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Merge pull request #1709 from karrika/atari7800clock

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[Atari7800] clock()
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Bob Andrews 2022-03-29 23:13:47 +02:00 • committed by GitHub
commit 84dba7f6ae
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6 changed files with 208 additions and 4 deletions
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2
cfg/atari7800.cfg
View file

@ -10,7 +10,7 @@ SYMBOLS {
__ENCRYPT_BOTTOM__: value = $ff7a, type = export;
__ENCRYPT_SIZE__: value = $80, type = export;
__MEMORY_TOP__: value = __ENCRYPT_BOTTOM__, type = export;
__INIT_SIZE__: value = 69, type = export;
__INIT_SIZE__: value = 121, type = export;
__MEMORY_INIT__: value = __MEMORY_TOP__ - __INIT_SIZE__, type = export;
__MEMORY_BOTTOM__: value = $10000 - __CARTSIZE__, type = weak;
__FREE_ROM_SIZE__: value = __MEMORY_INIT__ - __MEMORY_BOTTOM__, type = export;

69
libsrc/atari7800/clock.s Normal file
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@ -0,0 +1,69 @@
;
; 2022-03-15, Karri Kaksonen
;
; clock_t clock (void);
;
.export _clock, clock_count
.interruptor update_clock, 2 ; (low priority)
.constructor init_clock
.import sreg: zp
.import _zonecounter
.include "atari7800.inc"
.macpack generic
.code
;-----------------------------------------------------------------------------
; Read the clock counter.
;
.proc _clock
lda #0
sta sreg+1 ; Promote 24 bits up to 32 bits
lda clock_count+2
sta sreg
ldx clock_count+1
lda clock_count
rts
.endproc
;-----------------------------------------------------------------------------
; This interrupt handler increments a 24-bit counter at every video
; vertical-blanking time.
; Update the clock only on interrupt while the drawing on screen is on
; _zonecounter == 1 (from 1st visible scanline to last visible scanline)
;
update_clock:
lda _zonecounter
and #01
beq @L1
inc clock_count
bne @L1
inc clock_count+1
bne @L1
inc clock_count+2
@L1: ;clc ; General interrupt was not reset
rts
;-----------------------------------------------------------------------------
; Set time to zero at startup
;
.segment "ONCE"
init_clock:
lda #0
sta clock_count+2
sta clock_count+1
sta clock_count
rts
;-----------------------------------------------------------------------------
; Store time in 3 bytes
;
.bss
clock_count:
.res 3

34
libsrc/atari7800/clocks_per_sec.s Normal file
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@ -0,0 +1,34 @@
;
; 2022-03-15, Karri Kaksonen
;
; clock_t _clocks_per_sec (void);
;
.export __clocks_per_sec
.import sreg: zp
.import _paldetected
.include "atari7800.inc"
.macpack generic
.code
;-----------------------------------------------------------------------------
; Return the number of clock ticks in one second.
;
.proc __clocks_per_sec
lda #0
tax
sta sreg ; return 32 bits
sta sreg+1
lda _paldetected
bne pal
lda #60 ; NTSC - 60Hz
rts
pal:
lda #50 ; PAL - 50Hz
rts
.endproc

6
libsrc/atari7800/crt0.s
View file

@ -5,12 +5,12 @@
.import __RAM3_START__, __RAM3_SIZE__
.import initlib, donelib
.import zerobss, copydata
.import IRQStub
.import push0, _main
.include "atari7800.inc"
.include "zeropage.inc"
INPTCTRL = $01
OFFSET = $38
CTRL = $3c
.segment "STARTUP"
start:
@ -50,7 +50,7 @@ _exit:
NMIHandler:
inc _zonecounter
rti
jmp IRQStub
IRQHandler:
rti

65
libsrc/atari7800/get_tv.s Normal file
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@ -0,0 +1,65 @@
;
; Karri Kaksonen, 2022-03-25
;
; unsigned char get_tv (void)
;
.include "atari7800.inc"
.include "get_tv.inc"
.export _get_tv
.export _paldetected
.segment "DATA"
_paldetected:
.byte $FF
; ---------------------------------------------------------------
; unsigned char get_tv (void)
; ---------------------------------------------------------------
.segment "CODE"
.proc _get_tv: near
.segment "CODE"
ldx #$00
lda #$FF
cmp _paldetected
bne L8
L1: lda MSTAT
and #$80
bne L1
L2: lda MSTAT
and #$80
beq L2
L3: lda MSTAT
and #$80
bne L3
lda #$00
sta M0001
jmp L5
L4: sta MWSYNC
sta MWSYNC
dec M0001
L5: lda MSTAT
and #$80
beq L4
lda M0001
cmp #$78
bcc L6
lda #TV::NTSC
jmp L7
L6: lda #TV::PAL
L7: sta _paldetected
ldx #$00
L8: lda _paldetected
rts
.segment "BSS"
M0001:
.res 1,$00
.endproc

36
libsrc/atari7800/irq.s Normal file
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@ -0,0 +1,36 @@
;
; IRQ handling (Atari 7800 version)
;
.export initirq, doneirq, IRQStub
.import __INTERRUPTOR_COUNT__, callirq
.include "atari7800.inc"
.code
; ------------------------------------------------------------------------
initirq:
doneirq:
rts
; ------------------------------------------------------------------------
IRQStub:
cld ; Just to be sure
pha
lda #<(__INTERRUPTOR_COUNT__ * 2)
beq @L1
txa
pha
tya
pha
jsr callirq ; Call the functions
pla
tay
pla
tax
@L1: pla
rti