30 lines
503 B
ArmAsm
30 lines
503 B
ArmAsm
.define Ror
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.sect .text
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.sect .rom
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.sect .data
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.sect .bss
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.sect .text
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! This subroutine rotates right a integer twobyte word.
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! The number of rotates is in X.
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! The result is returned in registerpair AX.
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Ror:
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txa
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bne 1f ! a zero rotate just return input
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jmp Pop
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1: tay
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jsr Pop ! get word
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stx Ytmp ! save lowbyte
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2: clc
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ror a ! rotate highbyte
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ror Ytmp ! rotate lowbyte
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bcc 1f ! no carry
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ora #0x80 ! put carry in leftmost bit
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1: dey
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bne 2b
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ldx Ytmp ! get lowbyte
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rts
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