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decContext.c
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decContext.c
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/* Decimal context module for the decNumber C Library.
Copyright (C) 2005-2018 Free Software Foundation, Inc.
Contributed by IBM Corporation. Author Mike Cowlishaw.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.
GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.
You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
<http://www.gnu.org/licenses/>. */
/* ------------------------------------------------------------------ */
/* Decimal Context module */
/* ------------------------------------------------------------------ */
/* This module comprises the routines for handling arithmetic */
/* context structures. */
/* ------------------------------------------------------------------ */
#include <string.h> /* for strcmp */
#ifdef DECCHECK
#include <stdio.h> /* for printf if DECCHECK */
#endif
#include "dconfig.h" /* for GCC definitions */
#include "decContext.h" /* context and base types */
#include "decNumberLocal.h" /* decNumber local types, etc. */
/* compile-time endian tester [assumes sizeof(Int)>1] */
static const Int mfcone=1; /* constant 1 */
static const Flag *mfctop=(const Flag *)&mfcone; /* -> top byte */
#define LITEND *mfctop /* named flag; 1=little-endian */
/* ------------------------------------------------------------------ */
/* round-for-reround digits */
/* ------------------------------------------------------------------ */
const uByte DECSTICKYTAB[10]={1,1,2,3,4,6,6,7,8,9}; /* used if sticky */
/* ------------------------------------------------------------------ */
/* Powers of ten (powers[n]==10**n, 0<=n<=9) */
/* ------------------------------------------------------------------ */
const uInt DECPOWERS[10]={1, 10, 100, 1000, 10000, 100000, 1000000,
10000000, 100000000, 1000000000};
/* ------------------------------------------------------------------ */
/* decContextClearStatus -- clear bits in current status */
/* */
/* context is the context structure to be queried */
/* mask indicates the bits to be cleared (the status bit that */
/* corresponds to each 1 bit in the mask is cleared) */
/* returns context */
/* */
/* No error is possible. */
/* ------------------------------------------------------------------ */
decContext *decContextClearStatus(decContext *context, uInt mask) {
context->status&=~mask;
return context;
} /* decContextClearStatus */
/* ------------------------------------------------------------------ */
/* decContextDefault -- initialize a context structure */
/* */
/* context is the structure to be initialized */
/* kind selects the required set of default values, one of: */
/* DEC_INIT_BASE -- select ANSI X3-274 defaults */
/* DEC_INIT_DECIMAL32 -- select IEEE 754 defaults, 32-bit */
/* DEC_INIT_DECIMAL64 -- select IEEE 754 defaults, 64-bit */
/* DEC_INIT_DECIMAL128 -- select IEEE 754 defaults, 128-bit */
/* For any other value a valid context is returned, but with */
/* Invalid_operation set in the status field. */
/* returns a context structure with the appropriate initial values. */
/* ------------------------------------------------------------------ */
decContext * decContextDefault(decContext *context, Int kind) {
/* set defaults... */
context->digits=9; /* 9 digits */
context->emax=DEC_MAX_EMAX; /* 9-digit exponents */
context->emin=DEC_MIN_EMIN; /* .. balanced */
context->round=DEC_ROUND_HALF_UP; /* 0.5 rises */
context->traps=DEC_Errors; /* all but informational */
context->status=0; /* cleared */
context->clamp=0; /* no clamping */
#if DECSUBSET
context->extended=0; /* cleared */
#endif
switch (kind) {
case DEC_INIT_BASE:
/* [use defaults] */
break;
case DEC_INIT_DECIMAL32:
context->digits=7; /* digits */
context->emax=96; /* Emax */
context->emin=-95; /* Emin */
context->round=DEC_ROUND_HALF_EVEN; /* 0.5 to nearest even */
context->traps=0; /* no traps set */
context->clamp=1; /* clamp exponents */
#if DECSUBSET
context->extended=1; /* set */
#endif
break;
case DEC_INIT_DECIMAL64:
context->digits=16; /* digits */
context->emax=384; /* Emax */
context->emin=-383; /* Emin */
context->round=DEC_ROUND_HALF_EVEN; /* 0.5 to nearest even */
context->traps=0; /* no traps set */
context->clamp=1; /* clamp exponents */
#if DECSUBSET
context->extended=1; /* set */
#endif
break;
case DEC_INIT_DECIMAL128:
context->digits=34; /* digits */
context->emax=6144; /* Emax */
context->emin=-6143; /* Emin */
context->round=DEC_ROUND_HALF_EVEN; /* 0.5 to nearest even */
context->traps=0; /* no traps set */
context->clamp=1; /* clamp exponents */
#if DECSUBSET
context->extended=1; /* set */
#endif
break;
default: /* invalid Kind */
/* use defaults, and .. */
decContextSetStatus(context, DEC_Invalid_operation); /* trap */
}
return context;} /* decContextDefault */
/* ------------------------------------------------------------------ */
/* decContextGetRounding -- return current rounding mode */
/* */
/* context is the context structure to be queried */
/* returns the rounding mode */
/* */
/* No error is possible. */
/* ------------------------------------------------------------------ */
enum rounding decContextGetRounding(decContext *context) {
return context->round;
} /* decContextGetRounding */
/* ------------------------------------------------------------------ */
/* decContextGetStatus -- return current status */
/* */
/* context is the context structure to be queried */
/* returns status */
/* */
/* No error is possible. */
/* ------------------------------------------------------------------ */
uInt decContextGetStatus(decContext *context) {
return context->status;
} /* decContextGetStatus */
/* ------------------------------------------------------------------ */
/* decContextRestoreStatus -- restore bits in current status */
/* */
/* context is the context structure to be updated */
/* newstatus is the source for the bits to be restored */
/* mask indicates the bits to be restored (the status bit that */
/* corresponds to each 1 bit in the mask is set to the value of */
/* the correspnding bit in newstatus) */
/* returns context */
/* */
/* No error is possible. */
/* ------------------------------------------------------------------ */
decContext *decContextRestoreStatus(decContext *context,
uInt newstatus, uInt mask) {
context->status&=~mask; /* clear the selected bits */
context->status|=(mask&newstatus); /* or in the new bits */
return context;
} /* decContextRestoreStatus */
/* ------------------------------------------------------------------ */
/* decContextSaveStatus -- save bits in current status */
/* */
/* context is the context structure to be queried */
/* mask indicates the bits to be saved (the status bits that */
/* correspond to each 1 bit in the mask are saved) */
/* returns the AND of the mask and the current status */
/* */
/* No error is possible. */
/* ------------------------------------------------------------------ */
uInt decContextSaveStatus(decContext *context, uInt mask) {
return context->status&mask;
} /* decContextSaveStatus */
/* ------------------------------------------------------------------ */
/* decContextSetRounding -- set current rounding mode */
/* */
/* context is the context structure to be updated */
/* newround is the value which will replace the current mode */
/* returns context */
/* */
/* No error is possible. */
/* ------------------------------------------------------------------ */
decContext *decContextSetRounding(decContext *context,
enum rounding newround) {
context->round=newround;
return context;
} /* decContextSetRounding */
/* ------------------------------------------------------------------ */
/* decContextSetStatus -- set status and raise trap if appropriate */
/* */
/* context is the context structure to be updated */
/* status is the DEC_ exception code */
/* returns the context structure */
/* */
/* Control may never return from this routine, if there is a signal */
/* handler and it takes a long jump. */
/* ------------------------------------------------------------------ */
decContext * decContextSetStatus(decContext *context, uInt status) {
context->status|=status;
if (status & context->traps) raise(SIGFPE);
return context;} /* decContextSetStatus */
/* ------------------------------------------------------------------ */
/* decContextSetStatusFromString -- set status from a string trap */
/* */
/* context is the context structure to be updated */
/* string is a string exactly equal to one that might be returned */
/* by decContextStatusToString */
/* */
/* The status bit corresponding to the string is set, and a trap */
/* is raised if appropriate. */
/* */
/* returns the context structure, unless the string is equal to */
/* DEC_Condition_MU or is not recognized. In these cases NULL is */
/* returned. */
/* ------------------------------------------------------------------ */
decContext * decContextSetStatusFromString(decContext *context,
const char *string) {
if (strcmp(string, DEC_Condition_CS)==0)
return decContextSetStatus(context, DEC_Conversion_syntax);
if (strcmp(string, DEC_Condition_DZ)==0)
return decContextSetStatus(context, DEC_Division_by_zero);
if (strcmp(string, DEC_Condition_DI)==0)
return decContextSetStatus(context, DEC_Division_impossible);
if (strcmp(string, DEC_Condition_DU)==0)
return decContextSetStatus(context, DEC_Division_undefined);
if (strcmp(string, DEC_Condition_IE)==0)
return decContextSetStatus(context, DEC_Inexact);
if (strcmp(string, DEC_Condition_IS)==0)
return decContextSetStatus(context, DEC_Insufficient_storage);
if (strcmp(string, DEC_Condition_IC)==0)
return decContextSetStatus(context, DEC_Invalid_context);
if (strcmp(string, DEC_Condition_IO)==0)
return decContextSetStatus(context, DEC_Invalid_operation);
#if DECSUBSET
if (strcmp(string, DEC_Condition_LD)==0)
return decContextSetStatus(context, DEC_Lost_digits);
#endif
if (strcmp(string, DEC_Condition_OV)==0)
return decContextSetStatus(context, DEC_Overflow);
if (strcmp(string, DEC_Condition_PA)==0)
return decContextSetStatus(context, DEC_Clamped);
if (strcmp(string, DEC_Condition_RO)==0)
return decContextSetStatus(context, DEC_Rounded);
if (strcmp(string, DEC_Condition_SU)==0)
return decContextSetStatus(context, DEC_Subnormal);
if (strcmp(string, DEC_Condition_UN)==0)
return decContextSetStatus(context, DEC_Underflow);
if (strcmp(string, DEC_Condition_ZE)==0)
return context;
return NULL; /* Multiple status, or unknown */
} /* decContextSetStatusFromString */
/* ------------------------------------------------------------------ */
/* decContextSetStatusFromStringQuiet -- set status from a string */
/* */
/* context is the context structure to be updated */
/* string is a string exactly equal to one that might be returned */
/* by decContextStatusToString */
/* */
/* The status bit corresponding to the string is set; no trap is */
/* raised. */
/* */
/* returns the context structure, unless the string is equal to */
/* DEC_Condition_MU or is not recognized. In these cases NULL is */
/* returned. */
/* ------------------------------------------------------------------ */
decContext * decContextSetStatusFromStringQuiet(decContext *context,
const char *string) {
if (strcmp(string, DEC_Condition_CS)==0)
return decContextSetStatusQuiet(context, DEC_Conversion_syntax);
if (strcmp(string, DEC_Condition_DZ)==0)
return decContextSetStatusQuiet(context, DEC_Division_by_zero);
if (strcmp(string, DEC_Condition_DI)==0)
return decContextSetStatusQuiet(context, DEC_Division_impossible);
if (strcmp(string, DEC_Condition_DU)==0)
return decContextSetStatusQuiet(context, DEC_Division_undefined);
if (strcmp(string, DEC_Condition_IE)==0)
return decContextSetStatusQuiet(context, DEC_Inexact);
if (strcmp(string, DEC_Condition_IS)==0)
return decContextSetStatusQuiet(context, DEC_Insufficient_storage);
if (strcmp(string, DEC_Condition_IC)==0)
return decContextSetStatusQuiet(context, DEC_Invalid_context);
if (strcmp(string, DEC_Condition_IO)==0)
return decContextSetStatusQuiet(context, DEC_Invalid_operation);
#if DECSUBSET
if (strcmp(string, DEC_Condition_LD)==0)
return decContextSetStatusQuiet(context, DEC_Lost_digits);
#endif
if (strcmp(string, DEC_Condition_OV)==0)
return decContextSetStatusQuiet(context, DEC_Overflow);
if (strcmp(string, DEC_Condition_PA)==0)
return decContextSetStatusQuiet(context, DEC_Clamped);
if (strcmp(string, DEC_Condition_RO)==0)
return decContextSetStatusQuiet(context, DEC_Rounded);
if (strcmp(string, DEC_Condition_SU)==0)
return decContextSetStatusQuiet(context, DEC_Subnormal);
if (strcmp(string, DEC_Condition_UN)==0)
return decContextSetStatusQuiet(context, DEC_Underflow);
if (strcmp(string, DEC_Condition_ZE)==0)
return context;
return NULL; /* Multiple status, or unknown */
} /* decContextSetStatusFromStringQuiet */
/* ------------------------------------------------------------------ */
/* decContextSetStatusQuiet -- set status without trap */
/* */
/* context is the context structure to be updated */
/* status is the DEC_ exception code */
/* returns the context structure */
/* */
/* No error is possible. */
/* ------------------------------------------------------------------ */
decContext * decContextSetStatusQuiet(decContext *context, uInt status) {
context->status|=status;
return context;} /* decContextSetStatusQuiet */
/* ------------------------------------------------------------------ */
/* decContextStatusToString -- convert status flags to a string */
/* */
/* context is a context with valid status field */
/* */
/* returns a constant string describing the condition. If multiple */
/* (or no) flags are set, a generic constant message is returned. */
/* ------------------------------------------------------------------ */
const char *decContextStatusToString(const decContext *context) {
Int status=context->status;
/* test the five IEEE first, as some of the others are ambiguous when */
/* DECEXTFLAG=0 */
if (status==DEC_Invalid_operation ) return DEC_Condition_IO;
if (status==DEC_Division_by_zero ) return DEC_Condition_DZ;
if (status==DEC_Overflow ) return DEC_Condition_OV;
if (status==DEC_Underflow ) return DEC_Condition_UN;
if (status==DEC_Inexact ) return DEC_Condition_IE;
if (status==DEC_Division_impossible ) return DEC_Condition_DI;
if (status==DEC_Division_undefined ) return DEC_Condition_DU;
if (status==DEC_Rounded ) return DEC_Condition_RO;
if (status==DEC_Clamped ) return DEC_Condition_PA;
if (status==DEC_Subnormal ) return DEC_Condition_SU;
if (status==DEC_Conversion_syntax ) return DEC_Condition_CS;
if (status==DEC_Insufficient_storage ) return DEC_Condition_IS;
if (status==DEC_Invalid_context ) return DEC_Condition_IC;
#if DECSUBSET
if (status==DEC_Lost_digits ) return DEC_Condition_LD;
#endif
if (status==0 ) return DEC_Condition_ZE;
return DEC_Condition_MU; /* Multiple errors */
} /* decContextStatusToString */
/* ------------------------------------------------------------------ */
/* decContextTestEndian -- test whether DECLITEND is set correctly */
/* */
/* quiet is 1 to suppress message; 0 otherwise */
/* returns 0 if DECLITEND is correct */
/* 1 if DECLITEND is incorrect and should be 1 */
/* -1 if DECLITEND is incorrect and should be 0 */
/* */
/* A message is displayed if the return value is not 0 and quiet==0. */
/* */
/* No error is possible. */
/* ------------------------------------------------------------------ */
Int decContextTestEndian(Flag quiet) {
Int res=0; /* optimist */
uInt dle=(uInt)DECLITEND; /* unsign */
if (dle>1) dle=1; /* ensure 0 or 1 */
if (LITEND!=DECLITEND) {
if (!quiet) {
#if DECCHECK
const char *adj;
if (LITEND) adj="little";
else adj="big";
printf("Warning: DECLITEND is set to %d, but this computer appears to be %s-endian\n",
DECLITEND, adj);
#endif
}
res=(Int)LITEND-dle;
}
return res;
} /* decContextTestEndian */
/* ------------------------------------------------------------------ */
/* decContextTestSavedStatus -- test bits in saved status */
/* */
/* oldstatus is the status word to be tested */
/* mask indicates the bits to be tested (the oldstatus bits that */
/* correspond to each 1 bit in the mask are tested) */
/* returns 1 if any of the tested bits are 1, or 0 otherwise */
/* */
/* No error is possible. */
/* ------------------------------------------------------------------ */
uInt decContextTestSavedStatus(uInt oldstatus, uInt mask) {
return (oldstatus&mask)!=0;
} /* decContextTestSavedStatus */
/* ------------------------------------------------------------------ */
/* decContextTestStatus -- test bits in current status */
/* */
/* context is the context structure to be updated */
/* mask indicates the bits to be tested (the status bits that */
/* correspond to each 1 bit in the mask are tested) */
/* returns 1 if any of the tested bits are 1, or 0 otherwise */
/* */
/* No error is possible. */
/* ------------------------------------------------------------------ */
uInt decContextTestStatus(decContext *context, uInt mask) {
return (context->status&mask)!=0;
} /* decContextTestStatus */
/* ------------------------------------------------------------------ */
/* decContextZeroStatus -- clear all status bits */
/* */
/* context is the context structure to be updated */
/* returns context */
/* */
/* No error is possible. */
/* ------------------------------------------------------------------ */
decContext *decContextZeroStatus(decContext *context) {
context->status=0;
return context;
} /* decContextZeroStatus */