diff options
| -rw-r--r-- | README | 12 | ||||
| -rw-r--r-- | c/echo.c | 19 | ||||
| -rw-r--r-- | src-68k/echo.68k | 51 |
3 files changed, 59 insertions, 23 deletions
@@ -7,12 +7,12 @@ | | |_ |_ ___ | | | | | | | | | |_______ |_ |___| _| | | | | |_ |_____| _| |___________| |________| |___| |___| |_________| - ___ ___ _ _ ___ __ ___ ___ ___ _ ___ ___ _ ___ - | _| | | | | \ | _| | _| | | _| | | | _| - | |_| | | | | | | | | | |_| | | |_| | | | |_ _ _ ___ ___ | | | |_ - |_ | | | | | | | | | | _| | | | | | | | _| | | | __| _ \ | | |_ | - _| | | | | | | | | | | |_| | | | | | | | |_ | | | __| /_ | |_ _| | - |___|___|___|_|_|__/ |___|_|_|___|_|_|_|___| \_/|___|_|_\_| |_|_|___| + ___ ___ _ _ ___ __ ___ ___ ___ _ ___ ___ _ ___ _ + | _| | | | | \ | _| | _| | | _| | | | _| | + | |_| | | | | | | | | | |_| | | |_| | | | |_ _ _ ___ ___ | | | |_| | + |_ | | | | | | | | | | _| | | | | | | | _| | | | __| _ \ | | |_ | | + _| | | | | | | | | | | |_| | | | | | | | |_ | | | __| /_ | |_ _| | | + |___|___|___|_|_|__/ |___|_|_|___|_|_|_|___| \_/|___|_|_\_| |_|_|___|_| ============================================================================= @@ -375,6 +375,16 @@ void echo_set_pcm_rate(uint8_t rate) { //*************************************************************************** uint16_t echo_get_status(void) { + // Look-up tables used to work around the fact that playing/stopping + // won't set the status immediately (only when Echo processes the command) + // and this can catch programmers off guard + static const uint8_t and_flags[] = { + 0xFF,0xFF, 0xFF,0xFE,0xFF,0xFD, 0xFF,0xFF,0xFF + }; + static const uint8_t or_flags[] = { + 0x00,0x00, 0x01,0x00,0x02,0x00, 0x00,0x00,0x00 + }; + // We need access to the Z80 Z80_REQUEST(); @@ -386,6 +396,15 @@ uint16_t echo_get_status(void) { if (z80_ram[0x1F00] != 0xFF) status |= ECHO_STAT_DIRBUSY; + // Look ahead in the queue for any pending commands + // Adjust the flags accordingly if needed + uint8_t command = z80_ram[0x1FFF]; + status &= and_flags[command]; + status |= or_flags[command]; + command = z80_ram[0x1FFB]; + status &= and_flags[command]; + status |= or_flags[command]; + // Done with the Z80 Z80_RELEASE(); 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. |