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60 lines
980 B
ArmAsm
60 lines
980 B
ArmAsm
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;helper routines for arithmetic on 32 bit numbers
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;reuse the copy_* zero page locations as pointers for 32bit addition
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.importzp copy_src
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.importzp copy_dest
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acc32 =copy_src ;32bit accumulater (pointer)
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op32 =copy_dest ;32 bit operand (pointer)
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.exportzp acc32
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.exportzp op32
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.export add_32_32
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.export add_16_32
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;add a 32bit operand to the 32 bit accumulater
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;acc32=acc32+op32
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add_32_32:
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clc
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ldy #0
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lda (op32),y
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adc (acc32),y
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sta (acc32),y
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iny
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lda (op32),y
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adc (acc32),y
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sta (acc32),y
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iny
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lda (op32),y
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adc (acc32),y
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sta (acc32),y
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iny
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lda (op32),y
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adc (acc32),y
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sta (acc32),y
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rts
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;add a 16bit operand to the 32 bit accumulater
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;acc32=acc32+AX
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add_16_32:
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clc
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ldy #0
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adc (acc32),y
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sta (acc32),y
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iny
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txa
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adc (acc32),y
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sta (acc32),y
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iny
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lda #0
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adc (acc32),y
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sta (acc32),y
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iny
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lda #0
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adc (acc32),y
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sta (acc32),y
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rts
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