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5c5d01d84a
in the distribution. Added --forget-inc-paths to the command line of the assembler in the Makefiles, because the assembler does now have builtin paths and will find include files from an installation first. Hopefully fixed any problems that arose from the two changes. git-svn-id: svn://svn.cc65.org/cc65/trunk@4223 b7a2c559-68d2-44c3-8de9-860c34a00d81
109 lines
1.5 KiB
ArmAsm
109 lines
1.5 KiB
ArmAsm
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; Ullrich von Bassewitz, 27.09.1998
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;
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; void set_brk (unsigned Addr);
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; void reset_brk (void);
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;
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.export _set_brk, _reset_brk
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.destructor _reset_brk
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.export _brk_a, _brk_x, _brk_y, _brk_sr, _brk_pc
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.include "plus4.inc"
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.bss
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_brk_a: .res 1
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_brk_x: .res 1
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_brk_y: .res 1
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_brk_sr: .res 1
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_brk_pc: .res 2
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oldvec: .res 2 ; Old vector
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.data
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uservec: jmp $FFFF ; Patched at runtime
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.code
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; Set the break vector
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.proc _set_brk
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sta uservec+1
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stx uservec+2 ; Set the user vector
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lda oldvec
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ora oldvec+1 ; Did we save the vector already?
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bne L1 ; Jump if we installed the handler already
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lda BRKVec
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sta oldvec
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lda BRKVec+1
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sta oldvec+1 ; Save the old vector
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L1: lda #<brk_handler ; Set the break vector to our routine
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ldx #>brk_handler
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sta BRKVec
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stx BRKVec+1
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rts
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.endproc
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; Reset the break vector
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.proc _reset_brk
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lda oldvec
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ldx oldvec+1
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beq @L9 ; Jump if vector not installed
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sta BRKVec
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stx BRKVec+1
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lda #$00
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sta oldvec ; Clear the old vector
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stx oldvec+1
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@L9: rts
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.endproc
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; Break handler, called if a break occurs
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.proc brk_handler
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pla
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sta _brk_y
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pla
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sta _brk_x
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pla
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sta _brk_a
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pla
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and #$EF ; Clear break bit
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sta _brk_sr
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pla ; PC low
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sec
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sbc #2 ; Point to start of brk
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sta _brk_pc
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pla ; PC high
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sbc #0
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sta _brk_pc+1
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jsr uservec ; Call the user's routine
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lda _brk_pc+1
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pha
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lda _brk_pc
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pha
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lda _brk_sr
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pha
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ldx _brk_x
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ldy _brk_y
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lda _brk_a
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rti ; Jump back...
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.endproc
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