fp_x2.ptxh

// bls12_381: Arithmetic for BLS12-381
// Copyright 2022-2023 Dag Arne Osvik
// Copyright 2022-2023 Luan Cardoso dos Santos

#ifndef FP_X2

/**
 * @brief PTX macro for multiplication by 2. Z ← 2*X
 * Z and X may be the same. Modifies T6.
 * 
 * For inclusion directly into ptx code by the C preprocessor.
 */
#define FP_X2(Z, X, T) newline\
    /* z = x + x */ newline\
\
    add.u64.cc  Z##0, X##0, X##0; newline\
    addc.u64.cc Z##1, X##1, X##1; newline\
    addc.u64.cc Z##2, X##2, X##2; newline\
    addc.u64.cc Z##3, X##3, X##3; newline\
    addc.u64.cc Z##4, X##4, X##4; newline\
    addc.u64.cc Z##5, X##5, X##5; newline\
    addc.u32    T##6,    0,    0; newline\
\
    /* gt = (z>>320) > (m>>320) */ newline\
    /* nz = (z>>384) > 0 */ newline\
\
    setp.gt.u64 gt, Z##5, 0x1a0111ea397fe69aU; newline\
    setp.ne.u32 nz, T##6, 0; newline\
\
    /* If gt then subtract m */ newline\
\
    @gt sub.u64.cc  Z##0, Z##0, 0xb9feffffffffaaabU; newline\
    @gt subc.u64.cc Z##1, Z##1, 0x1eabfffeb153ffffU; newline\
    @gt subc.u64.cc Z##2, Z##2, 0x6730d2a0f6b0f624U; newline\
    @gt subc.u64.cc Z##3, Z##3, 0x64774b84f38512bfU; newline\
    @gt subc.u64.cc Z##4, Z##4, 0x4b1ba7b6434bacd7U; newline\
    @gt subc.u64.cc Z##5, Z##5, 0x1a0111ea397fe69aU; newline\
\
    /* If nz then subtract mmu0 (= 9m) */ newline\
\
    @nz sub.u64.cc  Z##0, Z##0, 0x89F6FFFFFFFD0003U; newline\
    @nz subc.u64.cc Z##1, Z##1, 0x140BFFF43BF3FFFDU; newline\
    @nz subc.u64.cc Z##2, Z##2, 0xA0B767A8AC38A745U; newline\
    @nz subc.u64.cc Z##3, Z##3, 0x8831A7AC8FADA8BAU; newline\
    @nz subc.u64.cc Z##4, Z##4, 0xA3F8E5685DA91392U; newline\
    @nz subc.u64.cc Z##5, Z##5, 0xEA09A13C057F1B6CU

#endif