sound, faster resampler for SMS FM

pico/pico_int.h

@@ -346,6 +346,7 @@ struct PicoMisc
 #define PMS_HW_LCD	0x2   // GG LCD
 #define PMS_HW_JAP	0x4   // japanese system
 #define PMS_HW_FM	0x8   // FM sound
+#define PMS_HW_FMUSED	0x10  // FM sound accessed
 
 #define PMS_MAP_AUTO	0
 #define PMS_MAP_SEGA	1

pico/sms.c

@@ -221,6 +221,7 @@ static void z80_sms_out(unsigned short a, unsigned char d)
       {
         case 0xf0:
           // FM reg port
+          Pico.m.hardware |= PMS_HW_FMUSED;
           YM2413_regWrite(d);
           break;
         case 0xf1:

pico/sound/sound.c

@@ -27,8 +27,11 @@ s16 cdda_out_buffer[2*1152];
 // sn76496
 extern int *sn76496_regs;
 
+// FM resampling polyphase FIR
+static resampler_t *fmresampler;
+static int (*PsndFMUpdate)(s32 *buffer, int length, int stereo, int is_buf_empty);
+
 // ym2413
-#define YM2413_CLK 3579545
 static OPLL *opll = NULL;
 static OPLL old_opll;
 static struct {
@@ -36,6 +39,14 @@ static struct {
   uint8_t reg[sizeof(opll->reg)];
 } opll_buf;
 
+
+void YM2413_regWrite(unsigned data){
+  OPLL_writeIO(opll,0,data);
+}
+void YM2413_dataWrite(unsigned data){
+  OPLL_writeIO(opll,1,data);
+}
+
 PICO_INTERNAL void *YM2413GetRegs(void)
 {
   memcpy(opll_buf.reg, opll->reg, sizeof(opll->reg));
@@ -54,12 +65,9 @@ PICO_INTERNAL void YM2413UnpackState(void)
   opll->adr = opll_buf.adr;
 }
 
-static resampler_t *fmresampler;
-static int (*PsndFMUpdate)(s32 *buffer, int length, int stereo, int is_buf_empty);
-
 PICO_INTERNAL void PsndInit(void)
 {
-  opll = OPLL_new(YM2413_CLK, PicoIn.sndRate);
+  opll = OPLL_new(OSC_NTSC/15, OSC_NTSC/15/72);
   OPLL_setChipType(opll,0);
   OPLL_reset(opll);
 }
@@ -95,7 +103,25 @@ static int YM2612UpdateFIR(s32 *buffer, int length, int stereo, int is_buf_empty
   return ymchans;
 }
 
-static void YM2612_setup_FIR(int inrate, int outrate, int stereo)
+// resample SMS FM from its native 49716Hz/49262Hz with polyphase FIR filter
+static void YM2413Update(s32 *buffer, int length, int stereo)
+{
+  while (length-- > 0) {
+    int16_t getdata = OPLL_calc(opll) * 3;
+    *buffer++ = getdata;
+    buffer += stereo; // only left for stereo, to be mixed to right later
+  }
+}
+
+static int YM2413UpdateFIR(s32 *buffer, int length, int stereo, int is_buf_empty)
+{
+  if (!is_buf_empty) memset(buffer, 0, (length << stereo) * sizeof(*buffer));
+  resampler_update(fmresampler, buffer, length, YM2413Update);
+  return 0;
+}
+
+// FIR setup, looks for a close enough rational number matching the ratio
+static void YMFM_setup_FIR(int inrate, int outrate, int stereo)
 {
   int mindiff = 999;
   int diff, mul, div;
@@ -132,21 +158,31 @@ void PsndRerate(int preserve_state)
   void *state = NULL;
   int target_fps = Pico.m.pal ? 50 : 60;
   int target_lines = Pico.m.pal ? 313 : 262;
+  int sms_clock = Pico.m.pal ? OSC_PAL/15 : OSC_NTSC/15;
   int ym2612_clock = Pico.m.pal ? OSC_PAL/7 : OSC_NTSC/7;
   int ym2612_rate = YM2612_NATIVE_RATE();
+  int ym2413_rate = (sms_clock + 36) / 72;
 
   if (preserve_state) {
     state = malloc(0x204);
     if (state == NULL) return;
     ym2612_pack_state();
     memcpy(state, YM2612GetRegs(), 0x204);
+
+    if (opll != NULL)
+       memcpy(&old_opll, opll, sizeof(OPLL)); // remember old state
   }
-  if ((PicoIn.opt & POPT_EN_FM_FILTER) && ym2612_rate != PicoIn.sndRate) {
+  if (PicoIn.AHW & PAHW_SMS) {
+    OPLL_setRate(opll, ym2413_rate);
+    OPLL_reset(opll);
+    YMFM_setup_FIR(ym2413_rate, PicoIn.sndRate, 0);
+    PsndFMUpdate = YM2413UpdateFIR;
+  } else if ((PicoIn.opt & POPT_EN_FM_FILTER) && ym2612_rate != PicoIn.sndRate) {
     // polyphase FIR resampler, resampling directly from native to output rate
     YM2612Init(ym2612_clock, ym2612_rate,
         ((PicoIn.opt&POPT_DIS_FM_SSGEG) ? 0 : ST_SSG) |
         ((PicoIn.opt&POPT_EN_FM_DAC)    ? ST_DAC : 0));
-    YM2612_setup_FIR(ym2612_rate, PicoIn.sndRate, PicoIn.opt & POPT_EN_STEREO);
+    YMFM_setup_FIR(ym2612_rate, PicoIn.sndRate, PicoIn.opt & POPT_EN_STEREO);
     PsndFMUpdate = YM2612UpdateFIR;
   } else {
     YM2612Init(ym2612_clock, PicoIn.sndRate,
@@ -158,20 +194,17 @@ void PsndRerate(int preserve_state)
     // feed it back it's own registers, just like after loading state
     memcpy(YM2612GetRegs(), state, 0x204);
     ym2612_unpack_state();
+
+    if (opll != NULL) {
+      memcpy(&opll->adr, &old_opll.adr, sizeof(OPLL)-20); // restore old state
+      OPLL_forceRefresh(opll);
+    }
   }
 
   if (preserve_state) memcpy(state, sn76496_regs, 28*4); // remember old state
   SN76496_init(Pico.m.pal ? OSC_PAL/15 : OSC_NTSC/15, PicoIn.sndRate);
   if (preserve_state) memcpy(sn76496_regs, state, 28*4); // restore old state
 
-  if(opll != NULL){
-    if (preserve_state) memcpy(&old_opll, opll, sizeof(OPLL)); // remember old state
-    OPLL_setRate(opll, PicoIn.sndRate);
-    OPLL_reset(opll);
-    if (preserve_state) memcpy(&opll->adr, &old_opll.adr, sizeof(OPLL)-20); // restore old state
-    OPLL_forceRefresh(opll);
-  }
-
   if (state)
     free(state);
 
@@ -284,12 +317,12 @@ PICO_INTERNAL void PsndDoPSG(int cyc_to)
   SN76496Update(PicoIn.sndOut + pos, len, stereo);
 }
 
-#if 0
+PICO_INTERNAL void PsndDoSMSFM(int cyc_to)
-PICO_INTERNAL void PsndDoYM2413(int cyc_to)
 {
   int pos, len;
   int stereo = 0;
-  s16 *buf;
+  s32 *buf32 = PsndBuffer;
+  s16 *buf = PicoIn.sndOut;
 
   // nothing to do if sound is off
   if (!PicoIn.sndOut) return;
@@ -312,22 +345,15 @@ PICO_INTERNAL void PsndDoYM2413(int cyc_to)
     pos <<= 1;
   }
 
-  buf = PicoIn.sndOut + pos;
+  if (Pico.m.hardware & PMS_HW_FMUSED) {
-  while (len-- > 0) {
+    buf += pos;
-    int16_t getdata = OPLL_calc(opll) * 3;
+    PsndFMUpdate(buf32, len, 0, 0);
-    *buf++ += getdata;
+    while (len--) {
-    buf += stereo; // only left for stereo, to be mixed to right later
+      *buf++ += *buf32++;
+      buf += stereo;
+    }
   }
 }
-#endif
-
-void YM2413_regWrite(unsigned data){
-  OPLL_writeIO(opll,0,data);
-}
-void YM2413_dataWrite(unsigned data){
-  OPLL_writeIO(opll,1,data);
-}
-
 
 PICO_INTERNAL void PsndDoFM(int cyc_to)
 {
@@ -515,6 +541,7 @@ PICO_INTERNAL void PsndGetSamples(int y)
 
 static int PsndRenderMS(int offset, int length)
 {
+  s32 *buf32 = PsndBuffer;
   int stereo = (PicoIn.opt & 8) >> 3;
   int psglen = ((Pico.snd.psg_pos+0x80000) >> 20);
   int ym2413len = ((Pico.snd.ym2413_pos+0x80000) >> 20);
@@ -536,11 +563,11 @@ static int PsndRenderMS(int offset, int length)
     s16 *ym2413buf = PicoIn.sndOut + (ym2413len << stereo);
     Pico.snd.ym2413_pos += (length-ym2413len) << 20;
     int len = (length-ym2413len);
-    if (PicoIn.opt & POPT_EN_YM2413){
+    if (Pico.m.hardware & PMS_HW_FMUSED) {
-      while (len-- > 0) {
+      PsndFMUpdate(buf32, len, 0, 0);
-        int16_t getdata = OPLL_calc(opll) * 3;
+      while (len--) {
-        *ym2413buf += getdata;
+        *ym2413buf++ += *buf32++;
-        ym2413buf += 1<<stereo;
+        ym2413buf += stereo;
       }
     }
   }