[Scummvm-cvs-logs] SF.net SVN: scummvm: [21245] scummvm/trunk/engines/kyra/sound_adlib.cpp
eriktorbjorn at users.sourceforge.net
eriktorbjorn at users.sourceforge.net
Sun Mar 12 14:34:03 CET 2006
Revision: 21245
Author: eriktorbjorn
Date: 2006-03-12 14:33:24 -0800 (Sun, 12 Mar 2006)
ViewCVS: http://svn.sourceforge.net/scummvm/?rev=21245&view=rev
Log Message:
-----------
Cleaned up comment and did some more renaming:
unk4 -> position (measured on a very short ruler :-)
unk5 -> duration
Modified Paths:
--------------
scummvm/trunk/engines/kyra/sound_adlib.cpp
Modified: scummvm/trunk/engines/kyra/sound_adlib.cpp
===================================================================
--- scummvm/trunk/engines/kyra/sound_adlib.cpp 2006-03-12 21:54:06 UTC (rev 21244)
+++ scummvm/trunk/engines/kyra/sound_adlib.cpp 2006-03-12 22:33:24 UTC (rev 21245)
@@ -108,9 +108,8 @@
//
// unk3 - Unknown. Used for turning off some notes.
// unk4 - Unknown. Related to sound timing?
- // unk5 - Unknown. Used for turning off some notes.
// unk7 - Unknown. Used for turning off some notes.
- // unk11 - Unknown. Used for updating unk5.
+ // unk11 - Unknown. Used for updating random durations.
// unk12 - Unknown. Used for updating unk7.
// unk16 - Sound-related. Possibly some sort of pitch bend.
// unk18 - Sound-effect. Used for secondaryEffect1()
@@ -135,7 +134,7 @@
struct OutputState {
uint8 opExtraLevel2;
uint8 *dataptr;
- uint8 unk5;
+ uint8 duration;
uint8 repeatCounter;
int8 baseOctave;
uint8 priority;
@@ -157,7 +156,7 @@
uint8 unk7;
uint8 baseFreq;
int8 tempo;
- int8 unk4;
+ int8 position;
uint8 regAx;
uint8 regBx;
typedef void (AdlibDriver::*Callback)(OutputState&);
@@ -617,8 +616,8 @@
table.priority = priority;
table.dataptr = ptr;
table.tempo = -1;
- table.unk4 = -1;
- table.unk5 = 1;
+ table.position = -1;
+ table.duration = 1;
if (index != 9) {
unkOutput2(index);
}
@@ -631,23 +630,24 @@
// A few words on opcode parsing and timing:
//
-// We have a timer callback that is called every 13888 us.
+// First of all, We simulate a timer callback 72 times per second. Each timeout
+// we update each channel that has something to play.
//
-// Each channel appears to have its own individual tempo, unk1, which is added
-// to unk4. If this causes unk4 to wrap around to negative, something happens.
+// Each channel has its own individual tempo, which is added to its position.
+// This will frequently cause the position to "wrap around" but that is
+// intentional. In fact, it's the signal to go ahead and do more stuff with
+// that channel.
//
-// When "something happens", unk5 is decreased. If unk5 is still non-zero,
-// nothing much happens. Notes may be turned off depending on unk3 and unk7,
-// but other than that no new commands are issued.
+// Each channel also has a duration, indicating how much time is left on the
+// its current task. This duration is decreased by one. As long as it still has
+// not reached zero, the only thing that can happen is that depending on unk3
+// and unk7 the current note may be stopped. Once the duration reaches zero, a
+// new set of musical opcodes are executed.
//
-// If unk5 reaches zero, a new set of music opcodes are executed. In effect,
-// unk5 is the duration of the channel's most recent opcode. Either a note or
-// a pause, presumably.
-//
// An opcode is one byte, followed by a variable number of parameters. Since
// most opcodes have at least one one-byte parameter, we read that as well. Any
-// opcode that doesn't have that one parameter is responsible for backing the
-// data pointer.
+// opcode that doesn't have that one parameter is responsible for moving the
+// data pointer back again.
//
// If the most significant bit of the opcode is 1, it's a function; call it. If
// it returns something greater than zero, it's the last opcode in the current
@@ -663,26 +663,6 @@
// Finally, most of the times that the callback is called, it will invoke the
// effects callbacks. The final opcode in a set can prevent this, if it's a
// function and it returns anything other than 1.
-//
-// To summarize:
-//
-// unk1 is the channel tempo, assisted by unk4
-// unk5 is the duration of the last opcode (probably a note) of a set
-// unk3 and unk7 can turn off notes prematurely; to implement staccatto?
-//
-// Some possible sources of tempo bugs:
-//
-// The timer has a 10 ms resolution. Over time it will be pretty accurate, but
-// individual calls may be a bit off. The only notes that are this short are
-// the ones played by the effects callbacks, so it shouldn't matter much.
-//
-// Adding unk1 to a negative unk4 does not necessarily take it out of the
-// negative range, so it may trigger twice in a row. Again, this shouldn't
-// matter much.
-//
-// The unk5 variable (duration) may be incorrectly set.
-//
-// An opcode function may be returning the wrong value.
void AdlibDriver::callbackProcess() {
for (_curTable = 9; _curTable >= 0; --_curTable) {
@@ -697,13 +677,13 @@
table.tempo = _tempo;
}
- int8 backup = table.unk4;
- table.unk4 += table.tempo;
- if (table.unk4 < backup) {
- if (--table.unk5) {
- if (table.unk5 == table.unk7)
+ int8 backup = table.position;
+ table.position += table.tempo;
+ if (table.position < backup) {
+ if (--table.duration) {
+ if (table.duration == table.unk7)
noteOff(table);
- if (table.unk5 == table.unk3 && _curTable != 9)
+ if (table.duration == table.unk3 && _curTable != 9)
noteOff(table);
} else {
int8 opcode = 0;
@@ -852,13 +832,13 @@
debugC(9, kDebugLevelSound, "setupDuration(%d, %d)", duration, &state - _outputTables);
_continueFlag = duration;
if (state.unk11) {
- state.unk5 = duration + (getRandomNr() & state.unk11);
+ state.duration = duration + (getRandomNr() & state.unk11);
return;
}
if (state.unk12) {
state.unk7 = (duration >> 3) * state.unk12;
}
- state.unk5 = duration;
+ state.duration = duration;
}
// This function may or may not play the note. It's usually followed by a call
@@ -1228,8 +1208,8 @@
state2.priority = priority;
state2.dataptr = ptr;
state2.tempo = -1;
- state2.unk4 = -1;
- state2.unk5 = 1;
+ state2.position = -1;
+ state2.duration = 1;
unkOutput2(table);
}
return 0;
@@ -1309,7 +1289,7 @@
int AdlibDriver::updateCallback15(uint8 *&dataptr, OutputState &state, uint8 value) {
OutputState &state2 = _outputTables[value];
- state2.unk5 = 0;
+ state2.duration = 0;
state2.priority = 0;
state2.dataptr = 0;
return 0;
@@ -1391,7 +1371,7 @@
}
dataptr -= 2;
- state.unk5 = 1;
+ state.duration = 1;
return 2;
}
@@ -1495,7 +1475,7 @@
_curTable = value;
OutputState &state2 = _outputTables[value];
- state2.unk5 = state2.priority = 0;
+ state2.duration = state2.priority = 0;
state2.dataptr = 0;
state2.opExtraLevel2 = 0;
This was sent by the SourceForge.net collaborative development platform, the world's largest Open Source development site.
More information about the Scummvm-git-logs
mailing list