text: #include "sc.h"
  #include "src/crypto/crypto_ops_builder/crypto_int64.h"
  #include "src/crypto/crypto_ops_builder/crypto_uint32.h"
  #include "src/crypto/crypto_ops_builder/crypto_uint64.h"
  
  static crypto_uint64 load_3(const unsigned char *in)
  {
    crypto_uint64 result;
    result = (crypto_uint64) in[0];
    result |= ((crypto_uint64) in[1]) << 8;
    result |= ((crypto_uint64) in[2]) << 16;
    return result;
  }
  
  static crypto_uint64 load_4(const unsigned char *in)
  {
    crypto_uint64 result;
    result = (crypto_uint64) in[0];
    result |= ((crypto_uint64) in[1]) << 8;
    result |= ((crypto_uint64) in[2]) << 16;
    result |= ((crypto_uint64) in[3]) << 24;
    return result;
  }
  
  /*
  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(unsigned char *s)
  {
    crypto_int64 s0 = 2097151 & load_3(s);
    crypto_int64 s1 = 2097151 & (load_4(s + 2) >> 5);
    crypto_int64 s2 = 2097151 & (load_3(s + 5) >> 2);
    crypto_int64 s3 = 2097151 & (load_4(s + 7) >> 7);
    crypto_int64 s4 = 2097151 & (load_4(s + 10) >> 4);
    crypto_int64 s5 = 2097151 & (load_3(s + 13) >> 1);
    crypto_int64 s6 = 2097151 & (load_4(s + 15) >> 6);
    crypto_int64 s7 = 2097151 & (load_3(s + 18) >> 3);
    crypto_int64 s8 = 2097151 & load_3(s + 21);
    crypto_int64 s9 = 2097151 & (load_4(s + 23) >> 5);
    crypto_int64 s10 = 2097151 & (load_3(s + 26) >> 2);
    crypto_int64 s11 = 2097151 & (load_4(s + 28) >> 7);
    crypto_int64 s12 = 2097151 & (load_4(s + 31) >> 4);
    crypto_int64 s13 = 2097151 & (load_3(s + 34) >> 1);
    crypto_int64 s14 = 2097151 & (load_4(s + 36) >> 6);
    crypto_int64 s15 = 2097151 & (load_3(s + 39) >> 3);
    crypto_int64 s16 = 2097151 & load_3(s + 42);
    crypto_int64 s17 = 2097151 & (load_4(s + 44) >> 5);
    crypto_int64 s18 = 2097151 & (load_3(s + 47) >> 2);
    crypto_int64 s19 = 2097151 & (load_4(s + 49) >> 7);
    crypto_int64 s20 = 2097151 & (load_4(s + 52) >> 4);
    crypto_int64 s21 = 2097151 & (load_3(s + 55) >> 1);
    crypto_int64 s22 = 2097151 & (load_4(s + 57) >> 6);
    crypto_int64 s23 = (load_4(s + 60) >> 3);
    crypto_int64 carry0;
    crypto_int64 carry1;
    crypto_int64 carry2;
    crypto_int64 carry3;
    crypto_int64 carry4;
    crypto_int64 carry5;
    crypto_int64 carry6;
    crypto_int64 carry7;
    crypto_int64 carry8;
    crypto_int64 carry9;
    crypto_int64 carry10;
    crypto_int64 carry11;
    crypto_int64 carry12;
    crypto_int64 carry13;
    crypto_int64 carry14;
    crypto_int64 carry15;
    crypto_int64 carry16;
  
    s11 += s23 * 666643;
    s12 += s23 * 470296;
    s13 += s23 * 654183;
    s14 -= s23 * 997805;
    s15 += s23 * 136657;
    s16 -= s23 * 683901;
    s23 = 0;
  
    s10 += s22 * 666643;
    s11 += s22 * 470296;
    s12 += s22 * 654183;
    s13 -= s22 * 997805;
    s14 += s22 * 136657;
    s15 -= s22 * 683901;
    s22 = 0;
  
    s9 += s21 * 666643;
    s10 += s21 * 470296;
    s11 += s21 * 654183;
    s12 -= s21 * 997805;
    s13 += s21 * 136657;
    s14 -= s21 * 683901;
    s21 = 0;
  
    s8 += s20 * 666643;
    s9 += s20 * 470296;
    s10 += s20 * 654183;
    s11 -= s20 * 997805;
    s12 += s20 * 136657;
    s13 -= s20 * 683901;
    s20 = 0;
  
    s7 += s19 * 666643;
    s8 += s19 * 470296;
    s9 += s19 * 654183;
    s10 -= s19 * 997805;
    s11 += s19 * 136657;
    s12 -= s19 * 683901;
    s19 = 0;
  
    s6 += s18 * 666643;
    s7 += s18 * 470296;
    s8 += s18 * 654183;
    s9 -= s18 * 997805;
    s10 += s18 * 136657;
    s11 -= s18 * 683901;
    s18 = 0;
  
    carry6 = (s6 + (1<<20)) >> 21; s7 += carry6; s6 -= carry6 << 21;
    carry8 = (s8 + (1<<20)) >> 21; s9 += carry8; s8 -= carry8 << 21;
    carry10 = (s10 + (1<<20)) >> 21; s11 += carry10; s10 -= carry10 << 21;
    carry12 = (s12 + (1<<20)) >> 21; s13 += carry12; s12 -= carry12 << 21;
    carry14 = (s14 + (1<<20)) >> 21; s15 += carry14; s14 -= carry14 << 21;
    carry16 = (s16 + (1<<20)) >> 21; s17 += carry16; s16 -= carry16 << 21;
  
    carry7 = (s7 + (1<<20)) >> 21; s8 += carry7; s7 -= carry7 << 21;
    carry9 = (s9 + (1<<20)) >> 21; s10 += carry9; s9 -= carry9 << 21;
    carry11 = (s11 + (1<<20)) >> 21; s12 += carry11; s11 -= carry11 << 21;
    carry13 = (s13 + (1<<20)) >> 21; s14 += carry13; s13 -= carry13 << 21;
    carry15 = (s15 + (1<<20)) >> 21; s16 += carry15; s15 -= carry15 << 21;
  
    s5 += s17 * 666643;
    s6 += s17 * 470296;
    s7 += s17 * 654183;
    s8 -= s17 * 997805;
    s9 += s17 * 136657;
    s10 -= s17 * 683901;
    s17 = 0;
  
    s4 += s16 * 666643;
    s5 += s16 * 470296;
    s6 += s16 * 654183;
    s7 -= s16 * 997805;
    s8 += s16 * 136657;
    s9 -= s16 * 683901;
    s16 = 0;
  
    s3 += s15 * 666643;
    s4 += s15 * 470296;
    s5 += s15 * 654183;
    s6 -= s15 * 997805;
    s7 += s15 * 136657;
    s8 -= s15 * 683901;
    s15 = 0;
  
    s2 += s14 * 666643;
    s3 += s14 * 470296;
    s4 += s14 * 654183;
    s5 -= s14 * 997805;
    s6 += s14 * 136657;
    s7 -= s14 * 683901;
    s14 = 0;
  
    s1 += s13 * 666643;
    s2 += s13 * 470296;
    s3 += s13 * 654183;
    s4 -= s13 * 997805;
    s5 += s13 * 136657;
    s6 -= s13 * 683901;
    s13 = 0;
  
    s0 += s12 * 666643;
    s1 += s12 * 470296;
    s2 += s12 * 654183;
    s3 -= s12 * 997805;
    s4 += s12 * 136657;
    s5 -= s12 * 683901;
    s12 = 0;
  
    carry0 = (s0 + (1<<20)) >> 21; s1 += carry0; s0 -= carry0 << 21;
    carry2 = (s2 + (1<<20)) >> 21; s3 += carry2; s2 -= carry2 << 21;
    carry4 = (s4 + (1<<20)) >> 21; s5 += carry4; s4 -= carry4 << 21;
    carry6 = (s6 + (1<<20)) >> 21; s7 += carry6; s6 -= carry6 << 21;
    carry8 = (s8 + (1<<20)) >> 21; s9 += carry8; s8 -= carry8 << 21;
    carry10 = (s10 + (1<<20)) >> 21; s11 += carry10; s10 -= carry10 << 21;
  
    carry1 = (s1 + (1<<20)) >> 21; s2 += carry1; s1 -= carry1 << 21;
    carry3 = (s3 + (1<<20)) >> 21; s4 += carry3; s3 -= carry3 << 21;
    carry5 = (s5 + (1<<20)) >> 21; s6 += carry5; s5 -= carry5 << 21;
    carry7 = (s7 + (1<<20)) >> 21; s8 += carry7; s7 -= carry7 << 21;
    carry9 = (s9 + (1<<20)) >> 21; s10 += carry9; s9 -= carry9 << 21;
    carry11 = (s11 + (1<<20)) >> 21; s12 += carry11; s11 -= carry11 << 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 << 21;
    carry1 = s1 >> 21; s2 += carry1; s1 -= carry1 << 21;
    carry2 = s2 >> 21; s3 += carry2; s2 -= carry2 << 21;
    carry3 = s3 >> 21; s4 += carry3; s3 -= carry3 << 21;
    carry4 = s4 >> 21; s5 += carry4; s4 -= carry4 << 21;
    carry5 = s5 >> 21; s6 += carry5; s5 -= carry5 << 21;
    carry6 = s6 >> 21; s7 += carry6; s6 -= carry6 << 21;
    carry7 = s7 >> 21; s8 += carry7; s7 -= carry7 << 21;
    carry8 = s8 >> 21; s9 += carry8; s8 -= carry8 << 21;
    carry9 = s9 >> 21; s10 += carry9; s9 -= carry9 << 21;
    carry10 = s10 >> 21; s11 += carry10; s10 -= carry10 << 21;
    carry11 = s11 >> 21; s12 += carry11; s11 -= carry11 << 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 << 21;
    carry1 = s1 >> 21; s2 += carry1; s1 -= carry1 << 21;
    carry2 = s2 >> 21; s3 += carry2; s2 -= carry2 << 21;
    carry3 = s3 >> 21; s4 += carry3; s3 -= carry3 << 21;
    carry4 = s4 >> 21; s5 += carry4; s4 -= carry4 << 21;
    carry5 = s5 >> 21; s6 += carry5; s5 -= carry5 << 21;
    carry6 = s6 >> 21; s7 += carry6; s6 -= carry6 << 21;
    carry7 = s7 >> 21; s8 += carry7; s7 -= carry7 << 21;
    carry8 = s8 >> 21; s9 += carry8; s8 -= carry8 << 21;
    carry9 = s9 >> 21; s10 += carry9; s9 -= carry9 << 21;
    carry10 = s10 >> 21; s11 += carry10; s10 -= carry10 << 21;
  
    s[0] = s0 >> 0;
    s[1] = s0 >> 8;
    s[2] = (s0 >> 16) | (s1 << 5);
    s[3] = s1 >> 3;
    s[4] = s1 >> 11;
    s[5] = (s1 >> 19) | (s2 << 2);
    s[6] = s2 >> 6;
    s[7] = (s2 >> 14) | (s3 << 7);
    s[8] = s3 >> 1;
    s[9] = s3 >> 9;
    s[10] = (s3 >> 17) | (s4 << 4);
    s[11] = s4 >> 4;
    s[12] = s4 >> 12;
    s[13] = (s4 >> 20) | (s5 << 1);
    s[14] = s5 >> 7;
    s[15] = (s5 >> 15) | (s6 << 6);
    s[16] = s6 >> 2;
    s[17] = s6 >> 10;
    s[18] = (s6 >> 18) | (s7 << 3);
    s[19] = s7 >> 5;
    s[20] = s7 >> 13;
    s[21] = s8 >> 0;
    s[22] = s8 >> 8;
    s[23] = (s8 >> 16) | (s9 << 5);
    s[24] = s9 >> 3;
    s[25] = s9 >> 11;
    s[26] = (s9 >> 19) | (s10 << 2);
    s[27] = s10 >> 6;
    s[28] = (s10 >> 14) | (s11 << 7);
    s[29] = s11 >> 1;
    s[30] = s11 >> 9;
    s[31] = s11 >> 17;
  }
  