Vibrato — HLE + bytecode
Vibrato — HLE reconstruction and DSP bytecode
DSPHLE selector 0x07 · program image prog50_vibrato · Intervention-pinned (a panel control was driven and the moving C-RAM cell identified).
LFO-swept pitch modulation; rate=0x02 (~4 Hz), depth=0x05.
This page pairs the bytecode the effect runs on the NEC µPD6383GF with the high-level reconstruction that makes it audible in MAME. The reconstruction is not the chip’s microcode — it is a textbook DSP block built from the decoded meaning of that microcode, and reading the two together is how the bytecode is understood (and, in time, driven toward a faithful low-level emulation). See also the signal-flow flowchart.
The bytecode below is the source of truth; the HLE reconstruction is not. The HLE is our best current interpretation and may contain mistakes — where the two disagree, the bytecode wins, and a better HLE should be updated here. This page is the permanent archive of the reference HLE: it is kept here even after the code is eventually removed from the MAME sources.
DSP bytecode (reverse-engineered microprogram)
The disassembled image the chip executes for this effect. Source (regenerable):
dsp/disasm/prog50_vibrato.dsm.
; Reverse-engineered disassembly of the KN5000 effects-DSP microcode
; (NEC uPD6383GF), recovered from the original firmware. The microcode is the
; work of its original authors; this is a disassembly for preservation and
; interoperability, and no claim of copyright is made over the disassembled program.
; KN5000 effects-DSP program -- VIBRATO
; image rep algo 50 | slots 50 | unit 0 (I-RAM load 84)
; family modulation | confidence high | 53 words, 12 class-A multiplies (2 named)
; role: vibrato: wet-only modulated delay
; coefficient cursor base 0x00
;
; GENERATED by dsp/tools/gen_dsp_disasm.py -- DO NOT EDIT.
; Put labels/comments in the matching dsp/sym/*.sym; analysis in dsp/algorithms/.
w0 00400008BC ?word 0x00400008BC ; 040.0.00.8BC hi12{?6 res=040} [SPECULATIVE: lo12 bit-11 modifier word + pointer-mode (bit11-family); the base selector/register is OPEN]
w1 088013000B ?word 0x088013000B ; 880.1.30.00B hi12{ESC ?7 res=080} [external delay-DRAM READ (FORCED, adjudication-round5 sect. 3 -- addr8 bit 6 is the direction field and 0x60 is the WRITE; this REVERSES R1 F1, which bounded the read latency to one repetition when the descriptors need twenty words); this end moves with the user's DELAY (ms) knob, and the delay is READ_CELL - WRITE_CELL; addr8 0x30 also marks the FIRST DRAM access of a body, 37 of 38 distinct images (R3 sect. 6.2). external delay-DRAM access; address = DESCRIPTOR_CELL[k] + G, from the host bank behind pointer ...825 / tag 0x4C (R3, PROVEN BY CONSTRUCTION) -- the k-th class-1 escape word of a body takes the k-th cell of that body's own descriptor block (the IDENTITY map, FORCED in adjudication-round5 sect. 1), so the address is NOT in this word]
w2 000020B1CD ld (p),(p)+11
w3 000020040E ld acc,(p)+0
w4 0212200000 mac.b (p)0,(p)+0 ; mem[p]<-acc, acc=0
w5 09001601D5 dly.w dsc[k],p+96
w6 0192A40000 mac.b (p)0,c+,(p)+64 ; store SUPPRESSED (bit7)
; C-RAM[0x00] (coeff, base 0x00 MEASURED)
w7 00822001C0 mac.b (p),(p)+0
w8 0C4032044C ldreg r4C,#25 ; immediate -> the register lo12 selects
w9 0A00000041 ?word 0x0A00000041 ; A00.0.00.041 hi12{ESC f98=2} [head of a fixed 3-word template (S-5); operands SRC 0x01/ACT 0x01 dark]
w10 08801202C7 dly.r dsc[k],p+32
w11 0102ABD4C8 ?word 0x0102ABD4C8 ; 102.A.BD.4C8 hi12{f98=1 f31=1} cur+ [gain multiply (same op in phaser all-pass and reverb diffuser)]
; C-RAM[0x01] (coeff, base 0x00 MEASURED)
w12 0000204407 ld.st acc,(p)+4
w13 0092A00200 mac.b c,c+,(p)+0 ; store SUPPRESSED (bit7)
; C-RAM[0x02] (coeff, base 0x00 MEASURED)
w14 00822001C0 mac.b (p),(p)+0
w15 0094A00200 wrap acc,c+ ; acc <- datum(acc) & coef (LFO modulus)
; C-RAM[0x03] (coeff, base 0x00 MEASURED)
w16 0000200447 ?word 0x0000200447 ; 000.2.00.447 hi12{-} [SPECULATIVE (prospective, not measured): SRC 0x11 = ACCB (2nd accumulator)]
w17 0092200700 ?word 0x0092200700 ; 092.2.00.700 hi12{ST f31=1 ?7 res=080} [SPECULATIVE (prospective, not measured): SRC 0x1C = control/mod source into MAC (100% MAC-consumed; LFO in mod fx, envelope/AGC in dynamics) -- NOT LFO-only: present in 19 non-LFO programs (dsp_datapath_fingerprint)]
w18 0000A001D5 ld (p),c+,(p)+0
; C-RAM[0x04] (coeff, base 0x00 MEASURED)
w19 0182200000 mac.b (p)0,(p)+0
w20 0040000C63 ?word 0x0040000C63 ; 040.0.00.C63 hi12{?6 res=040} [SPECULATIVE (prospective, not measured): SRC 0x11 = ACCB (2nd accumulator)]
w21 00006184CD ?word 0x00006184CD ; 000.6.18.4CD hi12{-} [table-lookup idiom, class-6 addr8 = table selector (INFERRED)]
w22 00124011CE ?word 0x00124011CE ; 012.4.01.1CE hi12{ST f31=1} [table-lookup idiom, third word (INFERRED)]
w23 01042FE1CE post (p),(p)-2
w24 0102200000 mac.b (p)0,(p)+0
w25 0000A00415 ld acc,c+,(p)+0
; C-RAM[0x05] (coeff, base 0x00 MEASURED)
; coeff C-RAM[0x05] = op0x66[0] (role mix/tap, INFERRED)
w26 0212200000 mac.b (p)0,(p)+0 ; mem[p]<-acc, acc=0
w27 0000203407 ld.st acc,(p)+3
w28 0092A00200 mac.b c,c+,(p)+0 ; store SUPPRESSED (bit7)
; C-RAM[0x06] (coeff, base 0x00 MEASURED)
w29 00822001C0 mac.b (p),(p)+0
w30 0094A00200 wrap acc,c+ ; acc <- datum(acc) & coef (LFO modulus)
; C-RAM[0x07] (coeff, base 0x00 MEASURED)
w31 0000200447 ?word 0x0000200447 ; 000.2.00.447 hi12{-} [SPECULATIVE (prospective, not measured): SRC 0x11 = ACCB (2nd accumulator)]
w32 0092200700 ?word 0x0092200700 ; 092.2.00.700 hi12{ST f31=1 ?7 res=080} [SPECULATIVE (prospective, not measured): SRC 0x1C = control/mod source into MAC (100% MAC-consumed; LFO in mod fx, envelope/AGC in dynamics) -- NOT LFO-only: present in 19 non-LFO programs (dsp_datapath_fingerprint)]
w33 0000A001D5 ld (p),c+,(p)+0
; C-RAM[0x08] (coeff, base 0x00 MEASURED)
w34 0182200000 mac.b (p)0,(p)+0
w35 0040000C63 ?word 0x0040000C63 ; 040.0.00.C63 hi12{?6 res=040} [SPECULATIVE (prospective, not measured): SRC 0x11 = ACCB (2nd accumulator)]
w36 00006184CD ?word 0x00006184CD ; 000.6.18.4CD hi12{-} [table-lookup idiom, class-6 addr8 = table selector (INFERRED)]
w37 00124011CE ?word 0x00124011CE ; 012.4.01.1CE hi12{ST f31=1} [table-lookup idiom, third word (INFERRED)]
w38 01042FE1CE post (p),(p)-2
w39 0102200000 mac.b (p)0,(p)+0
w40 0000AF4415 ld acc,c+,(p)-12
; C-RAM[0x09] (coeff, base 0x00 MEASURED)
; coeff C-RAM[0x09] = op0x66[1] (role mix/tap, INFERRED)
w41 021220A1CD mac (p),(p)+10 ; mem[p]<-acc, acc=0
w42 00002021CE ld (p),(p)+2
w43 0212200407 mac.st acc,(p)+0 ; mem[p]<-acc, acc=0
w44 09001601D5 dly.w dsc[k],p+96
w45 0192A41000 mac.b (p)0,c+,(p)+65 ; store SUPPRESSED (bit7)
; C-RAM[0x0A] (coeff, base 0x00 MEASURED)
w46 00822001C0 mac.b (p),(p)+0
w47 0C4032044C ldreg r4C,#25 ; immediate -> the register lo12 selects
w48 0A00000041 ?word 0x0A00000041 ; A00.0.00.041 hi12{ESC f98=2} [head of a fixed 3-word template (S-5); operands SRC 0x01/ACT 0x01 dark]
w49 08801202C7 dly.r dsc[k],p+32
w50 0102AAD4C8 ?word 0x0102AAD4C8 ; 102.A.AD.4C8 hi12{f98=1 f31=1} cur+ [gain multiply (same op in phaser all-pass and reverb diffuser)]
; C-RAM[0x0B] (coeff, base 0x00 MEASURED)
w51 0880160000 dly.w dsc[k],p+96
w52 040010E000 endblk #0E ; END OF BLOCK -- the last word of a block
HLE reconstruction (MAME, kn5000_tonegen.cpp)
The decode of the bytecode above, rebuilt as audible DSP. Two parts: the parameter refresh
(reads the decoded C-RAM coefficient cells once per update) and the per-sample insert (the
signal processing). Default OFF, behind the DSPHLE research port. Source:
src/mame/matsushita/kn5000_tonegen.cpp.
Parameter refresh (decode the C-RAM coefficients):
const bool vib_hle = (dsphle == 7);
double ens_inc = 0.0, ens_tap[3] = { 0, 0, 0 };
double vib_inc = 0.0, vib_depth = 0.0, vib_wet = 0.0;
if (ens_hle || vib_hle)
{
auto q22m = [](u32 v) -> double {
int32_t s = (v & 0x800000) ? int32_t(v) - 0x1000000 : int32_t(v);
return double(s) / 4194304.0; };
const bool bit1 = (dspcfg & 2) != 0;
const double cs = bit1 ? 1.0 : 2.0;
const double sr48 = double(STREAM_RATE) / 44100.0;
if (ens_hle)
{
const double inc = double(m_dsp1->cram_read(0x00) & 0xffffff) * cs;
ens_inc = std::clamp(inc * 44100.0 / 8388608.0, 0.02, 12.0) / double(STREAM_RATE);
// three per-channel voice tap delays (L cells 0x02/0x04/0x06), in 44.1k samples
ens_tap[0] = std::clamp(double(m_dsp1->cram_read(0x02) & 0xffffff) * cs, 2.0, 1500.0) * sr48;
ens_tap[1] = std::clamp(double(m_dsp1->cram_read(0x04) & 0xffffff) * cs, 2.0, 1500.0) * sr48;
ens_tap[2] = std::clamp(double(m_dsp1->cram_read(0x06) & 0xffffff) * cs, 2.0, 1500.0) * sr48;
}
if (vib_hle)
{
const double inc = double(m_dsp1->cram_read(0x02) & 0xffffff) * cs;
vib_inc = std::clamp(inc * 44100.0 / 8388608.0, 0.02, 12.0) / double(STREAM_RATE);
vib_depth = std::clamp(q22m(m_dsp1->cram_read(0x05)) * cs, 0.0, 1.0) * 240.0 * sr48; // sweep
vib_wet = std::clamp(q22m(m_dsp1->cram_read(0x0C)) * cs, 0.0, 1.0); // mix
}
Per-sample insert (the reconstructed signal path):
if (vib_hle)
{
m_vib_phase += vib_inc;
if (m_vib_phase >= 1.0) m_vib_phase -= 1.0;
const double sl = double(mix_l) / 32768.0, sr = double(mix_r) / 32768.0;
m_vib_l.write(sl); m_vib_r.write(sr);
const double d = vib_depth + vib_depth * (0.5 + 0.5 * std::sin(2.0 * M_PI * m_vib_phase));
const double tl = m_vib_l.read(std::max(2.0, d)), tr = m_vib_r.read(std::max(2.0, d));
const double w = std::max(vib_wet, 0.5); // vibrato is mostly wet
mix_l = int32_t(((1.0 - w) * sl + w * tl) * 32768.0);
mix_r = int32_t(((1.0 - w) * sr + w * tr) * 32768.0);
}