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CSND Shared Memory: Difference between revisions

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| 0x2
| 0x2
| 2
| 2
| CmdID 0x4
| CmdID 0x5
|-
|-
| 0xC
| 0xC
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| 0x2
| 0x2
| 2
| 2
| CmdID 0x4
| CmdID 0x6
|-
|-
| 0xC
| 0xC
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| 0x2
| 0x2
| 2
| 2
| CmdID 0x4
| CmdID 0x7
|-
|-
| 0xC
| 0xC
| 1
| 1
| Value
| Duty value (3 bits), see below
|-
|-
| 0x10
| 0x10
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|}
|}


This is similar to cmd2, except this updates channel CNT bit1-bit0.
This command updates bit0 through (at least) bit2 of the channel's CNT register. These bits control the duty of a PSG square wave:
 
  0  12.5% "_______-_______-_______-"
  1  25.0% "______--______--______--"
  2  37.5% "_____---_____---_____---"
  3  50.0% "____----____----____----"
  4  62.5% "___-----___-----___-----"
  5  75.0% "__------__------__------"
  6  87.5% "_-------_-------_-------"
  7  0.0% "________________________"


==Command 0x8==
==Command 0x8==
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| 0xC
| 0xC
| 2
| 2
| Left volume
| Left channel volume
|-
|-
| 0xE
| 0xE
| 2
| 2
| Right volume
| Right channel volume
|-
|-
| 0x10
| 0x10
| 0x10
| 2
| Usually zero?
| Left capture volume
|-
| 0x12
| 2
| Right capture volume
|}
|}


This sets the playback volumes for the specified channel. This command must be used after command 0x8(user processes use cmd8 a second time before using this command). The parameter values seem to have no affect when not using IMA-ADPCM encoding?
This sets the playback and capture volumes for the specified channel. This command is usually used after command 0x8(user processes use cmd8 a second time before using this command).


==Command 0xA==
==Command 0xA==
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|}
|}


This command is used for initializing IMA-ADPCM state(when IMA-ADPCM encoding is used), prior to using command 0xE. [[CSND]] <nowiki>channelslotregister+0x18 = (u16)cmdword[3] | ((cmdword[4] & 0xFF)<<16)</nowiki>. [[CSND]] channelslotregister+0x1C = 0.
This command is used for setting the IMA-ADPCM state used to play the first block (when IMA-ADPCM encoding is used), prior to using command 0xE. [[CSND]] <nowiki>channelslotregister+0x18 = (u16)cmdword[3] | ((cmdword[4] & 0xFF)<<16)</nowiki>. [[CSND]] channelslotregister+0x1C = 0.


==Command 0xC==
==Command 0xC==
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| 0x2
| 0x2
| 2
| 2
| CmdID 0xB
| CmdID 0xC
|-
|-
| 0xC
| 0xC
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|}
|}


This is used for initializing looping state for IMA-ADPCM encoding. <nowiki>channelslotregister+0x18 = (1<<31) | (u16)cmdword[3] | ((cmdword[4] & 0xFF)<<16)</nowiki>.
This is used for setting the IMA-ADPCM state used to play the second block (when IMA-ADPCM encoding is used). <nowiki>channelslotregister+0x1C = (1<<31) | (u16)cmdword[3] | ((cmdword[4] & 0xFF)<<16)</nowiki>.


==Command 0xD==
==Command 0xD==
Unknown.
{| class="wikitable" border="1"
|-
!  Index Byte
!  Size
!  Description
|-
| 0x2
| 2
| CmdID 0xD
|-
| 0xC
| 1
| 0 = disable ADPCM state reload for the second block, 1 = enable.
|}
 
This command configures bit31 of <nowiki>channelslotregister+0x1C</nowiki>. This bit indicates whether the hardware will load ADPCM state from said register everytime the second block is to be played; or if it will continue using the same state used for the previously emitted sample.


==Command 0xE==
==Command 0xE==
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| 0x8
| 0x8
| 4
| 4
| See below.
| See below. (Flags + Timer)
|-
|-
| 0xC
| 0xC
| 4
| 4
| See below. Usually zero?
| See below. (Channel volume)
|-
|-
| 0x10
| 0x10
| 4
| 4
| See below. Usually zero?
| See below. (Capture volume)
|-
|-
| 0x14
| 0x14
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|}
|}


This initializes the [[CSND]] channel registers located at: 0x1EC03400 + (channel_index*0x20). It is unknown if stereo samples are supported. When looping is disabled, the hardware plays the first block and then stops. When looping is enabled, the hardware plays the first block once and then repeats the second forever. Before playing a block, the hardware reads the corresponding address register in order to know where it is located. The block size is either read only once at the beginning or before each block (this is controlled by bit11 of word 0x8).
This initializes the [[CSND]] channel registers located at: 0x1EC03400 + (channel_index*0x20). It is unknown if stereo samples are supported. In manual mode, the hardware plays the audio data of the first block endlessly ignoring the size field. In one-shot mode, the hardware plays the first block with the specified size and then stops. When looping is enabled, the hardware plays the first block once and then repeats the second forever. Before playing a block, the hardware reads the corresponding address register in order to know where it is located. The block size is either read only once at the beginning (mode 3) or before each block (mode 1, normal looping).


===Parameter word 0x8===
===Parameter word 0x8===
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|-
|-
| 9-7
| 9-7
| ?
| Ignored
|-
| 10
| 0 = disable looping (one-shot sample), 1 = enable looping.
|-
|-
| 11
| 11-10
| 0 = read the block size only once, 1 = read the block size before each block.
| Repeat mode: 0 = manual, 1 = normal looping, 2 = one-shot, 3 = looping with constant block size.
|-
|-
| 13-12
| 13-12
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|-
|-
| 15
| 15
| ?
| Ignored
|-
|-
| 31-16
| 31-16
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|}
|}


PSG: Channels 8 through 13 play a square tone that is 16 samples long. Channels 14 and 15 play noise. It is currently unknown how to set the duty of the square tones.
Bits 0 through 5 are written as zero to the CNT register.
 
PSG: Channels 8 through 13 play a square tone that is 32 samples long. Channels 14 and 15 play noise. The duty of the square tones is set using command 0x7.


===Parameter word 0xC===
===Parameter word 0xC===
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|-
|-
| 15-0
| 15-0
| Unknown, this value is clamped to the following range(by the user process): 0x0-0x8000.
| Left channel volume, this value is clamped to the following range(by the user process): 0x0-0x8000.
|-
|-
| 31-16
| 31-16
| Unknown, this value is clamped to the following range(by the user process): 0x0-0x8000.
| Right channel volume, this value is clamped to the following range(by the user process): 0x0-0x8000.
|}
|}


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|-
|-
| 15-0
| 15-0
| Unknown, this value is clamped to the following range(by the user process): 0x0-0x8000.
| Left capture volume, this value is clamped to the following range(by the user process): 0x0-0x8000.
|-
|-
| 31-16
| 31-16
| Unknown, this value is clamped to the following range(by the user process): 0x0-0x8000.
| Right capture volume, this value is clamped to the following range(by the user process): 0x0-0x8000.
|}
|}


==Command 0xF==
==Command 0xF==
Unknown.
{| class="wikitable" border="1"
|-
!  Index Byte
!  Size
!  Description
|-
| 0x2
| 2
| CmdID 0xF
|-
| 0x8
| 4
| Flags, as in command 0xE. Only the timer and the start/stop (bit14) bits are used.
|-
| 0xC
| 4
| Channel volume, same as in command 0xE.
|-
| 0x10
| 4
| Capture volume, same as in command 0xE.
|-
| 0x14
| 4
| Duty (see command 0x7).
|}
 
This channel is similar to command 0xE, but it is tailored for configuring PSG Tone channels (8, 9, 10, 11, 12, 13) as it contains a duty parameter. Channel format is set to PSG.
 
==Command 0x10==
{| class="wikitable" border="1"
|-
!  Index Byte
!  Size
!  Description
|-
| 0x2
| 2
| CmdID 0xF
|-
| 0x8
| 4
| Flags, as in command 0xE. Only the timer and the start/stop (bit14) bits are used. Channel format is set to PSG.
|-
| 0xC
| 4
| Channel volume, same as in command 0xE.
|-
| 0x10
| 4
| Capture volume, same as in command 0xE.
|}
 
This channel is identical to command 0xF except for not having a duty parameter. Presumably used to configure PSG Noise channels (14, 15).


==Command 0x100==
==Command 0x100==
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==Command 0x104==
==Command 0x104==
Sets (u16*)(0x1EC03800+16*X+4) = Y.
Sets (u16*)(0x1EC03800+16*X+4) = -Y.


==Command 0x105==
==Command 0x105==
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