1 files changed, 329 insertions, 0 deletions
diff --git a/appl/lib/sets.b b/appl/lib/sets.b
new file mode 100644
index 00000000..22f25d7b
--- /dev/null
+++ b/appl/lib/sets.b
@@ -0,0 +1,329 @@
+implement Sets;
+include "sys.m";
+	sys: Sys;
+include "draw.m";
+include "sets.m";
+
+init()
+{
+	sys = load Sys Sys->PATH;
+}
+
+BPW: con 32;
+SHIFT: con 5;
+MASK: con 31;
+
+# Set adt contains:
+#	a - array holding membership of set s for n (0 ≤ n < len a * BPW).
+#		∀ n: 0≤n<(len a*BPW), (s.a[n >> SHIFT] & (1 << (n & MASK)) != 0) iff s ∋ n
+#	m - "most significant bits", extrapolate membership for n >= len a * BPW.
+#		m is 0 if members are excluded by default,
+#		or ~0 if members are included by default.
+
+swapops := array[16] of {
+	byte 2r0000, byte 2r0001, byte 2r0100, byte 2r0101,
+	byte 2r0010, byte 2r0011, byte 2r0110, byte 2r0111,
+	byte 2r1000, byte 2r1001, byte 2r1100, byte 2r1101,
+	byte 2r1010, byte 2r1011, byte 2r1110, byte 2r1111,
+};
+
+Set.X(s1: self Set, o: int, s2: Set): Set
+{
+	if (len s1.a > len s2.a) {
+		(s1, s2) = (s2, s1);
+		o = int swapops[o & 2r1111];
+	}
+	r := Set(0, array[len s2.a] of int);
+	for (i := 0; i < len s1.a; i++)
+		r.a[i] = op(o, s1.a[i], s2.a[i]);
+	for (; i < len s2.a; i++)
+		r.a[i] = op(o, s1.m, s2.a[i]);
+	r.m = op(o, s1.m, s2.m);
+	return r;
+}
+
+Set.invert(s: self Set): Set
+{
+	r := Set(~s.m, array[len s.a] of int);
+	for (i := 0; i < len s.a; i++)
+		r.a[i] = ~s.a[i];
+	return r;
+}
+
+# copy s, ensuring that the copy is big enough to hold n.
+copy(s: Set, n: int): Set
+{
+	if (n >= 0) {
+		req := (n >> SHIFT) + 1;
+		if (req > len s.a) {
+			a := array[req] of int;
+			a[0:] = s.a;
+			for (i := len s.a; i < len a; i++)
+				a[i] = s.m;
+			return (s.m, a);
+		}
+	}
+	a: array of int;
+	if (len s.a > 0) {
+		a = array[len s.a] of int;
+		a[0:] = s.a;
+	}
+	return (s.m, a);
+}
+
+Set.add(s: self Set, n: int): Set
+{
+	d := n >> SHIFT;
+	if (s.m && d >= len s.a)
+		return s;
+	r := copy(s, n);
+	r.a[d] |= 1<< (n & MASK);
+	return r;
+}
+
+Set.addlist(s: self Set, ns: list of int): Set
+{
+	r: Set;
+	if (s.m == 0) {
+		max := -1;
+		for (l := ns; l != nil; l = tl l)
+			if (hd l > max)
+				max = hd l;
+		r = copy(s, max);
+	} else
+		r = copy(s, -1);
+	for (; ns != nil; ns = tl ns) {
+		n := hd ns;
+		d := n >> SHIFT;
+		if (d < len r.a)
+			r.a[d] |= 1 << (n & MASK);
+	}
+	return r;
+}
+
+
+Set.del(s: self Set, n: int): Set
+{
+	d := n >> SHIFT;
+	if (!s.m && d >= len s.a)
+		return s;
+	r := copy(s, n);
+	r.a[d] &= ~(1 << (n & MASK));
+	return r;
+}
+
+Set.holds(s: self Set, n: int): int
+{
+	d := n >> SHIFT;
+	if (d >= len s.a)
+		return s.m;
+	return s.a[d] & (1 << (n & MASK));
+}
+
+Set.limit(s: self Set): int
+{
+	for (i := len s.a - 1; i >= 0; i--)
+		if (s.a[i] != s.m)
+			return (i<<SHIFT) + topbit(s.m ^ s.a[i]);
+	return 0;
+}
+
+Set.eq(s1: self Set, s2: Set): int
+{
+	if (len s1.a > len s2.a)
+		(s1, s2) = (s2, s1);
+	for (i := 0; i < len s1.a; i++)
+		if (s1.a[i] != s2.a[i])
+			return 0;
+	for (; i < len s2.a; i++)
+		if (s1.m != s2.a[i])
+			return 0;
+	return s1.m == s2.m;
+}
+
+Set.isempty(s: self Set): int
+{
+	return Set(0, nil).eq(s);
+}
+
+Set.msb(s: self Set): int
+{
+	return s.m != 0;
+}
+
+Set.bytes(s: self Set, n: int): array of byte
+{
+	m := (s.limit() >> 3) + 1;
+	if(m > n)
+		n = m;
+	d := array[n] of byte;
+	# XXX this could proably be made substantially faster by unrolling the
+	# loop a little.
+	for(i := 0; i < len d; i++){
+		j := i >> 2;
+		if(j >= len s.a)
+			d[i] = byte s.m;
+		else
+			d[i] = byte (s.a[j] >> ((i & 3) << 3));
+	}
+	return d;
+}
+
+bytes2set(d: array of byte): Set
+{
+	if(len d == 0)
+		return (0, nil);
+	a := array[(len d + 3) >> 2] of int;		# round up
+	n := len d >> 2;
+	for(i := 0; i < n; i++){
+		j := i << 2;
+		a[i] = int d[j] + (int d[j+1] << 8) + (int d[j+2] << 16) + (int d[j+3] << 24);
+	}
+	msb := ~(int (d[len d - 1] >> 7) - 1);
+	j := i << 2;
+	case len d & 3 {
+	0 =>
+		;
+	1 =>
+		a[i] = int d[j] | (msb & int 16rffffff00);
+	2 =>
+		a[i] = int d[j] | (int d[j+1] << 8) | (msb & int 16rffff0000);
+	3 =>
+		a[i] = int d[j] | (int d[j+1] << 8) | (int d[j+2] << 16) | (msb & int 16rff000000);
+	}
+	return (msb, a);
+}
+
+Set.str(s: self Set): string
+{
+	str: string;
+
+	# discard all top bits that are the same as msb.
+	sig := 0;
+loop:
+	for (i := len s.a - 1; i >= 0; i--) {
+		t := 16rf << (BPW - 4);
+		sig = 8;
+		while (t != 0) {
+			if ((s.m & t) != (s.a[i] & t))
+				break loop;
+			sig--;
+			t = (t >> 4) & 16r0fffffff;		# logical shift right
+		}
+	}
+	if (i >= 0) {
+		top := s.a[i];
+		if (sig < 8)		# shifting left by 32 bits is undefined.
+			top &= (1 << (sig << 2)) - 1;
+		str = sys->sprint("%.*ux", sig, top);
+		for (i--; i >= 0; i--)
+			str += sys->sprint("%.8ux", s.a[i]);
+	}
+	return str + ":" + string (s.m & 1);
+}
+
+str2set(str: string): Set
+{
+	n := len str;
+	if (n < 2 || str[n - 2] != ':')
+		return (0, nil);
+	c := str[n - 1];
+	if (c != '0' && c != '1')
+		return (0, nil);
+	msb := ~(c - '1');
+
+	n -= 2;
+	if (n == 0)
+		return (msb, nil);
+	req := ((n * 4 - 1) >> SHIFT) + 1;
+	a := array[req] of int;
+	d := 0;
+	for (i := n; i > 0; ) {
+		j := i - 8;
+		if (j < 0)
+			j = 0;
+		a[d++] = hex2int(str[j:i], msb);
+		i = j;
+	}
+	return (msb, a);
+}
+
+Set.debugstr(s: self Set): string
+{
+	str: string;
+	for (i := len s.a - 1; i >= 0; i--)
+		str += sys->sprint("%ux:", s.a[i]);
+	str += sys->sprint(":%ux", s.m);
+	return str;
+}
+
+set(): Set
+{
+	return (0, nil);
+}
+
+hex2int(s: string, fill: int): int
+{
+	n := fill;
+	for (i := 0; i < len s; i++) {
+		c := s[i];
+		if (c >= '0' && c <= '9')
+			c -= '0';
+		else if (c >= 'a' && c <= 'f')
+			c -= 'a' - 10;
+		else if (c >= 'A' && c <= 'F')
+			c -= 'A' - 10;
+		else
+			c = 0;
+		n = (n << 4) | c;
+	}
+	return n;
+}
+
+op(o: int, a, b: int): int
+{
+	case o &  2r1111 {
+	2r0000 => return 0;
+	2r0001 => return ~(a | b);
+	2r0010 => return a & ~b;
+	2r0011 => return ~b;
+	2r0100 => return ~a & b;
+	2r0101 => return ~a;
+	2r0110 => return a ^ b;
+	2r0111 => return ~(a & b);
+	2r1000 => return a & b;
+	2r1001 => return ~(a ^ b);
+	2r1010 => return a;
+	2r1011 => return a | ~b;
+	2r1100 => return b;
+	2r1101 => return ~(a | b);
+	2r1110 => return a | b;
+	2r1111 => return ~0;
+	}
+	return 0;
+}
+
+topbit(v: int): int
+{
+	if (v == 0)
+		return 0;
+	(b, n, mask) := (1, 16, int 16rffff0000);
+	while (n != 0) {
+		if (v & mask) {
+			b += n;
+			v >>= n;		# could return if v==0 here if we thought it worth it
+		}
+		n >>= 1;
+		mask >>= n;
+	}
+	return b;
+}
+
+nbits(n: int): int
+{
+	n = ((n >> 1) & 16r55555555) + (n & 16r55555555) ;
+	n = ((n >> 2) & 16r33333333) + (n & 16r33333333) ;
+	n = ((n >> 4) + n) & 16r0F0F0F0F ;
+	n = ((n >> 8) + n) ;
+	return ((n >> 16) + n) & 16rFF ;
+}