diff options
Diffstat (limited to 'doc/api-asm.68k')
| -rw-r--r-- | doc/api-asm.68k | 30 |
1 files changed, 27 insertions, 3 deletions
diff --git a/doc/api-asm.68k b/doc/api-asm.68k index 8c0995c..3293b9e 100644 --- a/doc/api-asm.68k +++ b/doc/api-asm.68k @@ -20,6 +20,7 @@ Unless stated otherwise, calling the API subroutines will *not* modify the *** Initialization *** Echo_Init + in a0 = pointer to instrument list Initializes Echo. Loads the instrument list, loads the Z80 engine and gets it running. You need to call this before you can use Echo (usually when @@ -42,20 +43,29 @@ Echo_Init *** Background music *** Echo_PlayBGM + in a0 = pointer to ESF data to play Starts playback of the specified background music. The register a0 points to the ESF data for the background music. Echo_StopBGM - Stops playback of background music. Used both to stop and to pause music - (the latter can be undone with Echo_ResumeBGM, see below). + Stops playback of background music. Used both to stop and to pause music. + +Echo_PauseBGM + + Pauses BGM playback (SFXs should be unaffected). + +Echo_ResumeBGM + + Resumes BGM playback after it has been paused with Echo_PauseBGM. ============================================================================= *** Sound effects *** Echo_PlaySFX + in a0 = pointer to ESF data to play Starts playback of the specified sound effect. The register a0 points to the ESF data for the sound effect. @@ -69,6 +79,7 @@ Echo_StopSFX *** Direct events *** Echo_PlayDirect + in a0 = pointer to ESF data to inject Injects events to be played as part of the BGM the next tick. The register a0 points to the ESF data to be injected. @@ -91,6 +102,7 @@ Echo_PlayDirect *** Control *** Echo_GetStatus + out d0 = status (see below) Gets the current status of Echo. The status is returned as a word in d0, with the following bits set as relevant: @@ -105,6 +117,7 @@ Echo_GetStatus the 68000 until Echo is ready to take more commands. Echo_SetVolume + in d0 = new volume ($00 = quietest, $FF = loudest) Sets the global volume. Register d0 is a byte value ranging from 0 (quietest) to 255 (loudest), and every channel is affected immediately. @@ -114,20 +127,26 @@ Echo_SetVolume on the volume value (the cut off point is at 25%). Echo_SetVolumeEx + in a0 = pointer to volume data (see below) Sets the global volume for each channel separately. Register a0 points to - a list of 13 bytes (one for each Echo channel). Values for FM and PSG + 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. The last byte (the one belonging to the PCM channel) is used to toggle whether PCM plays, either 0 (disabled) or 1 (enabled). + + NOTE: the Echo 1.4 docs requested for 13 bytes instead of 16. This has + been changed for the sake of expansion. Currently the extra bytes are + ignored, but consider adapting your code (just set them to zero). ============================================================================= *** Settings *** Echo_SetPCMRate + in d0 = new PCM rate (see below) Changes the sample rate of PCM. Note this is a global parameter as it affects both BGM and SFX. The value is what one would write in timer A of @@ -153,17 +172,22 @@ Echo_SetPCMRate *** Raw access *** Echo_SendCommand + in d0 = command Sends an argument-less command to Echo. The command ID is given as a byte in register d0. Echo_SendCommandAddr + in d0 = command + in a0 = address Sends a command to Echo that takes an address as its argument. The command ID is given as a byte in register d0, while the address argument is given in register a0. Echo_SendCommandByte + in d0 = command + in d1 = argument Sends a command to Echo that takes a byte as its argument. The command ID is given as a byte in register d0, while the byte argument is given in |