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author | Ulrich Drepper <drepper@redhat.com> | 1997-03-27 01:59:53 +0000 |
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committer | Ulrich Drepper <drepper@redhat.com> | 1997-03-27 01:59:53 +0000 |
commit | e7fd8a39abd3a9c9d2139e686b17efb5dc3bf444 (patch) | |
tree | 637853189c42709eb7fa91817173d6097765888a /sysdeps/libm-ieee754/s_log2.c | |
parent | 34b402e5a967b97fc73cc45fbef61bbeb8526f3d (diff) | |
download | glibc-e7fd8a39abd3a9c9d2139e686b17efb5dc3bf444.tar.gz glibc-e7fd8a39abd3a9c9d2139e686b17efb5dc3bf444.tar.xz glibc-e7fd8a39abd3a9c9d2139e686b17efb5dc3bf444.zip |
1997-03-27 02:28 Ulrich Drepper <drepper@cygnus.com> * gmon/gmon.c (monstartup): Mark all messages. (write_call_graph): Rewrite to use larger I/O vector for writev call to reduce syscall overhead. (write_bb_counts): Simplify writev handling. * inet/rexec.c: Make string parameters `const'. * resolv/netdb.h: Add prototypes for rcmd, rexec, ruserok, and rresvport. * math/Makefile: Don't define CFLAGS-* macros to prevent inlining in libm-test. * math/libm-test.c (this_does_nothing): Remove functions. It's notuseful on any platform but ix86. (inverse_func_pair_test): Don't use this_does_nothing. Use memory reference. (identities1_test): Likewise. (identities2_test): Likewise. (identities3_test): Likewise. (basic_test): Likewise. Patch by Andreas Schwab. (BUILD_COMPLEX): New macro. Create complex number from real and imaginary parts. This works around bugs/inefficiencies in current gcc. (cexp_test): Use BUILD_COMPLEX. Add more tests. * nss/nsswitch.c: Fix typo. * posix/glob.h: Add declaration for glob_pattern_p. * posix/glob.c: Rename glob_pattern_p to __glob_pattern_p and make glob_pattern_p a weak alias. This function is used in other packages (e.g. bash). * signal/Makefile (routines): Add sigisempty, sigandset, and sigorset. * signal/signal.h: Add prototypes for sigisempty, sigandset, and sigorset. * signal/sigisempty.c: New file. * signal/sigandset.c: New file. * signal/sigorset.c: New file. * sysdeps/generic/sigset.h: Define __sigisemptyset, __sigandset, and __sigorset. * sysdeps/unix/sysv/linux/sigset.h: Likewise. * stdlib/strtod.c: Handle `n-char-sequence' in NaN parsing. It determines the bits in the mantissa part of the NaN. * stdlib/strtof.c: Define SET_MANTISSA for float type. * wcsmbs/wcstof.c: Define SET_MANTISSA for float type. * stdlib/strtold.c: Define SET_MANTISSA for long double type. * wcsmbs/wcstold.c: Define SET_MANTISSA for long double type. * sysdeps/libm-ieee754/s_cexp.c: Use explicit assignment to complex number components. Some more corrects for special cases. * sysdeps/libm-ieee754/s_cexpf.c: Likewise. * sysdeps/libm-ieee754/s_cexpl.c: Likewise. * sysdeps/sparc/elf/start.S: Remove as per request of Miguel de Icaza. * sysdeps/unix/sysv/linux/netinet/icmp.h: Remove since we have ip_icmp.h. Reported by HJ Lu. 1997-03-25 03:50 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de> * sysdeps/m68k/Makefile (CFLAGS-rtld.c): Add -Wno-unused. * sysdeps/m68k/dl-machine.h (elf_machine_rela): Rewritten as for i386. (elf_machine_lookup_noexec_p, elf_machine_lookup_noplt_p, ELF_MACHINE_RELOC_NOPLT): Define. 1997-03-25 03:48 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de> * grp/grp.h: Include <stddef.h> only once. 1997-03-25 09:38 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de> * sysdeps/unix/sysv/linux/termbits.h (OXTABS): Don't define. * sysdeps/unix/sysv/linux/alpha/termbits.h (OXTABS): Likewise. * termios/sys/ttydefaults.h (TTYDEF_OFLAG): Use either OXTABS or TAB3, if one of them is defined. 1997-03-26 04:53 Ulrich Drepper <drepper@cygnus.com> * posix/glob.c (next_brace_sub): Decrement depth counter when '}' is found. Patch by Dennis Henriksen <opus@flamingo.osrl.dk>. 1997-03-25 16:25 Thorsten Kukuk <kukuk@vt.uni-paderborn.de> * sunrpc/Makefile: Comment gccwarn out. * sunrpc/auth_none.c: Fix prototypes and parameters for compiling with enabled warnings. * sunrpc/auth_unix.c: Likewise. * sunrpc/authuxprot.c: Likewise. * sunrpc/bindrsvprt.c: Likewise. * sunrpc/clnt_gen.c: Likewise. * sunrpc/clnt_perr.c: Likewise. * sunrpc/clnt_raw.c: Likewise. * sunrpc/clnt_simp.c: Likewise. * sunrpc/clnt_tcp.c: Likewise. * sunrpc/clnt_udp.c: Likewise. * sunrpc/get_myaddr.c: Likewise. * sunrpc/getrpcport.c: Likewise. * sunrpc/pm_getmaps.c: Likewise. * sunrpc/pm_getport.c: Likewise. * sunrpc/pmap_clnt.c: Likewise. * sunrpc/pmap_prot.c: Likewise. * sunrpc/pmap_prot2.c: Likewise. * sunrpc/pmap_rmt.c: Likewise. * sunrpc/rpc/auth.h: Likewise. * sunrpc/rpc/clnt.h: Likewise. * sunrpc/rpc/pmap_clnt.h: Likewise. * sunrpc/rpc/svc.h: Likewise. * sunrpc/rpc/svc_auth.h: Likewise. * sunrpc/rpc/types.h: Likewise. * sunrpc/rpc/xdr.h: Likewise. * sunrpc/rpc_clntout.c: Likewise. * sunrpc/rpc_cmsg.c: Likewise. * sunrpc/rpc_dtable.c: Likewise. * sunrpc/rpc_prot.c: Likewise. * sunrpc/svc.c: Likewise. * sunrpc/svc_auth.c: Likewise. * sunrpc/svc_authux.c: Likewise. * sunrpc/svc_raw.c: Likewise. * sunrpc/svc_run.c: Likewise. * sunrpc/svc_simple.c: Likewise. * sunrpc/svc_tcp.c: Likewise. * sunrpc/svc_udp.c: Likewise. * sunrpc/xdr.c: Likewise. * sunrpc/xdr_array.c: Likewise. * sunrpc/xdr_mem.c: Likewise. * sunrpc/xdr_rec.c: Likewise. * sunrpc/xdr_ref.c: Likewise. * sunrpc/xdr_stdio.c: Likewise. 1997-03-25 13:39 Ulrich Drepper <drepper@cygnus.com> * math/libm-test.c (log2_test): Compile this function and call it. (exp2_test): Likewise, but check whether function really exists before testing. * math/Makefile (libm-calls): Add s_log2 and s_exp2. 1997-03-25 04:50 Ulrich Drepper <drepper@cygnus.com> Implement exp2 function. * sysdeps/libm-i387/s_exp2.S: New file. * sysdeps/libm-i387/s_exp2f.S: New file. * sysdeps/libm-i387/s_exp2l.S: New file. Implement log2 function. * sysdeps/libm-i387/s_log2.S: New file. * sysdeps/libm-i387/s_log2f.S: New file. * sysdeps/libm-i387/s_log2l.S: New file. * sysdeps/libm-ieee754/s_log2.c: New file. * sysdeps/libm-ieee754/s_log2f.c: New file. * sysdeps/stub/s_log2.c: New file. Stub version.
Diffstat (limited to 'sysdeps/libm-ieee754/s_log2.c')
-rw-r--r-- | sysdeps/libm-ieee754/s_log2.c | 129 |
1 files changed, 129 insertions, 0 deletions
diff --git a/sysdeps/libm-ieee754/s_log2.c b/sysdeps/libm-ieee754/s_log2.c new file mode 100644 index 0000000000..03a7deaa67 --- /dev/null +++ b/sysdeps/libm-ieee754/s_log2.c @@ -0,0 +1,129 @@ +/* Adapted for log2 by Ulrich Drepper <drepper@cygnus.com>. +/* + * ==================================================== + * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. + * + * Developed at SunPro, a Sun Microsystems, Inc. business. + * Permission to use, copy, modify, and distribute this + * software is freely granted, provided that this notice + * is preserved. + * ==================================================== + */ + +/* __log2(x) + * Return the logarithm to base 2 of x + * + * Method : + * 1. Argument Reduction: find k and f such that + * x = 2^k * (1+f), + * where sqrt(2)/2 < 1+f < sqrt(2) . + * + * 2. Approximation of log(1+f). + * Let s = f/(2+f) ; based on log(1+f) = log(1+s) - log(1-s) + * = 2s + 2/3 s**3 + 2/5 s**5 + ....., + * = 2s + s*R + * We use a special Reme algorithm on [0,0.1716] to generate + * a polynomial of degree 14 to approximate R The maximum error + * of this polynomial approximation is bounded by 2**-58.45. In + * other words, + * 2 4 6 8 10 12 14 + * R(z) ~ Lg1*s +Lg2*s +Lg3*s +Lg4*s +Lg5*s +Lg6*s +Lg7*s + * (the values of Lg1 to Lg7 are listed in the program) + * and + * | 2 14 | -58.45 + * | Lg1*s +...+Lg7*s - R(z) | <= 2 + * | | + * Note that 2s = f - s*f = f - hfsq + s*hfsq, where hfsq = f*f/2. + * In order to guarantee error in log below 1ulp, we compute log + * by + * log(1+f) = f - s*(f - R) (if f is not too large) + * log(1+f) = f - (hfsq - s*(hfsq+R)). (better accuracy) + * + * 3. Finally, log(x) = k + log(1+f). + * = k+(f-(hfsq-(s*(hfsq+R)))) + * + * Special cases: + * log2(x) is NaN with signal if x < 0 (including -INF) ; + * log2(+INF) is +INF; log(0) is -INF with signal; + * log2(NaN) is that NaN with no signal. + * + * Constants: + * The hexadecimal values are the intended ones for the following + * constants. The decimal values may be used, provided that the + * compiler will convert from decimal to binary accurately enough + * to produce the hexadecimal values shown. + */ + +#include "math.h" +#include "math_private.h" + +#ifdef __STDC__ +static const double +#else +static double +#endif +two54 = 1.80143985094819840000e+16, /* 43500000 00000000 */ +Lg1 = 6.666666666666735130e-01, /* 3FE55555 55555593 */ +Lg2 = 3.999999999940941908e-01, /* 3FD99999 9997FA04 */ +Lg3 = 2.857142874366239149e-01, /* 3FD24924 94229359 */ +Lg4 = 2.222219843214978396e-01, /* 3FCC71C5 1D8E78AF */ +Lg5 = 1.818357216161805012e-01, /* 3FC74664 96CB03DE */ +Lg6 = 1.531383769920937332e-01, /* 3FC39A09 D078C69F */ +Lg7 = 1.479819860511658591e-01; /* 3FC2F112 DF3E5244 */ + +#ifdef __STDC__ +static const double zero = 0.0; +#else +static double zero = 0.0; +#endif + +#ifdef __STDC__ + double __log2(double x) +#else + double __log2(x) + double x; +#endif +{ + double hfsq,f,s,z,R,w,t1,t2,dk; + int32_t k,hx,i,j; + u_int32_t lx; + + EXTRACT_WORDS(hx,lx,x); + + k=0; + if (hx < 0x00100000) { /* x < 2**-1022 */ + if (((hx&0x7fffffff)|lx)==0) + return -two54/zero; /* log(+-0)=-inf */ + if (hx<0) return (x-x)/zero; /* log(-#) = NaN */ + k -= 54; x *= two54; /* subnormal number, scale up x */ + GET_HIGH_WORD(hx,x); + } + if (hx >= 0x7ff00000) return x+x; + k += (hx>>20)-1023; + hx &= 0x000fffff; + i = (hx+0x95f64)&0x100000; + SET_HIGH_WORD(x,hx|(i^0x3ff00000)); /* normalize x or x/2 */ + k += (i>>20); + dk = (double) k; + f = x-1.0; + if((0x000fffff&(2+hx))<3) { /* |f| < 2**-20 */ + if(f==zero) return dk; + R = f*f*(0.5-0.33333333333333333*f); + return dk-(R-f); + } + s = f/(2.0+f); + z = s*s; + i = hx-0x6147a; + w = z*z; + j = 0x6b851-hx; + t1= w*(Lg2+w*(Lg4+w*Lg6)); + t2= z*(Lg1+w*(Lg3+w*(Lg5+w*Lg7))); + i |= j; + R = t2+t1; + if(i>0) { + hfsq=0.5*f*f; + return dk-((hfsq-(s*(hfsq+R)))-f); + } else { + return dk-((s*(f-R))-f); + } +} |