Initial support for extended FM2 channels

NSS can now encode and playback Furnace modules that make use of
YM2610's extended FM2, which allows four independent notes (one
note per operator) on channel FM2.

Author: dciabrin

nullsound/align.inc

@@ -19,14 +19,27 @@
 ;;; Constants for linking data with desired RAM alignment
 ;;;
 
-        ;; Those constants ensure that the entire state of a sound channel
-        ;; never crosses a single 256 bytes boundary, which eases additions
-        ;; and indexing.
-        ;; the .bndry statement is only local to a single file, i.e. it is
-        ;; only enforced by the assembler, not by the linker. So we have
-        ;; to tune the constants below to achieve our desired alignment.
+        ;; These macros ensure that the data between two .align_start
+        ;; and .align_end macro calls stick in a single 256 bytes
+        ;; boundary, to make 16bit arithmetic faster.
 
-        .lclequ ALIGN_OFFSET_FM,        0xbc
-        .lclequ ALIGN_OFFSET_SSG,       0x4b
-        .lclequ ALIGN_OFFSET_ADPCM_A,   0x52
-        .lclequ ALIGN_OFFSET_ADPCM_B,   0x10
+        .macro  .align_begin sym
+        _'sym'_align: .blkb _padding_'sym
+        _'sym'_begin:
+        .endm
+
+        .macro  .align_end sym
+        _'sym'_end:
+        .endm
+
+        ;; Those constants tweak the alignment of symbols in RAM to match
+        ;; our 256bytes boundaries constraints.
+        
+        .lclequ _padding_state_timer,   0x0
+        .lclequ _padding_state_fm1,     0xb5
+        .lclequ _padding_state_fm2,     0xc6
+        .lclequ _padding_state_fm3,     0x26
+        .lclequ _padding_state_fm4,     0x0
+        .lclequ _padding_state_ssg,     0x8c
+        .lclequ _padding_state_adpcm,   0x48
+        .lclequ _padding_state_adpcm_b, 0xc0

nullsound/check-bounds.py

@@ -4,11 +4,12 @@
 ram={}
 with open(sys.argv[1],"r") as f:
     for l in f.readlines():
-        m = re.match(r' *0000(F...) *(_state[^ ]*) *nullsound', l)
+        m = re.match(r' *0000(F...) *(_state[^ ]*_(begin|end)) *nullsound', l)
         if m:
             ram[m.group(2)] = m.group(1)
-range_keys=list(set([re.sub(r"_(start|end)", "", x) for x in ram]))
+range_keys=list(dict.fromkeys([re.sub(r"_(begin|end)", "", x) for x in ram]))
 for k in range_keys:
-    start, end = ram[k+"_start"], ram[k+"_end"]
+    start, end = ram[k+"_begin"], ram[k+"_end"]
+    # print(k, start, end)
     if start[0:2] != end[0:2]:
         sys.exit("range \"%s\" crosses 256 bytes boundaries: [%s, %s]"%(k, start, end))

nullsound/fx-legato.s

@@ -132,6 +132,7 @@ quick_legato_down::
 ;;; hl modified
 legato::
         set     BIT_FX_LEGATO, NOTE_FX(ix)
+        ld      a, #1
         ret
 
 
@@ -142,4 +143,5 @@ legato::
 ;;; hl modified
 legato_off::
         res     BIT_FX_LEGATO, NOTE_FX(ix)
+        ld      a, #1
         ret

nullsound/nss-adpcm-a.s

@@ -31,44 +31,46 @@
         .lclequ ADPCM_A_MAX_VOL,0x1f
 
         ;; getters for ADPCM-A state
+        .lclequ INSTR_VOL, (state_a_instr_vol-state_a)
         .lclequ OUT_VOL, (state_a_out_vol-state_a)
         .lclequ PAN, (state_a_pan-state_a)
 
         .equ    NSS_ADPCM_A_INSTRUMENT_PROPS,   4
         .equ    NSS_ADPCM_A_NEXT_REGISTER,      8
 
-        ;; specific pipeline state for SSG channel
+        ;; specific pipeline state for ADPCM-A channel
         .lclequ STATE_START_NOTE, 0x04
         .lclequ BIT_START_NOTE,      2
 
 
-
         .area  DATA
 
 
 ;;; ADPCM playback state tracker
 ;;; ------
-        ;; This padding ensures the entire _state_ssg data sticks into
-        ;; a single 256 byte boundary to make 16bit arithmetic faster
-        .blkb   ALIGN_OFFSET_ADPCM_A
 
-_state_adpcm_start:
+.align_begin state_adpcm
+;;; { ...
 
 ;;; ADPCM-A1
 state_a1:
-;;; state
+;;; { ...
 state_a_start:
-;;; stream pipeline
-state_a:
-state_a_pipeline:               .blkb   1       ; actions to run at every tick (load note, vol, other regs)
-state_a_fx:                     .blkb   1       ; enabled FX for this channel
+        
 ;;; volume state tracker
 state_a_vol_cfg:                .blkb   1       ; configured volume
 state_a_vol16:                  .blkb   2       ; current decimal volume
 ;;; FX state trackers
+state_a_fx:                     .blkb   1       ; enabled FX for this channel
 state_a_fx_vol_slide:           .blkb   SLIDE_SIZE
 state_a_fx_trigger:             .blkb   TRIGGER_SIZE
+
+;;; actions to run at the end of every tick
+state_a:
+state_a_pipeline:               .blkb   1       ; action: load note, load vol, load other regs
+
 ;;; ADPCM-A-specific state
+state_a_instr_vol:              .blkb   1       ; instrument volume
 state_a_out_vol:                .blkb   1       ; ym2610 volume after the FX pipeline
 ;;; pan
 state_a_pan:                    .blkb   1       ; configured pan (b7: left, b6: right)
@@ -89,18 +91,21 @@ state_a5:
 ;;; ADPCM-A6
 state_a6:
 .blkb   ADPCM_A_STATE_SIZE
+
+;;; ... }
 state_a6_end:
 
+;;; ... }
+.align_end state_adpcm
+
 ;;; context: current adpcm channel for opcode actions
 state_adpcm_a_channel::
         .blkb   1
 
-
 ;;; Global volume attenuation for all ADPCM-A channels
 state_adpcm_a_volume_attenuation::   .blkb   1
 
 
-_state_adpcm_end:
 
 
 
@@ -128,7 +133,7 @@ init_nss_adpcm_state_tracker::
         ld      bc, #(state_a6_end-1-state_a_start)
         ldir
         ;; init flags
-        ld      iy, #state_a1
+        ld      iy, #state_a_pipeline
         ld      bc, #ADPCM_A_STATE_SIZE
         ld      d, #6
 _a_init:
@@ -417,9 +422,9 @@ _adpcm_a_loop:
         dec     d
         jp      nz, _adpcm_a_loop
 
-        ;; d: ADPCM-A channel
-        ld      a, (state_adpcm_a_channel)
-        ld      d, a
+        ;; instrument volume
+        ld      a, (hl)
+        ld      INSTR_VOL(ix), a 
 
         pop     de
         pop     hl
@@ -583,11 +588,21 @@ _adpcm_a_clamp_level:
 
 ;;; Compute the YM2610 output volume from the current channel
 ;;; ------
+;;; IN:
+;;;    ix: FM pipeline
+;;;    iy: Volume FX
 ;;; modified: c
 compute_ym2610_a_vol::
-        ;; c: note vol for current channel
-        ld      c, VOL16+1(ix)
-
+        ;; c: instrument attenuation [-0x1f..0]
+        ld      a, #-0x1f
+        add     INSTR_VOL(ix)
+        ld      c, a
+        
+        ;; c: current volume after instrument attenuation [-0x1f..0x1f]
+        ld      a, VOL16+1(ix)
+        add     c
+        ld      c, a
+        
         ;; attenuation to match the configured ADPCM-A output level
         ld      a, (state_adpcm_a_volume_attenuation)
         neg

nullsound/nss-adpcm-b.s

@@ -48,37 +48,38 @@
         .area  DATA
 
 
-        ;; FIXME: temporary padding to ensures the next data sticks into
-        ;; a single 256 byte boundary to make 16bit arithmetic faster
-        .blkb   ALIGN_OFFSET_ADPCM_B
 
 
 ;;; ADPCM playback state tracker
 ;;; ------
-
-_state_adpcm_b_start:
+.align_begin state_adpcm_b
+;;; { ...
 
 ;;; ADPCM-B mirrored state
-;;; state
+;;; { ...
 state_b_start:
-;;; additional note and FX state tracker
-state_b_note_fx:                .blkb   1       ; enabled note FX for this channel
+
+;;; note state tracker
 state_b_note_cfg:               .blkb   1       ; configured note
 state_b_note16:                 .blkb   2       ; current decimal note
+;;; note FX state tracker
+state_b_note_fx:                .blkb   1       ; enabled note FX for this channel
 state_b_fx_note_slide:          .blkb   SLIDE_SIZE
 state_b_fx_vibrato:             .blkb   VIBRATO_SIZE
 state_b_fx_arpeggio:            .blkb   ARPEGGIO_SIZE
 state_b_fx_legato:              .blkb   LEGATO_SIZE
-;;; stream pipeline
-state_b:
-state_b_pipeline:               .blkb   1       ; actions to run at every tick (load note, vol, other regs)
-state_b_fx:                     .blkb   1       ; enabled FX for this channel
 ;;; volume state tracker
 state_b_vol_cfg:                .blkb   1       ; configured volume
 state_b_vol16:                  .blkb   2       ; current decimal volume
 ;;; FX state trackers
+state_b_fx:                     .blkb   1       ; enabled FX for this channel
 state_b_fx_vol_slide:           .blkb   SLIDE_SIZE
 state_b_trigger:                .blkb   TRIGGER_SIZE
+
+;;; actions to run at the end of every tick
+state_b:
+state_b_pipeline:               .blkb   1       ; action: load note, load vol, load other regs
+
 ;;; ADPCM-B-specific state
 ;;; Note
 state_b_note:
@@ -94,16 +95,17 @@ state_b_out_vol:                .blkb   1       ; ym2610 volume after the FX pip
 ;;; pan
 state_b_pan:                    .blkb   1       ; configured pan (b7: left, b6: right)
 ;;;
+
+;;; ... }
 state_b_end:
 
+;;; ... }
+.align_end state_adpcm_b
 
 ;;; Global volume attenuation for ADPCM-B channel
 state_adpcm_b_volume_attenuation::   .blkb   1
 
 
-_state_adpcm_b_end:
-
-
 
         .area  CODE
 
@@ -388,6 +390,7 @@ adpcm_b_instrument::
 
         ;; a: start of ADPCM-B property registers
         ld      a, #REG_ADPCM_B_ADDR_START_LSB
+        ;; TODO remove useless +0?
         add     b
 
 _adpcm_b_loop: