scrying technical notes

• uses structures so not so easy.
• but structures are abstracted apart from some cell pointer arithmetic

flat string storage

/* cell structure */
struct cell {
        unsigned short _flag;
        union {
                struct {
                        char   *_svalue;
                        short   _keynum;
                } _string;
                struct {
                        long    _ivalue;
                } _number;
                struct {
                        struct cell *_car;
                        struct cell *_cdr;
                } _cons;
        } _object;
};

translates into svalue,keynum,ivalue,car,cdr

We use algorithm E (Knuth, The Art of Computer Programming Vol.1, sec.3.5) for marking.

should be easy

very easy to read

dispatching

2450 lines

short   op = (short) OP_LOAD; // as first operation

marks 8/10

can't compile. too messy with dynload and other stuff though similar in some respects to minischeme

marks 2/10

can't compile. too large and unwieldy

marks 1/10

typedef int obj;

static obj heap[2 * heap_size];
static char marks[heap_size];
static int hp = heap_size;      /* heap pointer */

static obj stack[stack_size];
static int sp = 0;              /* stack pointer */

translates to:

heap, marks, stack

so very simple.

unsure of this

simple memory, messy implementation with some features missing

marks 5/10

plus: memory abstraction, knowledge of code, simple base

minus: much to fix and add, GC to add, reader code is messy(could be abstracted further)

file:sync/root/projects/scryer/lisps/ActorNet-1.0/ActorNet/eval.c::eval c

interesting in terms of actors and mobile code, but builds on tinyOS so can't use, is also harder to follow code

also has virtual memory VM management with cached pages from serial flash which could be useful

where is GC?

file:sync/root/projects/scryer/lisps/ActorNet-1.0/ActorNet/data.c::data c

file:sync/root/projects/scryer/lisps/XS/xs/eval.c::

looks very messy