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path: root/src/internal/floatscan.c
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2012-08-17fix float parsing logic for long decimal expansionsRich Felker-1/+1
this affects at least the case of very long inputs, but may also affect shorter inputs that become long due to growth while upscaling. basically, the logic for the circular buffer indices of the initial base-10^9 digit and the slot one past the final digit, and for simplicity of the loop logic, assumes an invariant that they're not equal. the upscale loop, which can increase the length of the base-10^9 representation, attempted to preserve this invariant, but was actually only ensuring that the end index did not loop around past the start index, not that the two never become equal. the main (only?) effect of this bug was that subsequent logic treats the excessively long number as having no digits, leading to junk results.
2012-06-08fix scanning of "-0x" pseudo-hex float (must give negative zero)Rich Felker-1/+1
2012-04-30fix off-by-one error that caused uninitialized memory read in floatscanRich Felker-1/+1
this caused misreading of certain floating point values that are exact multiples of large powers of ten, unpredictable depending on prior stack contents.
2012-04-22remove redundant (unmaintained) check in floatscanRich Felker-3/+3
also be extra careful to avoid wrapping the circular buffer early
2012-04-21make floatscan correctly set errno for overflow/underflowRich Felker-4/+16
care is taken that the setting of errno correctly reflects underflow condition. scanning exact denormal values does not result in ERANGE, nor does scanning values (such as the usual string definition of FLT_MIN) which are actually less than the smallest normal number but which round to a normal result. only the decimal case is handled so far; hex float require a separate fix to come later.
2012-04-21skip leading zeros even after decimal point in floatscanRich Felker-4/+9
in principle this should just be an optimization, but it happens to also fix a nasty bug where values like 0.00000000001 were getting caught by the early zero detection path and wrongly scanned as zero.
2012-04-21fix overread (consuming an extra byte) scanning NANRich Felker-1/+1
bug detected by glib test suite
2012-04-19fix really bad breakage in strtol, etc.: failure to accept leading spacesRich Felker-2/+3
2012-04-18fix typo in exponent reading code or floatsRich Felker-1/+1
this was basically harmless, but could have resulted in misreading inputs with more than a few gigabytes worth of digits..
2012-04-17fix failure to read infinity in scanfRich Felker-3/+4
this code worked in strtod, but not in scanf. more evidence that i should design a better interface for discarding multiple tail characters than just calling unget repeatedly...
2012-04-16floatscan: fix incorrect count of leading nonzero digitsRich Felker-1/+1
this off-by-one error was causing values with just one digit past the decimal point to be treated by the integer case. in many cases it would yield the correct result, but if expressions are evaluated in excess precision, double rounding may occur.
2012-04-12remove magic numbers from floatscanRich Felker-5/+5
2012-04-12optimize more integer cases in floatscan; comment the whole procedureRich Felker-8/+27
2012-04-11revert invalid optimization in floatscanRich Felker-2/+2
2012-04-11fix stupid typo in floatscan that caused excess rounding of some valuesRich Felker-1/+1
2012-04-11optimize floatscan downscaler to skip results that won't be neededRich Felker-2/+3
when upscaling, even the very last digit is needed in cases where the input is exact; no digits can be discarded. but when downscaling, any digits less significant than the mantissa bits are destined for the great bitbucket; the only influence they can have is their presence (being nonzero). thus, we simply throw them away early. the result is nearly a 4x performance improvement for processing huge values. the particular threshold LD_B1B_DIG+3 is not chosen sharply; it's simply a "safe" distance past the significant bits. it would be nice to replace it with a sharp bound, but i suspect performance will be comparable (within a few percent) anyway.
2012-04-11simplify/debloat radix point alignment code in floatscanRich Felker-9/+4
now that this is the first operation, it can rely on the circular buffer contents not being wrapped when it begins. we limit the number of digits read slightly in the initial parsing loops too so that this code does not have to consider the case where it might cause the circular buffer to wrap; this is perfectly fine because KMAX is chosen as a power of two for circular-buffer purposes and is much larger than it otherwise needs to be, anyway. these changes should not affect performance at all.
2012-04-11optimize floatscan: avoid excessive upscalingRich Felker-27/+27
upscaling by even one step too much creates 3-29 extra iterations for the next loop. this is still suboptimal since it always goes by 2^29 rather than using a smaller upscale factor when nearing the target, but performance on common, small-magnitude, few-digit values has already more than doubled with this change. more optimizations on the way...
2012-04-11fix bug parsing lone zero followed by junk, and hex float over-readingRich Felker-6/+5
2012-04-10fix float scanning of certain values ending in zerosRich Felker-1/+3
for example, "1000000000" was being read as "1" due to this loop exiting early. it's necessary to actually update z and zero the entries so that the subsequent rounding code does not get confused; before i did that, spurious inexact exceptions were being raised.
2012-04-10fix potential overflow in exponent readingRich Felker-1/+1
note that there's no need for a precise cutoff, because exponents this large will always result in overflow or underflow (it's impossible to read enough digits to compensate for the exponent magnitude; even at a few nanoseconds per digit it would take hundreds of years).
2012-04-10set errno properly when parsing floating pointRich Felker-4/+21
2012-04-10add "scan helper getc" and rework strtod, etc. to use itRich Felker-72/+59
the immediate benefit is a significant debloating of the float parsing code by moving the responsibility for keeping track of the number of characters read to a different module. by linking shgetc with the stdio buffer logic, counting logic is defered to buffer refill time, keeping the calls to shgetc fast and light. in the future, shgetc will also be useful for integrating the new float code with scanf, which needs to not only count the characters consumed, but also limit the number of characters read based on field width specifiers. shgetc may also become a useful tool for simplifying the integer parsing code.
2012-04-10new floating point parser/converterRich Felker-0/+438
this version is intended to be fully conformant to the ISO C, POSIX, and IEEE standards for conversion of decimal/hex floating point strings to float, double, and long double (ld64 or ld80 only at present) values. in particular, all results are intended to be rounded correctly according to the current rounding mode. further, this implementation aims to set the floating point underflow, overflow, and inexact flags to reflect the conversion performed. a moderate amount of testing has been performed (by nsz and myself) prior to integration of the code in musl, but it still may have bugs. so far, only strto(d|ld|f) use the new code. scanf integration will be done as a separate commit, and i will add implementations of the wide character functions later.