add oscilloscope view

13 files changed, 405 insertions, 26 deletions

diff --git a/gtk/oscilloview.c b/gtk/oscilloview.c
new file mode 100644
index 0000000..724ada9
--- /dev/null
+++ b/gtk/oscilloview.c
@@ -0,0 +1,83 @@
+#include <gtk/gtk.h>
+#include <cairo.h>
+#include "oscilloview.h"
+#include <string.h>
+
+struct oscilloview oscilloview_g = {
+  .flag = ATOMIC_FLAG_INIT
+};
+
+enum {
+  VIEW_SAMPLES = 1024,
+  VIEW_SKIP = 2,
+  WIDTH = 600,
+  HEIGHT = 300,
+};
+
+static struct {
+  GtkWidget *win;
+  struct oscillodata oscillodata[LIBOPNA_OSCILLO_TRACK_COUNT];
+} g;
+
+static void on_destroy(GtkWidget *w, gpointer ptr) {
+  (void)w;
+  (void)ptr;
+  g.win = 0;
+}
+
+static void draw_track(cairo_t *cr,
+                       double x, double y, double w, double h,
+                       const struct oscillodata *data) {
+  int start = OSCILLO_SAMPLE_COUNT - VIEW_SAMPLES;
+  start -= (data->offset >> OSCILLO_OFFSET_SHIFT);
+  if (start < 0) start = 0;
+  for (int i = 0; i < (VIEW_SAMPLES / VIEW_SKIP); i++) {
+    cairo_line_to(cr, x + ((i)*w)/(VIEW_SAMPLES / VIEW_SKIP), y + h/2.0 - (data[0].buf[start + i*VIEW_SKIP] / 16384.0) * h/2);
+  }
+  cairo_stroke(cr);
+}
+
+static gboolean draw_cb(GtkWidget *w,
+                        cairo_t *cr,
+                        gpointer ptr) {
+  (void)w;
+  (void)ptr;
+  cairo_set_antialias(cr, CAIRO_ANTIALIAS_NONE);
+  if (!atomic_flag_test_and_set_explicit(
+    &oscilloview_g.flag, memory_order_acquire)) {
+    memcpy(g.oscillodata,
+           oscilloview_g.oscillodata,
+           sizeof(oscilloview_g.oscillodata));
+    atomic_flag_clear_explicit(&oscilloview_g.flag, memory_order_release);
+  }
+  cairo_set_source_rgb(cr, 0.0, 0.0, 0.0);
+  cairo_paint(cr);
+  cairo_set_source_rgb(cr, 1.0, 1.0, 1.0);
+  for (int x = 0; x < 3; x++) {
+    for (int y = 0; y < 3; y++) {
+      draw_track(cr, x*WIDTH, y*HEIGHT, WIDTH, HEIGHT, &g.oscillodata[x*3+y]);
+    }
+  }
+  return FALSE;
+}
+
+static gboolean tick_cb(GtkWidget *w, GdkFrameClock *clock, gpointer ptr) {
+  (void)clock;
+  (void)ptr;
+  gtk_widget_queue_draw(w);
+  return G_SOURCE_CONTINUE;
+}
+
+void show_oscilloview(void) {
+  if (!g.win) {
+    g.win = gtk_window_new(GTK_WINDOW_TOPLEVEL);
+    gtk_window_set_title(GTK_WINDOW(g.win), "Oscilloscope view");
+    g_signal_connect(g.win, "destroy", G_CALLBACK(on_destroy), 0);
+  }
+  GtkWidget *drawarea = gtk_drawing_area_new();
+  gtk_container_add(GTK_CONTAINER(g.win), drawarea);
+  gtk_widget_set_size_request(drawarea, WIDTH*3, HEIGHT*3);
+  g_signal_connect(drawarea, "draw", G_CALLBACK(draw_cb), 0);
+  gtk_widget_add_tick_callback(drawarea, tick_cb, 0, 0);
+  gtk_widget_show_all(g.win);
+}
diff --git a/gtk/oscilloview.h b/gtk/oscilloview.h
new file mode 100644
index 0000000..edabcd9
--- /dev/null
+++ b/gtk/oscilloview.h
@@ -0,0 +1,17 @@
+#ifndef MYON_FMPLAYER_GTK_OSCILLOVIEW_H_INCLUDED
+#define MYON_FMPLAYER_GTK_OSCILLOVIEW_H_INCLUDED
+
+#include "libopna/opna.h"
+#include "oscillo/oscillo.h"
+
+#include <stdatomic.h>
+
+extern struct oscilloview {
+  atomic_flag flag;
+  struct oscillodata oscillodata[LIBOPNA_OSCILLO_TRACK_COUNT];
+} oscilloview_g;
+
+void show_oscilloview(void);
+
+#endif // MYON_FMPLAYER_GTK_OSCILLOVIEW_H_INCLUDED
+
diff --git a/libopna/opna.c b/libopna/opna.c
index 10155d0..1b0aa6c 100644
--- a/libopna/opna.c
+++ b/libopna/opna.c
@@ -1,4 +1,6 @@
 #include "opna.h"
+#include "oscillo/oscillo.h"
+#include <string.h>
 
 void opna_reset(struct opna *opna) {
   opna_fm_reset(&opna->fm);
@@ -23,8 +25,20 @@ unsigned opna_readreg(const struct opna *opna, unsigned reg) {
 }
 
 void opna_mix(struct opna *opna, int16_t *buf, unsigned samples) {
-  opna_fm_mix(&opna->fm, buf, samples);
-  opna_ssg_mix_55466(&opna->ssg, &opna->resampler, buf, samples);
+  opna_mix_oscillo(opna, buf, samples, 0);
+}
+
+void opna_mix_oscillo(struct opna *opna, int16_t *buf, unsigned samples, struct oscillodata *oscillo) {
+  if (oscillo) {
+    for (int i = 0; i < LIBOPNA_OSCILLO_TRACK_COUNT; i++) {
+      memmove(&oscillo[i].buf[0],
+              &oscillo[i].buf[samples],
+              (OSCILLO_SAMPLE_COUNT - samples)*sizeof(oscillo[i].buf[0]));
+    }
+  }
+  unsigned offset = OSCILLO_SAMPLE_COUNT - samples;
+  opna_fm_mix(&opna->fm, buf, samples, &oscillo[0], offset);
+  opna_ssg_mix_55466(&opna->ssg, &opna->resampler, buf, samples, &oscillo[6], offset);
   opna_drum_mix(&opna->drum, buf, samples);
   opna_adpcm_mix(&opna->adpcm, buf, samples);
 }
diff --git a/libopna/opna.h b/libopna/opna.h
index 7d7d722..2ebca0d 100644
--- a/libopna/opna.h
+++ b/libopna/opna.h
@@ -30,6 +30,10 @@ enum {
   LIBOPNA_CHAN_ADPCM = 0x8000,
 };
 
+enum {
+  LIBOPNA_OSCILLO_TRACK_COUNT = 11
+};
+
 struct opna {
   struct opna_fm fm;
   struct opna_ssg ssg;
@@ -43,6 +47,8 @@ void opna_reset(struct opna *opna);
 void opna_writereg(struct opna *opna, unsigned reg, unsigned val);
 unsigned opna_readreg(const struct opna *opna, unsigned reg);
 void opna_mix(struct opna *opna, int16_t *buf, unsigned samples);
+struct oscillodata;
+void opna_mix_oscillo(struct opna *opna, int16_t *buf, unsigned samples, struct oscillodata *oscillo);
 unsigned opna_get_mask(const struct opna *opna);
 void opna_set_mask(struct opna *opna, unsigned mask);
 
diff --git a/libopna/opnafm.c b/libopna/opnafm.c
index 3f5367f..abc36fa 100644
--- a/libopna/opnafm.c
+++ b/libopna/opnafm.c
@@ -1,4 +1,5 @@
 #include "opnafm.h"
+#include "oscillo/oscillo.h"
 
 #include "opnatables.h"
 
@@ -539,7 +540,46 @@ void opna_fm_chan_env(struct opna_fm_channel *chan) {
   }
 }
 
-void opna_fm_mix(struct opna_fm *fm, int16_t *buf, unsigned samples) {
+static int gcd(int a, int b) {
+  if (a < b) {
+    int t = a;
+    a = b;
+    b = t;
+  }
+  for (;;) {
+    int r = a % b;
+    if (!r) break;
+    a = b;
+    b = r;
+  }
+  return b;
+}
+
+
+
+void opna_fm_mix(struct opna_fm *fm, int16_t *buf, unsigned samples,
+                 struct oscillodata *oscillo, unsigned offset) {
+  if (oscillo) {
+    for (unsigned c = 0; c < 6; c++) {
+      const struct opna_fm_channel *ch = &fm->channel[c];
+      unsigned freq = blkfnum2freq(ch->blk, ch->fnum);
+      int mul[4];
+      for (int i = 0; i < 4; i++) {
+        mul[i] = ch->slot[i].mul << 1;
+        if (!mul[i]) mul[i] = 1;
+      }
+      freq *= gcd(gcd(gcd(mul[0], mul[1]), mul[2]), mul[3]);
+      freq /= 2;
+      unsigned period = 0;
+      if (freq) period = (1u<<(20+OSCILLO_OFFSET_SHIFT)) / freq;
+      if (period) {
+        oscillo[c].offset += (samples << OSCILLO_OFFSET_SHIFT);
+        oscillo[c].offset %= period;
+      } else {
+        oscillo[c].offset = 0;
+      }
+    }
+  }
   for (unsigned i = 0; i < samples; i++) {
     if (!fm->env_div3) {
       for (int c = 0; c < 6; c++) {
@@ -554,6 +594,7 @@ void opna_fm_mix(struct opna_fm *fm, int16_t *buf, unsigned samples) {
 
     for (int c = 0; c < 6; c++) {
       int16_t o = opna_fm_chanout(&fm->channel[c]);
+      if (oscillo) oscillo[c].buf[offset+i] = o*2;
       // TODO: CSM
       if (c == 2 && fm->ch3.mode != CH3_MODE_NORMAL) {
         opna_fm_chan_phase_se(&fm->channel[c], fm);
diff --git a/libopna/opnafm.h b/libopna/opnafm.h
index 1a7f55a..b62556e 100644
--- a/libopna/opnafm.h
+++ b/libopna/opnafm.h
@@ -88,7 +88,8 @@ struct opna_fm {
 };
 
 void opna_fm_reset(struct opna_fm *fm);
-void opna_fm_mix(struct opna_fm *fm, int16_t *buf, unsigned samples);
+struct oscillodata;
+void opna_fm_mix(struct opna_fm *fm, int16_t *buf, unsigned samples, struct oscillodata *oscillo, unsigned offset);
 void opna_fm_writereg(struct opna_fm *fm, unsigned reg, unsigned val);
 
 //
diff --git a/libopna/opnassg.c b/libopna/opnassg.c
index 223758c..ec03437 100644
--- a/libopna/opnassg.c
+++ b/libopna/opnassg.c
@@ -1,4 +1,5 @@
 #include "opnassg.h"
+#include "oscillo/oscillo.h"
 /*
 static const float voltable[32] = {
   0.0f,           0.0f,           0x1.ae89f9p-8f, 0x1.000000p-7f,
@@ -126,10 +127,12 @@ static bool opna_ssg_tone_out(const struct opna_ssg *ssg, int chan) {
   return (ssg->ch[chan].out || (reg & 0x1)) && ((ssg->lfsr & 1) || (reg & 0x8));
 }
 
+#if 0
 static bool opna_ssg_tone_silent(const struct opna_ssg *ssg, int chan) {
   unsigned reg = ssg->regs[0x7] >> chan;
   return (reg & 0x1) && (reg & 0x8);
 }
+#endif
 
 static int opna_ssg_noise_period(const struct opna_ssg *ssg) {
   return ssg->regs[0x6] & 0x1f;
@@ -149,6 +152,10 @@ int opna_ssg_channel_level(const struct opna_ssg *ssg, int ch) {
        : (opna_ssg_tone_volume(ssg, ch) << 1) + 1;
 }
 
+#define COEFF 0x3fff
+#define COEFFSH 14
+
+// 3 samples per frame
 void opna_ssg_generate_raw(struct opna_ssg *ssg, int16_t *buf, int samples) {
   for (int i = 0; i < samples; i++) {
     if (((++ssg->noise_counter) >> 1) >= opna_ssg_noise_period(ssg)) {
@@ -173,31 +180,38 @@ void opna_ssg_generate_raw(struct opna_ssg *ssg, int16_t *buf, int samples) {
       }
     }
 
-    int16_t out = 0;
+    //int16_t out = 0;
     for (int ch = 0; ch < 3; ch++) {
+      buf[i*3+ch] = 0;
       if (++ssg->ch[ch].tone_counter >= opna_ssg_tone_period(ssg, ch)) {
         ssg->ch[ch].tone_counter = 0;
         ssg->ch[ch].out = !ssg->ch[ch].out;
       }
-      if (ssg->mask & (1<<ch)) continue;
 #if 1
-      // may output DC offset
       // YMF288 seems to disable output when 0 <= Tp < 8
+      int32_t previntmp = 0;
       if (opna_ssg_tone_out(ssg, ch)) {
         int level = opna_ssg_chan_env(ssg, ch)
           ? opna_ssg_env_level(ssg)
           : (opna_ssg_tone_volume(ssg, ch) << 1) + 1;
-        out += voltable[level];
+        //out += voltable[level];
+        previntmp = voltable[level]/2;
       }
+      previntmp *= COEFF;
+      ssg->prevout[ch] = previntmp - ssg->previn[ch] + ((((int64_t)COEFF)*ssg->prevout[ch]) >> COEFFSH);
+      ssg->previn[ch] = previntmp;
+      buf[i*3+ch] = ssg->prevout[ch] >> COEFFSH;
+      //buf[i*3+ch] = voltable[level]/2;
 #else
       if (!opna_ssg_tone_silent(ssg, ch)) {
         int level = opna_ssg_channel_level(ssg, ch);
-        out += (opna_ssg_tone_out(ssg, ch) ? voltable[level] : -voltable[level]) / 2;
+        //out += (opna_ssg_tone_out(ssg, ch) ? voltable[level] : -voltable[level]) / 2;
+        buf[i*3+ch] = (opna_ssg_tone_out(ssg, ch) ? voltable[level] : -voltable[level]) / 4;
       }
 #endif
       
     }
-    buf[i] = out / 2;
+    //buf[i] = out / 2;
   }
 }
 
@@ -205,27 +219,46 @@ void opna_ssg_generate_raw(struct opna_ssg *ssg, int16_t *buf, int samples) {
 
 void opna_ssg_mix_55466(
   struct opna_ssg *ssg, struct opna_ssg_resampler *resampler,
-  int16_t *buf, int samples) {
+  int16_t *buf, int samples,
+  struct oscillodata *oscillo, unsigned offset
+) {
+  if (oscillo) {
+    for (unsigned c = 0; c < 3; c++) {
+      unsigned period = (opna_ssg_tone_period(ssg, c) << OSCILLO_OFFSET_SHIFT) * 2 * 32 / 144;
+      if (period) {
+        oscillo[c].offset += (samples << OSCILLO_OFFSET_SHIFT);
+        oscillo[c].offset %= period;
+      } else {
+        oscillo[c].offset = 0;
+      }
+    }
+  }
   for (int i = 0; i < samples; i++) {
     {
       int ssg_samples = ((resampler->index + 9)>>1) - ((resampler->index)>>1);
-      int16_t ssgbuf[5];
+      int16_t ssgbuf[15];
       opna_ssg_generate_raw(ssg, ssgbuf, ssg_samples);
       for (int j = 0; j < ssg_samples; j++) {
-        resampler->buf[BUFINDEX(j)] = ssgbuf[j];
+        resampler->buf[BUFINDEX(j)*3+0] = ssgbuf[j*3+0];
+        resampler->buf[BUFINDEX(j)*3+1] = ssgbuf[j*3+1];
+        resampler->buf[BUFINDEX(j)*3+2] = ssgbuf[j*3+2];
       }
       resampler->index += 9;
     }
     int32_t sample = 0;
-    for (int j = 0; j < SINCTABLELEN; j++) {
-      unsigned sincindex = j*2;
-      if (!(resampler->index&1)) sincindex++;
-      bool sincsign = sincindex & (1<<(SINCTABLEBIT));
-      unsigned sincmask = ((1<<(SINCTABLEBIT))-1);
-      sincindex = (sincindex & sincmask) ^ (sincsign ? sincmask : 0);
-      sample += (resampler->buf[BUFINDEX(j)] * sinctable[sincindex])>>2;
+    for (int ch = 0; ch < 3; ch++) {
+      int32_t chsample = 0;
+      for (int j = 0; j < SINCTABLELEN; j++) {
+        unsigned sincindex = j*2;
+        if (!(resampler->index&1)) sincindex++;
+        bool sincsign = sincindex & (1<<(SINCTABLEBIT));
+        unsigned sincmask = ((1<<(SINCTABLEBIT))-1);
+        sincindex = (sincindex & sincmask) ^ (sincsign ? sincmask : 0);
+        chsample += (resampler->buf[BUFINDEX(j)*3+ch] * sinctable[sincindex])>>2;
+      }
+      if (oscillo) oscillo[ch].buf[offset+i] = chsample >> 13;
+      if (!(ssg->mask & (1<<ch))) sample += chsample;
     }
-
     sample >>= 16;
     sample *= 13000;
     sample >>= 14;
diff --git a/libopna/opnassg.h b/libopna/opnassg.h
index 8a59d91..0321163 100644
--- a/libopna/opnassg.h
+++ b/libopna/opnassg.h
@@ -25,10 +25,12 @@ struct opna_ssg {
   bool env_hld;
   bool env_holding;
   unsigned mask;
+  int32_t previn[3];
+  int32_t prevout[3];
 };
 
 struct opna_ssg_resampler {
-  int16_t buf[(1<<7)];
+  int16_t buf[(1<<7)*3];
   unsigned index;
 };
 
@@ -46,9 +48,10 @@ void opna_ssg_generate_raw(struct opna_ssg *ssg, int16_t *buf, int samples);
 // call to buffer written with OPNA output
 // samplerate: 7987200/144 Hz
 //            (55466.66..) Hz
+struct oscillodata;
 void opna_ssg_mix_55466(
   struct opna_ssg *ssg, struct opna_ssg_resampler *resampler,
-  int16_t *buf, int samples);
+  int16_t *buf, int samples, struct oscillodata *oscillo, unsigned offset);
 void opna_ssg_writereg(struct opna_ssg *ssg, unsigned reg, unsigned val);
 unsigned opna_ssg_readreg(const struct opna_ssg *ssg, unsigned reg);
 // channel level (0 - 31)
diff --git a/libopna/opnatimer.c b/libopna/opnatimer.c
index 789c28e..142176f 100644
--- a/libopna/opnatimer.c
+++ b/libopna/opnatimer.c
@@ -1,5 +1,6 @@
 #include "opnatimer.h"
 #include "opna.h"
+#include "oscillo/oscillo.h"
 
 enum {
   TIMERA_BITS = 10,
@@ -65,9 +66,12 @@ void opna_timer_writereg(struct opna_timer *timer, unsigned reg, unsigned val) {
     }
   }
 }
-#include <stdio.h>
-#include <stdlib.h>
+
 void opna_timer_mix(struct opna_timer *timer, int16_t *buf, unsigned samples) {
+  opna_timer_mix_oscillo(timer, buf, samples, 0);
+}
+
+void opna_timer_mix_oscillo(struct opna_timer *timer, int16_t *buf, unsigned samples, struct oscillodata *oscillo) {
   do {
     unsigned generate_samples = samples;
     if (timer->timerb_enable && timer->timerb_load) {
@@ -82,7 +86,7 @@ void opna_timer_mix(struct opna_timer *timer, int16_t *buf, unsigned samples) {
         generate_samples = timera_samples;
       }
     }
-    opna_mix(timer->opna, buf, generate_samples);
+    opna_mix_oscillo(timer->opna, buf, generate_samples, oscillo);
     if (timer->mix_cb) {
       timer->mix_cb(timer->mix_userptr, buf, generate_samples);
     }
diff --git a/libopna/opnatimer.h b/libopna/opnatimer.h
index ad0fe0b..c7b9511 100644
--- a/libopna/opnatimer.h
+++ b/libopna/opnatimer.h
@@ -37,6 +37,8 @@ void opna_timer_set_mix_callback(struct opna_timer *timer,
                                  opna_timer_mix_cb_t func, void *userptr);
 void opna_timer_writereg(struct opna_timer *timer, unsigned reg, unsigned val);
 void opna_timer_mix(struct opna_timer *timer, int16_t *buf, unsigned samples);
+struct oscillodata;
+void opna_timer_mix_oscillo(struct opna_timer *timer, int16_t *buf, unsigned samples, struct oscillodata *oscillo);
 
 #ifdef __cplusplus
 }
diff --git a/oscillo/oscillo.h b/oscillo/oscillo.h
new file mode 100644
index 0000000..451f9f4
--- /dev/null
+++ b/oscillo/oscillo.h
@@ -0,0 +1,17 @@
+#ifndef MYON_FMPLAYER_OSCILLO_H_INCLUDED
+#define MYON_FMPLAYER_OSCILLO_H_INCLUDED
+
+#include <stdint.h>
+
+enum {
+  OSCILLO_SAMPLE_COUNT = 8192,
+  OSCILLO_OFFSET_SHIFT = 10,
+};
+
+struct oscillodata {
+  int16_t buf[OSCILLO_SAMPLE_COUNT];
+  unsigned offset;
+  
+};
+
+#endif // MYON_FMPLAYER_OSCILLO_H_INCLUDED
diff --git a/win32/oscilloview.c b/win32/oscilloview.c
new file mode 100644
index 0000000..9759cc1
--- /dev/null
+++ b/win32/oscilloview.c
@@ -0,0 +1,139 @@
+#include "oscilloview.h"
+#include <mmsystem.h>
+#include <shellapi.h>
+#include <windowsx.h>
+
+enum {
+  TIMER_UPDATE = 1
+};
+
+struct oscilloview oscilloview_g = {
+  .flag = ATOMIC_FLAG_INIT
+};
+
+enum {
+  VIEW_SAMPLES = 1024,
+  VIEW_SKIP = 2,
+};
+
+static struct {
+  HINSTANCE hinst;
+  HWND parent;
+  HWND oscilloview;
+  ATOM oscilloview_class;
+  struct oscillodata oscillodata[LIBOPNA_OSCILLO_TRACK_COUNT];
+  UINT mmtimer;
+} g;
+
+static void on_destroy(HWND hwnd) {
+  g.oscilloview = 0;
+  timeKillEvent(g.mmtimer);
+}
+
+static void CALLBACK mmtimer_cb(UINT timerid, UINT msg,
+                                DWORD_PTR userptr,
+                                DWORD_PTR dw1, DWORD_PTR dw2) {
+  PostMessage(g.oscilloview, WM_USER, 0, 0);
+}
+
+static bool on_create(HWND hwnd, const CREATESTRUCT *cs) {
+  ShowWindow(hwnd, SW_SHOW);
+  //SetTimer(hwnd, TIMER_UPDATE, 16, 0);
+  g.mmtimer = timeSetEvent(16, 16, mmtimer_cb, 0, TIME_PERIODIC);
+  DragAcceptFiles(hwnd, TRUE);
+  return true;
+}
+
+static void draw_track(HDC dc,
+                       int x, int y, int w, int h,
+                       const struct oscillodata *data) {
+  int start = OSCILLO_SAMPLE_COUNT - VIEW_SAMPLES;
+  start -= (data->offset >> OSCILLO_OFFSET_SHIFT);
+  if (start < 0) start = 0;
+  MoveToEx(dc, x, y + h/2.0 - (data->buf[start] / 16384.0) * h/2, 0);
+  for (int i = 0; i < (VIEW_SAMPLES / VIEW_SKIP); i++) {
+    LineTo(dc, (double)x + ((i)*w)/(VIEW_SAMPLES / VIEW_SKIP), y + h/2.0 - (data->buf[start + i*VIEW_SKIP] / 16384.0) * h/2);
+  }
+}
+
+static void on_paint(HWND hwnd) {
+  RECT cr;
+  GetClientRect(hwnd, &cr);
+  PAINTSTRUCT ps;
+  HDC dc = BeginPaint(hwnd, &ps);
+  HDC mdc = CreateCompatibleDC(dc);
+  HBITMAP bitmap = CreateCompatibleBitmap(dc, cr.right, cr.bottom);
+  SelectObject(mdc, bitmap);
+
+  FillRect(mdc, &cr, GetStockObject(BLACK_BRUSH));
+  SelectObject(mdc, GetStockObject(WHITE_PEN));
+  int width = cr.right / 3;
+  int height = cr.bottom / 3;
+  for (int x = 0; x < 3; x++) {
+    for (int y = 0; y < 3; y++) {
+      draw_track(mdc, x*width, y*height, width, height, &g.oscillodata[x*3+y]);
+    }
+  }
+
+  BitBlt(dc, 0, 0, cr.right, cr.bottom, mdc, 0, 0, SRCCOPY);
+  SelectObject(mdc, 0);
+  DeleteObject(bitmap);
+  DeleteDC(mdc);
+  EndPaint(hwnd, &ps);
+}
+
+static LRESULT CALLBACK wndproc(
+  HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam
+) {
+  switch (msg) {
+  HANDLE_MSG(hwnd, WM_DESTROY, on_destroy);
+  HANDLE_MSG(hwnd, WM_CREATE, on_create);
+  //HANDLE_MSG(hwnd, WM_TIMER, on_timer);
+  HANDLE_MSG(hwnd, WM_PAINT, on_paint);
+  case WM_ERASEBKGND:
+    return 1;
+  case WM_USER:
+    if (!atomic_flag_test_and_set_explicit(
+      &oscilloview_g.flag, memory_order_acquire)) {
+      memcpy(g.oscillodata,
+             oscilloview_g.oscillodata,
+             sizeof(oscilloview_g.oscillodata));
+      atomic_flag_clear_explicit(&oscilloview_g.flag, memory_order_release);
+    }
+    InvalidateRect(hwnd, 0, FALSE);
+    return 0;
+  case WM_DROPFILES:
+    return SendMessage(g.parent, msg, wParam, lParam);
+  }
+  return DefWindowProc(hwnd, msg, wParam, lParam);
+}
+
+void show_oscilloview(HINSTANCE hinst, HWND parent) {
+  g.hinst = hinst;
+  g.parent = parent;
+  if (!g.oscilloview) {
+    if (!g.oscilloview_class) {
+      WNDCLASS wc = {0};
+      wc.style = 0;
+      wc.lpfnWndProc = wndproc;
+      wc.hInstance = g.hinst;
+      wc.hIcon = LoadIcon(g.hinst, MAKEINTRESOURCE(1));
+      wc.hCursor = LoadCursor(NULL, IDC_ARROW);
+      wc.hbrBackground = (HBRUSH)(COLOR_BTNFACE+1);
+      wc.lpszClassName = L"myon_fmplayer_ym2608_oscilloviewer";
+      g.oscilloview_class = RegisterClass(&wc);
+    }
+    if (!g.oscilloview_class) {
+      MessageBox(parent, L"Cannot register oscilloviewer class", L"Error", MB_ICONSTOP);
+      return;
+    }
+    g.oscilloview = CreateWindowEx(0,
+                                     MAKEINTATOM(g.oscilloview_class),
+                                     L"FMPlayer Oscilloview",
+                                     WS_CAPTION | WS_SYSMENU | WS_CLIPCHILDREN | WS_SIZEBOX | WS_MAXIMIZEBOX,
+                                     CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT,
+                                     parent, 0, g.hinst, 0);
+  } else {
+    SetForegroundWindow(g.oscilloview);
+  }
+}
diff --git a/win32/oscilloview.h b/win32/oscilloview.h
new file mode 100644
index 0000000..8849830
--- /dev/null
+++ b/win32/oscilloview.h
@@ -0,0 +1,19 @@
+#ifndef MYON_FMPLAYER_WIN32_OSCILLOVIEW_H_INCLUDED
+#define MYON_FMPLAYER_WIN32_OSCILLOVIEW_H_INCLUDED
+
+#include "libopna/opna.h"
+#include "oscillo/oscillo.h"
+
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+#include <stdatomic.h>
+
+extern struct oscilloview {
+  atomic_flag flag;
+  struct oscillodata oscillodata[LIBOPNA_OSCILLO_TRACK_COUNT];
+} oscilloview_g;
+
+void show_oscilloview(HINSTANCE hinst, HWND parent);
+
+#endif // MYON_FMPLAYER_WIN32_OSCILLOVIEW_H_INCLUDED
+