Assignment 9 Solution

Overview
In this assignment, you will write 2 macros. These will be tested with a driver program that will be provided.
You may find it useful to examine the material on macros in the textbook, Chapter 9, and the discussion in the Notes and Examples book, Chapter 19.

The first macro is called STRLEN. Its purpose is to calculate the length of a C-style string. A C-style string is a character value ending with a byte of X'00'.
For example, if the string is X'C1C2C300', the length is 3. If the string is X'00', the length is 0.
STRLEN has two symbolic parameters, both positional:
    • &STR is the label or D(B) address of a character value terminated with X'00'.
    • &LEN is the label or D(B) address of a fullword in which the macro will return the length.
The STRLEN macro should verify that each of its mandatory symbolic parameters is present. If a parameter is missing, the macro should print an informative error message using MNOTE and then MEXIT.
The STRLEN macro should not change the value of any of its parameters, and it should not change the values of any registers.

The second macro is called FROMHEX. Its purpose is to convert an input value which is a base-16 number, 6 bytes long, all in printable characters, and convert it to a base-10 number, 16 bytes long, all in printable characters.
That is, we have an input value written in base 16 (printable characters) and we want to convert it to base 10 (printable characters). For instance, if the input is XL6'F0F0F0F0C1F5', which is CL6'0000A5', then the numerical value of the input is F'165' and the output value should be XL16'40F0F0F0F0F0F0F0F0F0F0F0F0F1F6F5', which is CL16' 0000000000000165'.
You may assume that all the input values are nonnegative and that they are right-justified in 6 bytes, padded on the left with X'F0' as needed.
You need to convert the input value to a number in a register, and then use CVD followed by ED or UNPK.
FROMHEX has two symbolic parameters, both positional:
    • &IN is the label or D(B) address of a 6-byte character value.
    • &OUT is the label of D(B) address of a 16-byte character value.
The FROMHEX macro should verify that each of its mandatory symbolic parameters is present. If a parameter is missing, the macro should print an informative error message using MNOTE and then MEXIT.
How can you convert the input value to a number in a register? You can do this one byte at a time.
    • Set a register to 0.
    • Get hold of a byte, find its numeric value (0 to 15), and add it to the register.
    • Multiply the value in the register by 16 (maybe with SLA).
    • Repeat. When you work with the last byte, don't multiply by 16.
How can you convert one byte at a time to its numeric value? All you need to decide is whether it is in the range X'F0' to X'F9', in which case you can subtract 240 from it to get 0 to 9, or whether it is in the range X'C1' to X'C6', in which case you can subtract 183 from it to get 10 to 15. (There are other ways to do this as well.)
Along the way, you may find that you need IC, SLA, SRA, CVD and UNPK or ED.

Job Control Language
Use the following Job Control Language (JCL) to execute Assignment 9 The fields described in lower case are the same as described in Chapter 2 of your Notes and Examples book. This JCL combines your macros with the driver program.
The driver program is a complete program. It begins with CSECT and ends with END. Do not supply anything other than your two macros.
//jobname JOB ,'your name',MSGCLASS=H
//STEP1   EXEC  PGM=ASSIST,PARM='MACRO=H'
//STEPLIB   DD  DSN=KC02293.ASSIST.LOADLIB,DISP=SHR
//SYSPRINT  DD  SYSOUT=*
//SYSIN     DD  * 
  Your Macros go here.  Each Macro must begin with 
  MACRO and a Prototype statement.  Your model
  statements follow and the Macro ends with MEND.
  (You should remove these four lines.)
//          DD DSN=KC02314.SUMMER18.CSCI360.HW9DRVR,DISP=SHR
//FT05F001  DD DUMMY
//FT06F001  DD SYSOUT=*
//

Other Requirements
Document your macros completely. See pp 23-24 of Notes and Examples.