#include <fp.h>

/*
 * If ctl == 0x00000000, then *d is set to a0
 * If ctl == 0xFFFFFFFF, then *d is set to a1
 * ctl MUST be either 0x00000000 or 0xFFFFFFFF.
 */
void
fp_select(fp_t *d, const fp_t *a0, const fp_t *a1, uint32_t ctl)
{
    digit_t cw = (int32_t)ctl;
    for (unsigned int i = 0; i < NWORDS_FIELD; i++) {
        (*d)[i] = (*a0)[i] ^ (cw & ((*a0)[i] ^ (*a1)[i]));
    }
}