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Reduce flicker by waiting for horizontal retrace before switching ROM and

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CHARGEN. Can be disabled by setting USEWSYNC to 0.
This commit is contained in:
Christian Groessler 2013-09-11 23:59:24 +02:00
parent 387f6e9b21
commit 5a1dcbbe4c
1 changed files with 70 additions and 31 deletions
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101
libsrc/atari/shadow_ram_handlers.s
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@ -5,6 +5,7 @@
;
DEBUG = 1
USEWSYNC= 1
CHKBUF = 1 ; check if bounce buffering is needed (bounce buffering is always done if set to 0)
.if .defined(__ATARIXL__)
@ -24,7 +25,22 @@ CHKBUF = 1 ; check if bounce buffering is needed (bounce buffering is always don
BUFSZ = 128 ; bounce buffer size
BUFSZ_SIO = 256
.macro wsync
.if USEWSYNC
sta WSYNC
.endif
.endmacro
.macro disable_rom
lda PORTB
and #$fe
wsync
sta PORTB
lda #>__CHARGEN_START__
sta CHBAS
sta CHBASE
.endmacro
.macro disable_rom_quick
lda PORTB
and #$fe
sta PORTB
@ -32,7 +48,25 @@ BUFSZ_SIO = 256
sta CHBAS
sta CHBASE
.endmacro
.macro disable_rom_val val
lda val
wsync
sta PORTB
lda #>__CHARGEN_START__
sta CHBAS
sta CHBASE
.endmacro
.macro enable_rom
lda PORTB
ora #1
wsync
sta PORTB
lda #$E0
sta CHBAS
sta CHBASE
.endmacro
.macro enable_rom_quick
lda PORTB
ora #1
sta PORTB
@ -48,9 +82,9 @@ BUFSZ_SIO = 256
sram_init:
; disable all interrupts
sei
ldx #0
stx NMIEN ; disable NMI
sei
; disable ROMs
disable_rom
@ -72,9 +106,9 @@ sram_init:
sta $fffb
; enable interrupts
cli
lda #$40
sta NMIEN
cli
rts
@ -104,14 +138,14 @@ bounce_buffer: .res BUFSZ_SIO
.macro int_wrap orgvec
.local ret
pha
enable_rom
enable_rom_quick
lda #>ret
pha
lda #<ret
pha
php
jmp (orgvec)
ret: disable_rom
ret: disable_rom_quick
pla
rti
.endmacro
@ -209,26 +243,6 @@ CIO_filename2:
jmp CIO_fn_cont
; enable ROM, call CIO, disable ROM
CIO_call_a:
lda CIO_a
CIOV_call:
pha
lda PORTB
sta cur_CIOV_PORTB
enable_rom
pla
jsr CIOV_org
php
pha
lda cur_CIOV_PORTB
sta PORTB
pla
plp
rts
; CIO handler
; We have buffer pointer and length entries in the IOCB, but their
@ -264,6 +278,28 @@ CIO_handler:
bcs CIO_call_a ; other commands: assume no buffer
; not reached
; enable ROM, call CIO, disable ROM
CIO_call_a:
lda CIO_a
CIOV_call:
pha
lda PORTB
sta cur_CIOV_PORTB
enable_rom
pla
jsr CIOV_org
php
pha
disable_rom_val cur_CIOV_PORTB
; lda cur_CIOV_PORTB
; sta PORTB
pla
plp
rts
CIO_write_jmp:
jmp CIO_write
@ -859,8 +895,9 @@ SIO_call:
jsr SIOV_org
php
pha
lda cur_SIOV_PORTB
sta PORTB
disable_rom_val cur_SIOV_PORTB
; lda cur_SIOV_PORTB
; sta PORTB
pla
plp
rts
@ -933,7 +970,7 @@ SIO_write:
bcs sio_write_len_ok
lda #DERROR ; don't know a better status code for this
bne SIO_err
jmp SIO_err
sio_write_len_ok:
lda DBUFLO
@ -1080,8 +1117,9 @@ KEYBDV_handler:
pha
rts ; call keyboard handler
kret: pha
lda cur_KEYBDV_PORTB
sta PORTB
disable_rom_val cur_KEYBDV_PORTB
; lda cur_KEYBDV_PORTB
; sta PORTB
pla
rts
@ -1097,8 +1135,9 @@ SETVBV_handler:
jsr SETVBV_org
php
pha
lda cur_SETVBV_PORTB
sta PORTB
disable_rom_val cur_SETVBV_PORTB
; lda cur_SETVBV_PORTB
; sta PORTB
pla
plp
rts