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+// license:BSD-3-Clause
+// copyright-holders:Olivier Galibert
+/*
+ GI SP0250 digital LPC sound synthesizer
+
+ By O. Galibert.
+
+ Unknown:
+ - Exact clock divider
+ - Exact noise algorithm
+ - Exact noise pitch (probably ok)
+ - 7 bits output mapping
+ - Whether the pitch starts counting from 0 or 1
+
+ Unimplemented:
+ - Direct Data test mode (pin 7)
+
+ Sound quite reasonably already though.
+*/
+
+#include "emu.h"
+#include "sp0250.h"
+
+/*
+standard external clock is 3.12MHz
+the chip provides a 445.7kHz output clock, which is = 3.12MHz / 7
+therefore I expect the clock divider to be a multiple of 7
+Also there are 6 cascading filter stages so I expect the divider to be a multiple of 6.
+
+The SP0250 manual states that the original speech is sampled at 10kHz, so the divider
+should be 312, but 312 = 39*8 so it doesn't look right because a divider by 39 is unlikely.
+
+7*6*8 = 336 gives a 9.286kHz sample rate and matches the samples from the Sega boards.
+*/
+#define CLOCK_DIVIDER (7*6*8)
+
+const device_type SP0250 = &device_creator<sp0250_device>;
+
+sp0250_device::sp0250_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock)
+ : device_t(mconfig, SP0250, "SP0250", tag, owner, clock, "sp0250", __FILE__),
+ device_sound_interface(mconfig, *this),
+ m_amp(0),
+ m_pitch(0),
+ m_repeat(0),
+ m_pcount(0),
+ m_rcount(0),
+ m_playing(0),
+ m_RNG(0),
+ m_stream(NULL),
+ m_voiced(0),
+ m_fifo_pos(0),
+ m_drq(*this)
+{
+ for (int i = 0; i < 15; i++)
+ {
+ m_fifo[i] = 0;
+ }
+
+ for (int i = 0; i < 6; i++)
+ {
+ m_filter[i].F = 0;
+ m_filter[i].B = 0;
+ m_filter[i].z1 = 0;
+ m_filter[i].z2 = 0;
+ }
+}
+
+//-------------------------------------------------
+// device_start - device-specific startup
+//-------------------------------------------------
+
+void sp0250_device::device_start()
+{
+ m_RNG = 1;
+ m_drq.resolve_safe();
+ if (!m_drq.isnull())
+ {
+ m_drq( ASSERT_LINE);
+ machine().scheduler().timer_pulse(attotime::from_hz(clock()) * CLOCK_DIVIDER, timer_expired_delegate(FUNC(sp0250_device::timer_tick), this));
+ }
+
+ m_stream = machine().sound().stream_alloc(*this, 0, 1, clock() / CLOCK_DIVIDER);
+
+ save_item(NAME(m_amp));
+ save_item(NAME(m_pitch));
+ save_item(NAME(m_repeat));
+ save_item(NAME(m_pcount));
+ save_item(NAME(m_rcount));
+ save_item(NAME(m_playing));
+ save_item(NAME(m_RNG));
+ save_item(NAME(m_voiced));
+ save_item(NAME(m_fifo));
+ save_item(NAME(m_fifo_pos));
+}
+
+static UINT16 sp0250_ga(UINT8 v)
+{
+ return (v & 0x1f) << (v>>5);
+}
+
+static INT16 sp0250_gc(UINT8 v)
+{
+ // Internal ROM to the chip, cf. manual
+ static const UINT16 coefs[128] =
+ {
+ 0, 9, 17, 25, 33, 41, 49, 57, 65, 73, 81, 89, 97, 105, 113, 121,
+ 129, 137, 145, 153, 161, 169, 177, 185, 193, 201, 203, 217, 225, 233, 241, 249,
+ 257, 265, 273, 281, 289, 297, 301, 305, 309, 313, 317, 321, 325, 329, 333, 337,
+ 341, 345, 349, 353, 357, 361, 365, 369, 373, 377, 381, 385, 389, 393, 397, 401,
+ 405, 409, 413, 417, 421, 425, 427, 429, 431, 433, 435, 437, 439, 441, 443, 445,
+ 447, 449, 451, 453, 455, 457, 459, 461, 463, 465, 467, 469, 471, 473, 475, 477,
+ 479, 481, 482, 483, 484, 485, 486, 487, 488, 489, 490, 491, 492, 493, 494, 495,
+ 496, 497, 498, 499, 500, 501, 502, 503, 504, 505, 506, 507, 508, 509, 510, 511
+ };
+ INT16 res = coefs[v & 0x7f];
+
+ if (!(v & 0x80))
+ res = -res;
+ return res;
+}
+
+void sp0250_device::load_values()
+{
+ int f;
+
+
+ m_filter[0].B = sp0250_gc(m_fifo[ 0]);
+ m_filter[0].F = sp0250_gc(m_fifo[ 1]);
+ m_amp = sp0250_ga(m_fifo[ 2]);
+ m_filter[1].B = sp0250_gc(m_fifo[ 3]);
+ m_filter[1].F = sp0250_gc(m_fifo[ 4]);
+ m_pitch = m_fifo[ 5];
+ m_filter[2].B = sp0250_gc(m_fifo[ 6]);
+ m_filter[2].F = sp0250_gc(m_fifo[ 7]);
+ m_repeat = m_fifo[ 8] & 0x3f;
+ m_voiced = m_fifo[ 8] & 0x40;
+ m_filter[3].B = sp0250_gc(m_fifo[ 9]);
+ m_filter[3].F = sp0250_gc(m_fifo[10]);
+ m_filter[4].B = sp0250_gc(m_fifo[11]);
+ m_filter[4].F = sp0250_gc(m_fifo[12]);
+ m_filter[5].B = sp0250_gc(m_fifo[13]);
+ m_filter[5].F = sp0250_gc(m_fifo[14]);
+ m_fifo_pos = 0;
+ m_drq(ASSERT_LINE);
+
+ m_pcount = 0;
+ m_rcount = 0;
+
+ for (f = 0; f < 6; f++)
+ m_filter[f].z1 = m_filter[f].z2 = 0;
+
+ m_playing = 1;
+}
+
+TIMER_CALLBACK_MEMBER( sp0250_device::timer_tick )
+{
+ m_stream->update();
+}
+
+WRITE8_MEMBER( sp0250_device::write )
+{
+ m_stream->update();
+ if (m_fifo_pos != 15)
+ {
+ m_fifo[m_fifo_pos++] = data;
+ if (m_fifo_pos == 15)
+ m_drq(CLEAR_LINE);
+ }
+ else
+ logerror("%s: overflow SP0250 FIFO\n", machine().describe_context());
+}
+
+
+UINT8 sp0250_device::drq_r()
+{
+ m_stream->update();
+ return (m_fifo_pos == 15) ? CLEAR_LINE : ASSERT_LINE;
+}
+
+//-------------------------------------------------
+// sound_stream_update - handle a stream update
+//-------------------------------------------------
+
+void sp0250_device::sound_stream_update(sound_stream &stream, stream_sample_t **inputs, stream_sample_t **outputs, int samples)
+{
+ stream_sample_t *output = outputs[0];
+ int i;
+ for (i = 0; i < samples; i++)
+ {
+ if (m_playing)
+ {
+ INT16 z0;
+ int f;
+
+ if (m_voiced)
+ {
+ if(!m_pcount)
+ z0 = m_amp;
+ else
+ z0 = 0;
+ }
+ else
+ {
+ // Borrowing the ay noise generation LFSR
+ if(m_RNG & 1)
+ {
+ z0 = m_amp;
+ m_RNG ^= 0x24000;
+ }
+ else
+ z0 = -m_amp;
+
+ m_RNG >>= 1;
+ }
+
+ for (f = 0; f < 6; f++)
+ {
+ z0 += ((m_filter[f].z1 * m_filter[f].F) >> 8)
+ + ((m_filter[f].z2 * m_filter[f].B) >> 9);
+ m_filter[f].z2 = m_filter[f].z1;
+ m_filter[f].z1 = z0;
+ }
+
+ // Physical resolution is only 7 bits, but heh
+
+ // max amplitude is 0x0f80 so we have margin to push up the output
+ output[i] = z0 << 3;
+
+ m_pcount++;
+ if (m_pcount >= m_pitch)
+ {
+ m_pcount = 0;
+ m_rcount++;
+ if (m_rcount >= m_repeat)
+ m_playing = 0;
+ }
+ }
+ else
+ output[i] = 0;
+
+ if (!m_playing)
+ {
+ if(m_fifo_pos == 15)
+ load_values();
+ }
+ }
+}