Defining new functions (GNU MIX Development Kit (mdk))

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>

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.

3.4.3 Defining new functions