CS 270
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; IO Recitation ; Author: name ; Date: date ; Email: email ; Class: CS270 ; Description: Converts hexadecimal number in ASCII to binary number ;-------------------------------------------------------------------------- ; Begin reserved section: do not change ANYTHING in reserved section! .ORIG x3000 JSR read ; read number from keyboard JSR convert ; convert to binary number HALT ; Decinal value Result .BLKW 1 ; space to store result ; String value String .BLKW 4 ; End reserved section: do not change ANYTHING in reserved section! ;-------------------------------------------------------------------------- ; Constants Four .FILL 4 ; the number 4 AsciiA .FILL xFFBF ; minus ASCII 'A' Ascii0 .FILL xFFD0 ; minus ASCII '0' Prompt .STRINGZ "Hexadecimal: " ;-------------------------------------------------------------------------- ; read - reads four ASCII digits from console and stores them in string read_ra .BLKW 1 ; return address read ST R7,read_ra ; save return address LD R1,Four ; R1 = loop counter = 4 ; R2 = string pointer ; Display prompt using PUTS ; loop0 ; Input character using GETC ; Output character using OUT STR R0,R2,0 ; Store next character ; Increment pointer ADD R1,R1,-1 ; Decrement counter BRp loop0 ; Loop if positive LD R7,read_ra ; restore return address RET ;-------------------------------------------------------------------------- ; convert - converts four ASCII digits to binary number convert_ra .BLKW 1 ; return address convert ; save return address LD R1,Four ; R1 = loop counter = 4 ; R2 = string pointer ; R3 = result = 0 loop1 ; R0 = load next character LD R4,AsciiA ; Minus 'A' ADD R4,R0,R4 ; Compare 'A' ; Branch to letter if >= 'A' digit LD R4,Ascii0 ; Minus '0' ADD R4,R0,R4 ; Compare '0' BR continue ; Processed digit letter ADD R4,R4,10 ; Letter to digit continue ; result *= 16 ; ; ; ; result += digit ; Increment pointer ; Decrement counter BRp loop1 ; Loop if positive ST R3,Result ; Store result ; restore return address RET ;-------------------------------------------------------------------------- .END
~cs270/lc3tools/lc3as IO.asm
~cs270/lc3tools/lc3sim-tk &