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58 lines
1.0 KiB
ArmAsm
58 lines
1.0 KiB
ArmAsm
;text file parsing routines
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; first call parser_init
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; then call parser_skip_next
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.export parse_integer
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.importzp copy_dest
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.import mul_8_16
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.importzp acc16
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target_string=copy_dest
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.include "../inc/common.i"
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.bss
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int_value: .res 2
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.code
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;parses a string, returns integer (up to 16 bits)
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;inputs: AX points to a string containing an integer
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;outputs: AX contains integer
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parse_integer:
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stax target_string
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lda #0
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sta int_value
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sta int_value+1
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tay
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@parse_int:
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lda (target_string),y
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cmp #$30
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bcc @end_of_int ;any non-decimal char should be treated as end of integer
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cmp #$39
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bcs @end_of_int ;any non-decimal char should be treated as end of integer
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ldax int_value
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stax acc16
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lda #10
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jsr mul_8_16
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ldax acc16
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stax int_value
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lda (target_string),y
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sec
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sbc #'0'
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clc
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adc int_value
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sta int_value
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bcc @no_rollover
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inc int_value+1
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@no_rollover:
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iny
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bne @parse_int
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@end_of_int:
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ldax int_value
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clc
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rts
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