WIP global volume

Author: dciabrin

nullsound/Makefile.in

@@ -19,7 +19,7 @@ all: nullsound.lib linkcheck.map
 -include ../Makefile.config
 
 INCLUDE_FILES=helpers ports ym2610
-OBJS=entrypoint bios-commands adpcm ym2610 stream timer nss-fm nss-adpcm nss-ssg fx-vibrato fx-slide
+OBJS=entrypoint bios-commands adpcm ym2610 stream timer nss-fm nss-adpcm nss-ssg fx-vibrato fx-slide volume
 LIB=nullsound.lib
 
 VERSION=@version@

nullsound/nss-adpcm.s

@@ -235,6 +235,9 @@ _adpcm_a_loop:
         add     d
         ld      l, a
         ld      a, (hl)
+        ;; add global volume attenuation and clamp
+        call    adpcm_a_global_attenuation
+
         or      #0xc0           ; default pan (L+R)
         ld      c, a
 
@@ -344,6 +347,32 @@ _off_bit:
         ld      a, #1
         ret
 
+;;; TODO doc
+;;; modified: c
+adpcm_a_global_attenuation::
+        ld      c, a
+        ld      a, (state_volume_adpcm_a_global)
+        neg
+        add     c
+        bit     7, a
+        jr      z, _adpcm_a_post_global_clamp
+        ld      a, #0
+_adpcm_a_post_global_clamp:
+        ret
+
+
+adpcm_b_global_attenuation::
+        ld      c, a
+        ld      a, (state_volume_adpcm_b_global)
+        cp      c
+        jr      nc, _adpcm_b_vol_clamp
+        neg
+        add     c
+        ret
+_adpcm_b_vol_clamp:
+        ld      a, #0
+        ret
+        
 
 ;;; ADPCM_A_VOL
 ;;; Set playback volume of the current ADPCM-A channel
@@ -373,6 +402,9 @@ adpcm_a_vol::
 
         ;; c: volume + default pan (L/R)
         ld      a, c
+        ;; add global volume attenuation and clamp
+        call    adpcm_a_global_attenuation
+
         or      #0xc0
         ld      c, a
 
@@ -443,6 +475,7 @@ _adpcm_b_post_loop_chk:
         ;;  current volume
         ld      b, #REG_ADPCM_B_VOLUME
         ld      a, (state_adpcm_b_vol)
+        call    adpcm_b_global_attenuation
         ld      c, a
         call    ym2610_write_port_a
 
@@ -585,6 +618,7 @@ adpcm_b_vol::
 
         ;; new configured volume for ADPCM-B
         ld      (state_adpcm_b_vol), a
+        call    adpcm_b_global_attenuation
 
         ;; set volume in the YM2610
         ld      b, #REG_ADPCM_B_VOLUME

nullsound/nss-fm.s

@@ -62,7 +62,7 @@ state_fm_channel::
         .db     0
 state_fm_ym2610_channel::
         .db     0
-
+        
 ;;; FM mirrored state
 state_fm:
 ;;; FM1
@@ -388,7 +388,7 @@ _ops_loop:
         bit     0, e
         jr      z, _ops_no_out
 _ops_out:
-        ;; configure OP from instrument TL faded with current volume
+        ;; configure OP from instrument's TL faded with current volume
         ;; current OP's total level per instrument
         ld      a, (hl)
         ;; mix with note volume and clamp
@@ -397,7 +397,16 @@ _ops_out:
         jr      z, _ops_post_clamp
         ld      a, #127
 _ops_post_clamp:
+        ;;  CHECK aren't we always below 128 here?
         and     #0x7f
+        ;; apply global FM volume attenuation, clamp to 0
+        ld      c, a
+        ld      a, (state_volume_fm_global)
+        add     c
+        bit     7, a
+        jr      z, _ops_post_global_clamp
+        ld      a, #127
+_ops_post_global_clamp:
         ld      c, a
         jr      _ops_set_and_next
 _ops_no_out:

nullsound/nss-ssg.s

@@ -363,12 +363,21 @@ ssg_mix_volume::
         ;; l: current note volume for channel
         ld      l, (hl)
 
-        ;; mix volumes, min to 0
+        ;; attenuate instrument volume with note volume, clamp to 0
         ld      a, c
         sub     l
         jr      nc, _mix_set
         ld      a, #0
 _mix_set:
+        ;; apply global SSG volume attenuation, clamp to 0
+        ld      c, a
+        ld      a, (state_volume_ssg_global)
+        neg
+        add     c
+        bit     7, a
+        jr      z, _ssg_post_global_clamp
+        ld      a, #0
+_ssg_post_global_clamp:
         ld      c, a
         ld      a, b
         add     #REG_SSG_A_VOLUME

nullsound/stream.s

@@ -360,6 +360,8 @@ _stream_play_init_loop:
         ;; reset state trackers
         call    snd_stream_reset_state
 
+        call    init_volume_state_tracker
+
         ;; start stream playback, it will get preempted
         ;; as soon as a wait opcode shows up in the stream
         call    update_stream_state_tracker

nullsound/volume.s

@@ -0,0 +1,56 @@
+;;;
+;;; nullsound - modular sound driver
+;;; Copyright (c) 2024 Damien Ciabrini
+;;; This file is part of ngdevkit
+;;;
+;;; ngdevkit is free software: you can redistribute it and/or modify
+;;; it under the terms of the GNU Lesser General Public License as
+;;; published by the Free Software Foundation, either version 3 of the
+;;; License, or (at your option) any later version.
+;;;
+;;; ngdevkit is distributed in the hope that it will be useful,
+;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;; GNU Lesser General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU Lesser General Public License
+;;; along with ngdevkit.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; The following driver is based on doc found on neogeodev wiki
+;;; https://wiki.neogeodev.org/index.php?title=68k/Z80_communication
+
+        .module nullsound
+
+        .include "ym2610.inc"
+        .include "ports.inc"
+
+
+;;;
+;;; Volume state tracker
+;;; -------------------
+;;;  Keep track of the global volume and fade out state
+;;;
+        .area  DATA
+
+;;; Global volume attenuation for FM channels
+state_volume_fm_global::        .blkb   1
+;;; Global volume attenuation for SSG channels
+state_volume_ssg_global::       .blkb   1
+;;; Global volume attenuation for ADPCM-A channels
+state_volume_adpcm_a_global::   .blkb   1
+;;; Global volume attenuation for ADPCM-B channels
+state_volume_adpcm_b_global::   .blkb   1
+
+
+        .area  CODE
+
+init_volume_state_tracker::
+        ld      a, #0x0
+        ld      (state_volume_fm_global), a
+        ld      a, #0x0
+        ld      (state_volume_ssg_global), a
+        ld      a, #0x0
+        ld      (state_volume_adpcm_a_global), a
+        ld      a, #0x0
+        ld      (state_volume_adpcm_b_global), a
+        ret