Routines
Prev: FCAB Up: Map Next: FD0C
FCB3: Play Menu Music Tick
Used by the routine at Wait_KeyWithMenuMusic.
One tick of the two-channel menu tune while the key-scan waits. Reads both stream cursors, looks each byte up in Table_MenuMusicDelay, then either bit-bangs the speaker on port FE (toggling bit 04 via 10) or takes the Continue_MenuMusicTick continue path. Called every pass of Wait_KeyWithMenuMusic_Loop.
Play_MenuMusicTick FCB3 LD HL,$FC87 Point HL at music cursor one (FC87).
FCB6 CALL Read_MusicStreamByte Call Read_MusicStreamByte to read the next stream-one byte.
FCB9 LD ($FC84),A Store it at MenuMusic_Workspace.
FCBC LD HL,$FC8B Point HL at music cursor two (FC8B).
FCBF CALL Read_MusicStreamByte Call Read_MusicStreamByte to read the next stream-two byte.
FCC2 LD ($FC85),A Store it at FC85.
FCC5 LD HL,$FC84 Point HL at stream-one's stored byte (MenuMusic_Workspace).
FCC8 CALL Decode_MusicDelay Call Decode_MusicDelay to decode its delay pair.
FCCB RL E Rotate E left through carry to test the channel flag.
FCCD JP C,Continue_MenuMusicTick If carry is set, jump to Continue_MenuMusicTick for the continue path.
FCD0 PUSH HL Stash the decoded delay on the stack.
FCD1 LD HL,$FC85 Point HL at stream-two's stored byte (FC85).
FCD4 CALL Decode_MusicDelay Call Decode_MusicDelay to decode its delay pair.
FCD7 POP DE Restore stream-one's delay into DE.
FCD8 LD A,H If stream-one's duration is not 01, jump to Play_MenuMusic_PreparePulse.
FCD9 DEC A
FCDA JR NZ,Play_MenuMusic_PreparePulse
FCDC LD A,D If stream-two's duration is 01, jump to Hold_MenuMusicSilence.
FCDD DEC A
FCDE JR Z,Hold_MenuMusicSilence
Prepare the speaker output value and enter the tone pulse loop.
Play_MenuMusic_PreparePulse FCE0 LD A,($FC8F) Load the delay phase from FC8F into C and clear B.
FCE3 LD C,A
FCE4 LD B,$00
FCE6 LD A,($FC86) Load the border and speaker bits from FC86.
FCE9 EX AF,AF' Switch to the alternate accumulator.
FCEA LD A,($FC86) Reload the border and speaker bits from FC86.
FCED LD IXh,D Keep the inner delay count in IXh.
FCEF LD D,$10 Load D with 10 (speaker bit mask).
This entry point is used by the routine at Play_MenuMusic_PulseTail.
Inner tone loop: burn delay, write port FE, and toggle the speaker bit.
Play_MenuMusic_PulseLoop FCF1 NOP Timing pad before the port write.
FCF2 NOP
This entry point is used by the routine at Play_MenuMusic_PulseTail.
Write the speaker level and advance the dual delay counters.
Play_MenuMusic_PulseWrite FCF3 EX AF,AF' Switch back to the primary accumulator.
FCF4 DEC E Decrease the fine delay in E.
FCF5 OUT ($FE),A Write the border and speaker bits to port FE.
FCF7 JR NZ,Play_MenuMusic_PulseTail If the fine delay remains, jump to Play_MenuMusic_PulseTail.
FCF9 LD E,IXh Reload the fine delay from IXh.
FCFB XOR D Toggle the speaker bit (10) in A via D.
FCFC EX AF,AF' Switch to the alternate accumulator.
FCFD DEC L Decrease the coarse delay in L.
FCFE JP NZ,Play_MenuMusic_PulseTailWrite If the coarse delay remains, jump to Play_MenuMusic_PulseTailWrite.
This entry point is used by the routine at Play_MenuMusic_PulseTail.
Reload the coarse delay from H and keep pulsing.
Play_MenuMusic_ReloadCoarse FD01 OUT ($FE),A Write the speaker level to port FE.
FD03 LD L,H Copy H into L to reload the coarse delay.
FD04 XOR D Toggle the speaker bit (10) in A via D.
FD05 DJNZ Play_MenuMusic_PulseLoop Decrease B and loop to Play_MenuMusic_PulseLoop while the outer count remains.
FD07 INC C Advance the phase counter in C.
FD08 JP NZ,Play_MenuMusic_PulseWrite If the phase remains, jump to Play_MenuMusic_PulseWrite.
FD0B RET Return.
Prev: FCAB Up: Map Next: FD0C