tolower.mas

/ This program presents a simple tolower(ptr) function.
/ #L8-9		Sets the argument `str_ptr` for the tolower function.
/ #L10		Calls the tolower function.
/ #L27 		Adds the offset between upper and lower case letters on ascii table.
/		0x41 ('A') 0x61 ('a') --> 0x20

			ORG		0
			LOAD		str_ptr
			STORE		tolower_ptr
			JNS		tolower
			HALT
			
tolower_itr,		DEC		0
tolower_ptr,		HEX		0
tolower_idx,		HEX		0
tolower_offset,		HEX		20	
tolower,		HEX		0
tolower_while,		LOAD		tolower_ptr
			ADD		tolower_itr
			STORE		tolower_idx
			CLEAR
			ADDI		tolower_idx
			SKIPCOND	400
			JUMP		tolower_do
			JUMPI		tolower

tolower_do,		ADD 		tolower_offset
			OUTPUT
			LOAD		tolower_itr
			ADD 		ONE
			STORE		tolower_itr
			JUMP		tolower_while

str_ptr,		HEX		18			/ memory location of str
str,			HEX		48			/ H
			HEX		45			/ E
			HEX		4C			/ L
			HEX		4C			/ L
			HEX		4F			/ O
			HEX		D			/ carriage return
			HEX		57			/ W
			HEX		4F			/ O
			HEX		52			/ R
			HEX		4C			/ L
			HEX		44			/ D
			HEX		0			/ NULL char

/ constants
ONE,				DEC		1