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Round without overflow (Fix #59) #64

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merged 1 commit into from
Mar 27, 2018
Merged

Round without overflow (Fix #59) #64

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31 changes: 19 additions & 12 deletions src/DecFP.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -150,15 +150,20 @@ for w in (32,64,128)

$BID(x::AbstractString) = parse($BID, x)

function tostring(x::$BID)
# fills global _buffer
ccall(($(bidsym(w,"to_string")), libbid), Cvoid, (Ptr{UInt8}, $BID), _buffer, x)
end

function Base.show(io::IO, x::$BID)
isnan(x) && (write(io, "NaN"); return)
isinf(x) && (write(io, signbit(x) ? "-Inf" : "Inf"); return)
x == 0 && (write(io, signbit(x) ? "-0.0" : "0.0"); return)
ccall(($(bidsym(w,"to_string")), libbid), Cvoid, (Ptr{UInt8}, $BID), _buffer, x)
tostring(x)
if _buffer[1] == UInt8('-')
write(io, '-')
end
normalized_exponent = nox(ccall(($(bidsym(w,"ilogb")), libbid), Cint, ($BID,), x))
normalized_exponent = exponent10(x)
lastdigitindex = Compat.findfirst(equalto(UInt8('E')), _buffer) - 1
lastnonzeroindex = Compat.findlast(!equalto(UInt8('0')), view(_buffer, 1:lastdigitindex))
if -5 < normalized_exponent < 6
Expand Down Expand Up @@ -210,13 +215,12 @@ for w in (32,64,128)
if n > length(DIGITS) - 1
n = length(DIGITS) - 1
end
# rounded = round(x * exp10($BID(n)), RoundNearestTiesAway)
rounded = @xchk(ccall(($(bidsym(w,"round_integral_nearest_away")), libbid), $BID, ($BID,), x * exp10($BID(n))), InexactError, :round, $BID, x, mask=INVALID | OVERFLOW)
rounded = round(ldexp10(x, n), RoundNearestTiesAway)
if rounded == 0
DIGITS[1] = UInt8('0')
return Int32(1), Int32(1), signbit(x)
end
ccall(($(bidsym(w,"to_string")), libbid), Cvoid, (Ptr{UInt8}, $BID), _buffer, rounded)
tostring(rounded)
trailing_zeros = 0
i = 2
while _buffer[i] != UInt8('E')
Expand Down Expand Up @@ -258,16 +262,19 @@ for w in (32,64,128)
end
return Int32(1), Int32(1), signbit(x)
end
normalized_exponent = nox(ccall(($(bidsym(w,"ilogb")), libbid), Cint, ($BID,), x))
# rounded = round(x * exp10($BID(n - 1 - normalized_exponent)), RoundNearestTiesAway)
rounded = @xchk(ccall(($(bidsym(w,"round_integral_nearest_away")), libbid), $BID, ($BID,), x * exp10($BID(n - 1 - normalized_exponent))), InexactError, :round, $BID, x, mask=INVALID | OVERFLOW)
rounded_exponent = nox(ccall(($(bidsym(w,"ilogb")), libbid), Cint, ($BID,), rounded))
ccall(($(bidsym(w,"to_string")), libbid), Cvoid, (Ptr{UInt8}, $BID), _buffer, rounded)
normalized_exponent = exponent10(x)
rounded = round(ldexp10(x, n - 1 - normalized_exponent), RoundNearestTiesAway)
rounded_exponent = exponent10(rounded)
tostring(rounded)
i = 2
while _buffer[i] != UInt8('E')
DIGITS[i - 1] = _buffer[i]
i += 1
end
while i <= n + 1
DIGITS[i - 1] = UInt8('0')
i += 1
end
pt = normalized_exponent + rounded_exponent - n + 2
neg = signbit(x)
return Int32(n), Int32(pt), neg
Expand All @@ -287,8 +294,8 @@ for w in (32,64,128)
Base.eps(x::$BID) = ifelse(isfinite(x), @xchk(nextfloat(x) - x, OverflowError, "$($BID) value overflow", mask=OVERFLOW), $(_parse(T, "NaN")))

# the meaning of the exponent is different than for binary FP: it is 10^n, not 2^n:
# Base.exponent(x::$BID) = nox(ccall(($(bidsym(w,"ilogb")), libbid), Cint, ($BID,), x))
# Base.ldexp(x::$BID, n::Integer) = nox(ccall(($(bidsym(w,"ldexp")), libbid), $BID, ($BID,Cint), x, n))
exponent10(x::$BID) = nox(ccall(($(bidsym(w,"ilogb")), libbid), Cint, ($BID,), x))
ldexp10(x::$BID, n::Integer) = nox(ccall(($(bidsym(w,"ldexp")), libbid), $BID, ($BID,Cint), x, n))
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Should these be exported?

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Maybe in a separate PR.

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OK. I'll export these in a separate PR.

end

for (f,c) in ((:isnan,"isNaN"), (:isinf,"isInf"), (:isfinite,"isFinite"), (:issubnormal,"isSubnormal"))
Expand Down
4 changes: 2 additions & 2 deletions test/runtests.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -195,8 +195,8 @@ for T in (Dec32, Dec64, Dec128)
@test_throws DomainError sqrt(yd)
@test_throws DomainError acosh(zd)

# @test ldexp(parse(T, "1"), 3) == 1000
# @test exponent(parse(T, "1000")) == 3
@test DecFP.ldexp10(parse(T, "1"), 3) == 1000
@test DecFP.exponent10(parse(T, "1000")) == 3
@test sqrt(complex(yd)) ≈ sqrt(complex(y))

@test typeof(xd * pi) == T
Expand Down