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TMS5220: Force OLDP and OLDE to be updated only on the A

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subcycle of IP=0 PC=0; this has no effect whatsoever on the
output, it is merely to better document how the chip works.
[Lord Nightmare]
TMS5220: Emulate circuit 412 from the patent, which should
prevent spurious clicks on interpolation-inhibited frame
transitions; This may improve the tie fighter sounds in
starwars, and some clicking in eprom/eproma. [Lord Nightmare]
This commit is contained in:
Jonathan Gevaryahu 2011-06-12 18:39:47 +00:00
parent 7dcf617e34
commit 525c0431e2
1 changed files with 21 additions and 11 deletions
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32
src/emu/sound/tms5220.c
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@ -900,10 +900,10 @@ static void tms5220_process(tms5220_state *tms, INT16 *buffer, unsigned int size
while ((size > 0) && tms->speaking_now)
{
/* if it is the appropriate time to update the old energy/pitch idxes,
* i.e. when IP=7, PC=12, T=17, do so. Since IP=7 PC=12 T=17 is JUST
* BEFORE the transition to IP=0 PC=0 T=0 (4 T-cycles later), we change
* on the latter.*/
if ((tms->interp_period == 0) && (tms->PC == 0))
* i.e. when IP=7, PC=12, T=17, subcycle=2, do so. Since IP=7 PC=12 T=17
* is JUST BEFORE the transition to IP=0 PC=0 T=0 sybcycle=(0 or 1),
* which happens 4 T-cycles later), we change on the latter.*/
if ((tms->interp_period == 0) && (tms->PC == 0) && (tms->subcycle < 2))
{
tms->OLDE = (tms->new_frame_energy_idx == 0);
tms->OLDP = (tms->new_frame_pitch_idx == 0);
@ -998,7 +998,7 @@ static void tms5220_process(tms5220_state *tms, INT16 *buffer, unsigned int size
}
else // Not a new frame, just interpolate the existing frame.
{
if (tms->interp_period == 0) tms->inhibit = 0; // disable inhibit when reaching the last interp period
int inhibit_state = ((tms->inhibit==1)&&(tms->interp_period != 0)); // disable inhibit when reaching the last interp period, but don't overwrite the tms->inhibit value
#ifdef PERFECT_INTERPOLATION_HACK
int samples_per_frame = tms->subc_reload?175:266; // either (13 A cycles + 12 B cycles) * 7 interps for normal SPEAK/SPKEXT, or (13*2 A cycles + 12 B cycles) * 7 interps for SPKSLOW
//int samples_per_frame = tms->subc_reload?200:304; // either (13 A cycles + 12 B cycles) * 8 interps for normal SPEAK/SPKEXT, or (13*2 A cycles + 12 B cycles) * 8 interps for SPKSLOW
@ -1016,10 +1016,10 @@ static void tms5220_process(tms5220_state *tms, INT16 *buffer, unsigned int size
// now adjust each value to be exactly correct for each of the samples per frame
if (tms->interp_period != 0) // if we're still interpolating...
{
tms->current_energy += (((tms->target_energy - tms->current_energy)*(1-tms->inhibit))*current_sample)/samples_per_frame;
tms->current_pitch += (((tms->target_pitch - tms->current_pitch)*(1-tms->inhibit))*current_sample)/samples_per_frame;
tms->current_energy += (((tms->target_energy - tms->current_energy)*(1-inhibit_state))*current_sample)/samples_per_frame;
tms->current_pitch += (((tms->target_pitch - tms->current_pitch)*(1-inhibit_state))*current_sample)/samples_per_frame;
for (i = 0; i < tms->coeff->num_k; i++)
tms->current_k[i] += (((tms->target_k[i] - tms->current_k[i])*(1-tms->inhibit))*current_sample)/samples_per_frame;
tms->current_k[i] += (((tms->target_k[i] - tms->current_k[i])*(1-inhibit_state))*current_sample)/samples_per_frame;
}
else // we're done, play this frame for 1/8 frame.
{
@ -1035,14 +1035,14 @@ static void tms5220_process(tms5220_state *tms, INT16 *buffer, unsigned int size
switch(tms->PC)
{
case 0: /* PC = 0, B cycle, write updated energy */
tms->current_energy += (((tms->target_energy - tms->current_energy)*(1-tms->inhibit)) INTERP_SHIFT);
tms->current_energy += (((tms->target_energy - tms->current_energy)*(1-inhibit_state)) INTERP_SHIFT);
break;
case 1: /* PC = 1, B cycle, write updated pitch */
tms->current_pitch += (((tms->target_pitch - tms->current_pitch)*(1-tms->inhibit)) INTERP_SHIFT);
tms->current_pitch += (((tms->target_pitch - tms->current_pitch)*(1-inhibit_state)) INTERP_SHIFT);
break;
case 2: case 3: case 4: case 5: case 6: case 7: case 8: case 9: case 10: case 11:
/* PC = 2 thru 11, B cycle, write updated K1 thru K10 */
tms->current_k[tms->PC-2] += (((tms->target_k[tms->PC-2] - tms->current_k[tms->PC-2])*(1-tms->inhibit)) INTERP_SHIFT);
tms->current_k[tms->PC-2] += (((tms->target_k[tms->PC-2] - tms->current_k[tms->PC-2])*(1-inhibit_state)) INTERP_SHIFT);
break;
case 12: /* PC = 12, do nothing */
break;
@ -1172,8 +1172,18 @@ static void tms5220_process(tms5220_state *tms, INT16 *buffer, unsigned int size
tms->subcycle = tms->subc_reload;
tms->PC++;
}
/* Circuit 412 in the patent ensures that when INHIBIT is true,
* during the period from IP=7 PC=12 T12, to IP=0 PC=12 T12, the pitch
* count is forced to 0; since the initial stop happens right before
* the switch to IP=0 PC=0 and this code is located after the switch would
* happen, we check for ip=0 inhibit=1, which covers that whole range.
* The purpose of Circuit 412 is to prevent a spurious click caused by
* the voiced source being fed to the filter before all the values have
* been updated during ip=0 when interpolation was inhibited.
*/
tms->pitch_count++;
if (tms->pitch_count >= tms->current_pitch) tms->pitch_count = 0;
if ((tms->interp_period == 0)&&(tms->inhibit==1)) tms->pitch_count = 0;
tms->pitch_count &= 0x1FF;
buf_count++;
size--;