diff options
Diffstat (limited to 'src-68k/echo.68k')
| -rw-r--r-- | src-68k/echo.68k | 51 |
1 files changed, 34 insertions, 17 deletions
diff --git a/src-68k/echo.68k b/src-68k/echo.68k index e6682bd..7abdbf8 100644 --- a/src-68k/echo.68k +++ b/src-68k/echo.68k @@ -161,10 +161,6 @@ Echo_PlaySFX: bsr Echo_SendCommandAddr ; Send command to Echo move.w (sp)+, d0 ; Restore register - Echo_Z80Request ; We need Z80 RAM access... - ori.b #$01, ($A01FF0) ; Force SFX flag to be on - Echo_Z80Release ; OK done with it for real - rts ; End of subroutine ;**************************************************************************** @@ -178,10 +174,6 @@ Echo_StopSFX: bsr Echo_SendCommand ; Send command to Echo move.w (sp)+, d0 ; Restore register - Echo_Z80Request ; We need Z80 RAM access... - andi.b #$FE, ($A01FF0) ; Force SFX flag to be off - Echo_Z80Release ; OK done with it for real - rts ; End of subroutine ;**************************************************************************** @@ -197,10 +189,6 @@ Echo_PlayBGM: bsr Echo_SendCommandAddr ; Send command to Echo move.w (sp)+, d0 ; Restore register - Echo_Z80Request ; We need Z80 RAM access... - ori.b #$02, ($A01FF0) ; Force BGM flag to be on - Echo_Z80Release ; OK done with it for real - rts ; End of subroutine ;**************************************************************************** @@ -214,10 +202,6 @@ Echo_StopBGM: bsr Echo_SendCommand ; Send command to Echo move.w (sp)+, d0 ; Restore register - Echo_Z80Request ; We need Z80 RAM access... - andi.b #$FD, ($A01FF0) ; Force BGM flag to be off - Echo_Z80Release ; OK done with it for real - rts ; End of subroutine ;**************************************************************************** @@ -403,7 +387,9 @@ Echo_SetVolumeEx: ;**************************************************************************** Echo_GetStatus: - moveq #0, d0 + movem.l d1/a1, -(sp) ; Save registers + + clr.w d0 ; Set all needed bits to 0 Echo_Z80Request ; We need the Z80 bus move.b ($A01FF0), d0 ; Get the status flags @@ -417,9 +403,40 @@ Echo_GetStatus: bset.l #14, d0 ; If so, set the relevant flag @DirectEmpty: + moveq #0, d1 ; Clear unused bits from index + lea @AndTable(pc), a1 ; Get pointer to look-up tables + + move.b ($A01FFF), d1 ; Get next pending command (if any) + beq.s @QueueChecked ; No commands left to process? + move.b (a1,d1.w), d1 ; Get mask of flags to leave + and.b d1, d0 ; Remove flags that should be clear + move.b @OrTable-@AndTable(a1,d1.w), d1 ; Get mask of flags to set + or.b d1, d0 ; Insert flags that should be set + + move.b ($A01FFB), d1 ; Repeat that with 2nd pending command + beq.s @QueueChecked + move.b (a1,d1.w), d1 + and.b d1, d0 + move.b @OrTable-@AndTable(a1,d1.w), d1 + or.b d1, d0 + +@QueueChecked: Echo_Z80Release ; Let the Z80 go! + movem.l (sp)+, d1/a1 ; Restore registers rts ; End of subroutine +;---------------------------------------------------------------------------- +; Look-up tables used to readjust the status flags based on pending commands +; that haven't been processed yet (normally they wouldn't be updated yet, but +; this can catch programmers off guard so we cheat it). +; +; Every byte represents a possible command. +;---------------------------------------------------------------------------- + +@AndTable: dc.b $FF,$FF, $FF,$FE,$FF,$FD, $FF,$FF,$FF +@OrTable: dc.b $00,$00, $01,$00,$02,$00, $00,$00,$00 + even + ;**************************************************************************** ; Echo_GetFlags ; Gets the current values of the flags. |