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Minimise performance issues of None Maskable Interupt

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hugova 2025-05-02 18:55:33 +02:00
parent 3bdf52d1a8
commit 1a8d4593ed
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wip-hugo/STARTUP.s
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@ -1,82 +1,109 @@
.scope STARTUP .scope STARTUP
;;; -*- Mode: asm; indent-tabs-mode: t; tab-width: 8 -*- ;;; -*- Mode: asm; indent-tabs-mode: t; tab-width: 8 -*-
;;Settings positions ;; Settings positions
CR1 = $d011; ;Graphic settings CR1 = $d011; Graphic settings
VIC_bank_settings = $DD00 ; Vic position VIC_bank_settings = $DD00 ; Vic position
Screen_RAM_settings =$D018 ;Screen RAM position relative to VIC Screen_RAM_settings =$D018 ; Screen RAM position relative to VIC
;;########## VIC_BANK ################ ;;########## VIC_BANK ################
;;# BITMAP | $4000 -$5F3F ;;# BITMAP | $4000 -$5F3F
;;# Unused? | $5F3F - $6000 ;;# Unused? | $5F3F - $6000
;;# SCREAN RAM (color) | $6000 -$63E7 ;;# SCREAN RAM (color) | $6000 -$63E7
;;# Unused? | $63E8 - $7FFF ;;# Unused? | $63E8 - $7FFF
;;# ;;#
;;#################################### ;;####################################
;;Memory positions ;; Memory positions
VIC_bank = $4000 VIC_bank = $4000
VIC_bank_end = VIC_bank + $3FFF VIC_bank_end = VIC_bank + $3FFF
Bitmap = VIC_bank Bitmap = VIC_bank
Bitmap_end = $5F3F Bitmap_end = $5F3F
Screen_RAM = $2000 + VIC_bank Screen_RAM = $2000 + VIC_bank
Screen_RAM_end = Screen_RAM + $03E7 Screen_RAM_end = Screen_RAM + $03E7
Character_generator_ROM = $D000 Character_generator_ROM = $D000
;;Free upp memory ;; Free upp memory
;;https://www.c64-wiki.com/wiki/Bank_Switching ;; https://www.c64-wiki.com/wiki/Bank_Switching
;;
;;Sets grafic mode [Standard bitmap mode]
;;https://www.c64-wiki.com/wiki/Standard_Bitmap_Mode
LDA #%10111111 ; ECM = False
AND CR1
STA CR1
LDA #%00100000; BMM = True ;; Sets grafic mode [Standard bitmap mode]
ORA CR1 ;; https://www.c64-wiki.com/wiki/Standard_Bitmap_Mode
STA CR1 LDA #%10111111 ; ECM = False
AND CR1
STA CR1
;;Set VIC bank to bank 1 LDA #%00100000; BMM = True
;;https://www.c64-wiki.com/wiki/VIC_bank ORA CR1
LDA #%11111110 ;bit_0 = False STA CR1
AND VIC_bank_settings
STA VIC_bank_settings
LDA #%00000010; bit_1 = True ;; Set VIC bank to bank 1
ORA VIC_bank_settings ;; https://www.c64-wiki.com/wiki/VIC_bank
STA VIC_bank_settings LDA #%11111110 ;bit_0 = False
AND VIC_bank_settings
STA VIC_bank_settings
;;Set Scren-RAM to offset 8 ;https://www.c64-wiki.com/wiki/53272 (offset is 8k byte = 1024*8-ich) LDA #%00000010; bit_1 = True
LDA #%10001111 ; bit_6 =bit_5=bit_4 = Falsw ORA VIC_bank_settings
AND Screen_RAM_settings STA VIC_bank_settings
STA Screen_RAM_settings
LDA #%10000000; bit_1 = True ;; Set Scren-RAM to offset 8 ;https://www.c64-wiki.com/wiki/53272 (offset is 8k byte = 1024*8-ich)
ORA Screen_RAM_settings LDA #%10001111 ; bit_6 =bit_5=bit_4 = Falsw
STA Screen_RAM_settings AND Screen_RAM_settings
STA Screen_RAM_settings
;;Paint the bitmap black. More bitmap: https://www.c64-wiki.com/wiki/53272, https://www.c64-wiki.com/wiki/Screen_RAM#Moving_of_screen_RAM LDA #%10000000; bit_1 = True
Mov_16 B_start, B_start + 1, #<VIC_bank, #>VIC_bank ORA Screen_RAM_settings
Mov_16 B_end, B_end + 1, #<$5f3f, #>$5f3f STA Screen_RAM_settings
LDA #$00
jsr memset ;; Paint the bitmap black. More bitmap: https://www.c64-wiki.com/wiki/53272, https://www.c64-wiki.com/wiki/Screen_RAM#Moving_of_screen_RAM
Mov_16 B_start, B_start + 1, #<VIC_bank, #>VIC_bank
Mov_16 B_end, B_end + 1, #<$5f3f, #>$5f3f
LDA #$00
jsr memset
;;Sets the screen color to black and white ;; Sets the screen color to black and white
Mov_16 B_start, B_start + 1, #<Screen_RAM, #>Screen_RAM Mov_16 B_start, B_start + 1, #<Screen_RAM, #>Screen_RAM
Mov_16 B_end, B_end + 1, #<Screen_RAM_end, #>Screen_RAM_end Mov_16 B_end, B_end + 1, #<Screen_RAM_end, #>Screen_RAM_end
LDA #%11110000 LDA #%11110000
jsr memset jsr memset
SEI ;Disable interups (not all)
;;Disable BASIC ROM mohahaha ;; Disable maskeble interups (not all)
LDA #%11111110 SEI
AND $0001 ;; Disable BASIC ROM mohahaha
STA $0001 LDA #%11111110
;https://www.c64-wiki.com/wiki/Bank_Switching AND $0001
;Disable IO, CHAREN =0 STA $0001
LDA #%11111011 ; https://www.c64-wiki.com/wiki/Bank_Switching
AND $0001 ; Disable IO, CHAREN =0
STA $0001 LDA #%11111011
AND $0001
STA $0001
;;Disable non maskable interupts
;;https://codebase64.org/doku.php?id=base:nmi_lock_without_kernal
;; write to $FFFA/$FFFB possible (and needed) if BASIC ROM is disabled
LDA #$00
STA $CCCC
LDA #<NMI_routine
STA $FFFA
LDA #>NMI_routine
STA $FFFB
LDA #$00 ;; stop Timer A
STA $DD0E
STA $DD04 ;; set Timer A to 0, after starting
STA $DD05 ;; NMI will occur immediately
LDA #$81
STA $DD0D ;; set Timer A as source for NMI
LDA #$01
STA $DD0E ;; start Timer A -> NMI
;; from here on NMI is disabled
JMP NMI_routine_end
NMI_routine:
RTI ;; exit interrupt not acknowledged
NMI_routine_end:
.endscope .endscope