SuperNSF Timing Data
-------------------------------------

Cycles For Update (CFU): 40
Cycles For Mixing (CFM): 39,72,99,126 (1-4 PCM channels)

NES Cycle Execution Speed: 1789773 HZ

-------------------------------------

SuperNSF Main Program Flow

Init: <program entry>
 Initialize channels/data and jump to main loop

Main Loop:
 Mix pcm samples and output to DAC
 Run update routine *** (next section describes what is done here)
 Increment pcm channel data pointers (cycle errors occur here)
 Loop

Total execution time: "CFM+CFU+error" cycles

error:
  +12 cycles per channel crossing a memory page (256 bytes)
  +16 cycles per channel crossing a memory bank (4096 bytes)
  (12+16 total for a bank cross)

-------------------------------------

SuperNSF Update Flow ***

(each [] is an 'update cycle')
(each update cycle is done during one sample output)

Outside sequencer update:

[PCM Channel 1 Loop Test]
  [error:additional update if channel reaches loop point]
[PCM Channel 2 Loop Test] \
[PCM Channel 3 Loop Test]  > skipped if channel doesnt exist
[PCM Channel 4 Loop Test] /
[Sequencer Counter]
  <enter sequencer update if counter expires>

(Update cycles per sequencer counter iteration: "CHANNELS+1"+error)

(error: +1 update per channel that reaches its end/loop point)

---

Inside sequencer update:

[Read Event Header]
->(next update is determined by event header)

(2A03 SQUARE <0,1>)
[Sweep Reset Function]
[Period/Sweep Setting]
[Volume/Duty Setting]

(2A03 TRIANGLE <2>)
[Sweep Reset Function]
[Period/Sweep Setting]
  [Additional update only if writing complete period]
[Enable Setting]

(2A03 Noise <3>)
[Copy Settings]

(VRC6 Square/Sawtooth <4,5,6>)
[Sweep Reset Function]
[Period/Sweep Setting]
  [Additional update only if writing complete period]
[Volume/Duty Setting]

(PCM <7,8,9,10>)
[Preparation/Sample Setting]
[Sample Offset (1)]		\ 
[Sample Offset (2)]		 >skipped if no sample offset
[Sample Offset (3)]		/
[Sample Setting (1)] ---> skipped if no sample setting, or sample offset used
[Sample Setting (2)] ---> skipped if no sample setting, or sample offset used
[Volume Setting]
[Frequency/Sweep Setting]
  [Additional update only if writing complete frequency]

(Memory Page Cross <11>)
[Adjust Sequencer Position]

(End Frame/End Track <12,15>)
[Read next delta value]
(sequencer position is reset on command 15)

Sweeps are processed after the frame end
and then update execution returns to 'outside' mode

[Sweep Triangle Wave]
[Sweep VRC6 Pulse 1]
[Sweep VRC6 Pulse 2]
[Sweep VRC6 Sawtooth]
[PCM1 Frequency Sweep]
[PCM2 Frequency Sweep] \
[PCM3 Frequency Sweep]  > Skipped if channel isn't used in module
[PCM4 Frequency Sweep] /

Note: Sweep updates always occur, regardless if the sweep variable is 0
Another Note: The VRC6 sweep functions run regardless of vrc6 support.
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10:29 PM 8/5/2010