Initial submission of the PCem-Experimental source code.

src/resid-fp/wave.cc

@@ -0,0 +1,151 @@
+//  ---------------------------------------------------------------------------
+//  This file is part of reSID, a MOS6581 SID emulator engine.
+//  Copyright (C) 2004  Dag Lem <resid@nimrod.no>
+//
+//  This program is free software; you can redistribute it and/or modify
+//  it under the terms of the GNU General Public License as published by
+//  the Free Software Foundation; either version 2 of the License, or
+//  (at your option) any later version.
+//
+//  This program is distributed in the hope that it will be useful,
+//  but WITHOUT ANY WARRANTY; without even the implied warranty of
+//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//  GNU General Public License for more details.
+//
+//  You should have received a copy of the GNU General Public License
+//  along with this program; if not, write to the Free Software
+//  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+//  ---------------------------------------------------------------------------
+
+#define __WAVE_CC__
+#include "wave.h"
+
+// ----------------------------------------------------------------------------
+// Constructor.
+// ----------------------------------------------------------------------------
+WaveformGeneratorFP::WaveformGeneratorFP()
+{
+  sync_source = this;
+
+  set_chip_model(MOS6581FP);
+
+  reset();
+}
+
+
+// ----------------------------------------------------------------------------
+// Set sync source.
+// ----------------------------------------------------------------------------
+void WaveformGeneratorFP::set_sync_source(WaveformGeneratorFP* source)
+{
+  sync_source = source;
+  source->sync_dest = this;
+}
+
+
+// ----------------------------------------------------------------------------
+// Set chip model.
+// ----------------------------------------------------------------------------
+void WaveformGeneratorFP::set_chip_model(chip_model model)
+{
+  if (model == MOS6581FP) {
+    wave__ST = wave6581__ST;
+    wave_P_T = wave6581_P_T;
+    wave_PS_ = wave6581_PS_;
+    wave_PST = wave6581_PST;
+  }
+  else {
+    wave__ST = wave8580__ST;
+    wave_P_T = wave8580_P_T;
+    wave_PS_ = wave8580_PS_;
+    wave_PST = wave8580_PST;
+  }
+}
+
+
+// ----------------------------------------------------------------------------
+// Register functions.
+// ----------------------------------------------------------------------------
+void WaveformGeneratorFP::writeFREQ_LO(reg8 freq_lo)
+{
+  freq = (freq & 0xff00) | (freq_lo & 0x00ff);
+}
+
+void WaveformGeneratorFP::writeFREQ_HI(reg8 freq_hi)
+{
+  freq = ((freq_hi << 8) & 0xff00) | (freq & 0x00ff);
+}
+
+/* The original form was (acc >> 12) >= pw, where truth value is not affected
+ * by the contents of the low 12 bits. Therefore the lowest bits must be zero
+ * in the new formulation acc >= (pw << 12). */
+void WaveformGeneratorFP::writePW_LO(reg8 pw_lo)
+{
+  pw = (pw & 0xf00) | (pw_lo & 0x0ff);
+  pw_acc_scale = pw << 12;
+}
+
+void WaveformGeneratorFP::writePW_HI(reg8 pw_hi)
+{
+  pw = ((pw_hi << 8) & 0xf00) | (pw & 0x0ff);
+  pw_acc_scale = pw << 12;
+}
+
+void WaveformGeneratorFP::writeCONTROL_REG(reg8 control)
+{
+  waveform = (control >> 4) & 0x0f;
+  ring_mod = control & 0x04;
+  sync = control & 0x02;
+
+  reg8 test_next = control & 0x08;
+
+  /* SounDemoN found out that test bit can be used to control the noise
+   * register. Hear the result in Bojojoing.sid. */
+
+  // testbit set. invert bit 19 and write it to bit 1
+  if (test_next && !test) {
+    accumulator = 0;
+    reg24 bit19 = (shift_register >> 19) & 1;
+    shift_register = (shift_register & 0x7ffffd) | ((bit19^1) << 1);
+    noise_overwrite_delay = 200000; /* 200 ms, probably too generous? */
+  }
+  // Test bit cleared.
+  // The accumulator starts counting, and the shift register is reset to
+  // the value 0x7ffff8.
+  else if (!test_next && test) {
+    reg24 bit0 = ((shift_register >> 22) ^ (shift_register >> 17)) & 0x1;
+    shift_register <<= 1;
+    shift_register |= bit0;
+  }
+  // clear output bits of shift register if noise and other waveforms
+  // are selected simultaneously
+  if (waveform > 8) {
+    shift_register &= 0x7fffff^(1<<22)^(1<<20)^(1<<16)^(1<<13)^(1<<11)^(1<<7)^(1<<4)^(1<<2);
+  }
+
+  test = test_next;
+  
+  /* update noise anyway, just in case the above paths triggered */
+  noise_output_cached = outputN___();
+}
+
+reg8 WaveformGeneratorFP::readOSC()
+{
+  return output() >> 4;
+}
+
+// ----------------------------------------------------------------------------
+// SID reset.
+// ----------------------------------------------------------------------------
+void WaveformGeneratorFP::reset()
+{
+  accumulator = 0;
+  previous = 0;
+  shift_register = 0x7ffffc;
+  freq = 0;
+  pw = 0;
+  pw_acc_scale = 0;
+  test = 0;
+  writeCONTROL_REG(0);
+  msb_rising = false;
+}