2000-10-26 20:43:54 +00:00
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;
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; Ullrich von Bassewitz, 26.10.2000
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;
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; CC65 runtime: Push value in a/x onto the stack
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;
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.export push0, pusha0, pushax
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.importzp sp
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push0: lda #0
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pusha0: ldx #0
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; This function is used *a lot*, so don't call any subroutines here.
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; Beware: The value in ax must not be changed by this function!
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; Beware^2: The optimizer knows about the value of Y after the function
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; returns!
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pushax: ldy sp
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beq @L1
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dey
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beq @L2
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dey
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@L0: sty sp
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2000-11-27 22:59:03 +00:00
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.ifpc02
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sta (sp) ; 65C02 version - saves 2 cycles and one byte
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ldy #1 ; get hi index
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.else
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ldy #0 ; get index
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sta (sp),y ; store lo byte
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iny ; bump idx
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.endif
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pha ; save it
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txa ; get hi byte
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2000-10-26 20:43:54 +00:00
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sta (sp),y ; store hi byte
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pla ; get A back
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rts ; done
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@L1: dey
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@L2: dey
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dec sp+1
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2000-11-27 22:59:03 +00:00
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.ifpc02
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bra @L0
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.else
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2000-10-26 20:43:54 +00:00
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jmp @L0
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2000-11-27 22:59:03 +00:00
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.endif
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2000-10-26 20:43:54 +00:00
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