From a8b0ecfc868834089c61cbd5595c4b0139859747 Mon Sep 17 00:00:00 2001
From: Zack Buhman <zack@buhman.org>
Date: Wed, 25 Jan 2023 23:59:05 -0800
Subject: [PATCH] update sound example

This is still an incomplete code fragment, but it does produce sound.
---
 example/sound.c | 99 +++++++++++++++++++++++++++++++++++++++----------
 1 file changed, 80 insertions(+), 19 deletions(-)

diff --git a/example/sound.c b/example/sound.c
index 8dbb3fe..8fc3b66 100644
--- a/example/sound.c
+++ b/example/sound.c
@@ -1,30 +1,91 @@
-  //
-  // scsp
-  //
+//
+// scsp
+//
 
-  // The SCSP will initialize the internal registers, etc. for about 30µ sec
-  // after the reset has been released.  For this reason, access is not allowed
-  // during the 30µ sec.
+// The SCSP will initialize the internal registers, etc. for about 30µ sec
+// after the reset has been released.  For this reason, access is not allowed
+// during the 30µ sec.
 
-  // Before downloading anything, make sure to set MEM4MB bit to 1 and DAC18B
-  // bit to 0 within the sound CPU (address) 10400H address.
+// Before downloading anything, make sure to set MEM4MB bit to 1 and DAC18B
+// bit to 0 within the sound CPU (address) 10400H address.
+
+smpc.reg.COMREG = COMREG__SNDON;
+while (smpc.reg.OREG31 != 0b00000110) {}
+for (long i = 0; i < 807; i++) { asm volatile ("nop"); }   // wait for (way) more than 30µs
+
+scsp.reg.common[0] = SCSP__0__MEM4MB | SCSP__0__DAC18B;
+
+u16 * m68k_main_start = (u16 *)&_binary_m68k_main_bin_start;
+u32 m68k_main_size = (u32)&_binary_m68k_main_bin_size;
+copy_16(m68k_main_start, &scsp.ram.u16[0], m68k_main_size);
+
+smpc.reg.COMREG = COMREG__SNDOFF;
+while (smpc.reg.OREG31 != 0b00000111) {}
+for (long i = 0; i < 807; i++) { asm volatile ("nop"); }   // wait for (way) more than 30µs
+
+smpc.reg.COMREG = COMREG__SNDON;
+while (smpc.reg.OREG31 != 0b00000110) {}
+for (long i = 0; i < 807; i++) { asm volatile ("nop"); }   // wait for (way) more than 30µs
+
+scsp.reg.common[0] = SCSP__0__MEM4MB | SCSP__0__DAC18B;
+
+///
+
+static signed int left_phase;
+
+static void fill_data(int16_t * output, int len)
+{
+  for (int i = 0; i < len; i++) {
+    *output++ = (signed short)left_phase;
+    left_phase += 327 / 2;
+    if (left_phase >= 32767) left_phase = -32768;
+  }
+}
+
+#include "scsp.h"
+
+void main_sound(void)
+{
+  while ((smpc.reg.SF & 0x01) == 1);
+
+  smpc.reg.SF = 1;
 
   smpc.reg.COMREG = COMREG__SNDON;
+  while ((smpc.reg.SF & 0x01) == 1);
   while (smpc.reg.OREG31 != 0b00000110) {}
+
   for (long i = 0; i < 807; i++) { asm volatile ("nop"); }   // wait for (way) more than 30µs
 
-  scsp.reg.common[0] = SCSP__0__MEM4MB | SCSP__0__DAC18B;
+  scsp.reg.common[0] = SCSP__0__MEM4MB | SCSP__0__DAC18B | 15;
 
-  u16 * m68k_main_start = (u16 *)&_binary_m68k_main_bin_start;
-  u32 m68k_main_size = (u32)&_binary_m68k_main_bin_size;
-  copy_16(m68k_main_start, &scsp.ram.u16[0], m68k_main_size);
+  left_phase = 0;
+  fill_data((int16_t*)&scsp.ram.u16[0], 44100);
 
-  smpc.reg.COMREG = COMREG__SNDOFF;
-  while (smpc.reg.OREG31 != 0b00000111) {}
-  for (long i = 0; i < 807; i++) { asm volatile ("nop"); }   // wait for (way) more than 30µs
+  scsp_slot& slot = scsp.reg.slot[0];
 
-  smpc.reg.COMREG = COMREG__SNDON;
-  while (smpc.reg.OREG31 != 0b00000110) {}
-  for (long i = 0; i < 807; i++) { asm volatile ("nop"); }   // wait for (way) more than 30µs
+  while (1) {
+    left_phase = 0;
+    fill_data((int16_t*)&scsp.ram.u16[0], 44100);
 
-  scsp.reg.common[0] = SCSP__0__MEM4MB | SCSP__0__DAC18B;
+    slot.field[0] = (1 << 11) | (1 << 5); // kx
+    slot.field[1] = 0; // start_addr
+    slot.field[2] = 0; // loop start address
+    slot.field[3] = 44100; // loop end address
+    slot.field[4] = 31; // d2r d1r ar
+    //slot.field[5] = (1 << 14) | (0xf << 10) | 0; // krs dl rr (key_decay_release)
+    slot.field[5] = 31; // krs dl rr (key_decay_release)
+    slot.field[6] = 1 << 3; // tl (attenuation)
+    slot.field[7] = 0; // mdl mdxsl mdysl (fm_data)
+    slot.field[8] = 0; // oct fns (ofc_fns)
+    slot.field[9] = 0; // lfof plfows (lfo_data)
+    slot.field[10] = 0; // isel imxl (input_sel)
+    slot.field[11] = (7 << 13); // disdl dipan efpan (pan_send)
+
+    slot.field[0] |= (1 << 12);
+
+    for (int32_t i = 0; i < 800000; i++) { asm volatile ("nop"); }
+
+    slot.field[0] |= (1 << 12);
+    slot.field[0] = 0;
+  }
+}