3.4.3 Defining new functions

Scheme is a powerful language, and you can use it inside mixguile to easily extend the MIX interpreter's capabilities. For example, you can easily define a function that loads a file, prints its name, executes it and, finally, shows the registers contents, all in one shot:

     guile> (define my-load-and-run  <RET>
              (lambda (file)   <RET>
                (mix-load file)   <RET>
                (display "File loaded: ")   <RET>
                (mix-pprog)   <RET>
                (mix-run)   <RET>
                (mix-preg)))   <RET>
     guile>

and use it to run your programs:

     guile> (my-load-and-run "hello")
     Program loaded. Start address: 3000
     File loaded: hello.mix
     Running ...
     MIXAL HELLO WORLD
     ... done
     Elapsed time: 11 /Total program time: 11 (Total uptime: 33)
     rA: + 00 00 00 00 00 (0000000000)
     rX: + 00 00 00 00 00 (0000000000)
     rJ: + 00 00 (0000)
     rI1: + 00 00 (0000)	rI2: + 00 00 (0000)
     rI3: + 00 00 (0000)	rI4: + 00 00 (0000)
     rI5: + 00 00 (0000)	rI6: + 00 00 (0000)
     guile>

Or, maybe, you want a function which sets a breakpoint at a specified line number before executing it:

     guile> (define my-load-and-run-with-bp
              (lambda (file line)
                (mix-load file)
                (mix-sbp line)
                (mix-run)))
     guile> (my-load-and-run-with-bp "samples/primes" 10)
     Program loaded. Start address: 3000
     Breakpoint set at line 10
     Running ...
     ... stopped: breakpoint at line 10 (address 3001)
     Elapsed time: 1 /Total program time: 1 (Total uptime: 45)
     guile>

As a third example, the following function loads a program, runs it and prints the contents of the memory between the program's start and end addresses:

     guile> (define my-run
              (lambda (file)
                (mix-load file)
                (let ((start (mix-loc)))
                  (mix-run)
                  (mix-pmem start (mix-loc)))))
     guile> (my-run "hello")
     Program loaded. Start address: 3000
     Running ...
     MIXAL HELLO WORLD
     ... done
     Elapsed time: 11 /Total program time: 11 (Total uptime: 11)
     3000: + 46 58 00 19 37 (0786957541)
     3001: + 00 00 00 02 05 (0000000133)
     3002: + 14 09 27 01 13 (0237350989)
     guile>

As you can see, the possibilities are virtually unlimited. Of course, you don't need to type a function definition each time you start mixguile. You can write it in a file, and load it using Scheme's load function. For instance, you can create a file named, say, functions.scm with your definitions (or any Scheme expression) and load it at the mixguile prompt:

     guile> (load "functions.scm")

Alternatively, you can make mixguile to load it for you. When mixguile starts, it looks for a file named mixguile.scm in your MDK configuration directory (~/.mdk) and, if it exists, loads it before entering the REPL. Therefore, you can copy your definitions in that file, or load the functions.scm file in mixguile.scm.