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Acme ASM Template (C-64)
;==============================================================================
; ACME_TEMPLATE - copy(l)eft 2018 http://harald.ist.org/
;==============================================================================
;;!cpu 6510 ; Enable illegal opcodes
!to "../acme_template cbm ; Output file
!sl "../acme_template.sym ; Symbols table
!convtab PET ; Character constants are PETSCII
!macro S_PROGRAM_VERSION .dummy {
!pet "v0.0a"
}
;==============================================================================
!zone BASIC_START_PROGRAM
;==============================================================================
*= $0801 ; Load point $0801 (BASIC START)
_FSTART ; This binary must begin with the bytes
; representing the BASIC program: 0 SYS2061
BASIC_program
!byte $0b,$08 ; $0801 Pointer to next line
!byte $00,$00 ; $0803 Line number (0)
!byte $9e ; $0805 SYS
!byte 48+(entry_point/1000)%10 ; Decimal address of program entry point
!byte 48+(entry_point/100)%10
!byte 48+(entry_point/10)%10
!byte 48+(entry_point/1)%10
!byte $00 ; $080a End of BASIC line
!byte $00,$00 ; $080b End of BASIC program
entry_point ;JMP boot ; $080d First byte after the BASIC program
;==============================================================================
!zone BOOT
;==============================================================================
boot JSR init
JSR main
JSR exit
RTS ; Return to BASIC
;==============================================================================
!zone INIT
;==============================================================================
init
;==============================================================================
JSR clear_heap
JSR save_zeropage
LDA #$0e ; Lower case font
JSR $ffd2 ; BSOUT
LDA #$08 ; Font case toggle disabled
JSR $ffd2 ; BSOUT
LDA #$00 ; Black
STA $d021 ; Border
STA $d020 ; Background
LDA #$01 ; White
STA $0286 ; Text color
JSR $e544 ; CLSR
RTS
;==============================================================================
!zone MAIN
;==============================================================================
main
;------------------------------------------------------------------------------
RTS
;==============================================================================
!zone EXIT
;==============================================================================
exit
;------------------------------------------------------------------------------
LDA #$8e ; Upper case font
JSR $ffd2 ; BSOUT
LDA #$09 ; Font case toggle enable
JSR $ffd2 ; BSOUT
LDA #$0e ; Blue
STA $d020 ; Background
LDA #$06 ; Light blue
STA $d021 ; Border
LDA #$0e ; Light blue
STA $0286 ; Text color
JSR $e544 ; CLSR
;LDX #<s_exit_message
;LDA #>s_exit_message
;JSR cputs
;------------------------------------------------------------------------------
.loop LDA $cb ; Currently pressed key
CMP #$40 ; $40 = no key pressed
BNE .loop ; Wait until key released
LDA #$00
STA $c6 ; Nr. keys in input buffer
JSR restore_zeropage ; Clean up the mess, we created
LDY # 5
LDX # 0
STY $d6 ; Store x-pos
STX $d3 ; Store y-pos
JSR $e56c ; Set cursor
RTS
;==============================================================================
!zone SAVE_RESTORE_ZEROPAGE
;==============================================================================
; Save/restore $0000..$00ff to/from heap. Enables return to BASIC.
save_zeropage
;------------------------------------------------------------------------------
LDY #$00
.save_loop LDA $00,Y
STA zp_backup,Y
INY
BNE .save_loop
RTS
restore_zeropage
;------------------------------------------------------------------------------
TYA
PHA
LDY #$00
.restore_loop LDA zp_backup,Y
STA $00,Y
INY
BNE .restore_loop
PLA
TAY
RTS
;==============================================================================
!zone CLEAR_HEAP
;==============================================================================
.tptr = $f7
clear_heap
;------------------------------------------------------------------------------
; Clear heap variables
LDA .tptr
PHA
LDA .tptr+1
PHA
LDY #<heap_vars_start
LDA #>heap_vars_start
STA .tptr+1
LDA # 0
STA .tptr
.loop STA (.tptr),Y
INY
BNE .loop
INC .tptr+1
LDX #>heap_vars_end
CPX .tptr+1
BCS .loop
PLA
STA .tptr+1
PLA
STA .tptr
RTS
;==============================================================================
!zone STATIC_DATA
;==============================================================================
s_exit_message !pet petscii_home, petscii_lblue, petscii_rvs_off, 13
!pet "asm-template", 13
!pet "------------------------", 13
!pet "http://harald.ist.org/", 13
!pet "copy(l)eft 2019"
!pet 0
;==============================================================================
!zone HEAP
;==============================================================================
heap_vars_start
zp_backup *=zp_backup + 256
heap_vars_end
;==============================================================================
!eof
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