/* ------------------------------------------------------------------ */ /* Decimal Context module */ /* ------------------------------------------------------------------ */ /* Copyright (c) IBM Corporation, 2000, 2009. 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, on the General Decimal Arithmetic page. */ /* */ /* 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 // for strcmp #include // for printf if DECCHECK #include "decNumber/decContext.h" // context and base types #include "decNumber/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) { // always refer to this #if DECPRINT 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