied clock divisor fix from DOSBOX SVN, http://www.vogons.org/viewtopic.php?p=344227#p344227 + ***************************************************************************/ #include "emu.h" @@ -159,6 +166,7 @@ saa1099_device::saa1099_device(const machine_config &mconfig, const char *tag, d void saa1099_device::device_start() { /* copy global parameters */ + m_master_clock = clock(); m_sample_rate = clock() / 256; /* for each chip allocate one stream */ @@ -204,7 +212,6 @@ void saa1099_device::device_start() void saa1099_device::sound_stream_update(sound_stream &stream, stream_sample_t **inputs, stream_sample_t **outputs, int samples) { int j, ch; - /* if the channels are disabled we're done */ if (!m_all_ch_enable) { @@ -218,10 +225,10 @@ void saa1099_device::sound_stream_update(sound_stream &stream, stream_sample_t * { switch (m_noise_params[ch]) { - case 0: m_noise[ch].freq = 31250.0 * 2; break; - case 1: m_noise[ch].freq = 15625.0 * 2; break; - case 2: m_noise[ch].freq = 7812.5 * 2; break; - case 3: m_noise[ch].freq = m_channels[ch * 3].freq; break; + case 0: m_noise[ch].freq = m_master_clock/256.0 * 2; break; + case 1: m_noise[ch].freq = m_master_clock/512.0 * 2; break; + case 2: m_noise[ch].freq = m_master_clock/1024.0 * 2; break; + case 3: m_noise[ch].freq = m_channels[ch * 3].freq; break; } } @@ -234,7 +241,7 @@ void saa1099_device::sound_stream_update(sound_stream &stream, stream_sample_t * for (ch = 0; ch < 6; ch++) { if (m_channels[ch].freq == 0.0) - m_channels[ch].freq = (double)((2 * 15625) << m_channels[ch].octave) / + m_channels[ch].freq = (double)((2 * m_master_clock / 512) << m_channels[ch].octave) / (511.0 - (double)m_channels[ch].frequency); /* check the actual position in the square wave */ @@ -242,7 +249,7 @@ void saa1099_device::sound_stream_update(sound_stream &stream, stream_sample_t * while (m_channels[ch].counter < 0) { /* calculate new frequency now after the half wave is updated */ - m_channels[ch].freq = (double)((2 * 15625) << m_channels[ch].octave) / + m_channels[ch].freq = (double)((2 * m_master_clock / 512) << m_channels[ch].octave) / (511.0 - (double)m_channels[ch].frequency); m_channels[ch].counter += m_sample_rate; @@ -255,22 +262,21 @@ void saa1099_device::sound_stream_update(sound_stream &stream, stream_sample_t * envelope_w(1); } - /* if the noise is enabled */ + // if the noise is enabled if (m_channels[ch].noise_enable) { - /* if the noise level is high (noise 0: chan 0-2, noise 1: chan 3-5) */ + // if the noise level is high (noise 0: chan 0-2, noise 1: chan 3-5) if (m_noise[ch/3].level & 1) { - /* subtract to avoid overflows, also use only half amplitude */ + // subtract to avoid overflows, also use only half amplitude output_l -= m_channels[ch].amplitude[ LEFT] * m_channels[ch].envelope[ LEFT] / 16 / 2; output_r -= m_channels[ch].amplitude[RIGHT] * m_channels[ch].envelope[RIGHT] / 16 / 2; } } - - /* if the square wave is enabled */ + // if the square wave is enabled if (m_channels[ch].freq_enable) { - /* if the channel level is high */ + // if the channel level is high if (m_channels[ch].level & 1) { output_l += m_channels[ch].amplitude[ LEFT] * m_channels[ch].envelope[ LEFT] / 16; |