1 files changed, 587 insertions, 0 deletions
diff --git a/lcc/src/simp.c b/lcc/src/simp.c
new file mode 100755
index 0000000..04699bb
--- /dev/null
+++ b/lcc/src/simp.c
@@ -0,0 +1,587 @@
+#include "c.h"
+#include <float.h>
+
+
+#define foldcnst(TYPE,VAR,OP) \
+	if (l->op == CNST+TYPE && r->op == CNST+TYPE) \
+		return cnsttree(ty, l->u.v.VAR OP r->u.v.VAR)
+#define commute(L,R) \
+	if (generic(R->op) == CNST && generic(L->op) != CNST) \
+		do { Tree t = L; L = R; R = t; } while(0)
+#define xfoldcnst(TYPE,VAR,OP,FUNC)\
+	if (l->op == CNST+TYPE && r->op == CNST+TYPE\
+	&& FUNC(l->u.v.VAR,r->u.v.VAR,\
+		ty->u.sym->u.limits.min.VAR,\
+		ty->u.sym->u.limits.max.VAR, needconst)) \
+		return cnsttree(ty, l->u.v.VAR OP r->u.v.VAR)
+#define xcvtcnst(FTYPE,SRC,DST,VAR,EXPR) \
+	if (l->op == CNST+FTYPE) do {\
+		if (!explicitCast\
+		&&  ((SRC) < DST->u.sym->u.limits.min.VAR || (SRC) > DST->u.sym->u.limits.max.VAR))\
+			warning("overflow in converting constant expression from `%t' to `%t'\n", l->type, DST);\
+		if (needconst\
+		|| !((SRC) < DST->u.sym->u.limits.min.VAR || (SRC) > DST->u.sym->u.limits.max.VAR))\
+			return cnsttree(ty, (EXPR)); } while(0)
+#define identity(X,Y,TYPE,VAR,VAL) \
+	if (X->op == CNST+TYPE && X->u.v.VAR == VAL) return Y
+#define zerofield(OP,TYPE,VAR) \
+	if (l->op == FIELD \
+	&&  r->op == CNST+TYPE && r->u.v.VAR == 0)\
+		return eqtree(OP, bittree(BAND, l->kids[0],\
+			cnsttree(unsignedtype, \
+				(unsigned long)fieldmask(l->u.field)<<fieldright(l->u.field))), r)
+#define cfoldcnst(TYPE,VAR,OP) \
+	if (l->op == CNST+TYPE && r->op == CNST+TYPE) \
+		return cnsttree(inttype, (long)(l->u.v.VAR OP r->u.v.VAR))
+#define foldaddp(L,R,RTYPE,VAR) \
+	if (L->op == CNST+P && R->op == CNST+RTYPE) { \
+		Tree e = tree(CNST+P, ty, NULL, NULL);\
+		e->u.v.p = (char *)L->u.v.p + R->u.v.VAR;\
+		return e; }
+#define ufoldcnst(TYPE,EXP) if (l->op == CNST+TYPE) return EXP
+#define sfoldcnst(OP) \
+	if (l->op == CNST+U && r->op == CNST+I \
+	&& r->u.v.i >= 0 && r->u.v.i < 8*l->type->size) \
+		return cnsttree(ty, (unsigned long)(l->u.v.u OP r->u.v.i))
+#define geu(L,R,V) \
+	if (R->op == CNST+U && R->u.v.u == 0) do { \
+		warning("result of unsigned comparison is constant\n"); \
+		return tree(RIGHT, inttype, root(L), cnsttree(inttype, (long)(V))); } while(0)
+#define idempotent(OP) if (l->op == OP) return l->kids[0]
+
+int needconst;
+int explicitCast;
+static int addi(long x, long y, long min, long max, int needconst) {
+	int cond = x == 0 || y == 0
+	|| x < 0 && y < 0 && x >= min - y
+	|| x < 0 && y > 0
+	|| x > 0 && y < 0
+	|| x > 0 && y > 0 && x <= max - y;
+	if (!cond && needconst) {
+		warning("overflow in constant expression\n");
+		cond = 1;
+	}
+	return cond;
+
+
+}
+
+static int addd(double x, double y, double min, double max, int needconst) {
+	int cond = x == 0 || y == 0
+	|| x < 0 && y < 0 && x >= min - y
+	|| x < 0 && y > 0
+	|| x > 0 && y < 0
+	|| x > 0 && y > 0 && x <= max - y;
+	if (!cond && needconst) {
+		warning("overflow in constant expression\n");
+		cond = 1;
+	}
+	return cond;
+
+
+}
+
+static Tree addrtree(Tree e, long n, Type ty) {
+	Symbol p = e->u.sym, q;
+
+	if (p->scope  == GLOBAL
+	||  p->sclass == STATIC || p->sclass == EXTERN)
+		NEW0(q, PERM);
+	else
+		NEW0(q, FUNC);
+	q->name = stringd(genlabel(1));
+	q->sclass = p->sclass;
+	q->scope = p->scope;
+	assert(isptr(ty) || isarray(ty));
+	q->type = isptr(ty) ? ty->type : ty;
+	q->temporary = p->temporary;
+	q->generated = p->generated;
+	q->addressed = p->addressed;
+	q->computed = 1;
+	q->defined = 1;
+	q->ref = 1;
+	if (p->scope  == GLOBAL
+	||  p->sclass == STATIC || p->sclass == EXTERN) {
+		if (p->sclass == AUTO)
+			q->sclass = STATIC;
+		(*IR->address)(q, p, n);
+	} else {
+		Code cp;
+		addlocal(p);
+		cp = code(Address);
+		cp->u.addr.sym = q;
+		cp->u.addr.base = p;
+		cp->u.addr.offset = n;
+	}
+	e = tree(e->op, ty, NULL, NULL);
+	e->u.sym = q;
+	return e;
+}
+
+/* div[id] - return 1 if min <= x/y <= max, 0 otherwise */
+static int divi(long x, long y, long min, long max, int needconst) {
+	int cond = y != 0 && !(x == min && y == -1);
+	if (!cond && needconst) {
+		warning("overflow in constant expression\n");
+		cond = 1;
+	}
+	return cond;
+
+
+}
+
+static int divd(double x, double y, double min, double max, int needconst) {
+	int cond;
+
+	if (x < 0) x = -x;
+	if (y < 0) y = -y;
+	cond = y != 0 && !(y < 1 && x > max*y);
+	if (!cond && needconst) {
+		warning("overflow in constant expression\n");
+		cond = 1;
+	}
+	return cond;
+
+}
+
+/* mul[id] - return 1 if min <= x*y <= max, 0 otherwise */
+static int muli(long x, long y, long min, long max, int needconst) {
+	int cond = x > -1 && x <= 1 || y > -1 && y <= 1
+	|| x < 0 && y < 0 && -x <= max/-y
+	|| x < 0 && y > 0 &&  x >= min/y
+	|| x > 0 && y < 0 &&  y >= min/x
+	|| x > 0 && y > 0 &&  x <= max/y;
+	if (!cond && needconst) {
+		warning("overflow in constant expression\n");
+		cond = 1;
+	}
+	return cond;
+
+
+}
+
+static int muld(double x, double y, double min, double max, int needconst) {
+	int cond = x >= -1 && x <= 1 || y >= -1 && y <= 1
+	|| x < 0 && y < 0 && -x <= max/-y
+	|| x < 0 && y > 0 &&  x >= min/y
+	|| x > 0 && y < 0 &&  y >= min/x
+	|| x > 0 && y > 0 &&  x <= max/y;
+	if (!cond && needconst) {
+		warning("overflow in constant expression\n");
+		cond = 1;
+	}
+	return cond;
+
+
+}
+/* sub[id] - return 1 if min <= x-y <= max, 0 otherwise */
+static int subi(long x, long y, long min, long max, int needconst) {
+	return addi(x, -y, min, max, needconst);
+}
+
+static int subd(double x, double y, double min, double max, int needconst) {
+	return addd(x, -y, min, max, needconst);
+}
+Tree constexpr(int tok) {
+	Tree p;
+
+	needconst++;
+	p = expr1(tok);
+	needconst--;
+	return p;
+}
+
+int intexpr(int tok, int n) {
+	Tree p = constexpr(tok);
+
+	needconst++;
+	if (p->op == CNST+I || p->op == CNST+U)
+		n = cast(p, inttype)->u.v.i;
+	else
+		error("integer expression must be constant\n");
+	needconst--;
+	return n;
+}
+Tree simplify(int op, Type ty, Tree l, Tree r) {
+	int n;
+	Tree p;
+
+	if (optype(op) == 0)
+		op = mkop(op, ty);
+	switch (op) {
+		case ADD+U:
+			foldcnst(U,u,+);
+			commute(r,l);
+			identity(r,l,U,u,0);
+			break;
+		case ADD+I:
+			xfoldcnst(I,i,+,addi);
+			commute(r,l);
+			identity(r,l,I,i,0);
+			break;
+		case CVI+I:
+			xcvtcnst(I,l->u.v.i,ty,i,(long)extend(l->u.v.i,ty));
+			break;
+		case CVU+I:
+			if (l->op == CNST+U) {
+				if (!explicitCast && l->u.v.u > ty->u.sym->u.limits.max.i)
+					warning("overflow in converting constant expression from `%t' to `%t'\n", l->type, ty);
+				if (needconst || !(l->u.v.u > ty->u.sym->u.limits.max.i))
+					return cnsttree(ty, (long)extend(l->u.v.u,ty));
+			}
+			break;
+		case CVP+U:
+			xcvtcnst(P,(unsigned long)l->u.v.p,ty,u,(unsigned long)l->u.v.p);
+			break;
+		case CVU+P:
+			xcvtcnst(U,(void*)l->u.v.u,ty,p,(void*)l->u.v.u);
+			break;
+		case CVP+P:
+			xcvtcnst(P,l->u.v.p,ty,p,l->u.v.p);
+			break;
+		case CVI+U:
+			xcvtcnst(I,l->u.v.i,ty,u,((unsigned long)l->u.v.i)&ones(8*ty->size));
+			break;
+		case CVU+U:
+			xcvtcnst(U,l->u.v.u,ty,u,l->u.v.u&ones(8*ty->size));
+			break;
+
+		case CVI+F:
+			xcvtcnst(I,l->u.v.i,ty,d,(long double)l->u.v.i);
+		case CVU+F:
+			xcvtcnst(U,l->u.v.u,ty,d,(long double)l->u.v.u);
+			break;
+		case CVF+I:
+			xcvtcnst(F,l->u.v.d,ty,i,(long)l->u.v.d);
+			break;
+		case CVF+F: {
+			float d;
+			if (l->op == CNST+F)
+				if (l->u.v.d < ty->u.sym->u.limits.min.d)
+					d = ty->u.sym->u.limits.min.d;
+				else if (l->u.v.d > ty->u.sym->u.limits.max.d)
+					d = ty->u.sym->u.limits.max.d;
+				else
+					d = l->u.v.d;
+			xcvtcnst(F,l->u.v.d,ty,d,(long double)d);
+			break;
+			}
+		case BAND+U:
+			foldcnst(U,u,&);
+			commute(r,l);
+			identity(r,l,U,u,ones(8*ty->size));
+			if (r->op == CNST+U && r->u.v.u == 0)
+				return tree(RIGHT, ty, root(l), cnsttree(ty, 0UL));
+			break;
+		case BAND+I:
+			foldcnst(I,i,&);
+			commute(r,l);
+			identity(r,l,I,i,ones(8*ty->size));
+			if (r->op == CNST+I && r->u.v.u == 0)
+				return tree(RIGHT, ty, root(l), cnsttree(ty, 0L));
+			break;
+
+		case MUL+U:
+			commute(l,r);
+			if (l->op == CNST+U && (n = ispow2(l->u.v.u)) != 0)
+				return simplify(LSH, ty, r, cnsttree(inttype, (long)n));
+			foldcnst(U,u,*);
+			identity(r,l,U,u,1);
+			break;
+		case NE+I:
+			cfoldcnst(I,i,!=);
+			commute(r,l);
+			zerofield(NE,I,i);
+			break;
+
+		case EQ+I:
+			cfoldcnst(I,i,==);
+			commute(r,l);
+			zerofield(EQ,I,i);
+			break;
+		case ADD+P:
+			foldaddp(l,r,I,i);
+			foldaddp(l,r,U,u);
+			foldaddp(r,l,I,i);
+			foldaddp(r,l,U,u);
+			commute(r,l);
+			identity(r,retype(l,ty),I,i,0);
+			identity(r,retype(l,ty),U,u,0);
+			if (isaddrop(l->op)
+			&& (r->op == CNST+I && r->u.v.i <= longtype->u.sym->u.limits.max.i
+			    && r->u.v.i >= longtype->u.sym->u.limits.min.i
+			|| r->op == CNST+U && r->u.v.u <= longtype->u.sym->u.limits.max.i))
+				return addrtree(l, cast(r, longtype)->u.v.i, ty);
+			if (l->op == ADD+P && isaddrop(l->kids[1]->op)
+			&& (r->op == CNST+I && r->u.v.i <= longtype->u.sym->u.limits.max.i
+			    && r->u.v.i >= longtype->u.sym->u.limits.min.i
+			||  r->op == CNST+U && r->u.v.u <= longtype->u.sym->u.limits.max.i))
+				return simplify(ADD+P, ty, l->kids[0],
+					addrtree(l->kids[1], cast(r, longtype)->u.v.i, ty));
+			if ((l->op == ADD+I || l->op == SUB+I)
+			&& l->kids[1]->op == CNST+I && isaddrop(r->op))
+				return simplify(ADD+P, ty, l->kids[0],
+					simplify(generic(l->op)+P, ty, r, l->kids[1]));
+			if (l->op == ADD+P && generic(l->kids[1]->op) == CNST
+			&& generic(r->op) == CNST)
+				return simplify(ADD+P, ty, l->kids[0],
+					simplify(ADD, l->kids[1]->type, l->kids[1], r));
+			if (l->op == ADD+I && generic(l->kids[1]->op) == CNST
+			&&  r->op == ADD+P && generic(r->kids[1]->op) == CNST)
+				return simplify(ADD+P, ty, l->kids[0],
+					simplify(ADD+P, ty, r->kids[0],
+					simplify(ADD, r->kids[1]->type, l->kids[1], r->kids[1])));
+			if (l->op == RIGHT && l->kids[1])
+				return tree(RIGHT, ty, l->kids[0],
+					simplify(ADD+P, ty, l->kids[1], r));
+			else if (l->op == RIGHT && l->kids[0])
+				return tree(RIGHT, ty,
+					simplify(ADD+P, ty, l->kids[0], r), NULL);
+			break;
+
+		case ADD+F:
+			xfoldcnst(F,d,+,addd);
+			commute(r,l);
+			break;
+		case AND+I:
+			op = AND;
+			ufoldcnst(I,l->u.v.i ? cond(r) : l);	/* 0&&r => 0, 1&&r => r */
+			break;
+		case OR+I:
+			op = OR;
+			/* 0||r => r, 1||r => 1 */
+			ufoldcnst(I,l->u.v.i ? cnsttree(ty, 1L) : cond(r));
+			break;
+		case BCOM+I:
+			ufoldcnst(I,cnsttree(ty, (long)extend((~l->u.v.i)&ones(8*ty->size), ty)));
+			idempotent(BCOM+U);
+			break;
+		case BCOM+U:
+			ufoldcnst(U,cnsttree(ty, (unsigned long)((~l->u.v.u)&ones(8*ty->size))));
+			idempotent(BCOM+U);
+			break;
+		case BOR+U:
+			foldcnst(U,u,|);
+			commute(r,l);
+			identity(r,l,U,u,0);
+			break;
+		case BOR+I:
+			foldcnst(I,i,|);
+			commute(r,l);
+			identity(r,l,I,i,0);
+			break;
+		case BXOR+U:
+			foldcnst(U,u,^);
+			commute(r,l);
+			identity(r,l,U,u,0);
+			break;
+		case BXOR+I:
+			foldcnst(I,i,^);
+			commute(r,l);
+			identity(r,l,I,i,0);
+			break;
+		case DIV+F:
+			xfoldcnst(F,d,/,divd);
+			break;
+		case DIV+I:
+			identity(r,l,I,i,1);
+			if (r->op == CNST+I && r->u.v.i == 0
+			||  l->op == CNST+I && l->u.v.i == ty->u.sym->u.limits.min.i
+			&&  r->op == CNST+I && r->u.v.i == -1)
+				break;
+			xfoldcnst(I,i,/,divi);
+			break;
+		case DIV+U:		
+			identity(r,l,U,u,1);
+			if (r->op == CNST+U && r->u.v.u == 0)
+				break;
+			if (r->op == CNST+U && (n = ispow2(r->u.v.u)) != 0)
+				return simplify(RSH, ty, l, cnsttree(inttype, (long)n));
+			foldcnst(U,u,/);
+			break;
+		case EQ+F:
+			cfoldcnst(F,d,==);
+			commute(r,l);
+			break;
+		case EQ+U:
+			cfoldcnst(U,u,==);
+			commute(r,l);
+			zerofield(EQ,U,u);
+			break;
+		case GE+F: cfoldcnst(F,d,>=); break;
+		case GE+I: cfoldcnst(I,i,>=); break;
+		case GE+U:
+			geu(l,r,1);	/* l >= 0 => (l,1) */
+			cfoldcnst(U,u,>=);
+			if (l->op == CNST+U && l->u.v.u == 0)	/* 0 >= r => r == 0 */
+				return eqtree(EQ, r, l);
+			break;
+		case GT+F: cfoldcnst(F,d, >); break;
+		case GT+I: cfoldcnst(I,i, >); break;
+		case GT+U:
+			geu(r,l,0);	/* 0 > r => (r,0) */
+			cfoldcnst(U,u, >);
+			if (r->op == CNST+U && r->u.v.u == 0)	/* l > 0 => l != 0 */
+				return eqtree(NE, l, r);
+			break;
+		case LE+F: cfoldcnst(F,d,<=); break;
+		case LE+I: cfoldcnst(I,i,<=); break;
+		case LE+U:
+			geu(r,l,1);	/* 0 <= r => (r,1) */
+			cfoldcnst(U,u,<=);
+			if (r->op == CNST+U && r->u.v.u == 0)	/* l <= 0 => l == 0 */
+				return eqtree(EQ, l, r);
+			break;
+		case LSH+I:
+			identity(r,l,I,i,0);
+			if (l->op == CNST+I && r->op == CNST+I
+			&& r->u.v.i >= 0 && r->u.v.i < 8*l->type->size
+			&& muli(l->u.v.i, 1<<r->u.v.i, ty->u.sym->u.limits.min.i, ty->u.sym->u.limits.max.i, needconst))
+				return cnsttree(ty, (long)(l->u.v.i<<r->u.v.i));
+			if (r->op == CNST+I && (r->u.v.i >= 8*ty->size || r->u.v.i < 0)) {
+				warning("shifting an `%t' by %d bits is undefined\n", ty, r->u.v.i);
+				break;
+			}
+
+			break;
+		case LSH+U:
+			identity(r,l,I,i,0);
+			sfoldcnst(<<);
+			if (r->op == CNST+I && (r->u.v.i >= 8*ty->size || r->u.v.i < 0)) {
+				warning("shifting an `%t' by %d bits is undefined\n", ty, r->u.v.i);
+				break;
+			}
+
+			break;
+
+		case LT+F: cfoldcnst(F,d, <); break;
+		case LT+I: cfoldcnst(I,i, <); break;
+		case LT+U:
+			geu(l,r,0);	/* l < 0 => (l,0) */
+			cfoldcnst(U,u, <);
+			if (l->op == CNST+U && l->u.v.u == 0)	/* 0 < r => r != 0 */
+				return eqtree(NE, r, l);
+			break;
+		case MOD+I:
+			if (r->op == CNST+I && r->u.v.i == 1)	/* l%1 => (l,0) */
+				return tree(RIGHT, ty, root(l), cnsttree(ty, 0L));
+			if (r->op == CNST+I && r->u.v.i == 0
+			||  l->op == CNST+I && l->u.v.i == ty->u.sym->u.limits.min.i
+			&&  r->op == CNST+I && r->u.v.i == -1)
+				break;
+			xfoldcnst(I,i,%,divi);
+			break;
+		case MOD+U:		
+			if (r->op == CNST+U && ispow2(r->u.v.u)) /* l%2^n => l&(2^n-1) */
+				return bittree(BAND, l, cnsttree(ty, r->u.v.u - 1));
+			if (r->op == CNST+U && r->u.v.u == 0)
+				break;
+			foldcnst(U,u,%);
+			break;
+		case MUL+F:
+			xfoldcnst(F,d,*,muld);
+			commute(l,r);
+			break;
+		case MUL+I:
+			commute(l,r);
+			xfoldcnst(I,i,*,muli);
+			if (l->op == CNST+I && r->op == ADD+I && r->kids[1]->op == CNST+I)
+				/* c1*(x + c2) => c1*x + c1*c2 */
+				return simplify(ADD, ty, simplify(MUL, ty, l, r->kids[0]),
+					simplify(MUL, ty, l, r->kids[1]));
+			if (l->op == CNST+I && r->op == SUB+I && r->kids[1]->op == CNST+I)
+				/* c1*(x - c2) => c1*x - c1*c2 */
+				return simplify(SUB, ty, simplify(MUL, ty, l, r->kids[0]),
+					simplify(MUL, ty, l, r->kids[1]));
+			if (l->op == CNST+I && l->u.v.i > 0 && (n = ispow2(l->u.v.i)) != 0)
+				/* 2^n * r => r<<n */
+				return simplify(LSH, ty, r, cnsttree(inttype, (long)n));
+			identity(r,l,I,i,1);
+			break;
+		case NE+F:
+			cfoldcnst(F,d,!=);
+			commute(r,l);
+			break;
+		case NE+U:
+			cfoldcnst(U,u,!=);
+			commute(r,l);
+			zerofield(NE,U,u);
+			break;
+		case NEG+F:
+			ufoldcnst(F,cnsttree(ty, -l->u.v.d));
+			idempotent(NEG+F);
+			break;
+		case NEG+I:
+			if (l->op == CNST+I) {
+				if (needconst && l->u.v.i == ty->u.sym->u.limits.min.i)
+					warning("overflow in constant expression\n");
+				if (needconst || l->u.v.i != ty->u.sym->u.limits.min.i)
+					return cnsttree(ty, -l->u.v.i);
+			}
+			idempotent(NEG+I);
+			break;
+		case NOT+I:
+			op = NOT;
+			ufoldcnst(I,cnsttree(ty, !l->u.v.i));
+			break;
+		case RSH+I:
+			identity(r,l,I,i,0);
+			if (l->op == CNST+I && r->op == CNST+I
+			&& r->u.v.i >= 0 && r->u.v.i < 8*l->type->size) {
+				long n = l->u.v.i>>r->u.v.i;
+				if (l->u.v.i < 0)
+					n |= ~0UL<<(8*l->type->size - r->u.v.i);
+				return cnsttree(ty, n);
+			}
+			if (r->op == CNST+I && (r->u.v.i >= 8*ty->size || r->u.v.i < 0)) {
+				warning("shifting an `%t' by %d bits is undefined\n", ty, r->u.v.i);
+				break;
+			}
+
+			break;
+		case RSH+U:
+			identity(r,l,I,i,0);
+			sfoldcnst(>>);
+			if (r->op == CNST+I && (r->u.v.i >= 8*ty->size || r->u.v.i < 0)) {
+				warning("shifting an `%t' by %d bits is undefined\n", ty, r->u.v.i);
+				break;
+			}
+
+			break;
+		case SUB+F:
+			xfoldcnst(F,d,-,subd);
+			break;
+		case SUB+I:
+			xfoldcnst(I,i,-,subi);
+			identity(r,l,I,i,0);
+			break;
+		case SUB+U:
+			foldcnst(U,u,-);
+			identity(r,l,U,u,0);
+			break;
+		case SUB+P:
+			if (l->op == CNST+P && r->op == CNST+P)
+				return cnsttree(ty, (long)((char *)l->u.v.p - (char *)r->u.v.p));
+			if (r->op == CNST+I || r->op == CNST+U)
+				return simplify(ADD, ty, l,
+					cnsttree(inttype, r->op == CNST+I ? -r->u.v.i : -(long)r->u.v.u));
+			if (isaddrop(l->op) && r->op == ADD+I && r->kids[1]->op == CNST+I)
+				/* l - (x + c) => l-c - x */
+				return simplify(SUB, ty,
+					simplify(SUB, ty, l, r->kids[1]), r->kids[0]);
+			break;
+		default:assert(0);
+	}
+	return tree(op, ty, l, r);
+}
+/* ispow2 - if u > 1 && u == 2^n, return n, otherwise return 0 */
+int ispow2(unsigned long u) {
+	int n;
+
+	if (u > 1 && (u&(u-1)) == 0)
+		for (n = 0; u; u >>= 1, n++)
+			if (u&1)
+				return n;
+	return 0;
+}
+