SX Microcontroller Radix Math Method

ASCII Hex to Binary

by Nikolai Golovchenko

; Input  - ASCII number in x
; Output - binary in x

	mov	W, #-'A'+10
	sb	x.6
	mov	W, #-'0'
	add	x, W
	

ASCII numbers '0'-'9' have codes 48-57, and 'A'-'F' have codes 65-70. The second group differs from the first one by a value of bit 6. To map '0'-'9' to 0-9 we need to substract '0' (if bit 6 is clear), and to map 'A'-'F' to 10-15 we substract 'A' and add 10 (if bit 6 is set).

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