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81 lines
3.1 KiB
Plaintext
81 lines
3.1 KiB
Plaintext
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;...........
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; init_pcm :
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; ===========================================================================
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; Arguments: (none)
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; Returns: (none)
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; Affects: A
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; ---------------------------------------------------------------------------
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; Call this before using any of the other routines.
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;
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; Initializes the memory locations used by PCMM player to a stopped playback
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; state, sets VERA playback rate to 0 (disabled) and clears the PCM FIFO
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; also sets the volume to 15 (F).
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;...........
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; play_pcm :
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; ===========================================================================
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; Arguments: (none)
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; Returns: (none)
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; Affects: A,X,Y
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; ---------------------------------------------------------------------------
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; Call this once per frame to ensure that the PCM samples are being fed
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; into VERA's PCM FIFO. While this routine is technically IRQ-safe, it is
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; recommended that it not be executed during the VSYNC IRQ, as higher
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; quality sample streams can consume up to ~30k CPU cycles to process.
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;
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; Consistent, jitter-free low-latency playback can be assured using a line IRQ
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;
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; If using ZSM player module, it is recommended that this call happen after
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; the ZSM player's update function (playmusic) so that any PCM events will
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; be processed on the same frame.
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;...........
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; stop_pcm :
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; ===========================================================================
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; Arguments: (none)
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; Returns: (none)
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; Affects: A
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; ---------------------------------------------------------------------------
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; Disables PCM playback in VERA_audio_rate register, clears the FIFO, and
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; sets the PCM player module's status to clear.
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;.............
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; start_digi :
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; ===========================================================================
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; Arguments: Pointer to digi parameter table in memory.
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; .A = RAM bank
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; .XY = Memory address
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; Returns: none
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; Affects: none
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; ---------------------------------------------------------------------------
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; Documentation and terminology in Zsound uses the term "digi" to refer to
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; a digital audio clip, as the term "sample" also refers to an individual
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; PCM sample. Thus "digi" disambiguates between the two.
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;
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; start_digi expects a pointer to a digi parameter table in memory (low or
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; high memory are both acceptable locations. If in Hi memory, the table
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; must exist entirely within the same bank.
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;
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; The table's contents are the same as the DIGITAB struct at the
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; beginning of this inc file.
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;
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; note that start_digi is a one-shot call to trigger a digi. There is
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; currently no infrastructure to make callbacks at the end of a digi's
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; playback, or any granular controls to modify a playback in progress
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; such as volume changes, etc.
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;
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; In the future, more granular controls are planned, but the exact
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; nature and functionality are as yet to be determined.
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;.................
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; set_pcm_volume :
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; ===========================================================================
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; Arguments: Pointer to digi parameter table in memory.
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; .A = new volume level (only the 4 LSB are used)
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;
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; Returns: none
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; Affects: none
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; ---------------------------------------------------------------------------
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; Sets the PCM volume level 0..F
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