add LCC - a better C-Compiler for WEGA

WEGA/contrib/lcc/lib/libc/port/gen/drand48.c

@@ -0,0 +1,177 @@
+/*
+ *	drand48, etc. pseudo-random number generator
+ *	This implementation assumes unsigned short integers of at least
+ *	16 bits, long integers of at least 32 bits, and ignores
+ *	overflows on adding or multiplying two unsigned integers.
+ *	Two's-complement representation is assumed in a few places.
+ *	Some extra masking is done if unsigneds are exactly 16 bits
+ *	or longs are exactly 32 bits, but so what?
+ *	An assembly-language implementation would run significantly faster.
+ */
+#ifndef HAVEFP
+#define HAVEFP 1
+#endif
+#define N	16
+#define MASK	((unsigned)(1 << (N - 1)) + (1 << (N - 1)) - 1)
+#define LOW(x)	((unsigned)(x) & MASK)
+#define HIGH(x)	LOW((x) >> N)
+#define MUL(x, y, z)	{ long l = (long)(x) * (long)(y); \
+		(z)[0] = LOW(l); (z)[1] = HIGH(l); }
+#define CARRY(x, y)	((long)(x) + (long)(y) > MASK)
+#define ADDEQU(x, y, z)	(z = CARRY(x, (y)), x = LOW(x + (y)))
+#define X0	0x330E
+#define X1	0xABCD
+#define X2	0x1234
+#define A0	0xE66D
+#define A1	0xDEEC
+#define A2	0x5
+#define C	0xB
+#define SET3(x, x0, x1, x2)	((x)[0] = (x0), (x)[1] = (x1), (x)[2] = (x2))
+#define SETLOW(x, y, n) SET3(x, LOW((y)[n]), LOW((y)[(n)+1]), LOW((y)[(n)+2]))
+#define SEED(x0, x1, x2) (SET3(x, x0, x1, x2), SET3(a, A0, A1, A2), c = C)
+#define REST(v)	for (i = 0; i < 3; i++) { xsubi[i] = x[i]; x[i] = temp[i]; } \
+		return (v);
+#define NEST(TYPE, f, F)	TYPE f(xsubi) register unsigned short *xsubi; { \
+	register int i; register TYPE v; unsigned temp[3]; \
+	for (i = 0; i < 3; i++) { temp[i] = x[i]; x[i] = LOW(xsubi[i]); }  \
+	v = F(); REST(v); }
+#define HI_BIT	(1L << (2 * N - 1))
+
+static unsigned x[3] = { X0, X1, X2 }, a[3] = { A0, A1, A2 }, c = C;
+static unsigned short lastx[3];
+static void next();
+
+#if HAVEFP
+double
+drand48()
+{
+	static double two16m = 1.0 / (1L << N);
+
+	next();
+	return (two16m * (two16m * (two16m * x[0] + x[1]) + x[2]));
+}
+
+NEST(double, erand48, drand48);
+
+#else
+
+long
+irand48(m)
+/* Treat x[i] as a 48-bit fraction, and multiply it by the 16-bit
+ * multiplier m.  Return integer part as result.
+ */
+register unsigned short m;
+{
+	unsigned r[4], p[2], carry0 = 0;
+
+	next();
+	MUL(m, x[0], &r[0]);
+	MUL(m, x[2], &r[2]);
+	MUL(m, x[1], p);
+	if (CARRY(r[1], p[0]))
+		ADDEQU(r[2], 1, carry0);
+	return (r[3] + carry0 + CARRY(r[2], p[1]));
+}
+
+long
+krand48(xsubi, m)
+/* same as irand48, except user provides storage in xsubi[] */
+register unsigned short *xsubi;
+unsigned short m;
+{
+	register int i;
+	register long iv;
+	unsigned temp[3];
+
+	for (i = 0; i < 3; i++) {
+		temp[i] = x[i];
+		x[i] = xsubi[i];
+	}
+	iv = irand48(m);
+	REST(iv);
+}
+#endif
+
+long
+lrand48()
+{
+	next();
+	return (((long)x[2] << (N - 1)) + (x[1] >> 1));
+}
+
+long
+mrand48()
+{
+	register long l;
+
+	next();
+	/* sign-extend in case length of a long > 32 bits
+						(as on Honeywell) */
+	return ((l = ((long)x[2] << N) + x[1]) & HI_BIT ? l | -HI_BIT : l);
+}
+
+static void
+next()
+{
+	unsigned p[2], q[2], r[2], carry0, carry1;
+
+	MUL(a[0], x[0], p);
+	ADDEQU(p[0], c, carry0);
+	ADDEQU(p[1], carry0, carry1);
+	MUL(a[0], x[1], q);
+	ADDEQU(p[1], q[0], carry0);
+	MUL(a[1], x[0], r);
+	x[2] = LOW(carry0 + carry1 + CARRY(p[1], r[0]) + q[1] + r[1] +
+		a[0] * x[2] + a[1] * x[1] + a[2] * x[0]);
+	x[1] = LOW(p[1] + r[0]);
+	x[0] = LOW(p[0]);
+}
+
+void
+srand48(seedval)
+long seedval;
+{
+	SEED(X0, LOW(seedval), HIGH(seedval));
+}
+
+unsigned short *
+seed48(seed16v)
+unsigned short seed16v[3];
+{
+	SETLOW(lastx, x, 0);
+	SEED(LOW(seed16v[0]), LOW(seed16v[1]), LOW(seed16v[2]));
+	return (lastx);
+}
+
+void
+lcong48(param)
+unsigned short param[7];
+{
+	SETLOW(x, param, 0);
+	SETLOW(a, param, 3);
+	c = LOW(param[6]);
+}
+
+NEST(long, nrand48, lrand48);
+
+NEST(long, jrand48, mrand48);
+
+#ifdef DRIVER
+/*
+	This should print the sequences of integers in Tables 2
+		and 1 of the TM:
+	1623, 3442, 1447, 1829, 1305, ...
+	657EB7255101, D72A0C966378, 5A743C062A23, ...
+ */
+#include <stdio.h>
+
+main()
+{
+	int i;
+
+	for (i = 0; i < 80; i++) {
+		printf("%4d ", (int)(4096 * drand48()));
+		printf("%.4X%.4X%.4X\n", x[2], x[1], x[0]);
+	}
+}
+#endif