#include "m.h"

#define PROGSIZE  8192

Inst prog[PROGSIZE];	/* the machine */
Instptr pc;		/* program counter during execution */
Instptr pp = prog;	/* next free spot for code generation */

// conversion between Inst (function pointer) and data (void *)
//
typedef union { void *v; Inst i; } U;

Inst d2i( void *v) // data to Inst
{
  U u;  u.v = v;  return u.i;
}

void *i2d( Inst i) // Inst to data
{
  U u;  u.i = i;  return u.v;
}

void initcode( void)
{
    pp = prog;
    sp = stack;
    fp = frame; fpush();
    got_return = got_break = got_continue = 0;
    inmat = instmt = inloop = insw = indef = 0;
}

Instptr code( Inst f)	/* install one instruction or operand */
{
    Instptr opp = pp;

    if( pp >= prog + PROGSIZE)
	error("program too big","");

    *pp++ = f;
    return opp;
}

Instptr code2( Inst f1, Inst f2)
{
    Instptr opp;

    opp = code(f1); code(f2);
    return opp;
}

Instptr code3( Inst f1, Inst f2, Inst f3)
{
    Instptr opp;

    opp = code(f1); code(f2); code(f3);
    return opp;
}

Instptr code4( Inst f1, Inst f2, Inst f3, Inst f4)
{
    Instptr opp;

    opp = code(f1); code(f2); code(f3); code(f4);
    return opp;
}

/*
 * copy program, from prog[0] to *(pp-1), for FUNCTION or PROCEDURE
 */
void define( Symbolptr a, int narg)
{
    int size = pp - prog;

    if( (a->u.fptr = (Instptr) malloc(size*sizeof(Inst))) == NULL)
	error("malloc() failed in define()","");

    prog[0] = d2i( defn());	/* pointer to fn source code */

    memcpy( a->u.fptr, prog, size*sizeof(Inst));

    NARG(a) = narg;
    SIZE(a) = size;
}

Instptr varpush( Symbolptr a)
{
    if( a->class == AUTO)
	return code2( local_push, (Inst)OFFSET(a));
    else
	return code2( sympush, d2i(a));
}

static void dup_check( Symbolptr a)	/* check for duplicates */
{
    Symbolptr *s;

    for( s = stack; s < sp; ++s)
	if( strcmp( (*s)->name, a->name) == 0)
	    dprint("warning: redeclaration of variable %s\n", a->name);
}

void mklocal( Symbolptr a, int class, Instptr init)
{
    dup_check(a);

    if( class == STATIC || class == AUTO) {

	if( a->class == NEW)
	    a->class = class;
	else
	    a = install( a->name, UNDEF, class, 0, 0);

    } else if( class == EXTERN) {

	if( a->class != NEW && a->class != EXTERN)
	    a = install( a->name, UNDEF, EXTERN, 0, 0);

    } else

	error("unrecognized class in mklocal()","");

    if( class == AUTO) {
	OFFSET(a) = sp - stack;
	code( m_install);
    }

    if( init)
    {
	if( class == AUTO)
	    code( m_copy);
	else if( class == STATIC) {
	    code2( sympush, d2i( a));
	    code3( m_copy, (Inst)pop, NULL);
#ifdef DEBUG
	    if( prog_debug) {
		dprint("\n");
		disasm(init,pp);
	    }
#endif
	    execute( init);
	    pp = init;
	    a->class = STATIC;
	} else {
	    code( (Inst)pop);
	    yyerror("initialization ignored in extern declaration");
	}
    }

    push(a);
}

void fnarg( int type, Symbolptr a)
{
    dup_check(a);

    if( a->class == NEW)
	a->class = AUTO;
    else
	a = install( a->name, UNDEF, AUTO, 0, 0);

    OFFSET(a) = sp - stack;
    push(a);
    code( (Inst)type);
}