toolchain/gcc/newlib/libm/common/s_matherr.c

   1
   2 /* @(#)s_matherr.c 5.1 93/09/24 */
   3 /*
   4  * ====================================================
   5  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   6  *
   7  * Developed at SunPro, a Sun Microsystems, Inc. business.
   8  * Permission to use, copy, modify, and distribute this
   9  * software is freely granted, provided that this notice
  10  * is preserved.
  11  * ====================================================
  12  */
  13
  14 /*
  15
  16 FUNCTION
  17         <<matherr>>---modifiable math error handler
  18
  19 INDEX
  20         matherr
  21
  22 ANSI_SYNOPSIS
  23         #include <math.h>
  24         int matherr(struct exception *<[e]>);
  25
  26 TRAD_SYNOPSIS
  27         #include <math.h>
  28         int matherr(*<[e]>)
  29         struct exception *<[e]>;
  30
  31 DESCRIPTION
  32 <<matherr>> is called whenever a math library function generates an error.
  33 You can replace <<matherr>> by your own subroutine to customize
  34 error treatment.  The customized <<matherr>> must return 0 if
  35 it fails to resolve the error, and non-zero if the error is resolved.
  36
  37 When <<matherr>> returns a nonzero value, no error message is printed
  38 and the value of <<errno>> is not modified.  You can accomplish either
  39 or both of these things in your own <<matherr>> using the information
  40 passed in the structure <<*<[e]>>>.
  41
  42 This is the <<exception>> structure (defined in `<<math.h>>'):
  43 .       struct exception {
  44 .               int type;
  45 .               char *name;
  46 .               double arg1, arg2, retval;
  47 .               int err;
  48 .       };
  49
  50 The members of the exception structure have the following meanings:
  51 o+
  52 o type
  53 The type of mathematical error that occured; macros encoding error
  54 types are also defined in `<<math.h>>'.
  55
  56 o name
  57 a pointer to a null-terminated string holding the
  58 name of the math library function where the error occurred.
  59
  60 o arg1, arg2
  61 The arguments which caused the error.
  62
  63 o retval
  64 The error return value (what the calling function will return).
  65
  66 o err
  67 If set to be non-zero, this is the new value assigned to <<errno>>.
  68 o-
  69
  70 The error types defined in `<<math.h>>' represent possible mathematical
  71 errors as follows:
  72
  73 o+
  74 o DOMAIN
  75 An argument was not in the domain of the function; e.g. <<log(-1.0)>>.
  76
  77 o SING
  78 The requested calculation would result in a singularity; e.g. <<pow(0.0,-2.0)>>
  79
  80 o OVERFLOW
  81 A calculation would produce a result too large to represent; e.g.
  82 <<exp(1000.0)>>.
  83
  84 o UNDERFLOW
  85 A calculation would produce a result too small to represent; e.g.
  86 <<exp(-1000.0)>>.
  87
  88 o TLOSS
  89 Total loss of precision.  The result would have no significant digits;
  90 e.g. <<sin(10e70)>>.
  91
  92 o PLOSS
  93 Partial loss of precision.
  94 o-
  95
  96
  97 RETURNS
  98 The library definition for <<matherr>> returns <<0>> in all cases.
  99
 100 You can change the calling function's result from a customized <<matherr>>
 101 by modifying <<e->retval>>, which propagates backs to the caller.
 102
 103 If <<matherr>> returns <<0>> (indicating that it was not able to resolve
 104 the error) the caller sets <<errno>> to an appropriate value, and prints
 105 an error message.
 106
 107 PORTABILITY
 108 <<matherr>> is not ANSI C.
 109 */
 110
 111 #include "fdlibm.h"
 112
 113 #ifdef __STDC__
 114         int matherr(struct exception *x)
 115 #else
 116         int matherr(x)
 117         struct exception *x;
 118 #endif
 119 {
 120         int n=0;
 121         if(x->arg1!=x->arg1) return 0;
 122         return n;
 123 }