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

   1
   2                 .include "pce.inc"
   3
   4                 .export psg_init
   5
   6 psg_init:
   7                 clx
   8                 stx     $0800   ; Select channel
   9 psg_clear_loop:
  10                 stz     $0801   ; Clear global balance
  11                 stz     $0802   ; Clear frequency LSB
  12                 stz     $0803   ; Clear frequency MSB
  13                 stz     $0804   ; Clear volume
  14                 stz     $0805   ; Clear balance
  15                 stz     $0807   ; Clear noise control
  16                 stz     $0808   ; Clear LFO frequency
  17                 stz     $0809   ; Clear LFO control
  18
  19                 cly
  20 psg_clear_waveform:     stz     $0806   ; Clear waveform byte
  21                 iny
  22                 cpy     #$20
  23                 bne     psg_clear_waveform
  24
  25                 inx
  26                 cpx     #$06
  27                 bne     psg_clear_loop
  28                 rts
  29