Repository: JuliaLang/julia
File: base/gmp.jl (Julia)

Code before:
    c = MPZ.scan0(x, 0)
    c == -1 && throw(DomainError(x, "`x` must not be equal to -1"))
    c
end

function count_ones(x::BigInt)
    c = MPZ.popcount(x)
    c == -1 && throw(DomainError(x, "`x` cannot be negative"))
    c
end

# generic definition is not used to provide a better error message
function count_zeros(x::BigInt)
    c = MPZ.popcount(~x)
    c == -1 && throw(DomainError(x, "`x` must be negative"))
    c
end

"""
    count_ones_abs(x::BigInt)

Number of ones in the binary representation of abs(x).
"""
count_ones_abs(x::BigInt) = iszero(x) ? 0 : MPZ.mpn_popcount(x)

"Assumes `x != 0`. Computes top_set_bit(abs(x))."
function _top_set_bit(x::BigInt)
    abs(x.size) * BITS_PER_LIMB - GC.@preserve x leading_zeros(unsafe_load(x.d, abs(x.size)))
end
function top_set_bit(x::BigInt)
    isnegative(x) && throw(DomainError(x, "top_set_bit only supports negative arguments when they have type BitSigned."))
    iszero(x) && return 0
    _top_set_bit(x)
end

divrem(x::BigInt, y::BigInt,  ::typeof(RoundToZero) = RoundToZero) = MPZ.tdiv_qr(x, y)
divrem(x::BigInt, y::Integer, ::typeof(RoundToZero) = RoundToZero) = MPZ.tdiv_qr(x, BigInt(y))

cmp(x::BigInt, y::BigInt) = sign(MPZ.cmp(x, y))
cmp(x::BigInt, y::ClongMax) = sign(MPZ.cmp_si(x, y))
cmp(x::BigInt, y::CulongMax) = sign(MPZ.cmp_ui(x, y))
cmp(x::BigInt, y::Integer) = cmp(x, big(y))
cmp(x::Integer, y::BigInt) = -cmp(y, x)

cmp(x::BigInt, y::CdoubleMax) = isnan(y) ? -1 : sign(MPZ.cmp_d(x, y))
cmp(x::CdoubleMax, y::BigInt) = -cmp(y, x)

isqrt(x::BigInt) = MPZ.sqrt(x)

^(x::BigInt, y::Culong) = MPZ.pow_ui(x, y)


Review comment (suggestion):
```suggestion
# Assumes `x != 0`. Computes top_set_bit(abs(x)).
```

I know this is a common comment style in some packages but afaik it's not common in Base

Code after:
    c = MPZ.scan0(x, 0)
    c == -1 && throw(DomainError(x, "`x` must not be equal to -1"))
    c
end

function count_ones(x::BigInt)
    c = MPZ.popcount(x)
    c == -1 && throw(DomainError(x, "`x` cannot be negative"))
    c
end

# generic definition is not used to provide a better error message
function count_zeros(x::BigInt)
    c = MPZ.popcount(~x)
    c == -1 && throw(DomainError(x, "`x` must be negative"))
    c
end

"""
    count_ones_abs(x::BigInt)

Number of ones in the binary representation of abs(x).
"""
count_ones_abs(x::BigInt) = iszero(x) ? 0 : MPZ.mpn_popcount(x)

function top_set_bit(x::BigInt)
    isnegative(x) && throw(DomainError(x, "top_set_bit only supports negative arguments when they have type BitSigned."))
    iszero(x) && return 0
    x.size * sizeof(Limb) << 3 - leading_zeros(GC.@preserve x unsafe_load(x.d, x.size))
end

divrem(x::BigInt, y::BigInt,  ::typeof(RoundToZero) = RoundToZero) = MPZ.tdiv_qr(x, y)
divrem(x::BigInt, y::Integer, ::typeof(RoundToZero) = RoundToZero) = MPZ.tdiv_qr(x, BigInt(y))

cmp(x::BigInt, y::BigInt) = sign(MPZ.cmp(x, y))
cmp(x::BigInt, y::ClongMax) = sign(MPZ.cmp_si(x, y))
cmp(x::BigInt, y::CulongMax) = sign(MPZ.cmp_ui(x, y))
cmp(x::BigInt, y::Integer) = cmp(x, big(y))
cmp(x::Integer, y::BigInt) = -cmp(y, x)

cmp(x::BigInt, y::CdoubleMax) = isnan(y) ? -1 : sign(MPZ.cmp_d(x, y))
cmp(x::CdoubleMax, y::BigInt) = -cmp(y, x)

isqrt(x::BigInt) = MPZ.sqrt(x)

^(x::BigInt, y::Culong) = MPZ.pow_ui(x, y)

function bigint_pow(x::BigInt, y::Integer)
    x == 1 && return x
    x == -1 && return isodd(y) ? x : -x
    if y<0; throw(DomainError(y, "`y` cannot be negative.")); end