source: trunk/third/mozilla/js/src/jsnum.h @ 18860

/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * The contents of this file are subject to the Netscape Public
 * License Version 1.1 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy of
 * the License at http://www.mozilla.org/NPL/
 *
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 *
 * The Original Code is Mozilla Communicator client code, released
 * March 31, 1998.
 *
 * The Initial Developer of the Original Code is Netscape
 * Communications Corporation.  Portions created by Netscape are
 * Copyright (C) 1998 Netscape Communications Corporation. All
 * Rights Reserved.
 *
 * Contributor(s): 
 *
 * Alternatively, the contents of this file may be used under the
 * terms of the GNU Public License (the "GPL"), in which case the
 * provisions of the GPL are applicable instead of those above.
 * If you wish to allow use of your version of this file only
 * under the terms of the GPL and not to allow others to use your
 * version of this file under the NPL, indicate your decision by
 * deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL.  If you do not delete
 * the provisions above, a recipient may use your version of this
 * file under either the NPL or the GPL.
 */

#ifndef jsnum_h___
#define jsnum_h___
/*
 * JS number (IEEE double) interface.
 *
 * JS numbers are optimistically stored in the top 31 bits of 32-bit integers,
 * but floating point literals, results that overflow 31 bits, and division and
 * modulus operands and results require a 64-bit IEEE double.  These are GC'ed
 * and pointed to by 32-bit jsvals on the stack and in object properties.
 *
 * When a JS number is treated as an object (followed by . or []), the runtime
 * wraps it with a JSObject whose valueOf method returns the unwrapped number.
 */

JS_BEGIN_EXTERN_C

/*
 * Stefan Hanske <sh990154@mail.uni-greifswald.de> reports:
 *  ARM is a little endian architecture but 64 bit double words are stored
 * differently: the 32 bit words are in little endian byte order, the two words
 * are stored in big endian`s way.
 */

#if defined(__arm) || defined(__arm32__) || defined(__arm26__) || defined(__arm__)
#define CPU_IS_ARM
#endif

#if (__GNUC__ == 2 && __GNUC_MINOR__ > 95) || __GNUC__ > 2
/*
 * This version of the macros is safe for the alias optimizations that gcc
 * does, but uses gcc-specific extensions.
 */
typedef union {
    jsdouble value;
    struct {
#if defined(IS_LITTLE_ENDIAN) && !defined(CPU_IS_ARM)
        uint32 lsw;
        uint32 msw;
#else
        uint32 msw;
        uint32 lsw;
#endif
    } parts;
} js_ieee_double_shape_type;

#define JSDOUBLE_HI32(x)   (__extension__ ({ js_ieee_double_shape_type sh_u;  \
                                             sh_u.value = (x);                \
                                             sh_u.parts.msw; }))
#define JSDOUBLE_LO32(x)   (__extension__ ({ js_ieee_double_shape_type sh_u;  \
                                             sh_u.value = (x);                \
                                             sh_u.parts.lsw; }))
#define JSDOUBLE_SET_HI32(x, y)  (__extension__ ({                            \
                                             js_ieee_double_shape_type sh_u;  \
                                             sh_u.value = (x);                \
                                             sh_u.parts.msw = (y);            \
                                             (x) = sh_u.value; }))
#define JSDOUBLE_SET_LO32(x, y)  (__extension__ ({                            \
                                             js_ieee_double_shape_type sh_u;  \
                                             sh_u.value = (x);                \
                                             sh_u.parts.lsw = (y);            \
                                             (x) = sh_u.value; }))

#else /* GNUC */

/*
 * We don't know of any non-gcc compilers that perform alias optimization,
 * so this code should work.
 */

#if defined(IS_LITTLE_ENDIAN) && !defined(CPU_IS_ARM)
#define JSDOUBLE_HI32(x)        (((uint32 *)&(x))[1])
#define JSDOUBLE_LO32(x)        (((uint32 *)&(x))[0])
#else
#define JSDOUBLE_HI32(x)        (((uint32 *)&(x))[0])
#define JSDOUBLE_LO32(x)        (((uint32 *)&(x))[1])
#endif

#define JSDOUBLE_SET_HI32(x, y) (JSDOUBLE_HI32(x)=(y))
#define JSDOUBLE_SET_LO32(x, y) (JSDOUBLE_LO32(x)=(y))

#endif /* GNUC */

#define JSDOUBLE_HI32_SIGNBIT   0x80000000
#define JSDOUBLE_HI32_EXPMASK   0x7ff00000
#define JSDOUBLE_HI32_MANTMASK  0x000fffff

#define JSDOUBLE_IS_NaN(x)                                                    \
    ((JSDOUBLE_HI32(x) & JSDOUBLE_HI32_EXPMASK) == JSDOUBLE_HI32_EXPMASK &&   \
     (JSDOUBLE_LO32(x) || (JSDOUBLE_HI32(x) & JSDOUBLE_HI32_MANTMASK)))

#define JSDOUBLE_IS_INFINITE(x)                                               \
    ((JSDOUBLE_HI32(x) & ~JSDOUBLE_HI32_SIGNBIT) == JSDOUBLE_HI32_EXPMASK &&  \
     !JSDOUBLE_LO32(x))

#define JSDOUBLE_IS_FINITE(x)                                                 \
    ((JSDOUBLE_HI32(x) & JSDOUBLE_HI32_EXPMASK) != JSDOUBLE_HI32_EXPMASK)

#define JSDOUBLE_IS_NEGZERO(d)  (JSDOUBLE_HI32(d) == JSDOUBLE_HI32_SIGNBIT && \
                                 JSDOUBLE_LO32(d) == 0)

/*
 * JSDOUBLE_IS_INT first checks that d is neither NaN nor infinite, to avoid
 * raising SIGFPE on platforms such as Alpha Linux, then (only if the cast is
 * safe) leaves i as (jsint)d.  This also avoid anomalous NaN floating point
 * comparisons under MSVC.
 */
#define JSDOUBLE_IS_INT(d, i) (JSDOUBLE_IS_FINITE(d)                          \
                               && !JSDOUBLE_IS_NEGZERO(d)                     \
                               && ((d) == (i = (jsint)(d))))

/* Initialize number constants and runtime state for the first context. */
extern JSBool
js_InitRuntimeNumberState(JSContext *cx);

extern void
js_FinishRuntimeNumberState(JSContext *cx);

/* Initialize the Number class, returning its prototype object. */
extern JSObject *
js_InitNumberClass(JSContext *cx, JSObject *obj);

/*
 * String constants for global function names, used in jsapi.c and jsnum.c.
 */
extern const char js_Infinity_str[];
extern const char js_NaN_str[];
extern const char js_isNaN_str[];
extern const char js_isFinite_str[];
extern const char js_parseFloat_str[];
extern const char js_parseInt_str[];

/* GC-allocate a new JS number. */
extern jsdouble *
js_NewDouble(JSContext *cx, jsdouble d);

extern void
js_FinalizeDouble(JSContext *cx, jsdouble *dp);

extern JSBool
js_NewDoubleValue(JSContext *cx, jsdouble d, jsval *rval);

extern JSBool
js_NewNumberValue(JSContext *cx, jsdouble d, jsval *rval);

/* Construct a Number instance that wraps around d. */
extern JSObject *
js_NumberToObject(JSContext *cx, jsdouble d);

/* Convert a number to a GC'ed string. */
extern JSString *
js_NumberToString(JSContext *cx, jsdouble d);

/*
 * Convert a value to a number, returning false after reporting any error,
 * otherwise returning true with *dp set.
 */
extern JSBool
js_ValueToNumber(JSContext *cx, jsval v, jsdouble *dp);

/*
 * Convert a value or a double to an int32, according to the ECMA rules
 * for ToInt32.
 */
extern JSBool
js_ValueToECMAInt32(JSContext *cx, jsval v, int32 *ip);

extern JSBool
js_DoubleToECMAInt32(JSContext *cx, jsdouble d, int32 *ip);

/*
 * Convert a value or a double to a uint32, according to the ECMA rules
 * for ToUint32.
 */
extern JSBool
js_ValueToECMAUint32(JSContext *cx, jsval v, uint32 *ip);

extern JSBool
js_DoubleToECMAUint32(JSContext *cx, jsdouble d, uint32 *ip);

/*
 * Convert a value to a number, then to an int32 if it fits by rounding to
 * nearest; but failing with an error report if the double is out of range
 * or unordered.
 */
extern JSBool
js_ValueToInt32(JSContext *cx, jsval v, int32 *ip);

/*
 * Convert a value to a number, then to a uint16 according to the ECMA rules
 * for ToUint16.
 */
extern JSBool
js_ValueToUint16(JSContext *cx, jsval v, uint16 *ip);

/*
 * Convert a jsdouble to an integral number, stored in a jsdouble.
 * If d is NaN, return 0.  If d is an infinity, return it without conversion.
 */
extern jsdouble
js_DoubleToInteger(jsdouble d);

/*
 * Similar to strtod except that replaces overflows with infinities of the correct
 * sign and underflows with zeros of the correct sign.  Guaranteed to return the
 * closest double number to the given input in dp.
 * Also allows inputs of the form [+|-]Infinity, which produce an infinity of the
 * appropriate sign.  The case of the "Infinity" string must match.
 * If the string does not have a number in it, set *ep to s and return 0.0 in dp.
 * Return false if out of memory.
 */
extern JSBool
js_strtod(JSContext *cx, const jschar *s, const jschar **ep, jsdouble *dp);

/*
 * Similar to strtol except that handles integers of arbitrary size.  Guaranteed to
 * return the closest double number to the given input when radix is 10 or a power of 2.
 * May experience roundoff errors for very large numbers of a different radix.
 * If the string does not have a number in it, set *ep to s and return 0.0 in dp.
 * Return false if out of memory.
 */
extern JSBool
js_strtointeger(JSContext *cx, const jschar *s, const jschar **ep, jsint radix, jsdouble *dp);

JS_END_EXTERN_C

#endif /* jsnum_h___ */