;demonstrate the A to H subroutine

; in THRSim11:

org ff00

lds #00ff

cli

ldaa #63

psha

jsr AtoH

pula

Stop: bra Stop

AtoH:

; Convert 8-bit ASCII to 4-bit Hex

; input registers: none - 8-bit

; local variable

; passed to stack

; output registers: none - 8-bit

; local variable

; passed to stack

; 4-bits of leading

; zeros, 4-bits data

;

pshx ; store old values of X and A

psha

tsx ; transfer SP contents to X

ldaa 5,x ; load ASCII char from stack

suba #30 ; stubtract 30 from ASCII

cmpa #a ; check if number was less than A (10)

blt Done ; if so, done, restore registers

suba #27 ; if not, convert to "a" thru "f" value

Done: staa 5,x ; put HEX number on stack

pula ; restore contents of A and X

pulx

rts