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* fix incorrect use of fabs on long double operand in floatscan.cRich Felker2019-10-181-4/+1
| | | | | | | | | | | | | | based on patch by Dan Gohman, who caught this via compiler warnings. analysis by Szabolcs Nagy determined that it's a bug, whereby errno can be set incorrectly for values where the coercion from long double to double causes rounding. it seems likely that floating point status flags may be set incorrectly as a result too. at the same time, clean up use of preprocessor concatenation involving LDBL_MANT_DIG, which spuriously depends on it being a single unadorned decimal integer literal, and instead use the equivalent formulation 2/LDBL_EPSILON. an equivalent change on the printf side was made in commit bff6095d915f3e41206e47ea2a570ecb937ef926.
* fix minor problem in previous strtod non-nearest rounding bug fixRich Felker2016-10-201-1/+1
| | | | | | | | | | | | commit 6ffdc4579ffb34f4aab69ab4c081badabc7c0a9a set lnz in the code path for non-zero digits after a huge string of zeros, but the assignment of dc to lnz truncates if the value of dc does not fit in int; this is possible for some pathologically long inputs, either via strings on 64-bit systems or via scanf-family functions. instead, simply set lnz to match the point at which we add the artificial trailing 1 bit to simulate nonzero digits after a huge run of zeros.
* fix strtod int optimization in non-nearest rounding modeSzabolcs Nagy2016-10-201-1/+4
| | | | | | | | | | | | | | the mid-sized integer optimization relies on lnz set up properly to mark the last non-zero decimal digit, but this was not done if the non-zero digit lied outside the KMAX digits of the base 10^9 number representation. so if the fractional part was a very long list of zeros (>2048*9 on x86) followed by non-zero digits then the integer optimization could kick in discarding the tiny non-zero fraction which can mean wrong result on non-nearest rounding mode. strtof, strtod and strtold were all affected.
* fix strtod and strtof rounding with many trailing zerosSzabolcs Nagy2016-10-201-0/+3
| | | | | | | | | | | | | | in certain cases excessive trailing zeros could cause incorrect rounding from long double to double or float in decfloat. e.g. in strtof("9444733528689243848704.000000", 0) the argument is 0x1.000001p+73, exactly halfway between two representible floats, this incorrectly got rounded to 0x1.000002p+73 instead of 0x1p+73, but with less trailing 0 the rounding was fine. the fix makes sure that the z index always points one past the last non-zero digit in the base 10^9 representation, this way trailing zeros don't affect the rounding logic.
* add IEEE binary128 long double support to floatscanSzabolcs Nagy2015-02-091-1/+9
| | | | | | | | | | | | | | | | | just defining the necessary constants: LD_B1B_MAX is 2^113 - 1 in base 10^9 KMAX is 2048 so the x array can hold up to 18432 decimal digits (the worst case is converting 2^-16495 = 5^16495 * 10^-16495 to binary, it requires the processing of int(log10(5)*16495)+1 = 11530 decimal digits after discarding the leading zeros, the conversion requires some headroom in x, but KMAX is more than enough for that) However this code is not optimal on archs with IEEE binary128 long double because the arithmetics is software emulated (on all such platforms as far as i know) which means big and slow strtod.
* clean up stdio_impl.hRich Felker2012-11-081-0/+1
| | | | | | | | | | | this header evolved to facilitate the extremely lazy practice of omitting explicit includes of the necessary headers in individual stdio source files; not only was this sloppy, but it also increased build time. now, stdio_impl.h is only including the headers it needs for its own use; any further headers needed by source files are included directly where needed.
* accept "nan(n-char-sequence)" in strtod/scanf functionsRich Felker2012-10-211-1/+19
| | | | | this will prevent gnulib from wrapping our strtod to handle this useless feature.
* fix float parsing logic for long decimal expansionsRich Felker2012-08-171-1/+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.
* fix scanning of "-0x" pseudo-hex float (must give negative zero)Rich Felker2012-06-081-1/+1
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* fix off-by-one error that caused uninitialized memory read in floatscanRich Felker2012-04-301-1/+1
| | | | | | this caused misreading of certain floating point values that are exact multiples of large powers of ten, unpredictable depending on prior stack contents.
* remove redundant (unmaintained) check in floatscanRich Felker2012-04-221-3/+3
| | | | also be extra careful to avoid wrapping the circular buffer early
* make floatscan correctly set errno for overflow/underflowRich Felker2012-04-211-4/+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.
* skip leading zeros even after decimal point in floatscanRich Felker2012-04-211-4/+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.
* fix overread (consuming an extra byte) scanning NANRich Felker2012-04-211-1/+1
| | | | bug detected by glib test suite
* fix really bad breakage in strtol, etc.: failure to accept leading spacesRich Felker2012-04-191-2/+3
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* fix typo in exponent reading code or floatsRich Felker2012-04-181-1/+1
| | | | | this was basically harmless, but could have resulted in misreading inputs with more than a few gigabytes worth of digits..
* fix failure to read infinity in scanfRich Felker2012-04-171-3/+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...
* floatscan: fix incorrect count of leading nonzero digitsRich Felker2012-04-161-1/+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.
* remove magic numbers from floatscanRich Felker2012-04-121-5/+5
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* optimize more integer cases in floatscan; comment the whole procedureRich Felker2012-04-121-8/+27
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* revert invalid optimization in floatscanRich Felker2012-04-111-2/+2
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* fix stupid typo in floatscan that caused excess rounding of some valuesRich Felker2012-04-111-1/+1
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* optimize floatscan downscaler to skip results that won't be neededRich Felker2012-04-111-2/+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.
* simplify/debloat radix point alignment code in floatscanRich Felker2012-04-111-9/+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.
* optimize floatscan: avoid excessive upscalingRich Felker2012-04-111-27/+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...
* fix bug parsing lone zero followed by junk, and hex float over-readingRich Felker2012-04-111-6/+5
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* fix float scanning of certain values ending in zerosRich Felker2012-04-101-1/+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.
* fix potential overflow in exponent readingRich Felker2012-04-101-1/+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).
* set errno properly when parsing floating pointRich Felker2012-04-101-4/+21
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* add "scan helper getc" and rework strtod, etc. to use itRich Felker2012-04-101-72/+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.
* new floating point parser/converterRich Felker2012-04-101-0/+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.