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Diffstat (limited to 'doc/api-asm.68k')
| -rw-r--r-- | doc/api-asm.68k | 24 |
1 files changed, 23 insertions, 1 deletions
diff --git a/doc/api-asm.68k b/doc/api-asm.68k index 3293b9e..8cbbdba 100644 --- a/doc/api-asm.68k +++ b/doc/api-asm.68k @@ -132,7 +132,9 @@ Echo_SetVolumeEx Sets the global volume for each channel separately. Register a0 points to a list of 16 bytes (one for each Echo channel). Values for FM and PSG channels are given in the same way as in events, that is: logarithmic - scale, 0..127 for FM, 0..15 for PSG, lower = louder. + scale, 0..127 for FM, 0..15 for PSG, lower = louder. You can use the + look-up tables described below (Echo_FMVolTable and Echo_PSGVolTable) to + convert from linear to . The last byte (the one belonging to the PCM channel) is used to toggle whether PCM plays, either 0 (disabled) or 1 (enabled). @@ -141,6 +143,17 @@ Echo_SetVolumeEx been changed for the sake of expansion. Currently the extra bytes are ignored, but consider adapting your code (just set them to zero). +Echo_FMVolTable +Echo_PSGVolTable + These two are not subroutines but rather look-up tables. They have 64 + byte-sized entries and they're used to convert a linear volume value into + a hardware volume value (e.g. for Echo_SetVolumeEx). + + To give an idea of how to use these: take what you'd pass in d0 to + Echo_SetVolume divided by 4 (shift right by 2), then use it as an offset + to these tables. The byte will be the volume as the hardware (or + Echo_SetVolumeEx) wants it. + ============================================================================= *** Settings *** @@ -167,6 +180,15 @@ Echo_SetPCMRate (which can hamper Echo's ability to process complex streams). Be careful if you increase the sample rate. +Echo_SetStereo + in d0 = $00 to use mono, otherwise to use stereo + + Toggles whether sound is forced to mono (d0 == $00) or if stereo panning + works (d0 != $00). Will take effect for all following panning events. Can + be used to implement a mono/stereo toggle in games. + + By default Echo is in stereo mode. + ============================================================================= *** Raw access *** |