436 lines
24 KiB
C
436 lines
24 KiB
C
/* ------------------------------------------------------------------ */
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/* Decimal Context module */
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/* ------------------------------------------------------------------ */
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/* Copyright (c) IBM Corporation, 2000-2010. All rights reserved. */
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/* */
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/* This software is made available under the terms of the */
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/* ICU License -- ICU 1.8.1 and later. */
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/* */
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/* The description and User's Guide ("The decNumber C Library") for */
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/* this software is called decNumber.pdf. This document is */
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/* available, together with arithmetic and format specifications, */
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/* testcases, and Web links, on the General Decimal Arithmetic page. */
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/* */
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/* Please send comments, suggestions, and corrections to the author: */
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/* mfc@uk.ibm.com */
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/* Mike Cowlishaw, IBM Fellow */
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/* IBM UK, PO Box 31, Birmingham Road, Warwick CV34 5JL, UK */
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/* ------------------------------------------------------------------ */
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/* This module comprises the routines for handling arithmetic */
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/* context structures. */
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/* ------------------------------------------------------------------ */
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#include <string.h> /* for strcmp */
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#include <stdio.h> /* for printf if DECCHECK */
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#include "decContext.h" /* context and base types */
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#include "decNumberLocal.h" /* decNumber local types, etc. */
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/* compile-time endian tester [assumes sizeof(Int)>1] */
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static const Int mfcone=1; /* constant 1 */
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static const Flag *mfctop=(Flag *)&mfcone; /* -> top byte */
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#define LITEND *mfctop /* named flag; 1=little-endian */
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/* ------------------------------------------------------------------ */
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/* round-for-reround digits */
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/* ------------------------------------------------------------------ */
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const uByte DECSTICKYTAB[10]={1,1,2,3,4,6,6,7,8,9}; /* used if sticky */
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/* ------------------------------------------------------------------ */
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/* Powers of ten (powers[n]==10**n, 0<=n<=9) */
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/* ------------------------------------------------------------------ */
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const uInt DECPOWERS[10]={1, 10, 100, 1000, 10000, 100000, 1000000,
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10000000, 100000000, 1000000000};
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/* ------------------------------------------------------------------ */
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/* decContextClearStatus -- clear bits in current status */
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/* */
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/* context is the context structure to be queried */
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/* mask indicates the bits to be cleared (the status bit that */
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/* corresponds to each 1 bit in the mask is cleared) */
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/* returns context */
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/* */
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/* No error is possible. */
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/* ------------------------------------------------------------------ */
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decContext *uprv_decContextClearStatus(decContext *context, uInt mask) {
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context->status&=~mask;
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return context;
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} /* decContextClearStatus */
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/* ------------------------------------------------------------------ */
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/* decContextDefault -- initialize a context structure */
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/* */
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/* context is the structure to be initialized */
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/* kind selects the required set of default values, one of: */
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/* DEC_INIT_BASE -- select ANSI X3-274 defaults */
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/* DEC_INIT_DECIMAL32 -- select IEEE 754 defaults, 32-bit */
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/* DEC_INIT_DECIMAL64 -- select IEEE 754 defaults, 64-bit */
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/* DEC_INIT_DECIMAL128 -- select IEEE 754 defaults, 128-bit */
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/* For any other value a valid context is returned, but with */
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/* Invalid_operation set in the status field. */
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/* returns a context structure with the appropriate initial values. */
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/* ------------------------------------------------------------------ */
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decContext * uprv_decContextDefault(decContext *context, Int kind) {
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/* set defaults... */
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context->digits=9; /* 9 digits */
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context->emax=DEC_MAX_EMAX; /* 9-digit exponents */
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context->emin=DEC_MIN_EMIN; /* .. balanced */
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context->round=DEC_ROUND_HALF_UP; /* 0.5 rises */
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context->traps=DEC_Errors; /* all but informational */
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context->status=0; /* cleared */
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context->clamp=0; /* no clamping */
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#if DECSUBSET
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context->extended=0; /* cleared */
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#endif
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switch (kind) {
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case DEC_INIT_BASE:
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/* [use defaults] */
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break;
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case DEC_INIT_DECIMAL32:
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context->digits=7; /* digits */
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context->emax=96; /* Emax */
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context->emin=-95; /* Emin */
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context->round=DEC_ROUND_HALF_EVEN; /* 0.5 to nearest even */
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context->traps=0; /* no traps set */
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context->clamp=1; /* clamp exponents */
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#if DECSUBSET
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context->extended=1; /* set */
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#endif
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break;
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case DEC_INIT_DECIMAL64:
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context->digits=16; /* digits */
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context->emax=384; /* Emax */
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context->emin=-383; /* Emin */
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context->round=DEC_ROUND_HALF_EVEN; /* 0.5 to nearest even */
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context->traps=0; /* no traps set */
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context->clamp=1; /* clamp exponents */
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#if DECSUBSET
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context->extended=1; /* set */
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#endif
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break;
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case DEC_INIT_DECIMAL128:
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context->digits=34; /* digits */
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context->emax=6144; /* Emax */
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context->emin=-6143; /* Emin */
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context->round=DEC_ROUND_HALF_EVEN; /* 0.5 to nearest even */
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context->traps=0; /* no traps set */
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context->clamp=1; /* clamp exponents */
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#if DECSUBSET
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context->extended=1; /* set */
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#endif
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break;
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default: /* invalid Kind */
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/* use defaults, and .. */
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uprv_decContextSetStatus(context, DEC_Invalid_operation); /* trap */
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}
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return context;} /* decContextDefault */
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/* ------------------------------------------------------------------ */
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/* decContextGetRounding -- return current rounding mode */
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/* */
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/* context is the context structure to be queried */
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/* returns the rounding mode */
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/* */
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/* No error is possible. */
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/* ------------------------------------------------------------------ */
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enum rounding uprv_decContextGetRounding(decContext *context) {
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return context->round;
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} /* decContextGetRounding */
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/* ------------------------------------------------------------------ */
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/* decContextGetStatus -- return current status */
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/* */
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/* context is the context structure to be queried */
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/* returns status */
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/* */
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/* No error is possible. */
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/* ------------------------------------------------------------------ */
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uInt uprv_decContextGetStatus(decContext *context) {
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return context->status;
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} /* decContextGetStatus */
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/* ------------------------------------------------------------------ */
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/* decContextRestoreStatus -- restore bits in current status */
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/* */
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/* context is the context structure to be updated */
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/* newstatus is the source for the bits to be restored */
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/* mask indicates the bits to be restored (the status bit that */
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/* corresponds to each 1 bit in the mask is set to the value of */
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/* the correspnding bit in newstatus) */
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/* returns context */
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/* */
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/* No error is possible. */
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/* ------------------------------------------------------------------ */
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decContext *uprv_decContextRestoreStatus(decContext *context,
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uInt newstatus, uInt mask) {
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context->status&=~mask; /* clear the selected bits */
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context->status|=(mask&newstatus); /* or in the new bits */
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return context;
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} /* decContextRestoreStatus */
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/* ------------------------------------------------------------------ */
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/* decContextSaveStatus -- save bits in current status */
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/* */
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/* context is the context structure to be queried */
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/* mask indicates the bits to be saved (the status bits that */
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/* correspond to each 1 bit in the mask are saved) */
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/* returns the AND of the mask and the current status */
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/* */
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/* No error is possible. */
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/* ------------------------------------------------------------------ */
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uInt uprv_decContextSaveStatus(decContext *context, uInt mask) {
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return context->status&mask;
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} /* decContextSaveStatus */
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/* ------------------------------------------------------------------ */
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/* decContextSetRounding -- set current rounding mode */
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/* */
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/* context is the context structure to be updated */
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/* newround is the value which will replace the current mode */
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/* returns context */
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/* */
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/* No error is possible. */
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/* ------------------------------------------------------------------ */
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decContext *uprv_decContextSetRounding(decContext *context,
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enum rounding newround) {
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context->round=newround;
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return context;
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} /* decContextSetRounding */
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/* ------------------------------------------------------------------ */
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/* decContextSetStatus -- set status and raise trap if appropriate */
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/* */
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/* context is the context structure to be updated */
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/* status is the DEC_ exception code */
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/* returns the context structure */
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/* */
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/* Control may never return from this routine, if there is a signal */
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/* handler and it takes a long jump. */
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/* ------------------------------------------------------------------ */
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decContext * uprv_decContextSetStatus(decContext *context, uInt status) {
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context->status|=status;
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if (status & context->traps) raise(SIGFPE);
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return context;} /* decContextSetStatus */
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/* ------------------------------------------------------------------ */
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/* decContextSetStatusFromString -- set status from a string + trap */
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/* */
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/* context is the context structure to be updated */
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/* string is a string exactly equal to one that might be returned */
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/* by decContextStatusToString */
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/* */
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/* The status bit corresponding to the string is set, and a trap */
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/* is raised if appropriate. */
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/* */
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/* returns the context structure, unless the string is equal to */
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/* DEC_Condition_MU or is not recognized. In these cases NULL is */
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/* returned. */
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/* ------------------------------------------------------------------ */
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decContext * uprv_decContextSetStatusFromString(decContext *context,
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const char *string) {
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if (strcmp(string, DEC_Condition_CS)==0)
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return uprv_decContextSetStatus(context, DEC_Conversion_syntax);
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if (strcmp(string, DEC_Condition_DZ)==0)
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return uprv_decContextSetStatus(context, DEC_Division_by_zero);
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if (strcmp(string, DEC_Condition_DI)==0)
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return uprv_decContextSetStatus(context, DEC_Division_impossible);
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if (strcmp(string, DEC_Condition_DU)==0)
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return uprv_decContextSetStatus(context, DEC_Division_undefined);
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if (strcmp(string, DEC_Condition_IE)==0)
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return uprv_decContextSetStatus(context, DEC_Inexact);
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if (strcmp(string, DEC_Condition_IS)==0)
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return uprv_decContextSetStatus(context, DEC_Insufficient_storage);
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if (strcmp(string, DEC_Condition_IC)==0)
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return uprv_decContextSetStatus(context, DEC_Invalid_context);
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if (strcmp(string, DEC_Condition_IO)==0)
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return uprv_decContextSetStatus(context, DEC_Invalid_operation);
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#if DECSUBSET
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if (strcmp(string, DEC_Condition_LD)==0)
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return uprv_decContextSetStatus(context, DEC_Lost_digits);
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#endif
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if (strcmp(string, DEC_Condition_OV)==0)
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return uprv_decContextSetStatus(context, DEC_Overflow);
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if (strcmp(string, DEC_Condition_PA)==0)
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return uprv_decContextSetStatus(context, DEC_Clamped);
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if (strcmp(string, DEC_Condition_RO)==0)
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return uprv_decContextSetStatus(context, DEC_Rounded);
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if (strcmp(string, DEC_Condition_SU)==0)
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return uprv_decContextSetStatus(context, DEC_Subnormal);
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if (strcmp(string, DEC_Condition_UN)==0)
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return uprv_decContextSetStatus(context, DEC_Underflow);
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if (strcmp(string, DEC_Condition_ZE)==0)
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return context;
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return NULL; /* Multiple status, or unknown */
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} /* decContextSetStatusFromString */
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/* ------------------------------------------------------------------ */
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/* decContextSetStatusFromStringQuiet -- set status from a string */
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/* */
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/* context is the context structure to be updated */
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/* string is a string exactly equal to one that might be returned */
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/* by decContextStatusToString */
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/* */
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/* The status bit corresponding to the string is set; no trap is */
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/* raised. */
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/* */
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/* returns the context structure, unless the string is equal to */
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/* DEC_Condition_MU or is not recognized. In these cases NULL is */
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/* returned. */
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/* ------------------------------------------------------------------ */
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decContext * uprv_decContextSetStatusFromStringQuiet(decContext *context,
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const char *string) {
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if (strcmp(string, DEC_Condition_CS)==0)
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return uprv_decContextSetStatusQuiet(context, DEC_Conversion_syntax);
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if (strcmp(string, DEC_Condition_DZ)==0)
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return uprv_decContextSetStatusQuiet(context, DEC_Division_by_zero);
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if (strcmp(string, DEC_Condition_DI)==0)
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return uprv_decContextSetStatusQuiet(context, DEC_Division_impossible);
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if (strcmp(string, DEC_Condition_DU)==0)
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return uprv_decContextSetStatusQuiet(context, DEC_Division_undefined);
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if (strcmp(string, DEC_Condition_IE)==0)
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return uprv_decContextSetStatusQuiet(context, DEC_Inexact);
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if (strcmp(string, DEC_Condition_IS)==0)
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return uprv_decContextSetStatusQuiet(context, DEC_Insufficient_storage);
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if (strcmp(string, DEC_Condition_IC)==0)
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return uprv_decContextSetStatusQuiet(context, DEC_Invalid_context);
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if (strcmp(string, DEC_Condition_IO)==0)
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return uprv_decContextSetStatusQuiet(context, DEC_Invalid_operation);
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#if DECSUBSET
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if (strcmp(string, DEC_Condition_LD)==0)
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return uprv_decContextSetStatusQuiet(context, DEC_Lost_digits);
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#endif
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if (strcmp(string, DEC_Condition_OV)==0)
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return uprv_decContextSetStatusQuiet(context, DEC_Overflow);
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if (strcmp(string, DEC_Condition_PA)==0)
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return uprv_decContextSetStatusQuiet(context, DEC_Clamped);
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if (strcmp(string, DEC_Condition_RO)==0)
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return uprv_decContextSetStatusQuiet(context, DEC_Rounded);
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if (strcmp(string, DEC_Condition_SU)==0)
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return uprv_decContextSetStatusQuiet(context, DEC_Subnormal);
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if (strcmp(string, DEC_Condition_UN)==0)
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return uprv_decContextSetStatusQuiet(context, DEC_Underflow);
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if (strcmp(string, DEC_Condition_ZE)==0)
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return context;
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return NULL; /* Multiple status, or unknown */
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} /* decContextSetStatusFromStringQuiet */
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/* ------------------------------------------------------------------ */
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/* decContextSetStatusQuiet -- set status without trap */
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/* */
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/* context is the context structure to be updated */
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/* status is the DEC_ exception code */
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/* returns the context structure */
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/* */
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/* No error is possible. */
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/* ------------------------------------------------------------------ */
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decContext * uprv_decContextSetStatusQuiet(decContext *context, uInt status) {
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context->status|=status;
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return context;} /* decContextSetStatusQuiet */
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/* ------------------------------------------------------------------ */
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/* decContextStatusToString -- convert status flags to a string */
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/* */
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/* context is a context with valid status field */
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/* */
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/* returns a constant string describing the condition. If multiple */
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/* (or no) flags are set, a generic constant message is returned. */
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/* ------------------------------------------------------------------ */
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const char *uprv_decContextStatusToString(const decContext *context) {
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Int status=context->status;
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/* test the five IEEE first, as some of the others are ambiguous when */
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/* DECEXTFLAG=0 */
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if (status==DEC_Invalid_operation ) return DEC_Condition_IO;
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if (status==DEC_Division_by_zero ) return DEC_Condition_DZ;
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if (status==DEC_Overflow ) return DEC_Condition_OV;
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if (status==DEC_Underflow ) return DEC_Condition_UN;
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if (status==DEC_Inexact ) return DEC_Condition_IE;
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if (status==DEC_Division_impossible ) return DEC_Condition_DI;
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if (status==DEC_Division_undefined ) return DEC_Condition_DU;
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if (status==DEC_Rounded ) return DEC_Condition_RO;
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if (status==DEC_Clamped ) return DEC_Condition_PA;
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if (status==DEC_Subnormal ) return DEC_Condition_SU;
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if (status==DEC_Conversion_syntax ) return DEC_Condition_CS;
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if (status==DEC_Insufficient_storage ) return DEC_Condition_IS;
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if (status==DEC_Invalid_context ) return DEC_Condition_IC;
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#if DECSUBSET
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if (status==DEC_Lost_digits ) return DEC_Condition_LD;
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#endif
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if (status==0 ) return DEC_Condition_ZE;
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return DEC_Condition_MU; /* Multiple errors */
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} /* decContextStatusToString */
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/* ------------------------------------------------------------------ */
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/* decContextTestEndian -- test whether DECLITEND is set correctly */
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/* */
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/* quiet is 1 to suppress message; 0 otherwise */
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/* returns 0 if DECLITEND is correct */
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/* 1 if DECLITEND is incorrect and should be 1 */
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/* -1 if DECLITEND is incorrect and should be 0 */
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/* */
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/* A message is displayed if the return value is not 0 and quiet==0. */
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/* */
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/* No error is possible. */
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/* ------------------------------------------------------------------ */
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Int uprv_decContextTestEndian(Flag quiet) {
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Int res=0; /* optimist */
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uInt dle=(uInt)DECLITEND; /* unsign */
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if (dle>1) dle=1; /* ensure 0 or 1 */
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if (LITEND!=DECLITEND) {
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const char *adj;
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if (!quiet) {
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if (LITEND) adj="little";
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else adj="big";
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printf("Warning: DECLITEND is set to %d, but this computer appears to be %s-endian\n",
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DECLITEND, adj);
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}
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res=(Int)LITEND-dle;
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}
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return res;
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} /* decContextTestEndian */
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/* ------------------------------------------------------------------ */
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/* decContextTestSavedStatus -- test bits in saved status */
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/* */
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/* oldstatus is the status word to be tested */
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/* mask indicates the bits to be tested (the oldstatus bits that */
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/* correspond to each 1 bit in the mask are tested) */
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/* returns 1 if any of the tested bits are 1, or 0 otherwise */
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/* */
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/* No error is possible. */
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/* ------------------------------------------------------------------ */
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uInt uprv_decContextTestSavedStatus(uInt oldstatus, uInt mask) {
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return (oldstatus&mask)!=0;
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} /* decContextTestSavedStatus */
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/* ------------------------------------------------------------------ */
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/* decContextTestStatus -- test bits in current status */
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/* */
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/* context is the context structure to be updated */
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/* mask indicates the bits to be tested (the status bits that */
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/* correspond to each 1 bit in the mask are tested) */
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/* returns 1 if any of the tested bits are 1, or 0 otherwise */
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/* */
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/* No error is possible. */
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/* ------------------------------------------------------------------ */
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uInt uprv_decContextTestStatus(decContext *context, uInt mask) {
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return (context->status&mask)!=0;
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} /* decContextTestStatus */
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/* ------------------------------------------------------------------ */
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/* decContextZeroStatus -- clear all status bits */
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/* */
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/* context is the context structure to be updated */
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/* returns context */
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/* */
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/* No error is possible. */
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/* ------------------------------------------------------------------ */
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decContext *uprv_decContextZeroStatus(decContext *context) {
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context->status=0;
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return context;
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} /* decContextZeroStatus */
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