On Wednesday, 19 February 2003 at 9:22:18 -0800, Wes Peters wrote: > On Tuesday 18 February 2003 22:36, Peter Jeremy wrote: >> >> I see this as a major advantage of arc4random() - if I want 32-bit >> random numbers I don't have to call random() twice and merge the >> results. I've never understood why random() was specified to return >> a '0' in the MSB. > > It probably had something to do with the PDP-11 architecture. This > rings a bell, but I can't recall what it was. Greg Lehey might be > able to help here, he has far better knowlege of the Good Old Days(tm) > than I do.
Difficult to say. I don't think that random() was in the Seventh
Edition. They used rand() instead. Read the code and shudder:
static long randx = 1;
srand(x)
unsigned x;
{
randx = x;
}
rand()
{
return(((randx = randx*1103515245 + 12345)>>16) & 077777);
}
That's the entire content of Seventh Edition /usr/src/libc/gen/rand.c.
Greg
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