#include <stdint.h>

# if defined(__GNUC__) && (__GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 1))
  /* even with gcc, the typedef won't work for 32-bit platforms */
typedef __uint128_t uint128_t;  /* nonstandard; implemented by gcc on 64-bit
                                 * platforms */
typedef __int128_t int128_t;
# else
#  error "Need GCC 3.1 or later to define type uint128_t"
# endif

typedef uint8_t u8;
typedef uint32_t u32;
typedef uint64_t u64;
typedef int64_t s64;

/*
 * The representation of field elements.
 * ------------------------------------
 *
 * We represent field elements with either four 128-bit values, eight 128-bit
 * values, or four 64-bit values. The field element represented is:
 *   v[0]*2^0 + v[1]*2^64 + v[2]*2^128 + v[3]*2^192  (mod p)
 * or:
 *   v[0]*2^0 + v[1]*2^64 + v[2]*2^128 + ... + v[8]*2^512  (mod p)
 *
 * 128-bit values are called 'limbs'. Since the limbs are spaced only 64 bits
 * apart, but are 128-bits wide, the most significant bits of each limb overlap
 * with the least significant bits of the next.
 *
 * A field element with four limbs is an 'felem'. One with eight limbs is a
 * 'longfelem'
 *
 * A field element with four, 64-bit values is called a 'smallfelem'. Small
 * values are used as intermediate values before multiplication.
 */

# define NLIMBS 4

typedef uint128_t limb;
typedef limb felem[NLIMBS];
typedef limb longfelem[NLIMBS * 2];
typedef u64 smallfelem[NLIMBS];

/*
 * The underlying field. P256 operates over GF(2^256-2^224+2^192+2^96-1). We
 * can serialise an element of this field into 32 bytes. We call this an
 * felem_bytearray.
 */

typedef u8 felem_bytearray[32];
void point_add(felem x3, felem y3, felem z3,
                      const felem x1, const felem y1, const felem z1,
                      const int mixed, const smallfelem x2,
                      const smallfelem y2, const smallfelem z2);