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* remove special nan handling from x86 sqrt asmRich Felker2012-03-151-3/+0
| | | | | | | a double precision nan, when converted to extended (80-bit) precision, will never end in 0x400, since the corresponding bits do not exist in the original double precision value. thus there's no need to waste time and code size on this check.
* simplify nan check in sqrt (x86 asm); result of sqrt is never negativeRich Felker2012-03-151-4/+3
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* avoid changing NaNs in sqrt (x86 asm) to satisfy c99 f.9 recommendationRich Felker2012-03-151-0/+4
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* correctly rounded sqrt() asm for x86 (i387)Rich Felker2012-03-151-0/+16
| | | | | | | | | | | | | | | | the fsqrt opcode is correctly rounded, but only in the fpu's selected precision mode, which is 80-bit extended precision. to get a correctly rounded double precision output, we check for the only corner cases where two-step rounding could give different results than one-step (extended-precision mantissa ending in 0x400) and adjust the mantissa slightly in the opposite direction of the rounding which the fpu already did (reported in the c1 flag of the fpu status word). this should have near-zero cost in the non-corner cases and at worst very low cost. note that in order for sqrt() to get used when compiling with gcc, the broken, non-conformant builtin sqrt must be disabled.
* first commit of the new libm!Rich Felker2012-03-131-0/+5
thanks to the hard work of Szabolcs Nagy (nsz), identifying the best (from correctness and license standpoint) implementations from freebsd and openbsd and cleaning them up! musl should now fully support c99 float and long double math functions, and has near-complete complex math support. tgmath should also work (fully on gcc-compatible compilers, and mostly on any c99 compiler). based largely on commit 0376d44a890fea261506f1fc63833e7a686dca19 from nsz's libm git repo, with some additions (dummy versions of a few missing long double complex functions, etc.) by me. various cleanups still need to be made, including re-adding (if they're correct) some asm functions that were dropped.