Nicolas Cellier uploaded a new version of System to project The Trunk:
http://source.squeak.org/trunk/System-nice.237.mcz==================== Summary ====================
Name: System-nice.237
Author: nice
Time: 18 January 2010, 6:17:16.267 pm
UUID: b246b97c-09b7-3c4c-b47d-58b312a3dbd8
Ancestors: System-nice.236
More ByteArray literals
=============== Diff against System-nice.236 ===============
Item was changed:
----- Method: MidiPrimTester>>playDrumRoll:count:onPort: (in category 'tests') -----
playDrumRoll: mSecsBetweenNotes count: tapCount onPort: portNum
"MidiPrimTester new playDrumRoll: 75 count: 64 onPort: 0"
"Play middle-C tapCount times with the given space between notes. This example works best with a short percussive voice, like a drum."
"Details: This test can be used to investigate the real-time performance of your system. On a 110 MHz PowerPC Mac, this method can genererate very fast and smooth drum rolls up to about 100 beats/sec (10 mSecs between notes). However, many factors can prevent one from seeing this level of performance including a slow CPU, lack of a level-2 cache, networking or other background processes stealing chunks of processor time from Squeak, or a sluggish MIDI synthesizer."
"Details: By default, this method does an incremental GC on every note. While not really needed for this example, it illustrates a useful technique for real-time processing in Squeak: do an incremental GC when you know you have a few milliseconds of idle time to avoid triggering one during a time-critical task. In this case, we're also using the GC time to provide a small delay between the note-on and note-off events. If the GC time is too short, as it could be on a fast machine, the note may not sound at all unless you add a few milliseconds of additional delay!!"
"Note: This example works best if the VM's millisecond clock has 1 millisecond resolution."
| gcDuringNote noteOn noteOff endTime waitTime |
gcDuringNote := true.
"these events use running status, so the command byte is omitted"
+ noteOn := #[ 60 100 ].
+ noteOff := #[ 60 0 ].
- noteOn := #(60 100) as: ByteArray.
- noteOff := #(60 0) as: ByteArray.
self primMIDIOpenPort: portNum readSemaIndex: 0 interfaceClockRate: 1000000.
"send an initial event with command byte to initiate running status"
self primMIDIWritePort: portNum from: #[144 60 0] at: 0.
1 to: tapCount do: [:i |
endTime := Time millisecondClockValue + mSecsBetweenNotes.
self primMIDIWritePort: portNum from: noteOn at: 0.
gcDuringNote
ifTrue: [
"do quick GC; takes a few milliseconds and provides the note-down time"
"Note: if GC is too fast on your machine, you need to add a few mSecs delay!!"
Smalltalk garbageCollectMost]
ifFalse: [(Delay forMilliseconds: 3) wait].
self primMIDIWritePort: portNum from: noteOff at: 0.
waitTime := endTime - Time millisecondClockValue.
waitTime > 0 ifTrue: [(Delay forMilliseconds: waitTime) wait]].
self primMIDIClosePort: portNum.
!
Locked
