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Fix interpolation on TMS52xx to match samples from real chip. [PlgDavid, Lord Nightmare]

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This commit is contained in:
Lord-Nightmare 2015-08-19 05:02:57 -04:00
parent ae407f7002
commit a8c10f43dc
1 changed files with 7 additions and 3 deletions
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10
src/emu/sound/tms5220.c
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@ -755,6 +755,7 @@ void tms5220_device::process(INT16 *buffer, unsigned int size)
* which happens 4 T-cycles later), we change on the latter.
* The indices are updated here ~12 PCs before the new frame is applied.
*/
/** TODO: the patents 4331836, 4335277, and 4419540 disagree about the timing of this **/
if ((m_IP == 0) && (m_PC == 0) && (m_subcycle < 2))
{
m_OLDE = (m_new_frame_energy_idx == 0);
@ -790,6 +791,7 @@ void tms5220_device::process(INT16 *buffer, unsigned int size)
#endif
if (m_speaking_now == 1) // we're done, set all coeffs to idle state but keep going for a bit...
{
/**TODO: should index clearing be done here, or elsewhere? **/
m_new_frame_energy_idx = 0;
m_new_frame_pitch_idx = 0;
for (i = 0; i < 4; i++)
@ -828,11 +830,13 @@ void tms5220_device::process(INT16 *buffer, unsigned int size)
Interpolation inhibit cases:
* Old frame was voiced, new is unvoiced
* Old frame was silence/zero energy, new has nonzero energy
* Old frame was unvoiced, new is voiced (note this is the case on the patent but may not be correct on the real final chip)
* Old frame was unvoiced, new is voiced
* Old frame was unvoiced, new frame is silence/zero energy (unique to tms52xx)
*/
if ( ((OLD_FRAME_UNVOICED_FLAG == 0) && (NEW_FRAME_UNVOICED_FLAG == 1))
|| ((OLD_FRAME_UNVOICED_FLAG == 1) && (NEW_FRAME_UNVOICED_FLAG == 0)) /* this line needs further investigation, starwars tie fighters may sound better without it */
|| ((OLD_FRAME_SILENCE_FLAG == 1) && (NEW_FRAME_SILENCE_FLAG == 0)) )
|| ((OLD_FRAME_UNVOICED_FLAG == 1) && (NEW_FRAME_UNVOICED_FLAG == 0))
|| ((OLD_FRAME_SILENCE_FLAG == 1) && (NEW_FRAME_SILENCE_FLAG == 0))
|| ((OLD_FRAME_UNVOICED_FLAG == 1) && (NEW_FRAME_SILENCE_FLAG == 1)) )
m_inhibit = 1;
else // normal frame, normal interpolation
m_inhibit = 0;