2020-12-05 12:45:18 +01:00
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; TI SN76489 sound chip display driver
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; @author Daniele Verducci
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;
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; USAGE:
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; call Snd_init <-- inits sound (and silences default tone)
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; call Snd_beep <-- system beep
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2020-12-06 15:51:26 +01:00
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; Sound card is on port 1
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SND_DATA_REG: EQU IO_1
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2020-12-06 14:09:48 +01:00
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2020-12-05 12:45:18 +01:00
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; Init device (silence all channels)
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; Bits meaning:
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; 1 R0 R1 R2 A0 A1 A2 A3
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; Bit0 is 1
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; Bit1,2,3 select the channel: 001, 011, 101, 111(noise)
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; Bit4,5,6,7 selecy the attenuation (0000=full volume, 1111=silent)
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Snd_init:
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; silence ch1
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2020-12-06 14:09:48 +01:00
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ld a,%10011111
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2020-12-05 12:45:18 +01:00
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out (SND_DATA_REG),a
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; silence ch2
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2020-12-06 14:09:48 +01:00
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ld a,%10111111
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2020-12-05 12:45:18 +01:00
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out (SND_DATA_REG),a
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; silence ch3
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2020-12-06 14:09:48 +01:00
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ld a,%11011111
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2020-12-05 12:45:18 +01:00
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out (SND_DATA_REG),a
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; silence noise ch
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ld a,%11111111
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out (SND_DATA_REG),a
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ret
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2020-12-06 14:09:48 +01:00
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; Plays the system beep.
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2020-12-05 12:45:18 +01:00
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Snd_beep:
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; ch1 max volume
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ld a,%10010000
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out (SND_DATA_REG),a
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; play beep freq
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ld a,%10000000
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out (SND_DATA_REG),a
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ld a,%00001000
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out (SND_DATA_REG),a
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2020-12-06 15:51:26 +01:00
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; wait
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2021-01-01 17:50:52 +01:00
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ld bc, (TIME_DUR_MILLIS * 10)
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2020-12-05 12:45:18 +01:00
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call Time_delay55
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; silence ch1
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ld a,%10011111
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out (SND_DATA_REG),a
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ret
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2020-12-06 14:09:48 +01:00
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; Sets the attenuation value for a channel
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; @param a Channel (0, 1, 2, 3(Noise))
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; @param c Attenuation (0 to 16)
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; Snd_setAtt:
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; cp a, 0
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