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scaling.go
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scaling.go
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package ring
// DivFloorByLastModulusNTTLvl divides (floored) the polynomial by its last modulus. The input must be in the NTT domain.
// Output poly level must be equal or one less than input level.
func (r *Ring) DivFloorByLastModulusNTTLvl(level int, p0, buff, p1 *Poly) {
r.InvNTTSingleLazy(level, p0.Coeffs[level], buff.Coeffs[0])
for i := 0; i < level; i++ {
r.NTTSingleLazy(i, buff.Coeffs[0], buff.Coeffs[1])
// (-x[i] + x[-1]) * -InvQ
SubVecAndMulScalarMontgomeryTwoQiVec(buff.Coeffs[1], p0.Coeffs[i], p1.Coeffs[i], r.RescaleParams[level-1][i], r.Modulus[i], r.MredParams[i])
}
}
// DivFloorByLastModulusLvl divides (floored) the polynomial by its last modulus.
// Output poly level must be equal or one less than input level.
func (r *Ring) DivFloorByLastModulusLvl(level int, p0, p1 *Poly) {
for i := 0; i < level; i++ {
SubVecAndMulScalarMontgomeryTwoQiVec(p0.Coeffs[level], p0.Coeffs[i], p1.Coeffs[i], r.RescaleParams[level-1][i], r.Modulus[i], r.MredParams[i])
}
}
// DivFloorByLastModulusManyNTTLvl divides (floored) sequentially nbRescales times the polynomial by its last modulus. Input must be in the NTT domain.
// Output poly level must be equal or nbRescales less than input level.
func (r *Ring) DivFloorByLastModulusManyNTTLvl(level, nbRescales int, p0, buff, p1 *Poly) {
if nbRescales == 0 {
if p0 != p1 {
copy(p1.Buff, p0.Buff)
}
} else {
r.InvNTTLvl(level, p0, buff)
for i := 0; i < nbRescales; i++ {
r.DivFloorByLastModulusLvl(level-i, buff, buff)
}
r.NTTLvl(level-nbRescales, buff, p1)
}
}
// DivFloorByLastModulusManyLvl divides (floored) sequentially nbRescales times the polynomial by its last modulus.
// Output poly level must be equal or nbRescales less than input level.
func (r *Ring) DivFloorByLastModulusManyLvl(level, nbRescales int, p0, buff, p1 *Poly) {
if nbRescales == 0 {
if p0 != p1 {
copy(p1.Buff, p0.Buff)
}
} else {
if nbRescales > 1 {
r.DivFloorByLastModulusLvl(level, p0, buff)
for i := 1; i < nbRescales; i++ {
if i == nbRescales-1 {
r.DivFloorByLastModulusLvl(level-i, buff, p1)
} else {
r.DivFloorByLastModulusLvl(level-i, buff, buff)
}
}
} else {
r.DivFloorByLastModulusLvl(level, p0, p1)
}
}
}
// DivRoundByLastModulusNTTLvl divides (rounded) the polynomial by its last modulus. The input must be in the NTT domain.
// Output poly level must be equal or one less than input level.
func (r *Ring) DivRoundByLastModulusNTTLvl(level int, p0, buff, p1 *Poly) {
r.InvNTTSingleLazy(level, p0.Coeffs[level], buff.Coeffs[level])
// Center by (p-1)/2
pj := r.Modulus[level]
pHalf := (pj - 1) >> 1
AddScalarVec(buff.Coeffs[level], buff.Coeffs[level], pHalf, pj)
for i := 0; i < level; i++ {
qi := r.Modulus[i]
AddScalarNoModVec(buff.Coeffs[level], buff.Coeffs[i], qi-BRedAdd(pHalf, qi, r.BredParams[i]))
r.NTTSingleLazy(i, buff.Coeffs[i], buff.Coeffs[i])
SubVecAndMulScalarMontgomeryTwoQiVec(buff.Coeffs[i], p0.Coeffs[i], p1.Coeffs[i], r.RescaleParams[level-1][i], qi, r.MredParams[i])
}
}
// DivRoundByLastModulusLvl divides (rounded) the polynomial by its last modulus. The input must be in the NTT domain.
// Output poly level must be equal or one less than input level.
func (r *Ring) DivRoundByLastModulusLvl(level int, p0, p1 *Poly) {
// Center by (p-1)/2
pj := r.Modulus[level]
pHalf := (pj - 1) >> 1
AddScalarVec(p0.Coeffs[level], p0.Coeffs[level], pHalf, pj)
for i := 0; i < level; i++ {
qi := r.Modulus[i]
AddScalarNoModAndNegTwoQiNoModVec(p0.Coeffs[i], p0.Coeffs[i], qi-BRedAdd(pHalf, qi, r.BredParams[i]), qi)
AddVecNoModAndMulScalarMontgomeryVec(p0.Coeffs[level], p0.Coeffs[i], p1.Coeffs[i], r.RescaleParams[level-1][i], qi, r.MredParams[i])
}
}
// DivRoundByLastModulusManyNTTLvl divides (rounded) sequentially nbRescales times the polynomial by its last modulus. The input must be in the NTT domain.
// Output poly level must be equal or nbRescales less than input level.
func (r *Ring) DivRoundByLastModulusManyNTTLvl(level, nbRescales int, p0, buff, p1 *Poly) {
if nbRescales == 0 {
if p0 != p1 {
copy(p1.Buff, p0.Buff)
}
} else {
if nbRescales > 1 {
r.InvNTTLvl(level, p0, buff)
for i := 0; i < nbRescales; i++ {
r.DivRoundByLastModulusLvl(level-i, buff, buff)
}
r.NTTLvl(level-nbRescales, buff, p1)
} else {
r.DivRoundByLastModulusNTTLvl(level, p0, buff, p1)
}
}
}
// DivRoundByLastModulusManyLvl divides (rounded) sequentially nbRescales times the polynomial by its last modulus.
// Output poly level must be equal or nbRescales less than input level.
func (r *Ring) DivRoundByLastModulusManyLvl(level, nbRescales int, p0, buff, p1 *Poly) {
if nbRescales == 0 {
if p0 != p1 {
copy(p1.Buff, p0.Buff)
}
} else {
if nbRescales > 1 {
r.DivRoundByLastModulusLvl(level, p0, buff)
for i := 1; i < nbRescales; i++ {
if i == nbRescales-1 {
r.DivRoundByLastModulusLvl(level-i, buff, p1)
} else {
r.DivRoundByLastModulusLvl(level-i, buff, buff)
}
}
} else {
r.DivRoundByLastModulusLvl(level, p0, p1)
}
}
}