Function cMov [src]

Conditonally replace a field element with a if c is positive

Prototype

pub fn cMov(fe: *Fe, a: Fe, c: u64) void

Parameters

fe: *Fea: Fec: u64

Source

  pub fn cMov(fe: *Fe, a: Fe, c: u64) void {
    const mask: u64 = 0 -% c;
    var x = fe.*;
    comptime var i = 0;
    inline while (i < 5) : (i += 1) {
        x.limbs[i] ^= a.limbs[i];
    }
    i = 0;
    inline while (i < 5) : (i += 1) {
        x.limbs[i] &= mask;
    }
    i = 0;
    inline while (i < 5) : (i += 1) {
        fe.limbs[i] ^= x.limbs[i];
    }
}  