git.sur5r.net Git - cc65/blob - libsrc/pce/psg.s

   1         .export         psg_init
   2
   3         .include        "pce.inc"
   4
   5         .segment        "ONCE"
   6 psg_init:
   7         clx
   8         stz     PSG_GLOBAL_PAN          ; Silence global balance
   9
  10 psg_clear_loop:
  11         stx     PSG_CHAN_SELECT         ; Select channel
  12         stz     PSG_FREQ_LO             ; Clear frequency LSB
  13         stz     PSG_FREQ_HI             ; Clear frequency MSB
  14         stz     PSG_CHAN_CTRL           ; Clear volume
  15         stz     PSG_CHAN_PAN            ; Clear balance
  16         stz     PSG_NOISE               ; Clear noise control
  17         stz     PSG_LFO_FREQ            ; Clear LFO frequency
  18         stz     PSG_LFO_CTRL            ; Clear LFO control
  19
  20         cly
  21 psg_clear_waveform:
  22         stz     PSG_CHAN_DATA           ; Clear waveform byte
  23         iny
  24         cpy     #$20
  25         bne     psg_clear_waveform
  26
  27         inx
  28         cpx     #$06
  29         bne     psg_clear_loop
  30         rts