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/* borrowed from libc/misc/drand48.c in Linux libc-5.4.46 this quick
* hack by Martin Hamilton <martinh@gnu.org> to make Squid build on
* Win32 with GNU-Win32 - sorry, folks! */
#ifndef HAVE_DRAND48
#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
static void next(void);
static unsigned x[3] = {X0, X1, X2}, a[3] = {A0, A1, A2}, c = C;
double drand48(void);
double
drand48(void)
{
static double two16m = 1.0 / (1L << N);
next();
return (two16m * (two16m * (two16m * x[0] + x[1]) + x[2]));
}
static void
next(void)
{
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]);
}
#endif /* HAVE_DRAND48 */
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