Audio Device - Revision history

Costel Mincea: Text replacement - "" to ""

2025-01-26T19:37:57Z

Text replacement - "<syntaxhighlight>" to "<syntaxhighlight lang="C" line>"

← Older revision		Revision as of 19:37, 26 January 2025
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	Audio device commands use an extended I/O request block named IOAudio to send commands to the audio device. This is the standard IORequest block with some extra fields added at the end.		Audio device commands use an extended I/O request block named IOAudio to send commands to the audio device. This is the standard IORequest block with some extra fields added at the end.

	<syntaxhighlight>		<syntaxhighlight lang="C" line>
	struct IOAudio		struct IOAudio
	{		{

Steven Solie: /* Device Interface */

2012-05-22T20:55:28Z

Device Interface

← Older revision		Revision as of 20:55, 22 May 2012
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	== Device Interface ==		== Device Interface ==

	The audio device operates like the other Amiga I/O devices. To make sound, you first open the audio device, then send I/O requests to it, and then close it when finished. See ~~the~~ [[~~Introduction~~ to ~~Amiga System Devices~~]] ~~chapter~~ for general information on device usage.		The audio device operates like the other Amiga I/O devices. To make sound, you first open the audio device, then send I/O requests to it, and then close it when finished. See [[Exec_Device_I/O\|Exec Device I/O]] for general information on device usage.

	Audio device commands use an extended I/O request block named IOAudio to send commands to the audio device. This is the standard IORequest block with some extra fields added at the end.		Audio device commands use an extended I/O request block named IOAudio to send commands to the audio device. This is the standard IORequest block with some extra fields added at the end.

Steven Solie: /* Device Interface */

2012-05-11T20:35:16Z

Device Interface

← Older revision		Revision as of 20:35, 11 May 2012
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	Audio device commands use an extended I/O request block named IOAudio to send commands to the audio device. This is the standard IORequest block with some extra fields added at the end.		Audio device commands use an extended I/O request block named IOAudio to send commands to the audio device. This is the standard IORequest block with some extra fields added at the end.

			<syntaxhighlight>

		⚫	struct IOAudio

⚫	~~<pre>~~struct IOAudio
	{		{
	struct IORequest ioa_Request; /* I/O request block. See exec/io.h. */		struct IORequest ioa_Request; /* I/O request block. See exec/io.h. */
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	UWORD ioa_Cycles; /* # of times to play sample. 0=forever. */		UWORD ioa_Cycles; /* # of times to play sample. 0=forever. */
	struct Message ioa_WriteMsg; /* Filled in by device - usually not used */		struct Message ioa_WriteMsg; /* Filled in by device - usually not used */
	};~~</pre>~~		};
			</syntaxhighlight>

	See the include file devices/audio.h for the complete structure definition.		See the include file devices/audio.h for the complete structure definition.

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	* Open the audio device. Call OpenDevice(), passing IOAudio.		* Open the audio device. Call OpenDevice(), passing IOAudio.

			<pre>
	~~<pre>~~struct MsgPort AudioMP; / Define storage for port pointer */		struct MsgPort AudioMP; / Define storage for port pointer */
	struct IOAudio AudioIO; / Define storage for IORequest pointer */		struct IOAudio AudioIO; / Define storage for IORequest pointer */

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	if (OpenDevice(AUDIONAME,0L,(struct IORequest *)AudioIO,0L) )		if (OpenDevice(AUDIONAME,0L,(struct IORequest *)AudioIO,0L) )
	printf("%s did not open\n",AUDIONAME);~~</pre>~~		printf("%s did not open\n",AUDIONAME);
			</pre>

	A special feature of the OpenDevice() function with the audio device allows you to automatically allocate channels for your program to use when the device is opened. This is convenient since you ''must'' allocate one or more channels before you can produce sound.		A special feature of the OpenDevice() function with the audio device allows you to automatically allocate channels for your program to use when the device is opened. This is convenient since you ''must'' allocate one or more channels before you can produce sound.

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	If you want to allocate channels at some later time, set the value of the ioa_Request.ioa_Length field of the IOAudio block to zero when you call OpenDevice(). For more on channel allocation and the ADCMD_ALLOCATE command, see the section on “Allocation and Arbitration” below.		If you want to allocate channels at some later time, set the value of the ioa_Request.ioa_Length field of the IOAudio block to zero when you call OpenDevice(). For more on channel allocation and the ADCMD_ALLOCATE command, see the section on “Allocation and Arbitration” below.

			<pre>
	~~<pre>~~UBYTE chans[] = {1,2,4,8}; /* get any of the four channels */		UBYTE chans[] = {1,2,4,8}; /* get any of the four channels */

	if (AudioIO)		if (AudioIO)
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	if (OpenDevice(AUDIONAME,0L,(struct IORequest *)AudioIO,0L) )		if (OpenDevice(AUDIONAME,0L,(struct IORequest *)AudioIO,0L) )
	printf(~~"~~%s did not open\n~~"~~,AUDIONAME);~~</pre>~~		printf("%s did not open\n", AUDIONAME);
			</pre>

	=== Audio Device Command Types ===		=== Audio Device Command Types ===

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	\|ADCMD_LOCK\|\|Tells if a channel has been stolen from you.		\|ADCMD_LOCK\|\|Tells if a channel has been stolen from you.
	\|}		\|}


	The hardware control commands are used to set up, start, and stop sounds on the audio device:		The hardware control commands are used to set up, start, and stop sounds on the audio device:

Alexandre Balaban: Categorizing

2012-05-10T21:40:56Z

Categorizing

← Older revision		Revision as of 21:40, 10 May 2012
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	{{CodeReview}}		[[Category:Devices\|Audio]]{{CodeReview}}
	== Audio Device ==		== Audio Device ==

Steven Solie: /* Audio Device Commands and Functions */

2012-04-14T02:46:51Z

Audio Device Commands and Functions

@@ Line 70: / Line 70: @@
 |-
 |'''CMD_WRITE'''||Start a write cycle on a single channel.
 |}

Alexandre Balaban: Changed from WIP to CodeReview

2012-04-12T14:14:29Z

Changed from WIP to CodeReview

← Older revision		Revision as of 14:14, 12 April 2012
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	{{~~WIP~~}}		{{CodeReview}}
	== Audio Device ==		== Audio Device ==

Alexandre Balaban: /* Additional Information on the Audio Device */ Layout fixed

2012-04-12T13:50:42Z

Additional Information on the Audio Device: Layout fixed

← Older revision		Revision as of 13:50, 12 April 2012
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	== Additional Information on the Audio Device ==		== Additional Information on the Audio Device ==

	Additional programming information on the audio device can be found in the include files and the Autodocs for the audio device. Both are contained in the ~~''Amiga ROM Kernel Reference Manual~~: ~~Includes and~~ Autodocs''. Information can also be found in the ''Amiga Hardware Reference Manual''.		Additional programming information on the audio device can be found in the include files and the Autodocs for the audio device. Both are contained in the [[Autodocs:Main\|Autodocs]]. Information can also be found in the ''Amiga Hardware Reference Manual''.

			{\| class="wikitable"
	\|ll\|
		⚫	!colspan="2"\|Audio Device Information

			\|-
⚫	~~2c'''~~Audio Device Information~~'''<br />~~
	Includes ~~&~~ devices/audio.h<br />		\|Includes\|\|devices/audio.h<br />devices/audio.i
			\|-
	& devices/audio.i<br />
			\|[[Autodocs:Main\|Autodocs]]\|\|[[audio.doc]]
	AutoDocs & audio.doc<br />
			\|}

Alexandre Balaban: /* CMD_READ */ Layout fixed

2012-04-12T13:47:08Z

CMD_READ: Layout fixed

← Older revision		Revision as of 13:47, 12 April 2012
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	=== CMD_READ ===		=== CMD_READ ===

	is a single-channel command. Its only function is to return a pointer to the current CMD_WRITE command. It enables you to determine which request is being processed.		CMD_READ is a single-channel command. Its only function is to return a pointer to the current CMD_WRITE command. It enables you to determine which request is being processed.

	== Double Buffered Sound Example ==		== Double Buffered Sound Example ==

Alexandre Balaban: /* CMD_START */ Layout fixed

2012-04-12T13:46:40Z

CMD_START: Layout fixed

← Older revision		Revision as of 13:46, 12 April 2012
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	=== CMD_START ===		=== CMD_START ===

	undoes the CMD_STOP command. Any cycles that were stopped by the CMD_STOP command are actually lost because of the impossibility of determining exactly where the DMA ceased. If the CMD_WRITE command was playing two cycles and the first one was playing when CMD_STOP was issued, the first one is lost and the second one will be played.		CMD_START undoes the CMD_STOP command. Any cycles that were stopped by the CMD_STOP command are actually lost because of the impossibility of determining exactly where the DMA ceased. If the CMD_WRITE command was playing two cycles and the first one was playing when CMD_STOP was issued, the first one is lost and the second one will be played.

	This command is also useful when you are playing the same wave form with the same period out of multiple channels. If the channels are stopped when the CMD_WRITE commands are issued, CMD_START exactly synchronizes them, avoiding cancellation and distortion. When channels are allocated, they are effectively started by the CMD_START command.		This command is also useful when you are playing the same wave form with the same period out of multiple channels. If the channels are stopped when the CMD_WRITE commands are issued, CMD_START exactly synchronizes them, avoiding cancellation and distortion. When channels are allocated, they are effectively started by the CMD_START command.

Alexandre Balaban: /* CMD_RESET */ Layout fixed

2012-04-12T13:45:57Z

CMD_RESET: Layout fixed

← Older revision		Revision as of 13:45, 12 April 2012
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	=== CMD_RESET ===		=== CMD_RESET ===

	restores all the audio hardware registers. It clears the attach bits, restores the audio interrupt vectors if the programmer has changed them, and performs the CMD_FLUSH command to cancel all requests to the channels. CMD_RESET also unstops channels that have had a CMD_STOP performed on them. CMD_RESET does not unlock channels that have been locked by ADCMD_LOCK.		CMD_RESET restores all the audio hardware registers. It clears the attach bits, restores the audio interrupt vectors if the programmer has changed them, and performs the CMD_FLUSH command to cancel all requests to the channels. CMD_RESET also unstops channels that have had a CMD_STOP performed on them. CMD_RESET does not unlock channels that have been locked by ADCMD_LOCK.

	=== ADCMD_WAITCYCLE ===		=== ADCMD_WAITCYCLE ===