if the bit is 0, -1¹ = -1 if it is 1. bitIdx := i + p.τ - 256 bit := (s[bitIdx/8] >> (bitIdx % 8)) & 1 if bit == 0 { c[j[0]] = one } else { c[j[0]] = minusOne } } return c } // coeffFromHalfByte implements CoeffFromHalfByte from FIPS 204. // // It maps a value in [0, 15] to a coefficient in [−η, η] func coeffFromHalfByte(b byte, p parameters) (fieldElement, bool) { if b > 15 { panic("internal error: half-byte out of range") } switch p.η { case 2: // Return z = 2 − (b mod 5), which maps from // //...