shithub: femtolisp

ref: ec2a902acc1c05ed0a95c26249bbda4032c668e7
dir: /3rd/mp/mprand.c/

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#include "platform.h"
#include "mp.h"

mpint *
mprand(int bits, void (*gen)(uint8_t*, int), mpint *b)
{
	mpdigit mask;

	if(b == nil)
		b = mpnew(bits);
	else
		mpbits(b, bits);

	b->sign = 1;
	b->top = DIGITS(bits);
	(*gen)((uint8_t*)b->p, b->top*Dbytes);

	mask = ((mpdigit)1 << (bits%Dbits))-1;
	if(mask != 0)
		b->p[b->top-1] &= mask;

	return mpnorm(b);
}