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/* ------------------------------------------------------------------ */
/* Decimal Context module */
/* ------------------------------------------------------------------ */
/* Copyright (c) IBM Corporation, 2000, 2005. All rights reserved. */
/* */
/* This software is made available under the terms of the */
/* ICU License -- ICU 1.8.1 and later. */
/* */
/* The description and User's Guide ("The decNumber C Library") for */
/* this software is called decNumber.pdf. This document is */
/* available, together with arithmetic and format specifications, */
/* testcases, and Web links, at: http://www2.hursley.ibm.com/decimal */
/* */
/* Please send comments, suggestions, and corrections to the author: */
/* mfc@uk.ibm.com */
/* Mike Cowlishaw, IBM Fellow */
/* IBM UK, PO Box 31, Birmingham Road, Warwick CV34 5JL, UK */
/* ------------------------------------------------------------------ */
/* This module comprises the routines for handling arithmetic */
/* context structures. */
/* ------------------------------------------------------------------ */
#include <string.h> // for strcmp
#include "decContext.h" // context and base types
#include "decNumberLocal.h" // decNumber local types, etc.
/* ------------------------------------------------------------------ */
/* 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 754r defaults, 32-bit */
/* DEC_INIT_DECIMAL64 -- select IEEE 754r defaults, 64-bit */
/* DEC_INIT_DECIMAL128 -- select IEEE 754r 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
/* ------------------------------------------------------------------ */
/* 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;
if (status==DEC_Conversion_syntax ) return DEC_Condition_CS;
if (status==DEC_Division_by_zero ) return DEC_Condition_DZ;
if (status==DEC_Division_impossible ) return DEC_Condition_DI;
if (status==DEC_Division_undefined ) return DEC_Condition_DU;
if (status==DEC_Inexact ) return DEC_Condition_IE;
if (status==DEC_Insufficient_storage ) return DEC_Condition_IS;
if (status==DEC_Invalid_context ) return DEC_Condition_IC;
if (status==DEC_Invalid_operation ) return DEC_Condition_IO;
#if DECSUBSET
if (status==DEC_Lost_digits ) return DEC_Condition_LD;
#endif
if (status==DEC_Overflow ) return DEC_Condition_OV;
if (status==DEC_Clamped ) return DEC_Condition_PA;
if (status==DEC_Rounded ) return DEC_Condition_RO;
if (status==DEC_Subnormal ) return DEC_Condition_SU;
if (status==DEC_Underflow ) return DEC_Condition_UN;
if (status==0 ) return DEC_Condition_ZE;
return DEC_Condition_MU; // Multiple errors
} // decContextStatusToString
/* ------------------------------------------------------------------ */
/* decContextSetStatusFromString -- set status from a string */
/* */
/* context is the controlling context */
/* 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
/* ------------------------------------------------------------------ */
/* decContextSetStatus -- set status and raise trap if appropriate */
/* */
/* context is the controlling context */
/* 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
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