Mercurial > repos > blastem
comparison ym_common.c @ 2565:eb588f22ec76
More work on OPL3 emulation
| author | Michael Pavone <pavone@retrodev.com> |
|---|---|
| date | Sun, 26 Jan 2025 23:32:40 -0800 |
| parents | 3f58fec775df |
| children |
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| 2564:553a0b4888db | 2565:eb588f22ec76 |
|---|---|
| 189 } | 189 } |
| 190 break; | 190 break; |
| 191 } | 191 } |
| 192 return output; | 192 return output; |
| 193 } | 193 } |
| 194 | |
| 195 void start_envelope(ym_operator *op, ym_channel *channel) | |
| 196 { | |
| 197 //Deal with "infinite" attack rates | |
| 198 uint8_t rate = op->rates[PHASE_ATTACK]; | |
| 199 if (rate) { | |
| 200 uint8_t ks = channel->keycode >> op->key_scaling;; | |
| 201 rate = rate*2 + ks; | |
| 202 } | |
| 203 if (rate >= 62) { | |
| 204 op->env_phase = PHASE_DECAY; | |
| 205 op->envelope = 0; | |
| 206 } else { | |
| 207 op->env_phase = PHASE_ATTACK; | |
| 208 } | |
| 209 } | |
| 210 | |
| 211 void keyon(ym_operator *op, ym_channel *channel) | |
| 212 { | |
| 213 start_envelope(op, channel); | |
| 214 op->phase_counter = 0; | |
| 215 op->inverted = op->ssg & SSG_INVERT; | |
| 216 } | |
| 217 | |
| 218 void keyoff(ym_operator *op) | |
| 219 { | |
| 220 op->env_phase = PHASE_RELEASE; | |
| 221 if (op->inverted) { | |
| 222 //Nemesis says the inversion state doesn't change here, but I don't see how that is observable either way | |
| 223 op->inverted = 0; | |
| 224 op->envelope = (SSG_CENTER - op->envelope) & MAX_ENVELOPE; | |
| 225 } | |
| 226 } |