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S-DSP/Sample Generation Loop
From SnesLab
(Redirected from Sampling Generation Loop)
The S-DSP's Sample Generation Loop takes 32 cycles to complete.
Note: most of this information was extracted from anomie's APU DSP doc with jwdonal.
| Cycle Number | Action | Voice 0 | Voice 1 | Voice 2 | Voice 3 | Voice 4 | Voice 5 | Voice 6 | Voice 7 |
|---|---|---|---|---|---|---|---|---|---|
| 0 | Tick the SPC700 Stage 1 timers, always for T2 and every 4 samples for T0 and T1. | V0:S5 | V1:S2 | ||||||
| 1 | V0:S6 | V1:S3 | |||||||
| 2 | V0:S7 | V1:S4 | V3:S1 | ||||||
| 3 | V0:S8 | V1:S5 | V2:S2 | ||||||
| 4 | V0:S9 | V1:S6 | V2:S3 | ||||||
| 5 | V1:S7 | V2:S4 | V4:S1 | ||||||
| 6 | V1:S8 | V2:S5 | V3:S2 | ||||||
| 7 | V1:S9 | V2:S6 | V3:S3 | ||||||
| 8 | V2:S7 | V3:S4 | V5:S1 | ||||||
| 9 | V2:S8 | V3:S5 | V4:S2 | ||||||
| 10 | V2:S9 | V3:S6 | V4:S3 | ||||||
| 11 | V3:S7 | V4:S4 | V6:S1 | ||||||
| 12 | V3:S8 | V4:S5 | V5:S2 | ||||||
| 13 | V3:S9 | V4:S6 | V5:S3 | ||||||
| 14 | V4:S7 | V5:S4 | V7:S1 | ||||||
| 15 | V4:S8 | V5:S5 | V6:S2 | ||||||
| 16 | Tick the SPC700 Stage 1 timer for T2. | V4:S9 | V5:S6 | V6:S3 | |||||
| 17 | V0:S1 | V5:S7 | V6:S4 | ||||||
| 18 | V5:S8 | V6:S5 | V7:S2 | ||||||
| 19 | V5:S9 | V6:S6 | V7:S3 | ||||||
| 20 | V1:S1 | V6:S7 | V7:S4 | ||||||
| 21 | V0:S2 | V6:S8 | V7:S5 | ||||||
| 22 | Apply ESA using the previously loaded value along with the previously calculated echo offset to calculate new echo pointer. Load left channel sample from the Echo Buffer. Load FFC0. | V0:S3a | V6:S9 | V7:S6 | |||||
| 23 | Load right channel sample from the echo buffer. Load FFC1 and FFC2. | V7:S7 | |||||||
| 24 | Load FFC3, FFC4, and FFC5. | V7:S8 | |||||||
| 25 | Load FFC6 and FFC7. | V0:S3b | V7:S9 | ||||||
| 26 | Load and apply MVOLL. Load and apply EVOLL. Output the left sample to the DAC. Load and apply EFB. | ||||||||
| 27 | Load and apply MVOLR. Load and apply EVOLR. Output the right sample to the DAC. Load PMON | ||||||||
| 28 | Load NON, EON, and DIR. Load FLG bit 5 (ECENx) for application to the left channel. | ||||||||
| 29 | Update Global Counter. Write left channel sample to the echo buffer, if allowed by ECENx. Load EDL - if the current echo offset is 0, apply EDL. Load ESA for future use. Load FLG bit 5 (ECENx) again for application to the right channel. Clear internal KON bits for any channels keyed on in the previous 2 samples. | ||||||||
| 30 | Write right channel sample to the echo buffer, if allowed by ECENx. Increment the echo offset, and set to 0 if it exceeds the buffer length. Load FLG bits 0-4 and update noise sample if necessary. Load KOFF and internal KON. | V0:S3c | |||||||
| 31 | V0:S4 | V2:S1 |