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87 lines
1.8 KiB
NASM
87 lines
1.8 KiB
NASM
;;; Simple Chorus
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;;; Author:Daniel Bertrand
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;;; Date: Oct 12, 2000
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;;; This program is free software; you can redistribute it and/or modify
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;;; it under the terms of the GNU General Public License as published by
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;;; the Free Software Foundation; either version 2 of the License, or
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;;; (at your option) any later version.
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;;; References:
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;;; http://www.harmony-central.com/Effects/Articles/Chorus
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;;; speed(formerly "delta")=2*pi*freq/48000
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;;; this give us our delta value for a specific freq (0.1-0.3Hz is good)
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include "emu_constants.asm"
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name "Chorus"
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in IO
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out equ in
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speed control 4e-05 , 0 , 1e-4 ; Controls frequency (radians)
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delay control &40e-3 ,&10e-3 , &80e-3; twice (2*) average delay (sec)
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width control #0.3 ,0 ,0.5 ; width control
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mix control #1 ,0 ,#1 ; forward mix
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;; sine generator storage spaces:
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sinx sta 0
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cosx sta #0.5
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tmp dyn
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tmp2 dyn
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;;; Two Delay Lines:
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dly delay &80e-3 ;10msec delay line
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write twrite dly,0 ; tram writes
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ready tread dly,0 ; tram reads
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reada tread dly,0
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;;;The code:
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;;; two opcode sinewave generator (I love this chip!):
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macs sinx,sinx,speed,cosx
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macs1 cosx,cosx,speed,sinx
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;;; 0.5Asint+0.5:
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macs tmp,C_2^30,sinx,width
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;;; calculate address:
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macs ready.a,write.a,delay,tmp
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;second addresses for interpolation:
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;(interesting how the emu engineers decided that $800 wasn't a needed value)
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macints reada.a,ready.a,C_8,C_256
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;;; Write to the delay line:
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macs write,C_0,in,C_2^29
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;;; output values:
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;;; 0x55 is 00100000 (?)
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macints tmp,C_0,reada.a,C_LSshift; get least significant part of address
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interp tmp2,ready,tmp,reada ;interpolate in-between the two delay line readings
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macs out,in,tmp2,mix
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end
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