or fladel_138 < 8 ;fladel^ + 138 ;get midpoint address pointer
I think I don't understand what this code does.
'< 'Means to move to the left 8 bits?
Can it be written as `fladel^ + 138`？
Thank you very much who can answer me。
The entire code is as follows：
Code: Select all
;Guitar reverb/flange
;pot0 = reverb mix
;pot1 = flange rate
;pot2 = flange mix
;
mem fladel 512
;
mem ap1 150 ;reverb allpass at reverb input
mem ap2 221 ;reverb allpass at reverb input
mem ap3 345 ;reverb allpass at reverb input
mem ap4 431 ;reverb allpass at reverb input
mem rap1 1157 ;reverb ring AP
mem rap1b 2257 ;reverb ring AP
mem rap2 1978 ;reverb ring AP
mem rap2b 1678 ;reverb ring AP
mem rap3 1850 ;reverb ring AP
mem rap3b 2456 ;reverb ring AP
mem rap4 1234 ;reverb ring AP
mem rap4b 1567 ;reverb ring AP
mem d1 2180 ;reverb ring delay
mem d2 3956 ;reverb ring delay
mem d3 4165 ;reverb ring delay
mem d4 3456 ;reverb ring delay
;
equ fladel_138 fladel+138 ;mid pointer to flange delay
equ fladel_139 fladel+139 ;mid pointer to flange delay +1
equ ramp reg0 ;used to generate ramp waveform
equ tri reg2 ;triangle made from ramp
equ flaout reg3 ;mixed flanger output
equ fladout reg4 ;flange delay output
equ mix reg5 ;mix coefficient for flanger
equ fbk reg6 ;fbk coefficient for feedback around mixed flanger
equ fract reg7 ;fractional portion of flange read address
equ k1 reg8 ;first coefficient for linear interpolation
equ k2 reg9 ;second coefficient for linear interpolation
equ temp reg10 ;general temp register
equ revin reg11 ;input to reverb ring
equ rfil reg12 ;reverb ring filter register
equ rt 0.5 ;reverb time
;-------------------------------------------------------
;set up lfo for reverb, 0.5Hz, +/-20 samples:
;-------------------------------------------------------
skp RUN, LOOP
wlds 0, 12, 160 ;setup LFO0
LOOP:
;-------------------------------------------------------
;--------------------------------------------------------
;prepare mix values from pot2:
;--------------------------------------------------------
rdax pot2, 1.999 ;make pot2 cause mix to be 1:1 at 50% rotation and greater.
wrax mix, 0 ;flange mix is pot2, gain causes saturation limit at approx 1.0, pot2 at midscale
rdax pot2, 1.0
mulx pot2
wrax fbk, 0 ;feedback is squared pot2, 0 to 1.0
;--------------------------------------------------------
;write input to flanger:
;--------------------------------------------------------
rdax fladout, 0.6 ;get fraction of flange output
mulx fbk ;multiply by feedback function
rdax adcl, 0.5 ;add inputs * 0.5 each
rdax adcr, 0.5
wra fladel, 0 ;write flange delay input, clear acc
;--------------------------------------------------------
; flange rate from pot 1
; as adder value to ramp
; gen, filtered at 0.3Hz:
;--------------------------------------------------------
rdax pot1, 1.0 ;read pot1
mulx pot1 ;square value, range = 0 to 1
sof 0.05, 0.005 ;scale to range of 0.005 to 0.55
sof .001, 0 ;scale further to 0.00005 to 0.0055
rdax ramp, 1.0 ;add to ramp value
and 0xbfffff ;allow for rollover (bypasses saturation limiting)
wrax ramp, 1.0 ;write back to ramp register, keep acc
sof 1.0, -0.25 ;subtract 0.25 to center rampwave about 0
maxx reg0, 0 ;get absolute value (make triangle wave from 0 to 0.25)
sof 1.0, -0.125 ;subtract 0.125 to make triangle wave go -0.125 to +0.125
sof .00015, 0 ;scale to filter
rdax tri, 0.9999 ;filter triangle waveform so that pitch bend does not get too great at high rates
wrax tri, 0 ;write triangle wave to register, clear accumulator
;--------------------------------------------------------
; now formulate delay pointer,
; and pass through to fract calc:
;--------------------------------------------------------
or fladel_138 < 8 ;fladel^ + 138 ;get midpoint address pointer
rdax tri, 0.03125 ;add triangle wave modulation, scaled to fit delay range
wrax addr_ptr, 1.0 ;establish address for lower interpolation sample
;--------------------------------------------------------
; address pointer set, now develop fraction of tri:
;-------------------------------------------------------
and 0x0000ff ;mask off integer portion of address, leaving a fractional value in the lowest acc byte
sof -2.0, 0 ;these operations shift the resulting fractional value to the range 0.0 to 0.999...
sof -2.0, 0 ;only -2.0 is exact, but it changes sign of shifted value
sof -2.0, 0
sof -2.0, 0
sof -2.0, 0
sof -2.0, 0
sof -2.0, 0
sof -2.0, 0
sof -2.0, 0
sof -2.0, 0
sof -2.0, 0
sof -2.0, 0
sof -2.0, 0
sof -2.0, 0
sof 1.9999 ,0 ;15 shifts, last one is positive, and 1.9999 is nearly 2.0...
wrax k2, 1.0 ;write result as coefficient for second sample read
sof -1.0, 0.999 ;K1 is 1-K2 (or very nearly)
wrax k1, 0.0 ;write result as coefficient for first sample read
;-------------------------------------------------------
;read from first pointer:
;-------------------------------------------------------
rmpa 1.0 ;read memory for first sample read
mulx k1 ;multiply by K1
wrax temp, 0 ;and store in temp, while clearing the acc
;-------------------------------------------------------
;get second pointer:
;-------------------------------------------------------
or fladel_139 < 8 ;fladel^ + 139 ;form second pointer
rdax tri, 0.03125 ;add triangle waveform again
wrax addr_ptr, 0 ;establish address for upper interpolation sample
rmpa 1.0 ;read second interpolation sample
mulx k2 ;multiply by K2
rdax temp, 1.0 ;add temp (first value*K1)
wrax fladout, 1.0 ;write the result to the flanger delay output
mulx mix ;multiply by the mix value
rda fladel, 1.0 ;add the input to the flanger delay
wrax flaout, 0.0 ;write result to flaout and clear acc
;
;-------------------------------------------------------
;do ap smearing to reverb ring allpass filters, modulating them with LFO0, sin, cos, inv sin, inv cos:
;-------------------------------------------------------
cho RDA, SIN0, 0x06, rap1+50
cho RDA, SIN0, 0, rap1+51
wra rap1+100, 0
cho RDA, SIN0, 0x07, rap2+50
cho RDA, SIN0, 1, rap2+51
wra rap2+100, 0
cho RDA, SIN0, 0x0E, rap3+50
cho RDA, SIN0, 0x08, rap3+51
wra rap3+100, 0
cho RDA, SIN0, 0x0F, rap4+50
cho RDA, SIN0, 0x09, rap4+51
wra rap4+100, 0
;
;do reverb input allpass filters:
;
rdax flaout, 0.5 ;read value from flanger process
rda ap1#, -0.6 ;do 4 all pass filters:
wrap ap1, 0.6
rda ap2#, -0.6
wrap ap2, 0.6
rda ap3#, -0.6
wrap ap3, 0.6
rda ap4#, -0.6
wrap ap4, 0.6
wrax revin, 0.0 ;write result to revin, clear acc
;
rda d4#, rt ;ring process, read last delay
rda rap1#, -0.6 ;do 1st ring allpass
wrap rap1, 0.6
rda rap1b#, -0.7 ;do second ring allpass
wrap rap1b, 0.7
rdax revin, 0.5 ;read value from input allpass filters.
wra d1, 0.0 ;write the output to the next delay, clear acc
;
rda d1#, rt ;do 3 more:
rda rap2#, -0.6
wrap rap2, 0.6
rda rap2b#, -0.7
wrap rap2b, 0.7
rdax revin, 0.5
wra d2, 0.0
;
rda d2#, rt
rda rap3#, -0.6
wrap rap3, 0.6
rda rap3b#, -0.7
wrap rap3b, 0.7
rdax revin, 0.5
wra d3, 0.0
;
rda d3#, rt
rda rap4#, -0.6
wrap rap4, 0.6
rda rap4b#, -0.7
wrap rap4b, 0.7
rdax revin, 0.5
wra d4, 0.0
;
rda d1+3000, 1.5 ;sum weighted taps from the reverb ring delays
rda d2+1239, 1.2
rda d3+2341, 1.05
rda d4+302, 0.9
rdfx rfil, 0.5
;
mulx pot0 ;multiply reverb output by pot0
mulx pot0 ;do again (as if pot0 was a square function)
rdax flaout, 0.5 ;add flaout
sof 1.999, 0 ;scale gain back up
wrax dacl, 1.0 ;write to right output, save accumulator
sof 1, -0.02
wrax dacr, 0 ;write to left output, clear acc