269 static const uint64_t MASK51 = 0x7ffffffffffff;  variable
308     h1 |= h0 >> 51; h0 &= MASK51;  in fe51_frombytes()
309     h2 |= h1 >> 51; h1 &= MASK51;  in fe51_frombytes()
310     h3 |= h2 >> 51; h2 &= MASK51;  in fe51_frombytes()
311     h4 |= h3 >> 51; h3 &= MASK51;  in fe51_frombytes()
338     h1 += h0 >> 51; h0 &= MASK51;  in fe51_tobytes()
339     h2 += h1 >> 51; h1 &= MASK51;  in fe51_tobytes()
340     h3 += h2 >> 51; h2 &= MASK51;  in fe51_tobytes()
341     h4 += h3 >> 51; h3 &= MASK51;  in fe51_tobytes()
342                     h4 &= MASK51;  in fe51_tobytes()
431     h3 += (uint64_t)(h2 >> 51); g2 = (uint64_t)h2 & MASK51;  in fe51_mul()
432     h1 += (uint64_t)(h0 >> 51); g0 = (uint64_t)h0 & MASK51;  in fe51_mul()
434     h4 += (uint64_t)(h3 >> 51); g3 = (uint64_t)h3 & MASK51;  in fe51_mul()
435     g2 += (uint64_t)(h1 >> 51); g1 = (uint64_t)h1 & MASK51;  in fe51_mul()
437     g0 += (uint64_t)(h4 >> 51) * 19; g4 = (uint64_t)h4 & MASK51;  in fe51_mul()
438     g3 += g2 >> 51; g2 &= MASK51;  in fe51_mul()
439     g1 += g0 >> 51; g0 &= MASK51;  in fe51_mul()
484     h3 += (uint64_t)(h2 >> 51); g2 = (uint64_t)h2 & MASK51;  in fe51_sq()
485     h1 += (uint64_t)(h0 >> 51); g0 = (uint64_t)h0 & MASK51;  in fe51_sq()
487     h4 += (uint64_t)(h3 >> 51); g3 = (uint64_t)h3 & MASK51;  in fe51_sq()
488     g2 += (uint64_t)(h1 >> 51); g1 = (uint64_t)h1 & MASK51;  in fe51_sq()
490     g0 += (uint64_t)(h4 >> 51) * 19; g4 = (uint64_t)h4 & MASK51;  in fe51_sq()
491     g3 += g2 >> 51; g2 &= MASK51;  in fe51_sq()
492     g1 += g0 >> 51; g0 &= MASK51;  in fe51_sq()
511     h3 += (uint64_t)(h2 >> 51); g2 = (uint64_t)h2 & MASK51;  in fe51_mul121666()
512     h1 += (uint64_t)(h0 >> 51); g0 = (uint64_t)h0 & MASK51;  in fe51_mul121666()
514     h4 += (uint64_t)(h3 >> 51); g3 = (uint64_t)h3 & MASK51;  in fe51_mul121666()
515     g2 += (uint64_t)(h1 >> 51); g1 = (uint64_t)h1 & MASK51;  in fe51_mul121666()
517     g0 += (uint64_t)(h4 >> 51) * 19; g4 = (uint64_t)h4 & MASK51;  in fe51_mul121666()
518     g3 += g2 >> 51; g2 &= MASK51;  in fe51_mul121666()
519     g1 += g0 >> 51; g0 &= MASK51;  in fe51_mul121666()