/*
 * Copyright (C) 2016 Andreas Steffen
 * HSR Hochschule fuer Technik Rapperswil
 *
 * Based on the public domain libsodium adaptation by Frank Denis
 * of the SUPERCOP ref10 implementation by  Daniel J. Bernstein,
 * Niels Duif, Peter Schwabe, Tanja Lange and Bo-Yin Yang.
 */

#include <stddef.h>
#include <stdint.h>
#include <string.h>

#include "ref10.h"

#include <utils/utils.h>

static uint64_t load_3(const uint8_t *in)
{
	uint64_t result;

	result = (uint64_t) in[0];
	result |= ((uint64_t) in[1]) << 8;
	result |= ((uint64_t) in[2]) << 16;

	return result;
}

static uint64_t load_4(const uint8_t *in)
{
	uint64_t result;

	result = (uint64_t) in[0];
	result |= ((uint64_t) in[1]) << 8;
	result |= ((uint64_t) in[2]) << 16;
	result |= ((uint64_t) in[3]) << 24;

	return result;
}

/**
 * h = 0
 */
static void fe_0(fe h)
{
	memset(&h[0], 0, 10 * sizeof h[0]);
}

/**
 * h = 1
 */
static void fe_1(fe h)
{
	h[0] = 1;
	h[1] = 0;
	memset(&h[2], 0, 8 * sizeof h[0]);
}

/**
 * h = f + g
 * Can overlap h with f or g.
 *
 * Preconditions:
 * |f| bounded by 1.1*2^25, 1.1*2^24, 1.1*2^25, 1.1*2^24, etc.
 * |g| bounded by 1.1*2^25, 1.1*2^24, 1.1*2^25, 1.1*2^24, etc.
 *
 * Postconditions:
 * |h| bounded by 1.1*2^26, 1.1*2^25, 1.1*2^26, 1.1*2^25, etc.
 */
static void fe_add(fe h, const fe f, const fe g)
{
	int32_t f0 = f[0];
	int32_t f1 = f[1];
	int32_t f2 = f[2];
	int32_t f3 = f[3];
	int32_t f4 = f[4];
	int32_t f5 = f[5];
	int32_t f6 = f[6];
	int32_t f7 = f[7];
	int32_t f8 = f[8];
	int32_t f9 = f[9];

	int32_t g0 = g[0];
	int32_t g1 = g[1];
	int32_t g2 = g[2];
	int32_t g3 = g[3];
	int32_t g4 = g[4];
	int32_t g5 = g[5];
	int32_t g6 = g[6];
	int32_t g7 = g[7];
	int32_t g8 = g[8];
	int32_t g9 = g[9];

	int32_t h0 = f0 + g0;
	int32_t h1 = f1 + g1;
	int32_t h2 = f2 + g2;
	int32_t h3 = f3 + g3;
	int32_t h4 = f4 + g4;
	int32_t h5 = f5 + g5;
	int32_t h6 = f6 + g6;
	int32_t h7 = f7 + g7;
	int32_t h8 = f8 + g8;
	int32_t h9 = f9 + g9;

	h[0] = h0;
	h[1] = h1;
	h[2] = h2;
	h[3] = h3;
	h[4] = h4;
	h[5] = h5;
	h[6] = h6;
	h[7] = h7;
	h[8] = h8;
	h[9] = h9;
}

/**
 * Replace (f,g) with (g,g) if b == 1;
 * replace (f,g) with (f,g) if b == 0.
 *
 * Preconditions: b in {0,1}.
 */
static void fe_cmov(fe f, const fe g, unsigned int b)
{
	int32_t f0 = f[0];
	int32_t f1 = f[1];
	int32_t f2 = f[2];
	int32_t f3 = f[3];
	int32_t f4 = f[4];
	int32_t f5 = f[5];
	int32_t f6 = f[6];
	int32_t f7 = f[7];
	int32_t f8 = f[8];
	int32_t f9 = f[9];

	int32_t g0 = g[0];
	int32_t g1 = g[1];
	int32_t g2 = g[2];
	int32_t g3 = g[3];
	int32_t g4 = g[4];
	int32_t g5 = g[5];
	int32_t g6 = g[6];
	int32_t g7 = g[7];
	int32_t g8 = g[8];
	int32_t g9 = g[9];

	int32_t x0 = f0 ^ g0;
	int32_t x1 = f1 ^ g1;
	int32_t x2 = f2 ^ g2;
	int32_t x3 = f3 ^ g3;
	int32_t x4 = f4 ^ g4;
	int32_t x5 = f5 ^ g5;
	int32_t x6 = f6 ^ g6;
	int32_t x7 = f7 ^ g7;
	int32_t x8 = f8 ^ g8;
	int32_t x9 = f9 ^ g9;

	b = (unsigned int) (- (int) b);

	x0 &= b;
	x1 &= b;
	x2 &= b;
	x3 &= b;
	x4 &= b;
	x5 &= b;
	x6 &= b;
	x7 &= b;
	x8 &= b;
	x9 &= b;

	f[0] = f0 ^ x0;
	f[1] = f1 ^ x1;
	f[2] = f2 ^ x2;
	f[3] = f3 ^ x3;
	f[4] = f4 ^ x4;
	f[5] = f5 ^ x5;
	f[6] = f6 ^ x6;
	f[7] = f7 ^ x7;
	f[8] = f8 ^ x8;
	f[9] = f9 ^ x9;
}

/**
 * h = f
 */
static void fe_copy(fe h, const fe f)
{
	int32_t f0 = f[0];
	int32_t f1 = f[1];
	int32_t f2 = f[2];
	int32_t f3 = f[3];
	int32_t f4 = f[4];
	int32_t f5 = f[5];
	int32_t f6 = f[6];
	int32_t f7 = f[7];
	int32_t f8 = f[8];
	int32_t f9 = f[9];

	h[0] = f0;
	h[1] = f1;
	h[2] = f2;
	h[3] = f3;
	h[4] = f4;
	h[5] = f5;
	h[6] = f6;
	h[7] = f7;
	h[8] = f8;
	h[9] = f9;
}

/**
 * Ignores top bit of h.
 */
static void fe_frombytes(fe h, const uint8_t *s)
{
	int64_t h0 = load_4(s);
	int64_t h1 = load_3(s + 4) << 6;
	int64_t h2 = load_3(s + 7) << 5;
	int64_t h3 = load_3(s + 10) << 3;
	int64_t h4 = load_3(s + 13) << 2;
	int64_t h5 = load_4(s + 16);
	int64_t h6 = load_3(s + 20) << 7;
	int64_t h7 = load_3(s + 23) << 5;
	int64_t h8 = load_3(s + 26) << 4;
	int64_t h9 = (load_3(s + 29) & 8388607) << 2;

	int64_t carry0, carry1, carry2, carry3, carry4;
	int64_t carry5, carry6, carry7, carry8, carry9;

	carry9 = (h9 + (int64_t) (1L << 24)) >> 25;
	h0 += carry9 * 19;
	h9 -= carry9 * ((uint64_t) 1L << 25);

	carry1 = (h1 + (int64_t) (1L << 24)) >> 25;
	h2 += carry1;
	h1 -= carry1 * ((uint64_t) 1L << 25);

	carry3 = (h3 + (int64_t) (1L << 24)) >> 25;
	h4 += carry3;
	h3 -= carry3 * ((uint64_t) 1L << 25);

	carry5 = (h5 + (int64_t) (1L << 24)) >> 25;
	h6 += carry5;
	h5 -= carry5 * ((uint64_t) 1L << 25);

	carry7 = (h7 + (int64_t) (1L << 24)) >> 25;
	h8 += carry7;
	h7 -= carry7 * ((uint64_t) 1L << 25);

	carry0 = (h0 + (int64_t) (1L << 25)) >> 26;
	h1 += carry0;
	h0 -= carry0 * ((uint64_t) 1L << 26);

	carry2 = (h2 + (int64_t) (1L << 25)) >> 26;
	h3 += carry2;
	h2 -= carry2 * ((uint64_t) 1L << 26);

	carry4 = (h4 + (int64_t) (1L << 25)) >> 26;
	h5 += carry4;
	h4 -= carry4 * ((uint64_t) 1L << 26);

	carry6 = (h6 + (int64_t) (1L << 25)) >> 26;
	h7 += carry6;
	h6 -= carry6 * ((uint64_t) 1L << 26);

	carry8 = (h8 + (int64_t) (1L << 25)) >> 26;
	h9 += carry8;
	h8 -= carry8 * ((uint64_t) 1L << 26);

	h[0] = (int32_t) h0;
	h[1] = (int32_t) h1;
	h[2] = (int32_t) h2;
	h[3] = (int32_t) h3;
	h[4] = (int32_t) h4;
	h[5] = (int32_t) h5;
	h[6] = (int32_t) h6;
	h[7] = (int32_t) h7;
	h[8] = (int32_t) h8;
	h[9] = (int32_t) h9;
}

/**
 * Preconditions:
 * |h| bounded by 1.1*2^26, 1.1*2^25, 1.1*2^26, 1.1*2^25, etc.
 *
 * Write p=2^255-19; q=floor(h/p).
 * Basic claim: q = floor(2^(-255)(h + 19 2^(-25)h9 + 2^(-1))).
 *
 * Proof:
 * Have |h|<=p so |q|<=1 so |19^2 2^(-255) q|<1/4.
 * Also have |h-2^230 h9|<2^231 so |19 2^(-255)(h-2^230 h9)|<1/4.
 *
 * Write y=2^(-1)-19^2 2^(-255)q-19 2^(-255)(h-2^230 h9).
 * Then 0<y<1.
 *
 * Write r=h-pq.
 * Have 0<=r<=p-1=2^255-20.
 * Thus 0<=r+19(2^-255)r<r+19(2^-255)2^255<=2^255-1.
 *
 * Write x=r+19(2^-255)r+y.
 * Then 0<x<2^255 so floor(2^(-255)x) = 0 so floor(q+2^(-255)x) = q.
 *
 * Have q+2^(-255)x = 2^(-255)(h + 19 2^(-25) h9 + 2^(-1))
 * so floor(2^(-255)(h + 19 2^(-25) h9 + 2^(-1))) = q.
 */
static void fe_tobytes(uint8_t *s, const fe h)
{
	int32_t h0 = h[0];
	int32_t h1 = h[1];
	int32_t h2 = h[2];
	int32_t h3 = h[3];
	int32_t h4 = h[4];
	int32_t h5 = h[5];
	int32_t h6 = h[6];
	int32_t h7 = h[7];
	int32_t h8 = h[8];
	int32_t h9 = h[9];

	int32_t carry0, carry1, carry2, carry3, carry4;
	int32_t carry5, carry6, carry7, carry8, carry9;
	int32_t q;

	q = (19 * h9 + ((uint32_t) 1L << 24)) >> 25;
	q = (h0 + q) >> 26;
	q = (h1 + q) >> 25;
	q = (h2 + q) >> 26;
	q = (h3 + q) >> 25;
	q = (h4 + q) >> 26;
	q = (h5 + q) >> 25;
	q = (h6 + q) >> 26;
	q = (h7 + q) >> 25;
	q = (h8 + q) >> 26;
	q = (h9 + q) >> 25;

	/* Goal: Output h-(2^255-19)q, which is between 0 and 2^255-20. */
	h0 += 19 * q;
	/* Goal: Output h-2^255 q, which is between 0 and 2^255-20. */

	carry0 = h0 >> 26;
	h1 += carry0;
	h0 -= carry0 * ((uint32_t) 1L << 26);

	carry1 = h1 >> 25;
	h2 += carry1;
	h1 -= carry1 * ((uint32_t) 1L << 25);

	carry2 = h2 >> 26;
	h3 += carry2;
	h2 -= carry2 * ((uint32_t) 1L << 26);

	carry3 = h3 >> 25;
	h4 += carry3;
	h3 -= carry3 * ((uint32_t) 1L << 25);

	carry4 = h4 >> 26;
	h5 += carry4;
	h4 -= carry4 * ((uint32_t) 1L << 26);

	carry5 = h5 >> 25;
	h6 += carry5;
	h5 -= carry5 * ((uint32_t) 1L << 25);

	carry6 = h6 >> 26;
	h7 += carry6;
	h6 -= carry6 * ((uint32_t) 1L << 26);

	carry7 = h7 >> 25;
	h8 += carry7;
	h7 -= carry7 * ((uint32_t) 1L << 25);

	carry8 = h8 >> 26;
	h9 += carry8;
	h8 -= carry8 * ((uint32_t) 1L << 26);

	carry9 = h9 >> 25;
	h9 -= carry9 * ((uint32_t) 1L << 25);
	/* h10 = carry9 */

	/**
	 * Goal: Output h0+...+2^255 h10-2^255 q, which is between 0 and 2^255-20.
	 * Have h0+...+2^230 h9 between 0 and 2^255-1;
	 * evidently 2^255 h10-2^255 q = 0.
	 * Goal: Output h0+...+2^230 h9.
	 */
	s[0]  = h0 >> 0;
	s[1]  = h0 >> 8;
	s[2]  = h0 >> 16;
	s[3]  = (h0 >> 24) | (h1 * ((uint32_t) 1 << 2));
	s[4]  = h1 >> 6;
	s[5]  = h1 >> 14;
	s[6]  = (h1 >> 22) | (h2 * ((uint32_t) 1 << 3));
	s[7]  = h2 >> 5;
	s[8]  = h2 >> 13;
	s[9]  = (h2 >> 21) | (h3 * ((uint32_t) 1 << 5));
	s[10] = h3 >> 3;
	s[11] = h3 >> 11;
	s[12] = (h3 >> 19) | (h4 * ((uint32_t) 1 << 6));
	s[13] = h4 >> 2;
	s[14] = h4 >> 10;
	s[15] = h4 >> 18;
	s[16] = h5 >> 0;
	s[17] = h5 >> 8;
	s[18] = h5 >> 16;
	s[19] = (h5 >> 24) | (h6 * ((uint32_t) 1 << 1));
	s[20] = h6 >> 7;
	s[21] = h6 >> 15;
	s[22] = (h6 >> 23) | (h7 * ((uint32_t) 1 << 3));
	s[23] = h7 >> 5;
	s[24] = h7 >> 13;
	s[25] = (h7 >> 21) | (h8 * ((uint32_t) 1 << 4));
	s[26] = h8 >> 4;
	s[27] = h8 >> 12;
	s[28] = (h8 >> 20) | (h9 * ((uint32_t) 1 << 6));
	s[29] = h9 >> 2;
	s[30] = h9 >> 10;
	s[31] = h9 >> 18;
}

/**
 * return 1 if f is in {1,3,5,...,q-2}
 * return 0 if f is in {0,2,4,...,q-1}
 *
 * Preconditions:
 * |f| bounded by 1.1*2^26, 1.1*2^25, 1.1*2^26, 1.1*2^25, etc.
 */
static int fe_isnegative(const fe f)
{
	uint8_t s[32];

	fe_tobytes(s,f);

	return s[0] & 1;
}

/**
 * return 1 if f != 0
 * return 0 if f == 0
 *
 * Preconditions:
 * |f| bounded by 1.1*2^26, 1.1*2^25, 1.1*2^26, 1.1*2^25,etc.
 */
static uint8_t zero[32];

static int fe_isnonzero(const fe f)
{
	uint8_t s[32];

	fe_tobytes(s, f);

	return !memeq_const(s, zero, 32);
}

/**
 * h = f * g
 * Can overlap h with f or g.
 *
 * Preconditions:
 * |f| bounded by 1.65*2^26, 1.65*2^25, 1.65*2^26, 1.65*2^25, etc.
 * |g| bounded by 1.65*2^26, 1.65*2^25, 1.65*2^26, 1.65*2^25, etc.
 *
 * Postconditions:
 * |h| bounded by 1.01*2^25, 1.01*2^24, 1.01*2^25, 1.01*2^24, etc.
 */

/**
 * Notes on implementation strategy:
 *
 * Using schoolbook multiplication.
 * Karatsuba would save a little in some cost models.
 *
 * Most multiplications by 2 and 19 are 32-bit precomputations;
 * cheaper than 64-bit postcomputations.
 *
 * There is one remaining multiplication by 19 in the carry chain;
 * one *19 precomputation can be merged into this,
 * but the resulting data flow is considerably less clean.
 *
 * There are 12 carries below.
 * 10 of them are 2-way parallelizable and vectorizable.
 * Can get away with 11 carries, but then data flow is much deeper.
 *
 * With tighter constraints on inputs can squeeze carries into int32.
 */

static void fe_mul(fe h, const fe f, const fe g)
{
	int32_t f0 = f[0];
	int32_t f1 = f[1];
	int32_t f2 = f[2];
	int32_t f3 = f[3];
	int32_t f4 = f[4];
	int32_t f5 = f[5];
	int32_t f6 = f[6];
	int32_t f7 = f[7];
	int32_t f8 = f[8];
	int32_t f9 = f[9];

	int32_t g0 = g[0];
	int32_t g1 = g[1];
	int32_t g2 = g[2];
	int32_t g3 = g[3];
	int32_t g4 = g[4];
	int32_t g5 = g[5];
	int32_t g6 = g[6];
	int32_t g7 = g[7];
	int32_t g8 = g[8];
	int32_t g9 = g[9];

	int32_t g1_19 = 19 * g1; /* 1.959375*2^29 */
	int32_t g2_19 = 19 * g2; /* 1.959375*2^30; still ok */
	int32_t g3_19 = 19 * g3;
	int32_t g4_19 = 19 * g4;
	int32_t g5_19 = 19 * g5;
	int32_t g6_19 = 19 * g6;
	int32_t g7_19 = 19 * g7;
	int32_t g8_19 = 19 * g8;
	int32_t g9_19 = 19 * g9;

	int32_t f1_2 = 2 * f1;
	int32_t f3_2 = 2 * f3;
	int32_t f5_2 = 2 * f5;
	int32_t f7_2 = 2 * f7;
	int32_t f9_2 = 2 * f9;

	int64_t f0g0	= f0   * (int64_t) g0;
	int64_t f0g1	= f0   * (int64_t) g1;
	int64_t f0g2	= f0   * (int64_t) g2;
	int64_t f0g3	= f0   * (int64_t) g3;
	int64_t f0g4	= f0   * (int64_t) g4;
	int64_t f0g5	= f0   * (int64_t) g5;
	int64_t f0g6	= f0   * (int64_t) g6;
	int64_t f0g7	= f0   * (int64_t) g7;
	int64_t f0g8	= f0   * (int64_t) g8;
	int64_t f0g9	= f0   * (int64_t) g9;

	int64_t f1g0	= f1   * (int64_t) g0;
	int64_t f1g1_2  = f1_2 * (int64_t) g1;
	int64_t f1g2	= f1   * (int64_t) g2;
	int64_t f1g3_2  = f1_2 * (int64_t) g3;
	int64_t f1g4	= f1   * (int64_t) g4;
	int64_t f1g5_2  = f1_2 * (int64_t) g5;
	int64_t f1g6	= f1   * (int64_t) g6;
	int64_t f1g7_2  = f1_2 * (int64_t) g7;
	int64_t f1g8	= f1   * (int64_t) g8;
	int64_t f1g9_38 = f1_2 * (int64_t) g9_19;

	int64_t f2g0	= f2   * (int64_t) g0;
	int64_t f2g1	= f2   * (int64_t) g1;
	int64_t f2g2	= f2   * (int64_t) g2;
	int64_t f2g3	= f2   * (int64_t) g3;
	int64_t f2g4	= f2   * (int64_t) g4;
	int64_t f2g5	= f2   * (int64_t) g5;
	int64_t f2g6	= f2   * (int64_t) g6;
	int64_t f2g7	= f2   * (int64_t) g7;
	int64_t f2g8_19 = f2   * (int64_t) g8_19;
	int64_t f2g9_19 = f2   * (int64_t) g9_19;

	int64_t f3g0	= f3   * (int64_t) g0;
	int64_t f3g1_2  = f3_2 * (int64_t) g1;
	int64_t f3g2	= f3   * (int64_t) g2;
	int64_t f3g3_2  = f3_2 * (int64_t) g3;
	int64_t f3g4	= f3   * (int64_t) g4;
	int64_t f3g5_2  = f3_2 * (int64_t) g5;
	int64_t f3g6	= f3   * (int64_t) g6;
	int64_t f3g7_38 = f3_2 * (int64_t) g7_19;
	int64_t f3g8_19 = f3   * (int64_t) g8_19;
	int64_t f3g9_38 = f3_2 * (int64_t) g9_19;

	int64_t f4g0	= f4   * (int64_t) g0;
	int64_t f4g1	= f4   * (int64_t) g1;
	int64_t f4g2	= f4   * (int64_t) g2;
	int64_t f4g3	= f4   * (int64_t) g3;
	int64_t f4g4	= f4   * (int64_t) g4;
	int64_t f4g5	= f4   * (int64_t) g5;
	int64_t f4g6_19 = f4   * (int64_t) g6_19;
	int64_t f4g7_19 = f4   * (int64_t) g7_19;
	int64_t f4g8_19 = f4   * (int64_t) g8_19;
	int64_t f4g9_19 = f4   * (int64_t) g9_19;

	int64_t f5g0	= f5   * (int64_t) g0;
	int64_t f5g1_2  = f5_2 * (int64_t) g1;
	int64_t f5g2	= f5   * (int64_t) g2;
	int64_t f5g3_2  = f5_2 * (int64_t) g3;
	int64_t f5g4	= f5   * (int64_t) g4;
	int64_t f5g5_38 = f5_2 * (int64_t) g5_19;
	int64_t f5g6_19 = f5   * (int64_t) g6_19;
	int64_t f5g7_38 = f5_2 * (int64_t) g7_19;
	int64_t f5g8_19 = f5   * (int64_t) g8_19;
	int64_t f5g9_38 = f5_2 * (int64_t) g9_19;

	int64_t f6g0	= f6   * (int64_t) g0;
	int64_t f6g1	= f6   * (int64_t) g1;
	int64_t f6g2	= f6   * (int64_t) g2;
	int64_t f6g3	= f6   * (int64_t) g3;
	int64_t f6g4_19 = f6   * (int64_t) g4_19;
	int64_t f6g5_19 = f6   * (int64_t) g5_19;
	int64_t f6g6_19 = f6   * (int64_t) g6_19;
	int64_t f6g7_19 = f6   * (int64_t) g7_19;
	int64_t f6g8_19 = f6   * (int64_t) g8_19;
	int64_t f6g9_19 = f6   * (int64_t) g9_19;

	int64_t f7g0	= f7   * (int64_t) g0;
	int64_t f7g1_2  = f7_2 * (int64_t) g1;
	int64_t f7g2	= f7   * (int64_t) g2;
	int64_t f7g3_38 = f7_2 * (int64_t) g3_19;
	int64_t f7g4_19 = f7   * (int64_t) g4_19;
	int64_t f7g5_38 = f7_2 * (int64_t) g5_19;
	int64_t f7g6_19 = f7   * (int64_t) g6_19;
	int64_t f7g7_38 = f7_2 * (int64_t) g7_19;
	int64_t f7g8_19 = f7   * (int64_t) g8_19;
	int64_t f7g9_38 = f7_2 * (int64_t) g9_19;

	int64_t f8g0	= f8   * (int64_t) g0;
	int64_t f8g1	= f8   * (int64_t) g1;
	int64_t f8g2_19 = f8   * (int64_t) g2_19;
	int64_t f8g3_19 = f8   * (int64_t) g3_19;
	int64_t f8g4_19 = f8   * (int64_t) g4_19;
	int64_t f8g5_19 = f8   * (int64_t) g5_19;
	int64_t f8g6_19 = f8   * (int64_t) g6_19;
	int64_t f8g7_19 = f8   * (int64_t) g7_19;
	int64_t f8g8_19 = f8   * (int64_t) g8_19;
	int64_t f8g9_19 = f8   * (int64_t) g9_19;

	int64_t f9g0	= f9   * (int64_t) g0;
	int64_t f9g1_38 = f9_2 * (int64_t) g1_19;
	int64_t f9g2_19 = f9   * (int64_t) g2_19;
	int64_t f9g3_38 = f9_2 * (int64_t) g3_19;
	int64_t f9g4_19 = f9   * (int64_t) g4_19;
	int64_t f9g5_38 = f9_2 * (int64_t) g5_19;
	int64_t f9g6_19 = f9   * (int64_t) g6_19;
	int64_t f9g7_38 = f9_2 * (int64_t) g7_19;
	int64_t f9g8_19 = f9   * (int64_t) g8_19;
	int64_t f9g9_38 = f9_2 * (int64_t) g9_19;

	int64_t h0 = f0g0    + f1g9_38 + f2g8_19 + f3g7_38 + f4g6_19 + f5g5_38 +
	             f6g4_19 + f7g3_38 + f8g2_19 + f9g1_38;
	int64_t h1 = f0g1    + f1g0    + f2g9_19 + f3g8_19 + f4g7_19 + f5g6_19 +
	             f6g5_19 + f7g4_19 + f8g3_19 + f9g2_19;
	int64_t h2 = f0g2    + f1g1_2  + f2g0    + f3g9_38 + f4g8_19 + f5g7_38 +
	             f6g6_19 + f7g5_38 + f8g4_19 + f9g3_38;
	int64_t h3 = f0g3    + f1g2    + f2g1    + f3g0    + f4g9_19 + f5g8_19 +
	             f6g7_19 + f7g6_19 + f8g5_19 + f9g4_19;
	int64_t h4 = f0g4    + f1g3_2  + f2g2    + f3g1_2  + f4g0    + f5g9_38 +
	             f6g8_19 + f7g7_38 + f8g6_19 + f9g5_38;
	int64_t h5 = f0g5    + f1g4    + f2g3    + f3g2    + f4g1    + f5g0    +
	             f6g9_19 + f7g8_19 + f8g7_19 + f9g6_19;
	int64_t h6 = f0g6    + f1g5_2  + f2g4    + f3g3_2  + f4g2    + f5g1_2  +
	             f6g0    + f7g9_38 + f8g8_19 + f9g7_38;
	int64_t h7 = f0g7    + f1g6    + f2g5    + f3g4    + f4g3    + f5g2    +
	             f6g1    + f7g0    + f8g9_19 + f9g8_19;
	int64_t h8 = f0g8    + f1g7_2  + f2g6    + f3g5_2  + f4g4    + f5g3_2  +
	             f6g2    + f7g1_2  + f8g0    + f9g9_38;
	int64_t h9 = f0g9    + f1g8    + f2g7    + f3g6    + f4g5    + f5g4    +
	             f6g3    + f7g2    + f8g1    + f9g0 ;

	int64_t carry0, carry1, carry2, carry3, carry4;
	int64_t carry5, carry6, carry7, carry8, carry9;

	/**
	 * |h0| <= (1.65*1.65*2^52*(1+19+19+19+19)+1.65*1.65*2^50*(38+38+38+38+38))
	 * i.e. |h0| <= 1.4*2^60; narrower ranges for h2, h4, h6, h8
	 * |h1| <= (1.65*1.65*2^51*(1+1+19+19+19+19+19+19+19+19))
	 * i.e. |h1| <= 1.7*2^59; narrower ranges for h3, h5, h7, h9
	 */

	carry0 = (h0 + (int64_t) (1L << 25)) >> 26;
	h1 += carry0;
	h0 -= carry0 * ((uint64_t) 1L << 26);
	/* |h0| <= 2^25 */
	/* |h1| <= 1.71*2^59 */

	carry4 = (h4 + (int64_t) (1L << 25)) >> 26;
	h5 += carry4;
	h4 -= carry4 * ((uint64_t) 1L << 26);
	/* |h4| <= 2^25 */
	/* |h5| <= 1.71*2^59 */

	carry1 = (h1 + (int64_t) (1L << 24)) >> 25;
	h2 += carry1;
	h1 -= carry1 * ((uint64_t) 1L << 25);
	/* |h1| <= 2^24; from now on fits into int32 */
	/* |h2| <= 1.41*2^60 */

	carry5 = (h5 + (int64_t) (1L << 24)) >> 25;
	h6 += carry5;
	h5 -= carry5 * ((uint64_t) 1L << 25);
	/* |h5| <= 2^24; from now on fits into int32 */
	/* |h6| <= 1.41*2^60 */

	carry2 = (h2 + (int64_t) (1L << 25)) >> 26;
	h3 += carry2;
	h2 -= carry2 * ((uint64_t) 1L << 26);
	/* |h2| <= 2^25; from now on fits into int32 unchanged */
	/* |h3| <= 1.71*2^59 */

	carry6 = (h6 + (int64_t) (1L << 25)) >> 26;
	h7 += carry6;
	h6 -= carry6 * ((uint64_t) 1L << 26);
	/* |h6| <= 2^25; from now on fits into int32 unchanged */
	/* |h7| <= 1.71*2^59 */

	carry3 = (h3 + (int64_t) (1L << 24)) >> 25;
	h4 += carry3;
	h3 -= carry3 * ((uint64_t) 1L << 25);
	/* |h3| <= 2^24; from now on fits into int32 unchanged */
	/* |h4| <= 1.72*2^34 */

	carry7 = (h7 + (int64_t) (1L << 24)) >> 25;
	h8 += carry7;
	h7 -= carry7 * ((uint64_t) 1L << 25);
	/* |h7| <= 2^24; from now on fits into int32 unchanged */
	/* |h8| <= 1.41*2^60 */

	carry4 = (h4 + (int64_t) (1L << 25)) >> 26;
	h5 += carry4;
	h4 -= carry4 * ((uint64_t) 1L << 26);
	/* |h4| <= 2^25; from now on fits into int32 unchanged */
	/* |h5| <= 1.01*2^24 */

	carry8 = (h8 + (int64_t) (1L << 25)) >> 26;
	h9 += carry8;
	h8 -= carry8 * ((uint64_t) 1L << 26);
	/* |h8| <= 2^25; from now on fits into int32 unchanged */
	/* |h9| <= 1.71*2^59 */

	carry9 = (h9 + (int64_t) (1L << 24)) >> 25;
	h0 += carry9 * 19;
	h9 -= carry9 * ((uint64_t) 1L << 25);
	/* |h9| <= 2^24; from now on fits into int32 unchanged */
	/* |h0| <= 1.1*2^39 */

	carry0 = (h0 + (int64_t) (1L << 25)) >> 26;
	h1 += carry0;
	h0 -= carry0 * ((uint64_t) 1L << 26);
	/* |h0| <= 2^25; from now on fits into int32 unchanged */
	/* |h1| <= 1.01*2^24 */

	h[0] = (int32_t) h0;
	h[1] = (int32_t) h1;
	h[2] = (int32_t) h2;
	h[3] = (int32_t) h3;
	h[4] = (int32_t) h4;
	h[5] = (int32_t) h5;
	h[6] = (int32_t) h6;
	h[7] = (int32_t) h7;
	h[8] = (int32_t) h8;
	h[9] = (int32_t) h9;
}

/**
 * h = -f
 *
 * Preconditions:
 * |f| bounded by 1.1*2^25, 1.1*2^24, 1.1*2^25, 1.1*2^24, etc.
 *
 * Postconditions:
 * |h| bounded by 1.1*2^25, 1.1*2^24, 1.1*2^25, 1.1*2^24, etc.
 */
static void fe_neg(fe h,const fe f)
{
	int32_t f0 = f[0];
	int32_t f1 = f[1];
	int32_t f2 = f[2];
	int32_t f3 = f[3];
	int32_t f4 = f[4];
	int32_t f5 = f[5];
	int32_t f6 = f[6];
	int32_t f7 = f[7];
	int32_t f8 = f[8];
	int32_t f9 = f[9];

	int32_t h0 = -f0;
	int32_t h1 = -f1;
	int32_t h2 = -f2;
	int32_t h3 = -f3;
	int32_t h4 = -f4;
	int32_t h5 = -f5;
	int32_t h6 = -f6;
	int32_t h7 = -f7;
	int32_t h8 = -f8;
	int32_t h9 = -f9;

	h[0] = h0;
	h[1] = h1;
	h[2] = h2;
	h[3] = h3;
	h[4] = h4;
	h[5] = h5;
	h[6] = h6;
	h[7] = h7;
	h[8] = h8;
	h[9] = h9;
}

/**
 * h = f * f
 * Can overlap h with f.
 *
 * Preconditions:
 * |f| bounded by 1.65*2^26, 1.65*2^25, 1.65*2^26, 1.65*2^25, etc.
 *
 * Postconditions:
 * |h| bounded by 1.01*2^25, 1.01*2^24, 1.01*2^25, 1.01*2^24, etc.
 *
 * See fe_mul.c for discussion of implementation strategy.
 */
static void fe_sq(fe h, const fe f)
{
	int32_t f0 = f[0];
	int32_t f1 = f[1];
	int32_t f2 = f[2];
	int32_t f3 = f[3];
	int32_t f4 = f[4];
	int32_t f5 = f[5];
	int32_t f6 = f[6];
	int32_t f7 = f[7];
	int32_t f8 = f[8];
	int32_t f9 = f[9];

	int32_t f0_2 = 2 * f0;
	int32_t f1_2 = 2 * f1;
	int32_t f2_2 = 2 * f2;
	int32_t f3_2 = 2 * f3;
	int32_t f4_2 = 2 * f4;
	int32_t f5_2 = 2 * f5;
	int32_t f6_2 = 2 * f6;
	int32_t f7_2 = 2 * f7;

	int32_t f5_38 = 38 * f5; /* 1.959375*2^30 */
	int32_t f6_19 = 19 * f6; /* 1.959375*2^30 */
	int32_t f7_38 = 38 * f7; /* 1.959375*2^30 */
	int32_t f8_19 = 19 * f8; /* 1.959375*2^30 */
	int32_t f9_38 = 38 * f9; /* 1.959375*2^30 */

	int64_t f0f0	= f0   * (int64_t) f0;
	int64_t f0f1_2  = f0_2 * (int64_t) f1;
	int64_t f0f2_2  = f0_2 * (int64_t) f2;
	int64_t f0f3_2  = f0_2 * (int64_t) f3;
	int64_t f0f4_2  = f0_2 * (int64_t) f4;
	int64_t f0f5_2  = f0_2 * (int64_t) f5;
	int64_t f0f6_2  = f0_2 * (int64_t) f6;
	int64_t f0f7_2  = f0_2 * (int64_t) f7;
	int64_t f0f8_2  = f0_2 * (int64_t) f8;
	int64_t f0f9_2  = f0_2 * (int64_t) f9;

	int64_t f1f1_2  = f1_2 * (int64_t) f1;
	int64_t f1f2_2  = f1_2 * (int64_t) f2;
	int64_t f1f3_4  = f1_2 * (int64_t) f3_2;
	int64_t f1f4_2  = f1_2 * (int64_t) f4;
	int64_t f1f5_4  = f1_2 * (int64_t) f5_2;
	int64_t f1f6_2  = f1_2 * (int64_t) f6;
	int64_t f1f7_4  = f1_2 * (int64_t) f7_2;
	int64_t f1f8_2  = f1_2 * (int64_t) f8;
	int64_t f1f9_76 = f1_2 * (int64_t) f9_38;

	int64_t f2f2	= f2   * (int64_t) f2;
	int64_t f2f3_2  = f2_2 * (int64_t) f3;
	int64_t f2f4_2  = f2_2 * (int64_t) f4;
	int64_t f2f5_2  = f2_2 * (int64_t) f5;
	int64_t f2f6_2  = f2_2 * (int64_t) f6;
	int64_t f2f7_2  = f2_2 * (int64_t) f7;
	int64_t f2f8_38 = f2_2 * (int64_t) f8_19;
	int64_t f2f9_38 = f2   * (int64_t) f9_38;

	int64_t f3f3_2  = f3_2 * (int64_t) f3;
	int64_t f3f4_2  = f3_2 * (int64_t) f4;
	int64_t f3f5_4  = f3_2 * (int64_t) f5_2;
	int64_t f3f6_2  = f3_2 * (int64_t) f6;
	int64_t f3f7_76 = f3_2 * (int64_t) f7_38;
	int64_t f3f8_38 = f3_2 * (int64_t) f8_19;
	int64_t f3f9_76 = f3_2 * (int64_t) f9_38;

	int64_t f4f4	= f4   * (int64_t) f4;
	int64_t f4f5_2  = f4_2 * (int64_t) f5;
	int64_t f4f6_38 = f4_2 * (int64_t) f6_19;
	int64_t f4f7_38 = f4   * (int64_t) f7_38;
	int64_t f4f8_38 = f4_2 * (int64_t) f8_19;
	int64_t f4f9_38 = f4   * (int64_t) f9_38;

	int64_t f5f5_38 = f5   * (int64_t) f5_38;
	int64_t f5f6_38 = f5_2 * (int64_t) f6_19;
	int64_t f5f7_76 = f5_2 * (int64_t) f7_38;
	int64_t f5f8_38 = f5_2 * (int64_t) f8_19;
	int64_t f5f9_76 = f5_2 * (int64_t) f9_38;

	int64_t f6f6_19 = f6   * (int64_t) f6_19;
	int64_t f6f7_38 = f6   * (int64_t) f7_38;
	int64_t f6f8_38 = f6_2 * (int64_t) f8_19;
	int64_t f6f9_38 = f6   * (int64_t) f9_38;

	int64_t f7f7_38 = f7   * (int64_t) f7_38;
	int64_t f7f8_38 = f7_2 * (int64_t) f8_19;
	int64_t f7f9_76 = f7_2 * (int64_t) f9_38;

	int64_t f8f8_19 = f8   * (int64_t) f8_19;
	int64_t f8f9_38 = f8   * (int64_t) f9_38;

	int64_t f9f9_38 = f9   * (int64_t) f9_38;

	int64_t h0 = f0f0   + f1f9_76 + f2f8_38 + f3f7_76 + f4f6_38 + f5f5_38;
	int64_t h1 = f0f1_2 + f2f9_38 + f3f8_38 + f4f7_38 + f5f6_38;
	int64_t h2 = f0f2_2 + f1f1_2  + f3f9_76 + f4f8_38 + f5f7_76 + f6f6_19;
	int64_t h3 = f0f3_2 + f1f2_2  + f4f9_38 + f5f8_38 + f6f7_38;
	int64_t h4 = f0f4_2 + f1f3_4  + f2f2    + f5f9_76 + f6f8_38 + f7f7_38;
	int64_t h5 = f0f5_2 + f1f4_2  + f2f3_2  + f6f9_38 + f7f8_38;
	int64_t h6 = f0f6_2 + f1f5_4  + f2f4_2  + f3f3_2  + f7f9_76 + f8f8_19;
	int64_t h7 = f0f7_2 + f1f6_2  + f2f5_2  + f3f4_2  + f8f9_38;
	int64_t h8 = f0f8_2 + f1f7_4  + f2f6_2  + f3f5_4  + f4f4    + f9f9_38;
	int64_t h9 = f0f9_2 + f1f8_2  + f2f7_2  + f3f6_2  + f4f5_2;

	int64_t carry0, carry1, carry2, carry3, carry4;
	int64_t carry5, carry6, carry7, carry8, carry9;

	carry0 = (h0 + (int64_t) (1L << 25)) >> 26;
	h1 += carry0;
	h0 -= carry0 * ((uint64_t) 1L << 26);

	carry4 = (h4 + (int64_t) (1L << 25)) >> 26;
	h5 += carry4;
	h4 -= carry4 * ((uint64_t) 1L << 26);

	carry1 = (h1 + (int64_t) (1L << 24)) >> 25;
	h2 += carry1;
	h1 -= carry1 * ((uint64_t) 1L << 25);

	carry5 = (h5 + (int64_t) (1L << 24)) >> 25;
	h6 += carry5;
	h5 -= carry5 * ((uint64_t) 1L << 25);

	carry2 = (h2 + (int64_t) (1L << 25)) >> 26;
	h3 += carry2;
	h2 -= carry2 * ((uint64_t) 1L << 26);

	carry6 = (h6 + (int64_t) (1L << 25)) >> 26;
	h7 += carry6;
	h6 -= carry6 * ((uint64_t) 1L << 26);

	carry3 = (h3 + (int64_t) (1L << 24)) >> 25;
	h4 += carry3;
	h3 -= carry3 * ((uint64_t) 1L << 25);

	carry7 = (h7 + (int64_t) (1L << 24)) >> 25;
	h8 += carry7;
	h7 -= carry7 * ((uint64_t) 1L << 25);

	carry4 = (h4 + (int64_t) (1L << 25)) >> 26;
	h5 += carry4;
	h4 -= carry4 * ((uint64_t) 1L << 26);

	carry8 = (h8 + (int64_t) (1L << 25)) >> 26;
	h9 += carry8;
	h8 -= carry8 * ((uint64_t) 1L << 26);

	carry9 = (h9 + (int64_t) (1L << 24)) >> 25;
	h0 += carry9 * 19;
	h9 -= carry9 * ((uint64_t) 1L << 25);

	carry0 = (h0 + (int64_t) (1L << 25)) >> 26;
	h1 += carry0;
	h0 -= carry0 * ((uint64_t) 1L << 26);

	h[0] = (int32_t) h0;
	h[1] = (int32_t) h1;
	h[2] = (int32_t) h2;
	h[3] = (int32_t) h3;
	h[4] = (int32_t) h4;
	h[5] = (int32_t) h5;
	h[6] = (int32_t) h6;
	h[7] = (int32_t) h7;
	h[8] = (int32_t) h8;
	h[9] = (int32_t) h9;
}

/**
 * h = 2 * f * f
 * Can overlap h with f.
 *
 * Preconditions:
 *|f| bounded by 1.65*2^26, 1.65*2^25, 1.65*2^26, 1.65*2^25, etc.
 *
 * Postconditions:
 * |h| bounded by 1.01*2^25, 1.01*2^24, 1.01*2^25, 1.01*2^24, etc.
 *
 * See fe_mul.c for discussion of implementation strategy.
 */
static void fe_sq2(fe h, const fe f)
{
	int32_t f0 = f[0];
	int32_t f1 = f[1];
	int32_t f2 = f[2];
	int32_t f3 = f[3];
	int32_t f4 = f[4];
	int32_t f5 = f[5];
	int32_t f6 = f[6];
	int32_t f7 = f[7];
	int32_t f8 = f[8];
	int32_t f9 = f[9];

	int32_t f0_2 = 2 * f0;
	int32_t f1_2 = 2 * f1;
	int32_t f2_2 = 2 * f2;
	int32_t f3_2 = 2 * f3;
	int32_t f4_2 = 2 * f4;
	int32_t f5_2 = 2 * f5;
	int32_t f6_2 = 2 * f6;
	int32_t f7_2 = 2 * f7;

	int32_t f5_38 = 38 * f5; /* 1.959375*2^30 */
	int32_t f6_19 = 19 * f6; /* 1.959375*2^30 */
	int32_t f7_38 = 38 * f7; /* 1.959375*2^30 */
	int32_t f8_19 = 19 * f8; /* 1.959375*2^30 */
	int32_t f9_38 = 38 * f9; /* 1.959375*2^30 */

	int64_t f0f0	= f0   * (int64_t) f0;
	int64_t f0f1_2  = f0_2 * (int64_t) f1;
	int64_t f0f2_2  = f0_2 * (int64_t) f2;
	int64_t f0f3_2  = f0_2 * (int64_t) f3;
	int64_t f0f4_2  = f0_2 * (int64_t) f4;
	int64_t f0f5_2  = f0_2 * (int64_t) f5;
	int64_t f0f6_2  = f0_2 * (int64_t) f6;
	int64_t f0f7_2  = f0_2 * (int64_t) f7;
	int64_t f0f8_2  = f0_2 * (int64_t) f8;
	int64_t f0f9_2  = f0_2 * (int64_t) f9;

	int64_t f1f1_2  = f1_2 * (int64_t) f1;
	int64_t f1f2_2  = f1_2 * (int64_t) f2;
	int64_t f1f3_4  = f1_2 * (int64_t) f3_2;
	int64_t f1f4_2  = f1_2 * (int64_t) f4;
	int64_t f1f5_4  = f1_2 * (int64_t) f5_2;
	int64_t f1f6_2  = f1_2 * (int64_t) f6;
	int64_t f1f7_4  = f1_2 * (int64_t) f7_2;
	int64_t f1f8_2  = f1_2 * (int64_t) f8;
	int64_t f1f9_76 = f1_2 * (int64_t) f9_38;

	int64_t f2f2	= f2   * (int64_t) f2;
	int64_t f2f3_2  = f2_2 * (int64_t) f3;
	int64_t f2f4_2  = f2_2 * (int64_t) f4;
	int64_t f2f5_2  = f2_2 * (int64_t) f5;
	int64_t f2f6_2  = f2_2 * (int64_t) f6;
	int64_t f2f7_2  = f2_2 * (int64_t) f7;
	int64_t f2f8_38 = f2_2 * (int64_t) f8_19;
	int64_t f2f9_38 = f2   * (int64_t) f9_38;

	int64_t f3f3_2  = f3_2 * (int64_t) f3;
	int64_t f3f4_2  = f3_2 * (int64_t) f4;
	int64_t f3f5_4  = f3_2 * (int64_t) f5_2;
	int64_t f3f6_2  = f3_2 * (int64_t) f6;
	int64_t f3f7_76 = f3_2 * (int64_t) f7_38;
	int64_t f3f8_38 = f3_2 * (int64_t) f8_19;
	int64_t f3f9_76 = f3_2 * (int64_t) f9_38;

	int64_t f4f4	= f4   * (int64_t) f4;
	int64_t f4f5_2  = f4_2 * (int64_t) f5;
	int64_t f4f6_38 = f4_2 * (int64_t) f6_19;
	int64_t f4f7_38 = f4   * (int64_t) f7_38;
	int64_t f4f8_38 = f4_2 * (int64_t) f8_19;
	int64_t f4f9_38 = f4   * (int64_t) f9_38;

	int64_t f5f5_38 = f5   * (int64_t) f5_38;
	int64_t f5f6_38 = f5_2 * (int64_t) f6_19;
	int64_t f5f7_76 = f5_2 * (int64_t) f7_38;
	int64_t f5f8_38 = f5_2 * (int64_t) f8_19;
	int64_t f5f9_76 = f5_2 * (int64_t) f9_38;

	int64_t f6f6_19 = f6   * (int64_t) f6_19;
	int64_t f6f7_38 = f6   * (int64_t) f7_38;
	int64_t f6f8_38 = f6_2 * (int64_t) f8_19;
	int64_t f6f9_38 = f6   * (int64_t) f9_38;

	int64_t f7f7_38 = f7   * (int64_t) f7_38;
	int64_t f7f8_38 = f7_2 * (int64_t) f8_19;
	int64_t f7f9_76 = f7_2 * (int64_t) f9_38;

	int64_t f8f8_19 = f8   * (int64_t) f8_19;
	int64_t f8f9_38 = f8   * (int64_t) f9_38;

	int64_t f9f9_38 = f9   * (int64_t) f9_38;

	int64_t h0 = f0f0   + f1f9_76 + f2f8_38 + f3f7_76 + f4f6_38 + f5f5_38;
	int64_t h1 = f0f1_2 + f2f9_38 + f3f8_38 + f4f7_38 + f5f6_38;
	int64_t h2 = f0f2_2 + f1f1_2  + f3f9_76 + f4f8_38 + f5f7_76 + f6f6_19;
	int64_t h3 = f0f3_2 + f1f2_2  + f4f9_38 + f5f8_38 + f6f7_38;
	int64_t h4 = f0f4_2 + f1f3_4  + f2f2    + f5f9_76 + f6f8_38 + f7f7_38;
	int64_t h5 = f0f5_2 + f1f4_2  + f2f3_2  + f6f9_38 + f7f8_38;
	int64_t h6 = f0f6_2 + f1f5_4  + f2f4_2  + f3f3_2  + f7f9_76 + f8f8_19;
	int64_t h7 = f0f7_2 + f1f6_2  + f2f5_2  + f3f4_2  + f8f9_38;
	int64_t h8 = f0f8_2 + f1f7_4  + f2f6_2  + f3f5_4  + f4f4    + f9f9_38;
	int64_t h9 = f0f9_2 + f1f8_2  + f2f7_2  + f3f6_2  + f4f5_2;

	int64_t carry0, carry1, carry2, carry3, carry4;
	int64_t carry5, carry6, carry7, carry8, carry9;

	h0 += h0;
	h1 += h1;
	h2 += h2;
	h3 += h3;
	h4 += h4;
	h5 += h5;
	h6 += h6;
	h7 += h7;
	h8 += h8;
	h9 += h9;

	carry0 = (h0 + (int64_t) (1L << 25)) >> 26;
	h1 += carry0;
	h0 -= carry0 * ((uint64_t) 1L << 26);

	carry4 = (h4 + (int64_t) (1L << 25)) >> 26;
	h5 += carry4;
	h4 -= carry4 * ((uint64_t) 1L << 26);

	carry1 = (h1 + (int64_t) (1L << 24)) >> 25;
	h2 += carry1;
	h1 -= carry1 * ((uint64_t) 1L << 25);

	carry5 = (h5 + (int64_t) (1L << 24)) >> 25;
	h6 += carry5;
	h5 -= carry5 * ((uint64_t) 1L << 25);

	carry2 = (h2 + (int64_t) (1L << 25)) >> 26;
	h3 += carry2;
	h2 -= carry2 * ((uint64_t) 1L << 26);

	carry6 = (h6 + (int64_t) (1L << 25)) >> 26;
	h7 += carry6;
	h6 -= carry6 * ((uint64_t) 1L << 26);

	carry3 = (h3 + (int64_t) (1L << 24)) >> 25;
	h4 += carry3;
	h3 -= carry3 * ((uint64_t) 1L << 25);

	carry7 = (h7 + (int64_t) (1L << 24)) >> 25;
	h8 += carry7;
	h7 -= carry7 * ((uint64_t) 1L << 25);

	carry4 = (h4 + (int64_t) (1L << 25)) >> 26;
	h5 += carry4;
	h4 -= carry4 * ((uint64_t) 1L << 26);

	carry8 = (h8 + (int64_t) (1L << 25)) >> 26;
	h9 += carry8;
	h8 -= carry8 * ((uint64_t) 1L << 26);

	carry9 = (h9 + (int64_t) (1L << 24)) >> 25;
	h0 += carry9 * 19;
	h9 -= carry9 * ((uint64_t) 1L << 25);

	carry0 = (h0 + (int64_t) (1L << 25)) >> 26;
	h1 += carry0;
	h0 -= carry0 * ((uint64_t) 1L << 26);

	h[0] = (int32_t) h0;
	h[1] = (int32_t) h1;
	h[2] = (int32_t) h2;
	h[3] = (int32_t) h3;
	h[4] = (int32_t) h4;
	h[5] = (int32_t) h5;
	h[6] = (int32_t) h6;
	h[7] = (int32_t) h7;
	h[8] = (int32_t) h8;
	h[9] = (int32_t) h9;
}

static void fe_invert(fe out, const fe z)
{
	fe t0, t1, t2, t3;
	int i;

	fe_sq(t0, z);
	fe_sq(t1, t0);
	fe_sq(t1, t1);
	fe_mul(t1, z, t1);
	fe_mul(t0, t0, t1);
	fe_sq(t2, t0);
	fe_mul(t1, t1, t2);
	fe_sq(t2, t1);

	for (i = 1; i < 5; ++i)
	{
		fe_sq(t2, t2);
	}

	fe_mul(t1, t2, t1);
	fe_sq(t2, t1);

	for (i = 1; i < 10; ++i)
	{
		fe_sq(t2, t2);
	}

	fe_mul(t2, t2, t1);
	fe_sq(t3, t2);

	for (i = 1; i < 20; ++i)
	{
		fe_sq(t3, t3);
	}

	fe_mul(t2, t3, t2);
	fe_sq(t2, t2);

	for (i = 1; i < 10; ++i)
	{
		fe_sq(t2, t2);
	}

	fe_mul(t1, t2, t1);
	fe_sq(t2, t1);

	for (i = 1; i < 50; ++i)
	{
		fe_sq(t2, t2);
	}

	fe_mul(t2, t2, t1);
	fe_sq(t3, t2);

	for (i = 1; i < 100; ++i)
	{
		fe_sq(t3, t3);
	}

	fe_mul(t2, t3, t2);
	fe_sq(t2, t2);

	for (i = 1; i < 50; ++i)
	{
		fe_sq(t2, t2);
	}

	fe_mul(t1, t2, t1);
	fe_sq(t1, t1);

	for (i = 1; i < 5; ++i)
	{
		fe_sq(t1, t1);
	}

	fe_mul(out, t1, t0);
}

static void fe_pow22523(fe out, const fe z)
{
	fe t0, t1, t2;
	int i;

	fe_sq(t0, z);
	fe_sq(t1, t0);
	fe_sq(t1, t1);
	fe_mul(t1, z, t1);
	fe_mul(t0, t0, t1);
	fe_sq(t0, t0);
	fe_mul(t0, t1, t0);
	fe_sq(t1, t0);

	for (i = 1; i < 5; ++i)
	{
		fe_sq(t1, t1);
	}

	fe_mul(t0, t1, t0);
	fe_sq(t1, t0);

	for (i = 1; i < 10; ++i)
	{
		fe_sq(t1, t1);
	}

	fe_mul(t1, t1, t0);
	fe_sq(t2, t1);

	for (i = 1; i < 20; ++i)
	{
		fe_sq(t2, t2);
	}

	fe_mul(t1, t2, t1);
	fe_sq(t1, t1);

	for (i = 1; i < 10; ++i)
	{
		fe_sq(t1, t1);
	}

	fe_mul(t0, t1, t0);
	fe_sq(t1, t0);

	for (i = 1; i < 50; ++i)
	{
		fe_sq(t1, t1);
	}

	fe_mul(t1, t1, t0);
	fe_sq(t2, t1);
	for (i = 1; i < 100; ++i)
	{
		fe_sq(t2, t2);
	}

	fe_mul(t1, t2, t1);
	fe_sq(t1, t1);

	for (i = 1; i < 50; ++i)
	{
		fe_sq(t1, t1);
	}

	fe_mul(t0, t1, t0);
	fe_sq(t0, t0);
	fe_sq(t0, t0);
	fe_mul(out, t0, z);
}

/**
 * h = f - g
 * Can overlap h with f or g.
 *
 * Preconditions:
 * |f| bounded by 1.1*2^25, 1.1*2^24, 1.1*2^25, 1.1*2^24, etc.
 * |g| bounded by 1.1*2^25, 1.1*2^24, 1.1*2^25, 1.1*2^24, etc.
 *
 * Postconditions:
 * |h| bounded by 1.1*2^26, 1.1*2^25, 1.1*2^26, 1.1*2^25, etc.
 */
static void fe_sub(fe h, const fe f, const fe g)
{
	int32_t f0 = f[0];
	int32_t f1 = f[1];
	int32_t f2 = f[2];
	int32_t f3 = f[3];
	int32_t f4 = f[4];
	int32_t f5 = f[5];
	int32_t f6 = f[6];
	int32_t f7 = f[7];
	int32_t f8 = f[8];
	int32_t f9 = f[9];

	int32_t g0 = g[0];
	int32_t g1 = g[1];
	int32_t g2 = g[2];
	int32_t g3 = g[3];
	int32_t g4 = g[4];
	int32_t g5 = g[5];
	int32_t g6 = g[6];
	int32_t g7 = g[7];
	int32_t g8 = g[8];
	int32_t g9 = g[9];

	int32_t h0 = f0 - g0;
	int32_t h1 = f1 - g1;
	int32_t h2 = f2 - g2;
	int32_t h3 = f3 - g3;
	int32_t h4 = f4 - g4;
	int32_t h5 = f5 - g5;
	int32_t h6 = f6 - g6;
	int32_t h7 = f7 - g7;
	int32_t h8 = f8 - g8;
	int32_t h9 = f9 - g9;

	h[0] = h0;
	h[1] = h1;
	h[2] = h2;
	h[3] = h3;
	h[4] = h4;
	h[5] = h5;
	h[6] = h6;
	h[7] = h7;
	h[8] = h8;
	h[9] = h9;
}

/**
 * r = p + q
 */
static void ge_add(ge_p1p1 *r, const ge_p3 *p, const ge_cached *q)
{
	fe t0;

	fe_add(r->X, p->Y, p->X);
	fe_sub(r->Y, p->Y, p->X);
	fe_mul(r->Z, r->X, q->YplusX);
	fe_mul(r->Y, r->Y, q->YminusX);
	fe_mul(r->T, q->T2d, p->T);
	fe_mul(r->X, p->Z, q->Z);
	fe_add(t0, r->X, r->X);
	fe_sub(r->X, r->Z, r->Y);
	fe_add(r->Y, r->Z, r->Y);
	fe_add(r->Z, t0, r->T);
	fe_sub(r->T, t0, r->T);
}

static void slide(int8_t *r, const uint8_t *a)
{
	int i, b, k;

	for (i = 0; i < 256; ++i)
	{
		r[i] = 1 & (a[i >> 3] >> (i & 7));
	}

	for (i = 0; i < 256; ++i)
	{
		if (r[i])
		{
			for (b = 1; b <= 6 && i + b < 256; ++b)
			{
				if (r[i + b])
				{
					if (r[i] + (r[i + b] << b) <= 15)
					{
						r[i] += r[i + b] << b; r[i + b] = 0;
					}
					else if (r[i] - (r[i + b] << b) >= -15)
					{
						r[i] -= r[i + b] << b;

						for (k = i + b; k < 256; ++k)
						{
							if (!r[k])
							{
								r[k] = 1;
								break;
							}
							r[k] = 0;
						}
					}
					else
					{
						break;
					}
				}
			}
		}
	}
}

static const ge_precomp Bi[8] = {
#include "base2.h"
};

/* 37095705934669439343138083508754565189542113879843219016388785533085940283555 */
static const fe d = {
	-10913610,  13857413, -15372611,   6949391,    114729,
	 -8787816,  -6275908,  -3247719, -18696448, -12055116
};

/* sqrt(-1) */
static const fe sqrtm1 = {
	-32595792,  -7943725,  9377950,    3500415,  12389472,
	  -272473, -25146209, -2005654,     326686,  11406482
};

int ge_frombytes_negate_vartime(ge_p3 *h, const uint8_t *s)
{
	fe u, v, v3, vxx, check;

	fe_frombytes(h->Y,s);
	fe_1(h->Z);
	fe_sq(u,h->Y);
	fe_mul(v,u,d);
	fe_sub(u,u,h->Z);	   /* u = y^2-1 */
	fe_add(v,v,h->Z);	   /* v = dy^2+1 */

	fe_sq(v3,v);
	fe_mul(v3,v3,v);		/* v3 = v^3 */
	fe_sq(h->X,v3);
	fe_mul(h->X,h->X,v);
	fe_mul(h->X,h->X,u);	/* x = uv^7 */

	fe_pow22523(h->X,h->X); /* x = (uv^7)^((q-5)/8) */
	fe_mul(h->X,h->X,v3);
	fe_mul(h->X,h->X,u);	/* x = uv^3(uv^7)^((q-5)/8) */

	fe_sq(vxx,h->X);
	fe_mul(vxx,vxx,v);
	fe_sub(check,vxx,u);	/* vx^2-u */

	if (fe_isnonzero(check))
	{
		fe_add(check,vxx,u);  /* vx^2+u */

		if (fe_isnonzero(check))
		{
			return -1;
		}
		fe_mul(h->X,h->X,sqrtm1);
	}

	if (fe_isnegative(h->X) == (s[31] >> 7))
	{
		fe_neg(h->X,h->X);
	}
	fe_mul(h->T,h->X,h->Y);

	return 0;
}

/**
 * r = p + q
 */
static void ge_madd(ge_p1p1 *r, const ge_p3 *p, const ge_precomp *q)
{
	fe t0;

	fe_add(r->X, p->Y, p->X);
	fe_sub(r->Y, p->Y, p->X);
	fe_mul(r->Z, r->X, q->yplusx);
	fe_mul(r->Y, r->Y, q->yminusx);
	fe_mul(r->T, q->xy2d, p->T);
	fe_add(t0, p->Z, p->Z);
	fe_sub(r->X, r->Z, r->Y);
	fe_add(r->Y, r->Z, r->Y);
	fe_add(r->Z, t0, r->T);
	fe_sub(r->T, t0, r->T);
}

/**
 * r = p - q
 */
static void ge_msub(ge_p1p1 *r, const ge_p3 *p, const ge_precomp *q)
{
	fe t0;

	fe_add(r->X, p->Y, p->X);
	fe_sub(r->Y, p->Y, p->X);
	fe_mul(r->Z, r->X, q->yminusx);
	fe_mul(r->Y, r->Y, q->yplusx);
	fe_mul(r->T, q->xy2d, p->T);
	fe_add(t0, p->Z, p->Z);
	fe_sub(r->X, r->Z, r->Y);
	fe_add(r->Y, r->Z, r->Y);
	fe_sub(r->Z, t0, r->T);
	fe_add(r->T, t0, r->T);
}

/**
 * r = p
 */
static void ge_p1p1_to_p2(ge_p2 *r, const ge_p1p1 *p)
{
	fe_mul(r->X,p->X,p->T);
	fe_mul(r->Y,p->Y,p->Z);
	fe_mul(r->Z,p->Z,p->T);
}

/**
 * r = p
 */
static void ge_p1p1_to_p3(ge_p3 *r, const ge_p1p1 *p)
{
	fe_mul(r->X,p->X,p->T);
	fe_mul(r->Y,p->Y,p->Z);
	fe_mul(r->Z,p->Z,p->T);
	fe_mul(r->T,p->X,p->Y);
}

static void ge_p2_0(ge_p2 *h)
{
	fe_0(h->X);
	fe_1(h->Y);
	fe_1(h->Z);
}

/**
 * r = 2 * p
 */
static void ge_p2_dbl(ge_p1p1 *r, const ge_p2 *p)
{
	fe t0;

	fe_sq(r->X, p->X);
	fe_sq(r->Z, p->Y);
	fe_sq2(r->T, p->Z);
	fe_add(r->Y, p->X, p->Y);
	fe_sq(t0, r->Y);
	fe_add(r->Y, r->Z, r->X);
	fe_sub(r->Z, r->Z, r->X);
	fe_sub(r->X, t0, r->Y);
	fe_sub(r->T, r->T, r->Z);
}

static void ge_p3_0(ge_p3 *h)
{
	fe_0(h->X);
	fe_1(h->Y);
	fe_1(h->Z);
	fe_0(h->T);
}

/**
 * r = p
 */

/* 2 * d = 16295367250680780974490674513165176452449235426866156013048779062215315747161 */
static const fe d2 = {
	-21827239,  -5839606, -30745221, 13898782,  229458,
	 15978800, -12551817,  -6495438, 29715968, 9444199
};

static void ge_p3_to_cached(ge_cached *r, const ge_p3 *p)
{
	fe_add(r->YplusX,p->Y,p->X);
	fe_sub(r->YminusX,p->Y,p->X);
	fe_copy(r->Z,p->Z);
	fe_mul(r->T2d,p->T,d2);
}

/**
 * r = p
 */
static void ge_p3_to_p2(ge_p2 *r, const ge_p3 *p)
{
	fe_copy(r->X,p->X);
	fe_copy(r->Y,p->Y);
	fe_copy(r->Z,p->Z);
}

void ge_p3_tobytes(uint8_t *s, const ge_p3 *h)
{
	fe recip, x, y;

	fe_invert(recip,h->Z);
	fe_mul(x,h->X,recip);
	fe_mul(y,h->Y,recip);
	fe_tobytes(s,y);

	s[31] ^= fe_isnegative(x) << 7;
}

/**
 * r = 2 * p
 */
static void ge_p3_dbl(ge_p1p1 *r, const ge_p3 *p)
{
	ge_p2 q;
	ge_p3_to_p2(&q,p);
	ge_p2_dbl(r,&q);
}

static void ge_precomp_0(ge_precomp *h)
{
	fe_1(h->yplusx);
	fe_1(h->yminusx);
	fe_0(h->xy2d);
}

static uint8_t equal(int8_t b, int8_t c)
{
	uint8_t ub = b;
	uint8_t uc = c;
	uint8_t x = ub ^ uc;  /* 0: yes; 1..255: no */
	uint32_t y = x;       /* 0: yes; 1..255: no */

	y -= 1;      /* 4294967295: yes; 0..254: no */
	y >>= 31;    /* 1: yes; 0: no */

	return y;
}

static uint8_t negative(int8_t b)
{
	uint64_t x = b; /* 18446744073709551361..18446744073709551615: yes; 0..255: no */

	x >>= 63;       /* 1: yes; 0: no */

	return x;
}

static void cmov(ge_precomp *t, const ge_precomp *u, uint8_t b)
{
	fe_cmov(t->yplusx,u->yplusx,b);
	fe_cmov(t->yminusx,u->yminusx,b);
	fe_cmov(t->xy2d,u->xy2d,b);
}

/**
 * base[i][j] = (j+1)*256^i*B
 */
static const ge_precomp base[32][8] = {
#include "base.h"
};

static void ge_select(ge_precomp *t, int pos, int8_t b)
{
	ge_precomp minust;
	uint8_t bnegative = negative(b);
	uint8_t babs = b - (((-bnegative) & b) * ((int8_t) 1 << 1));

	ge_precomp_0(t);
	cmov(t,&base[pos][0],equal(babs,1));
	cmov(t,&base[pos][1],equal(babs,2));
	cmov(t,&base[pos][2],equal(babs,3));
	cmov(t,&base[pos][3],equal(babs,4));
	cmov(t,&base[pos][4],equal(babs,5));
	cmov(t,&base[pos][5],equal(babs,6));
	cmov(t,&base[pos][6],equal(babs,7));
	cmov(t,&base[pos][7],equal(babs,8));
	fe_copy(minust.yplusx,t->yminusx);
	fe_copy(minust.yminusx,t->yplusx);
	fe_neg(minust.xy2d,t->xy2d);
	cmov(t,&minust,bnegative);
}

/**
 *r = p - q
 */
static void ge_sub(ge_p1p1 *r, const ge_p3 *p, const ge_cached *q)
{
	fe t0;

	fe_add(r->X, p->Y, p->X);
	fe_sub(r->Y, p->Y, p->X);
	fe_mul(r->Z, r->X, q->YminusX);
	fe_mul(r->Y, r->Y, q->YplusX);
	fe_mul(r->T, q->T2d, p->T);
	fe_mul(r->X, p->Z, q->Z);
	fe_add(t0, r->X, r->X);
	fe_sub(r->X, r->Z, r->Y);
	fe_add(r->Y, r->Z, r->Y);
	fe_sub(r->Z, t0, r->T);
	fe_add(r->T, t0, r->T);
}

void ge_tobytes(uint8_t *s, const ge_p2 *h)
{
	fe recip, x, y;

	fe_invert(recip,h->Z);
	fe_mul(x,h->X,recip);
	fe_mul(y,h->Y,recip);
	fe_tobytes(s,y);

	s[31] ^= fe_isnegative(x) << 7;
}

/**
 * h = a * B
 * where a = a[0]+256*a[1]+...+256^31 a[31]
 * B is the Ed25519 base point (x,4/5) with x positive.
 *
 * Preconditions:
 * a[31] <= 127
 */

/**
 * r = a * A + b * B
 * where a = a[0]+256*a[1]+...+256^31 a[31].
 * and b = b[0]+256*b[1]+...+256^31 b[31].
 * B is the Ed25519 base point (x,4/5) with x positive.
 */
void ge_double_scalarmult_vartime(ge_p2 *r, const uint8_t *a, const ge_p3 *A,
								  const uint8_t *b)
{
	int8_t aslide[256];
	int8_t bslide[256];
	ge_cached Ai[8];     /* A,3A,5A,7A,9A,11A,13A,15A */
	ge_p1p1 t;
	ge_p3 u, A2;
	int i;

	slide(aslide,a);
	slide(bslide,b);

	ge_p3_to_cached(&Ai[0],A);
	ge_p3_dbl(&t,A);
	ge_p1p1_to_p3(&A2,&t);

	ge_add(&t,&A2,&Ai[0]);
	ge_p1p1_to_p3(&u,&t);
	ge_p3_to_cached(&Ai[1],&u);

	ge_add(&t,&A2,&Ai[1]);
	ge_p1p1_to_p3(&u,&t);
	ge_p3_to_cached(&Ai[2],&u);

	ge_add(&t,&A2,&Ai[2]);
	ge_p1p1_to_p3(&u,&t);
	ge_p3_to_cached(&Ai[3],&u);

	ge_add(&t,&A2,&Ai[3]);
	ge_p1p1_to_p3(&u,&t);
	ge_p3_to_cached(&Ai[4],&u);

	ge_add(&t,&A2,&Ai[4]);
	ge_p1p1_to_p3(&u,&t);
	ge_p3_to_cached(&Ai[5],&u);

	ge_add(&t,&A2,&Ai[5]);
	ge_p1p1_to_p3(&u,&t);
	ge_p3_to_cached(&Ai[6],&u);

	ge_add(&t,&A2,&Ai[6]);
	ge_p1p1_to_p3(&u,&t);
	ge_p3_to_cached(&Ai[7],&u);

	ge_p2_0(r);

	for (i = 255; i >= 0; --i)
	{
		if (aslide[i] || bslide[i])
		{
			break;
		}
	}

	for (; i >= 0 ;--i)
	{
		ge_p2_dbl(&t,r);

		if (aslide[i] > 0)
		{
			ge_p1p1_to_p3(&u,&t);
			ge_add(&t,&u,&Ai[aslide[i]/2]);
		}
		else if (aslide[i] < 0)
		{
			ge_p1p1_to_p3(&u,&t);
			ge_sub(&t,&u,&Ai[(-aslide[i])/2]);
		}

		if (bslide[i] > 0)
		{
			ge_p1p1_to_p3(&u,&t);
			ge_madd(&t,&u,&Bi[bslide[i]/2]);
		}
		else if (bslide[i] < 0)
		{
			ge_p1p1_to_p3(&u,&t);
			ge_msub(&t,&u,&Bi[(-bslide[i])/2]);
		}
		ge_p1p1_to_p2(r,&t);
	}
}

void ge_scalarmult_base(ge_p3 *h, const uint8_t *a)
{
	int8_t e[64];
	int8_t carry = 0;
	ge_p1p1 r;
	ge_p2 s;
	ge_precomp t;
	int i;

	for (i = 0; i < 32; ++i)
	{
		e[2 * i + 0] = (a[i] >> 0) & 15;
		e[2 * i + 1] = (a[i] >> 4) & 15;
	}
	/* each e[i] is between 0 and 15 */
	/* e[63] is between 0 and 7 */

	for (i = 0; i < 63; ++i) {
		e[i] += carry;
		carry = e[i] + 8;
		carry >>= 4;
		e[i] -= carry * ((int8_t) 1 << 4);
	}
	e[63] += carry;
	/* each e[i] is between -8 and 8 */

	ge_p3_0(h);
	for (i = 1; i < 64; i += 2)
	{
		ge_select(&t,i / 2,e[i]);
		ge_madd(&r,h,&t); ge_p1p1_to_p3(h,&r);
	}

	ge_p3_dbl(&r,h);  ge_p1p1_to_p2(&s,&r);
	ge_p2_dbl(&r,&s); ge_p1p1_to_p2(&s,&r);
	ge_p2_dbl(&r,&s); ge_p1p1_to_p2(&s,&r);
	ge_p2_dbl(&r,&s); ge_p1p1_to_p3(h,&r);

	for (i = 0; i < 64; i += 2)
	{
		ge_select(&t,i / 2,e[i]);
		ge_madd(&r,h,&t);
		ge_p1p1_to_p3(h,&r);
	}
}

/**
 * Input:
 * a[0]+256*a[1]+...+256^31*a[31] = a
 * b[0]+256*b[1]+...+256^31*b[31] = b
 * c[0]+256*c[1]+...+256^31*c[31] = c
 *
 * Output:
 * s[0]+256*s[1]+...+256^31*s[31] = (ab+c) mod l
 * where l = 2^252 + 27742317777372353535851937790883648493.
 */
void sc_muladd(uint8_t *s, const uint8_t *a, const uint8_t *b, const uint8_t *c)
{
	int64_t a0  = 2097151 & load_3(a);
	int64_t a1  = 2097151 & (load_4(a + 2) >> 5);
	int64_t a2  = 2097151 & (load_3(a + 5) >> 2);
	int64_t a3  = 2097151 & (load_4(a + 7) >> 7);
	int64_t a4  = 2097151 & (load_4(a + 10) >> 4);
	int64_t a5  = 2097151 & (load_3(a + 13) >> 1);
	int64_t a6  = 2097151 & (load_4(a + 15) >> 6);
	int64_t a7  = 2097151 & (load_3(a + 18) >> 3);
	int64_t a8  = 2097151 & load_3(a + 21);
	int64_t a9  = 2097151 & (load_4(a + 23) >> 5);
	int64_t a10 = 2097151 & (load_3(a + 26) >> 2);
	int64_t a11 = (load_4(a + 28) >> 7);

	int64_t b0  = 2097151 & load_3(b);
	int64_t b1  = 2097151 & (load_4(b + 2) >> 5);
	int64_t b2  = 2097151 & (load_3(b + 5) >> 2);
	int64_t b3  = 2097151 & (load_4(b + 7) >> 7);
	int64_t b4  = 2097151 & (load_4(b + 10) >> 4);
	int64_t b5  = 2097151 & (load_3(b + 13) >> 1);
	int64_t b6  = 2097151 & (load_4(b + 15) >> 6);
	int64_t b7  = 2097151 & (load_3(b + 18) >> 3);
	int64_t b8  = 2097151 & load_3(b + 21);
	int64_t b9  = 2097151 & (load_4(b + 23) >> 5);
	int64_t b10 = 2097151 & (load_3(b + 26) >> 2);
	int64_t b11 = (load_4(b + 28) >> 7);

	int64_t c0  = 2097151 & load_3(c);
	int64_t c1  = 2097151 & (load_4(c + 2) >> 5);
	int64_t c2  = 2097151 & (load_3(c + 5) >> 2);
	int64_t c3  = 2097151 & (load_4(c + 7) >> 7);
	int64_t c4  = 2097151 & (load_4(c + 10) >> 4);
	int64_t c5  = 2097151 & (load_3(c + 13) >> 1);
	int64_t c6  = 2097151 & (load_4(c + 15) >> 6);
	int64_t c7  = 2097151 & (load_3(c + 18) >> 3);
	int64_t c8  = 2097151 & load_3(c + 21);
	int64_t c9  = 2097151 & (load_4(c + 23) >> 5);
	int64_t c10 = 2097151 & (load_3(c + 26) >> 2);
	int64_t c11 = (load_4(c + 28) >> 7);

	int64_t s0,  s1,  s2,  s3,  s4,  s5,  s6,  s7,  s8,  s9,  s10, s11;
	int64_t s12, s13, s14, s15, s16, s17, s18, s19, s20, s21, s22, s23;

	int64_t carry0,  carry1,  carry2,   carry3, carry4,  carry5,  carry6;
	int64_t carry7,  carry8,  carry9,  carry10, carry11, carry12, carry13;
	int64_t carry14, carry15, carry16, carry17, carry18, carry19, carry20;
	int64_t carry21, carry22;

	s0 = c0 + a0*b0;
	s1 = c1 + a0*b1 + a1*b0;
	s2 = c2 + a0*b2 + a1*b1 + a2*b0;
	s3 = c3 + a0*b3 + a1*b2 + a2*b1 + a3*b0;
	s4 = c4 + a0*b4 + a1*b3 + a2*b2 + a3*b1 + a4*b0;
	s5 = c5 + a0*b5 + a1*b4 + a2*b3 + a3*b2 + a4*b1 + a5*b0;
	s6 = c6 + a0*b6 + a1*b5 + a2*b4 + a3*b3 + a4*b2 + a5*b1 + a6*b0;
	s7 = c7 + a0*b7 + a1*b6 + a2*b5 + a3*b4 + a4*b3 + a5*b2 + a6*b1 + a7*b0;
	s8 = c8 + a0*b8 + a1*b7 + a2*b6 + a3*b5 + a4*b4 + a5*b3 + a6*b2 + a7*b1 + a8*b0;
	s9 = c9 + a0*b9 + a1*b8 + a2*b7 + a3*b6 + a4*b5 + a5*b4 + a6*b3 + a7*b2 + a8*b1 + a9*b0;
	s10 = c10 + a0*b10 + a1*b9 + a2*b8 + a3*b7 + a4*b6 + a5*b5 + a6*b4 + a7*b3 + a8*b2 + a9*b1 + a10*b0;
	s11 = c11 + a0*b11 + a1*b10 + a2*b9 + a3*b8 + a4*b7 + a5*b6 + a6*b5 + a7*b4 + a8*b3 + a9*b2 + a10*b1 + a11*b0;
	s12 = a1*b11 + a2*b10 + a3*b9 + a4*b8 + a5*b7 + a6*b6 + a7*b5 + a8*b4 + a9*b3 + a10*b2 + a11*b1;
	s13 = a2*b11 + a3*b10 + a4*b9 + a5*b8 + a6*b7 + a7*b6 + a8*b5 + a9*b4 + a10*b3 + a11*b2;
	s14 = a3*b11 + a4*b10 + a5*b9 + a6*b8 + a7*b7 + a8*b6 + a9*b5 + a10*b4 + a11*b3;
	s15 = a4*b11 + a5*b10 + a6*b9 + a7*b8 + a8*b7 + a9*b6 + a10*b5 + a11*b4;
	s16 = a5*b11 + a6*b10 + a7*b9 + a8*b8 + a9*b7 + a10*b6 + a11*b5;
	s17 = a6*b11 + a7*b10 + a8*b9 + a9*b8 + a10*b7 + a11*b6;
	s18 = a7*b11 + a8*b10 + a9*b9 + a10*b8 + a11*b7;
	s19 = a8*b11 + a9*b10 + a10*b9 + a11*b8;
	s20 = a9*b11 + a10*b10 + a11*b9;
	s21 = a10*b11 + a11*b10;
	s22 = a11*b11;
	s23 = 0;

	carry0 = (s0 + (int64_t) (1L << 20)) >> 21;
	s1 += carry0;
	s0 -= carry0 * ((uint64_t) 1L << 21);

	carry2 = (s2 + (int64_t) (1L << 20)) >> 21;
	s3 += carry2;
	s2 -= carry2 * ((uint64_t) 1L << 21);

	carry4 = (s4 + (int64_t) (1L << 20)) >> 21;
	s5 += carry4;
	s4 -= carry4 * ((uint64_t) 1L << 21);

	carry6 = (s6 + (int64_t) (1L << 20)) >> 21;
	s7 += carry6;
	s6 -= carry6 * ((uint64_t) 1L << 21);

	carry8 = (s8 + (int64_t) (1L << 20)) >> 21;
	s9 += carry8;
	s8 -= carry8 * ((uint64_t) 1L << 21);

	carry10 = (s10 + (int64_t) (1L << 20)) >> 21;
	s11 += carry10;
	s10 -= carry10 * ((uint64_t) 1L << 21);

	carry12 = (s12 + (int64_t) (1L << 20)) >> 21;
	s13 += carry12;
	s12 -= carry12 * ((uint64_t) 1L << 21);

	carry14 = (s14 + (int64_t) (1L << 20)) >> 21;
	s15 += carry14;
	s14 -= carry14 * ((uint64_t) 1L << 21);

	carry16 = (s16 + (int64_t) (1L << 20)) >> 21;
	s17 += carry16;
	s16 -= carry16 * ((uint64_t) 1L << 21);

	carry18 = (s18 + (int64_t) (1L << 20)) >> 21;
	s19 += carry18;
	s18 -= carry18 * ((uint64_t) 1L << 21);

	carry20 = (s20 + (int64_t) (1L << 20)) >> 21;
	s21 += carry20;
	s20 -= carry20 * ((uint64_t) 1L << 21);

	carry22 = (s22 + (int64_t) (1L << 20)) >> 21;
	s23 += carry22;
	s22 -= carry22 * ((uint64_t) 1L << 21);

	carry1 = (s1 + (int64_t) (1L << 20)) >> 21;
	s2 += carry1;
	s1 -= carry1 * ((uint64_t) 1L << 21);

	carry3 = (s3 + (int64_t) (1L << 20)) >> 21;
	s4 += carry3;
	s3 -= carry3 * ((uint64_t) 1L << 21);

	carry5 = (s5 + (int64_t) (1L << 20)) >> 21;
	s6 += carry5;
	s5 -= carry5 * ((uint64_t) 1L << 21);

	carry7 = (s7 + (int64_t) (1L << 20)) >> 21;
	s8 += carry7;
	s7 -= carry7 * ((uint64_t) 1L << 21);

	carry9 = (s9 + (int64_t) (1L << 20)) >> 21;
	s10 += carry9;
	s9 -= carry9 * ((uint64_t) 1L << 21);

	carry11 = (s11 + (int64_t) (1L << 20)) >> 21;
	s12 += carry11;
	s11 -= carry11 * ((uint64_t) 1L << 21);

	carry13 = (s13 + (int64_t) (1L << 20)) >> 21;
	s14 += carry13;
	s13 -= carry13 * ((uint64_t) 1L << 21);

	carry15 = (s15 + (int64_t) (1L << 20)) >> 21;
	s16 += carry15;
	s15 -= carry15 * ((uint64_t) 1L << 21);

	carry17 = (s17 + (int64_t) (1L << 20)) >> 21;
	s18 += carry17;
	s17 -= carry17 * ((uint64_t) 1L << 21);

	carry19 = (s19 + (int64_t) (1L << 20)) >> 21;
	s20 += carry19;
	s19 -= carry19 * ((uint64_t) 1L << 21);

	carry21 = (s21 + (int64_t) (1L << 20)) >> 21;
	s22 += carry21;
	s21 -= carry21 * ((uint64_t) 1L << 21);

	s11 += s23 * 666643;
	s12 += s23 * 470296;
	s13 += s23 * 654183;
	s14 -= s23 * 997805;
	s15 += s23 * 136657;
	s16 -= s23 * 683901;

	s10 += s22 * 666643;
	s11 += s22 * 470296;
	s12 += s22 * 654183;
	s13 -= s22 * 997805;
	s14 += s22 * 136657;
	s15 -= s22 * 683901;

	s9  += s21 * 666643;
	s10 += s21 * 470296;
	s11 += s21 * 654183;
	s12 -= s21 * 997805;
	s13 += s21 * 136657;
	s14 -= s21 * 683901;

	s8  += s20 * 666643;
	s9  += s20 * 470296;
	s10 += s20 * 654183;
	s11 -= s20 * 997805;
	s12 += s20 * 136657;
	s13 -= s20 * 683901;

	s7  += s19 * 666643;
	s8  += s19 * 470296;
	s9  += s19 * 654183;
	s10 -= s19 * 997805;
	s11 += s19 * 136657;
	s12 -= s19 * 683901;

	s6  += s18 * 666643;
	s7  += s18 * 470296;
	s8  += s18 * 654183;
	s9  -= s18 * 997805;
	s10 += s18 * 136657;
	s11 -= s18 * 683901;

	carry6 = (s6 + (int64_t) (1L << 20)) >> 21;
	s7 += carry6;
	s6 -= carry6 * ((uint64_t) 1L << 21);

	carry8 = (s8 + (int64_t) (1L << 20)) >> 21;
	s9 += carry8;
	s8 -= carry8 * ((uint64_t) 1L << 21);

	carry10 = (s10 + (int64_t) (1L << 20)) >> 21;
	s11 += carry10;
	s10 -= carry10 * ((uint64_t) 1L << 21);

	carry12 = (s12 + (int64_t) (1L << 20)) >> 21;
	s13 += carry12;
	s12 -= carry12 * ((uint64_t) 1L << 21);

	carry14 = (s14 + (int64_t) (1L << 20)) >> 21;
	s15 += carry14;
	s14 -= carry14 * ((uint64_t) 1L << 21);

	carry16 = (s16 + (int64_t) (1L << 20)) >> 21;
	s17 += carry16;
	s16 -= carry16 * ((uint64_t) 1L << 21);

	carry7 = (s7 + (int64_t) (1L << 20)) >> 21;
	s8 += carry7;
	s7 -= carry7 * ((uint64_t) 1L << 21);

	carry9 = (s9 + (int64_t) (1L << 20)) >> 21;
	s10 += carry9;
	s9 -= carry9 * ((uint64_t) 1L << 21);

	carry11 = (s11 + (int64_t) (1L << 20)) >> 21;
	s12 += carry11;
	s11 -= carry11 * ((uint64_t) 1L << 21);

	carry13 = (s13 + (int64_t) (1L << 20)) >> 21;
	s14 += carry13;
	s13 -= carry13 * ((uint64_t) 1L << 21);

	carry15 = (s15 + (int64_t) (1L << 20)) >> 21;
	s16 += carry15;
	s15 -= carry15 * ((uint64_t) 1L << 21);

	s5  += s17 * 666643;
	s6  += s17 * 470296;
	s7  += s17 * 654183;
	s8  -= s17 * 997805;
	s9  += s17 * 136657;
	s10 -= s17 * 683901;

	s4  += s16 * 666643;
	s5  += s16 * 470296;
	s6  += s16 * 654183;
	s7  -= s16 * 997805;
	s8  += s16 * 136657;
	s9  -= s16 * 683901;

	s3  += s15 * 666643;
	s4  += s15 * 470296;
	s5  += s15 * 654183;
	s6  -= s15 * 997805;
	s7  += s15 * 136657;
	s8  -= s15 * 683901;

	s2  += s14 * 666643;
	s3  += s14 * 470296;
	s4  += s14 * 654183;
	s5  -= s14 * 997805;
	s6  += s14 * 136657;
	s7  -= s14 * 683901;

	s1  += s13 * 666643;
	s2  += s13 * 470296;
	s3  += s13 * 654183;
	s4  -= s13 * 997805;
	s5  += s13 * 136657;
	s6  -= s13 * 683901;

	s0  += s12 * 666643;
	s1  += s12 * 470296;
	s2  += s12 * 654183;
	s3  -= s12 * 997805;
	s4  += s12 * 136657;
	s5  -= s12 * 683901;
	s12 = 0;

	carry0 = (s0 + (int64_t) (1L << 20)) >> 21;
	s1 += carry0;
	s0 -= carry0 * ((uint64_t) 1L << 21);

	carry2 = (s2 + (int64_t) (1L << 20)) >> 21;
	s3 += carry2;
	s2 -= carry2 * ((uint64_t) 1L << 21);

	carry4 = (s4 + (int64_t) (1L << 20)) >> 21;
	s5 += carry4;
	s4 -= carry4 * ((uint64_t) 1L << 21);

	carry6 = (s6 + (int64_t) (1L << 20)) >> 21;
	s7 += carry6;
	s6 -= carry6 * ((uint64_t) 1L << 21);

	carry8 = (s8 + (int64_t) (1L << 20)) >> 21;
	s9 += carry8;
	s8 -= carry8 * ((uint64_t) 1L << 21);

	carry10 = (s10 + (int64_t) (1L << 20)) >> 21;
	s11 += carry10;
	s10 -= carry10 * ((uint64_t) 1L << 21);

	carry1 = (s1 + (int64_t) (1L << 20)) >> 21;
	s2 += carry1;
	s1 -= carry1 * ((uint64_t) 1L << 21);

	carry3 = (s3 + (int64_t) (1L << 20)) >> 21;
	s4 += carry3;
	s3 -= carry3 * ((uint64_t) 1L << 21);

	carry5 = (s5 + (int64_t) (1L << 20)) >> 21;
	s6 += carry5;
	s5 -= carry5 * ((uint64_t) 1L << 21);

	carry7 = (s7 + (int64_t) (1L << 20)) >> 21;
	s8 += carry7;
	s7 -= carry7 * ((uint64_t) 1L << 21);

	carry9 = (s9 + (int64_t) (1L << 20)) >> 21;
	s10 += carry9;
	s9 -= carry9 * ((uint64_t) 1L << 21);

	carry11 = (s11 + (int64_t) (1L << 20)) >> 21;
	s12 += carry11;
	s11 -= carry11 * ((uint64_t) 1L << 21);

	s0 += s12 * 666643;
	s1 += s12 * 470296;
	s2 += s12 * 654183;
	s3 -= s12 * 997805;
	s4 += s12 * 136657;
	s5 -= s12 * 683901;
	s12 = 0;

	carry0 = s0 >> 21;
	s1 += carry0;
	s0 -= carry0 * ((uint64_t) 1L << 21);

	carry1 = s1 >> 21;
	s2 += carry1;
	s1 -= carry1 * ((uint64_t) 1L << 21);

	carry2 = s2 >> 21;
	s3 += carry2;
	s2 -= carry2 * ((uint64_t) 1L << 21);

	carry3 = s3 >> 21;
	s4 += carry3;
	s3 -= carry3 * ((uint64_t) 1L << 21);

	carry4 = s4 >> 21;
	s5 += carry4;
	s4 -= carry4 * ((uint64_t) 1L << 21);

	carry5 = s5 >> 21;
	s6 += carry5;
	s5 -= carry5 * ((uint64_t) 1L << 21);

	carry6 = s6 >> 21;
	s7 += carry6;
	s6 -= carry6 * ((uint64_t) 1L << 21);

	carry7 = s7 >> 21;
	s8 += carry7;
	s7 -= carry7 * ((uint64_t) 1L << 21);

	carry8 = s8 >> 21;
	s9 += carry8;
	s8 -= carry8 * ((uint64_t) 1L << 21);

	carry9 = s9 >> 21;
	s10 += carry9;
	s9 -= carry9 * ((uint64_t) 1L << 21);

	carry10 = s10 >> 21;
	s11 += carry10;
	s10 -= carry10 * ((uint64_t) 1L << 21);

	carry11 = s11 >> 21;
	s12 += carry11;
	s11 -= carry11 * ((uint64_t) 1L << 21);

	s0 += s12 * 666643;
	s1 += s12 * 470296;
	s2 += s12 * 654183;
	s3 -= s12 * 997805;
	s4 += s12 * 136657;
	s5 -= s12 * 683901;

	carry0 = s0 >> 21;
	s1 += carry0;
	s0 -= carry0 * ((uint64_t) 1L << 21);

	carry1 = s1 >> 21;
	s2 += carry1;
	s1 -= carry1 * ((uint64_t) 1L << 21);

	carry2 = s2 >> 21;
	s3 += carry2;
	s2 -= carry2 * ((uint64_t) 1L << 21);

	carry3 = s3 >> 21;
	s4 += carry3;
	s3 -= carry3 * ((uint64_t) 1L << 21);

	carry4 = s4 >> 21;
	s5 += carry4;
	s4 -= carry4 * ((uint64_t) 1L << 21);

	carry5 = s5 >> 21;
	s6 += carry5;
	s5 -= carry5 * ((uint64_t) 1L << 21);

	carry6 = s6 >> 21;
	s7 += carry6;
	s6 -= carry6 * ((uint64_t) 1L << 21);

	carry7 = s7 >> 21;
	s8 += carry7;
	s7 -= carry7 * ((uint64_t) 1L << 21);

	carry8 = s8 >> 21;
	s9 += carry8;
	s8 -= carry8 * ((uint64_t) 1L << 21);

	carry9 = s9 >> 21;
	s10 += carry9;
	s9 -= carry9 * ((uint64_t) 1L << 21);

	carry10 = s10 >> 21;
	s11 += carry10;
	s10 -= carry10 * ((uint64_t) 1L << 21);

	s[0]  = s0 >> 0;
	s[1]  = s0 >> 8;
	s[2]  = (s0 >> 16) | (s1 * ((uint64_t) 1 << 5));
	s[3]  = s1 >> 3;
	s[4]  = s1 >> 11;
	s[5]  = (s1 >> 19) | (s2 * ((uint64_t) 1 << 2));
	s[6]  = s2 >> 6;
	s[7]  = (s2 >> 14) | (s3 * ((uint64_t) 1 << 7));
	s[8]  = s3 >> 1;
	s[9]  = s3 >> 9;
	s[10] = (s3 >> 17) | (s4 * ((uint64_t) 1 << 4));
	s[11] = s4 >> 4;
	s[12] = s4 >> 12;
	s[13] = (s4 >> 20) | (s5 * ((uint64_t) 1 << 1));
	s[14] = s5 >> 7;
	s[15] = (s5 >> 15) | (s6 * ((uint64_t) 1 << 6));
	s[16] = s6 >> 2;
	s[17] = s6 >> 10;
	s[18] = (s6 >> 18) | (s7 * ((uint64_t) 1 << 3));
	s[19] = s7 >> 5;
	s[20] = s7 >> 13;
	s[21] = s8 >> 0;
	s[22] = s8 >> 8;
	s[23] = (s8 >> 16) | (s9 * ((uint64_t) 1 << 5));
	s[24] = s9 >> 3;
	s[25] = s9 >> 11;
	s[26] = (s9 >> 19) | (s10 * ((uint64_t) 1 << 2));
	s[27] = s10 >> 6;
	s[28] = (s10 >> 14) | (s11 * ((uint64_t) 1 << 7));
	s[29] = s11 >> 1;
	s[30] = s11 >> 9;
	s[31] = s11 >> 17;
}

/**
 * Input:
 * s[0]+256*s[1]+...+256^63*s[63] = s
 *
 * Output:
 * s[0]+256*s[1]+...+256^31*s[31] = s mod l
 * where l = 2^252 + 27742317777372353535851937790883648493.
 * Overwrites s in place.
 */
void sc_reduce(uint8_t *s)
{
	int64_t s0  = 2097151 & load_3(s);
	int64_t s1  = 2097151 & (load_4(s + 2) >> 5);
	int64_t s2  = 2097151 & (load_3(s + 5) >> 2);
	int64_t s3  = 2097151 & (load_4(s + 7) >> 7);
	int64_t s4  = 2097151 & (load_4(s + 10) >> 4);
	int64_t s5  = 2097151 & (load_3(s + 13) >> 1);
	int64_t s6  = 2097151 & (load_4(s + 15) >> 6);
	int64_t s7  = 2097151 & (load_3(s + 18) >> 3);
	int64_t s8  = 2097151 & load_3(s + 21);
	int64_t s9  = 2097151 & (load_4(s + 23) >> 5);
	int64_t s10 = 2097151 & (load_3(s + 26) >> 2);
	int64_t s11 = 2097151 & (load_4(s + 28) >> 7);
	int64_t s12 = 2097151 & (load_4(s + 31) >> 4);
	int64_t s13 = 2097151 & (load_3(s + 34) >> 1);
	int64_t s14 = 2097151 & (load_4(s + 36) >> 6);
	int64_t s15 = 2097151 & (load_3(s + 39) >> 3);
	int64_t s16 = 2097151 & load_3(s + 42);
	int64_t s17 = 2097151 & (load_4(s + 44) >> 5);
	int64_t s18 = 2097151 & (load_3(s + 47) >> 2);
	int64_t s19 = 2097151 & (load_4(s + 49) >> 7);
	int64_t s20 = 2097151 & (load_4(s + 52) >> 4);
	int64_t s21 = 2097151 & (load_3(s + 55) >> 1);
	int64_t s22 = 2097151 & (load_4(s + 57) >> 6);
	int64_t s23 = (load_4(s + 60) >> 3);

	int64_t carry0,  carry1,  carry2,   carry3,  carry4,  carry5,  carry6;
	int64_t carry7,  carry8,  carry9,  carry10, carry11, carry12, carry13;
	int64_t carry14, carry15, carry16;

	s11 += s23 * 666643;
	s12 += s23 * 470296;
	s13 += s23 * 654183;
	s14 -= s23 * 997805;
	s15 += s23 * 136657;
	s16 -= s23 * 683901;

	s10 += s22 * 666643;
	s11 += s22 * 470296;
	s12 += s22 * 654183;
	s13 -= s22 * 997805;
	s14 += s22 * 136657;
	s15 -= s22 * 683901;

	s9  += s21 * 666643;
	s10 += s21 * 470296;
	s11 += s21 * 654183;
	s12 -= s21 * 997805;
	s13 += s21 * 136657;
	s14 -= s21 * 683901;

	s8  += s20 * 666643;
	s9  += s20 * 470296;
	s10 += s20 * 654183;
	s11 -= s20 * 997805;
	s12 += s20 * 136657;
	s13 -= s20 * 683901;

	s7  += s19 * 666643;
	s8  += s19 * 470296;
	s9  += s19 * 654183;
	s10 -= s19 * 997805;
	s11 += s19 * 136657;
	s12 -= s19 * 683901;

	s6  += s18 * 666643;
	s7  += s18 * 470296;
	s8  += s18 * 654183;
	s9  -= s18 * 997805;
	s10 += s18 * 136657;
	s11 -= s18 * 683901;

	carry6 = (s6 + (int64_t) (1L << 20)) >> 21;
	s7 += carry6;
	s6 -= carry6 * ((uint64_t) 1L << 21);

	carry8 = (s8 + (int64_t) (1L << 20)) >> 21;
	s9 += carry8;
	s8 -= carry8 * ((uint64_t) 1L << 21);

	carry10 = (s10 + (int64_t) (1L << 20)) >> 21;
	s11 += carry10;
	s10 -= carry10 * ((uint64_t) 1L << 21);

	carry12 = (s12 + (int64_t) (1L << 20)) >> 21;
	s13 += carry12;
	s12 -= carry12 * ((uint64_t) 1L << 21);

	carry14 = (s14 + (int64_t) (1L << 20)) >> 21;
	s15 += carry14;
	s14 -= carry14 * ((uint64_t) 1L << 21);

	carry16 = (s16 + (int64_t) (1L << 20)) >> 21;
	s17 += carry16;
	s16 -= carry16 * ((uint64_t) 1L << 21);

	carry7 = (s7 + (int64_t) (1L << 20)) >> 21;
	s8 += carry7;
	s7 -= carry7 * ((uint64_t) 1L << 21);

	carry9 = (s9 + (int64_t) (1L << 20)) >> 21;
	s10 += carry9;
	s9 -= carry9 * ((uint64_t) 1L << 21);

	carry11 = (s11 + (int64_t) (1L << 20)) >> 21;
	s12 += carry11;
	s11 -= carry11 * ((uint64_t) 1L << 21);

	carry13 = (s13 + (int64_t) (1L << 20)) >> 21;
	s14 += carry13;
	s13 -= carry13 * ((uint64_t) 1L << 21);

	carry15 = (s15 + (int64_t) (1L << 20)) >> 21;
	s16 += carry15;
	s15 -= carry15 * ((uint64_t) 1L << 21);

	s5  += s17 * 666643;
	s6  += s17 * 470296;
	s7  += s17 * 654183;
	s8  -= s17 * 997805;
	s9  += s17 * 136657;
	s10 -= s17 * 683901;

	s4  += s16 * 666643;
	s5  += s16 * 470296;
	s6  += s16 * 654183;
	s7  -= s16 * 997805;
	s8  += s16 * 136657;
	s9  -= s16 * 683901;

	s3  += s15 * 666643;
	s4  += s15 * 470296;
	s5  += s15 * 654183;
	s6  -= s15 * 997805;
	s7  += s15 * 136657;
	s8  -= s15 * 683901;

	s2  += s14 * 666643;
	s3  += s14 * 470296;
	s4  += s14 * 654183;
	s5  -= s14 * 997805;
	s6  += s14 * 136657;
	s7  -= s14 * 683901;

	s1  += s13 * 666643;
	s2  += s13 * 470296;
	s3  += s13 * 654183;
	s4  -= s13 * 997805;
	s5  += s13 * 136657;
	s6  -= s13 * 683901;

	s0  += s12 * 666643;
	s1  += s12 * 470296;
	s2  += s12 * 654183;
	s3  -= s12 * 997805;
	s4  += s12 * 136657;
	s5  -= s12 * 683901;
	s12 = 0;

	carry0 = (s0 + (int64_t) (1L << 20)) >> 21;
	s1 += carry0;
	s0 -= carry0 * ((uint64_t) 1L << 21);

	carry2 = (s2 + (int64_t) (1L << 20)) >> 21;
	s3 += carry2;
	s2 -= carry2 * ((uint64_t) 1L << 21);

	carry4 = (s4 + (int64_t) (1L << 20)) >> 21;
	s5 += carry4;
	s4 -= carry4 * ((uint64_t) 1L << 21);

	carry6 = (s6 + (int64_t) (1L << 20)) >> 21;
	s7 += carry6;
	s6 -= carry6 * ((uint64_t) 1L << 21);

	carry8 = (s8 + (int64_t) (1L << 20)) >> 21;
	s9 += carry8;
	s8 -= carry8 * ((uint64_t) 1L << 21);

	carry10 = (s10 + (int64_t) (1L << 20)) >> 21;
	s11 += carry10;
	s10 -= carry10 * ((uint64_t) 1L << 21);

	carry1 = (s1 + (int64_t) (1L << 20)) >> 21;
	s2 += carry1;
	s1 -= carry1 * ((uint64_t) 1L << 21);

	carry3 = (s3 + (int64_t) (1L << 20)) >> 21;
	s4 += carry3;
	s3 -= carry3 * ((uint64_t) 1L << 21);

	carry5 = (s5 + (int64_t) (1L << 20)) >> 21;
	s6 += carry5;
	s5 -= carry5 * ((uint64_t) 1L << 21);

	carry7 = (s7 + (int64_t) (1L << 20)) >> 21;
	s8 += carry7;
	s7 -= carry7 * ((uint64_t) 1L << 21);

	carry9 = (s9 + (int64_t) (1L << 20)) >> 21;
	s10 += carry9;
	s9 -= carry9 * ((uint64_t) 1L << 21);

	carry11 = (s11 + (int64_t) (1L << 20)) >> 21;
	s12 += carry11;
	s11 -= carry11 * ((uint64_t) 1L << 21);

	s0 += s12 * 666643;
	s1 += s12 * 470296;
	s2 += s12 * 654183;
	s3 -= s12 * 997805;
	s4 += s12 * 136657;
	s5 -= s12 * 683901;
	s12 = 0;

	carry0 = s0 >> 21;
	s1 += carry0;
	s0 -= carry0 * ((uint64_t) 1L << 21);

	carry1 = s1 >> 21;
	s2 += carry1;
	s1 -= carry1 * ((uint64_t) 1L << 21);

	carry2 = s2 >> 21;
	s3 += carry2;
	s2 -= carry2 * ((uint64_t) 1L << 21);

	carry3 = s3 >> 21;
	s4 += carry3;
	s3 -= carry3 * ((uint64_t) 1L << 21);

	carry4 = s4 >> 21;
	s5 += carry4;
	s4 -= carry4 * ((uint64_t) 1L << 21);

	carry5 = s5 >> 21;
	s6 += carry5;
	s5 -= carry5 * ((uint64_t) 1L << 21);

	carry6 = s6 >> 21;
	s7 += carry6;
	s6 -= carry6 * ((uint64_t) 1L << 21);

	carry7 = s7 >> 21;
	s8 += carry7;
	s7 -= carry7 * ((uint64_t) 1L << 21);

	carry8 = s8 >> 21;
	s9 += carry8;
	s8 -= carry8 * ((uint64_t) 1L << 21);

	carry9 = s9 >> 21;
	s10 += carry9;
	s9 -= carry9 * ((uint64_t) 1L << 21);

	carry10 = s10 >> 21;
	s11 += carry10;
	s10 -= carry10 * ((uint64_t) 1L << 21);

	carry11 = s11 >> 21;
	s12 += carry11;
	s11 -= carry11 * ((uint64_t) 1L << 21);

	s0 += s12 * 666643;
	s1 += s12 * 470296;
	s2 += s12 * 654183;
	s3 -= s12 * 997805;
	s4 += s12 * 136657;
	s5 -= s12 * 683901;

	carry0 = s0 >> 21;
	s1 += carry0;
	s0 -= carry0 * ((uint64_t) 1L << 21);

	carry1 = s1 >> 21;
	s2 += carry1;
	s1 -= carry1 * ((uint64_t) 1L << 21);

	carry2 = s2 >> 21;
	s3 += carry2;
	s2 -= carry2 * ((uint64_t) 1L << 21);

	carry3 = s3 >> 21;
	s4 += carry3;
	s3 -= carry3 * ((uint64_t) 1L << 21);

	carry4 = s4 >> 21;
	s5 += carry4;
	s4 -= carry4 * ((uint64_t) 1L << 21);

	carry5 = s5 >> 21;
	s6 += carry5;
	s5 -= carry5 * ((uint64_t) 1L << 21);

	carry6 = s6 >> 21;
	s7 += carry6;
	s6 -= carry6 * ((uint64_t) 1L << 21);

	carry7 = s7 >> 21;
	s8 += carry7;
	s7 -= carry7 * ((uint64_t) 1L << 21);

	carry8 = s8 >> 21;
	s9 += carry8;
	s8 -= carry8 * ((uint64_t) 1L << 21);

	carry9 = s9 >> 21;
	s10 += carry9;
	s9 -= carry9 * ((uint64_t) 1L << 21);

	carry10 = s10 >> 21;
	s11 += carry10;
	s10 -= carry10 * ((uint64_t) 1L << 21);

	s[0]  = s0 >> 0;
	s[1]  = s0 >> 8;
	s[2]  = (s0 >> 16) | (s1 * ((uint64_t) 1 << 5));
	s[3]  = s1 >> 3;
	s[4]  = s1 >> 11;
	s[5]  = (s1 >> 19) | (s2 * ((uint64_t) 1 << 2));
	s[6]  = s2 >> 6;
	s[7]  = (s2 >> 14) | (s3 * ((uint64_t) 1 << 7));
	s[8]  = s3 >> 1;
	s[9]  = s3 >> 9;
	s[10] = (s3 >> 17) | (s4 * ((uint64_t) 1 << 4));
	s[11] = s4 >> 4;
	s[12] = s4 >> 12;
	s[13] = (s4 >> 20) | (s5 * ((uint64_t) 1 << 1));
	s[14] = s5 >> 7;
	s[15] = (s5 >> 15) | (s6 * ((uint64_t) 1 << 6));
	s[16] = s6 >> 2;
	s[17] = s6 >> 10;
	s[18] = (s6 >> 18) | (s7 * ((uint64_t) 1 << 3));
	s[19] = s7 >> 5;
	s[20] = s7 >> 13;
	s[21] = s8 >> 0;
	s[22] = s8 >> 8;
	s[23] = (s8 >> 16) | (s9 * ((uint64_t) 1 << 5));
	s[24] = s9 >> 3;
	s[25] = s9 >> 11;
	s[26] = (s9 >> 19) | (s10 * ((uint64_t) 1 << 2));
	s[27] = s10 >> 6;
	s[28] = (s10 >> 14) | (s11 * ((uint64_t) 1 << 7));
	s[29] = s11 >> 1;
	s[30] = s11 >> 9;
	s[31] = s11 >> 17;
}