nss: fix playback of ADPCM-B and add support for looping

nullsound/nss-adpcm.s

@@ -40,6 +40,9 @@
 state_adpcm_a_channel::
  .db 0
 
+;;; current ADPCM-B instrumment play command (with loop)
+state_adpcm_b_start_cmd::
+ .db 0
 
 
  .area CODE
@@ -51,6 +54,8 @@ state_adpcm_a_channel::
 init_nss_adpcm_state_tracker::
  ld a, #0
  ld (state_adpcm_a_channel), a
+ ld a, #0x80 ; start flag
+ ld (state_adpcm_b_start_cmd), a
  ret
 
 ;;; Reset ADPCM-A playback state.
@@ -354,6 +359,14 @@ _adpcm_b_loop:
  dec d
  jp nz, _adpcm_b_loop
 
+ ;; play command, with/without loop bit
+ ld a, #0x80
+ bit 0, (hl)
+ jr z, _adpcm_b_post_loop_chk
+ set 4, a
+_adpcm_b_post_loop_chk:
+ ld (state_adpcm_b_start_cmd), a
+
  pop de
  pop hl
  pop bc
@@ -463,7 +476,9 @@ _no_delta_shift:
 
  ;; start the ADPCM-B channel
  ld b, #REG_ADPCM_B_START_STOP
- ld c, #0x80 ; start flag
+ ;; start command (with loop when configured)
+ ld a, (state_adpcm_b_start_cmd)
+ ld c, a
  call ym2610_write_port_a
 
  pop hl

tools/furtool.py

@@ -81,6 +81,11 @@ def uf4(self):
  self.pos += 4
  return res
 
+ def s4(self):
+ res = unpack_from("<i", self.data, self.pos)[0]
+ self.pos += 4
+ return res
+
  def ustr(self):
  res = []
  b = self.u1()
@@ -208,6 +213,7 @@ class adpcm_b_sample:
 class pcm_sample:
  name: str = ""
  data: bytearray = field(default=b"", repr=False)
+ loop: bool = False
 
 
 @dataclass
@@ -239,6 +245,7 @@ class adpcm_a_instrument:
 class adpcm_b_instrument:
  name: str = ""
  sample: adpcm_b_sample = None
+ loop: bool = False
 
 
 def read_fm_instrument(bs):
@@ -418,6 +425,9 @@ def asm_ident(x):
  if itype in [37, 38]:
  ins = {37: adpcm_a_instrument,
  38: adpcm_b_instrument}[itype]()
+ # ADPCM-B loop information
+ if itype == 38:
+ ins.loop = smp[sample].loop
  if isinstance(smp[sample],pcm_sample):
  # the sample is encoded in PCM, so it has to be converted
  # to be played back on the hardware.
@@ -469,16 +479,17 @@ def read_sample(bs):
  else:
  error("sample '%s' is of unsupported type: %d"%(str(name), stype))
  # assert c4_freq == {5: 18500, 6: 44100}[stype]
- bs.u1() # unused play direction
+ bs.u1() # unused loop direction
  bs.u2() # unused flags
- bs.read(8) # unused looping info
+ loop_start, loop_end = bs.s4(), bs.s4()
  bs.read(16) # unused rom allocation
  data = bs.read(data_bytes) + bytearray(data_padding)
  # generate a ASM name for the instrument
  insname = re.sub(r"\W|^(?=\d)", "_", name).lower()
  ins = {5: adpcm_a_sample,
  6: adpcm_b_sample,
  16: pcm_sample}[stype](insname, data)
+ ins.loop = loop_start != -1 and loop_end != -1
  return ins
 
 
@@ -501,6 +512,12 @@ def read_samples(ptrs, bs):
  smp.append(read_sample(bs))
  return smp
 
+def check_for_unused_samples(smp, bs):
+ # module might have unused samples, leave them in the output
+ # if these are pcm_samples, convert them to adpcm_a to avoid errors
+ for i,s in enumerate(smp):
+ if isinstance(s, pcm_sample):
+ smp[i] = convert_sample(s, 37)
 
 def asm_fm_instrument(ins, fd):
  dtmul = tuple(ebit(ins.ops[i].detune, 6, 4) | ebit(ins.ops[i].multiply, 3, 0) for i in range(4))
@@ -597,6 +614,8 @@ def asm_adpcm_instrument(ins, fd):
  print("%s:" % ins.name, file=fd)
  print(" .db %s_START_LSB, %s_START_MSB ; start >> 8" % (name, name), file=fd)
  print(" .db %s_STOP_LSB, %s_STOP_MSB ; stop >> 8" % (name, name), file=fd)
+ if isinstance(ins, adpcm_b_instrument):
+ print(" .db 0x%02x ; loop" % (ins.loop,), file=fd)
  print("", file=fd)
 
 
@@ -683,11 +702,7 @@ def main():
  m = read_module(bs)
  smp = read_samples(m.samples, bs)
  ins = read_instruments(m.instruments, smp, bs)
- # module might have unused samples, leave them in the output
- # if these are pcm_samples, convert them to adpcm_a to avoid errors
- for i,s in enumerate(smp):
- if isinstance(s, pcm_sample):
- smp[i] = convert_sample(s, 37)
+ check_for_unused_samples(smp, bs)
 
  if arguments.output:
  outfd = open(arguments.output, "w")

tools/nsstool.py

@@ -74,6 +74,12 @@ def to_nss_note(furnace_note):
  nss_note = (octave << 4) + note
  return nss_note
 
+def to_nss_b_note(furnace_note):
+ octave = (furnace_note // 12) - 6
+ note = furnace_note % 12
+ nss_note = (octave << 4) + note
+ return nss_note
+
 def make_ssg_note(furnace_note):
  octave = (furnace_note // 12) - 5
  note = furnace_note % 12
@@ -413,7 +419,7 @@ def convert_b_row(row, channel, opcodes):
  if row.note == 180:
  opcodes.append(b_stop())
  else:
- opcodes.append(b_note(to_nss_note(row.note)))
+ opcodes.append(b_note(to_nss_b_note(row.note)))
  return jmp_to_order