Assembly Language Programming

Program Assignment #3

Write procedures to perform numeric input and output. These will be designed to be linked to other assembly language programs. The procedures should not change any registers unless specified. They should not use any named storage locations - allocate stack space for local variables if needed. Place the procedure definitions in NUM.asm. You should test your functions using a separate program of your own. Be sure to declare the functions as public - see 9.4 for info. Use a small memory model and near procedure declarations. Do not include a data segment in NUM.asm.

inNum proc near

This function reads a number from the keyboard. The input is converted to a 16-bit unsigned integer. You are given one argument in BL, a number in the range 2 through 16 indicating the radix of the input data. An illegal radix should be treated as radix 16. Your function must read characters using a DOS function that does not echo to the screen. Read (and ignore) characters until a digit (0 through radix-1) is encountered. This digit is then the start of the input value and should be echoed to the screen. Continue to read and echo characters until an illegal character is read (any non digit for the specified radix). Do not echo this character. Do not output a CRLF after input is correct. Return the value of the number input in AX and the last character read in DL. You are reading unsigned numbers, so detect overflow appropriately. If overflow occurs during the input processing, set the CF before returning, otherwise clear the CF. If overflow occurs, continue processing input normally as specified above. Note that the digits, A-F, can be upper or lower case. Only AX and DL may be changed (if you need to change other registers, you must restore them before returning)

outNum proc near

You are given a single word (on the stack), the unsigned representation of a value to be displayed. A second argument in BL will specify the radix (2-16) you should use to display the value. If the radix is illegal, use 16. No registers are to be changed by this function. Use uppercase A-F when displaying the value. Do not add a CRLF to the output.

Submit a single ZIP file containing your .ASM source file and the assembled object file. Please name the ZIP file with your last name and the digit 3. For example, I would submit MARGUSH_3.ZIP. I will assemble and link your procedures with my own test program. Turn in a printed copy of your program - it must look nice, so be careful about formatting it. E-mail the zip archive attached to a mail message. The subject line of the message must include the words: "Assembly Language Program 3". Try to make the return address correct as well! Submit a printed copy.