js/src/jsnum.h

   1 /* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
   2  *
   3  * ***** BEGIN LICENSE BLOCK *****
   4  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
   5  *
   6  * The contents of this file are subject to the Mozilla Public License Version
   7  * 1.1 (the "License"); you may not use this file except in compliance with
   8  * the License. You may obtain a copy of the License at
   9  * http://www.mozilla.org/MPL/
  10  *
  11  * Software distributed under the License is distributed on an "AS IS" basis,
  12  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
  13  * for the specific language governing rights and limitations under the
  14  * License.
  15  *
  16  * The Original Code is Mozilla Communicator client code, released
  17  * March 31, 1998.
  18  *
  19  * The Initial Developer of the Original Code is
  20  * Netscape Communications Corporation.
  21  * Portions created by the Initial Developer are Copyright (C) 1998
  22  * the Initial Developer. All Rights Reserved.
  23  *
  24  * Contributor(s):
  25  *
  26  * Alternatively, the contents of this file may be used under the terms of
  27  * either of the GNU General Public License Version 2 or later (the "GPL"),
  28  * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
  29  * in which case the provisions of the GPL or the LGPL are applicable instead
  30  * of those above. If you wish to allow use of your version of this file only
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  34  * and other provisions required by the GPL or the LGPL. If you do not delete
  35  * the provisions above, a recipient may use your version of this file under
  36  * the terms of any one of the MPL, the GPL or the LGPL.
  37  *
  38  * ***** END LICENSE BLOCK ***** */
  39
  40 #ifndef jsnum_h___
  41 #define jsnum_h___
  42 /*
  43  * JS number (IEEE double) interface.
  44  *
  45  * JS numbers are optimistically stored in the top 31 bits of 32-bit integers,
  46  * but floating point literals, results that overflow 31 bits, and division and
  47  * modulus operands and results require a 64-bit IEEE double.  These are GC'ed
  48  * and pointed to by 32-bit jsvals on the stack and in object properties.
  49  */
  50
  51 JS_BEGIN_EXTERN_C
  52
  53 /*
  54  * The ARM architecture supports two floating point models: VFP and FPA. When
  55  * targetting FPA, doubles are mixed-endian on little endian ARMs (meaning that
  56  * the high and low words are in big endian order).
  57  */
  58 #if defined(__arm) || defined(__arm32__) || defined(__arm26__) || defined(__arm__)
  59 #if !defined(__VFP_FP__)
  60 #define FPU_IS_ARM_FPA
  61 #endif
  62 #endif
  63
  64 typedef union jsdpun {
  65     struct {
  66 #if defined(IS_LITTLE_ENDIAN) && !defined(FPU_IS_ARM_FPA)
  67         uint32 lo, hi;
  68 #else
  69         uint32 hi, lo;
  70 #endif
  71     } s;
  72     jsdouble d;
  73 } jsdpun;
  74
  75 #if (__GNUC__ == 2 && __GNUC_MINOR__ > 95) || __GNUC__ > 2
  76 /*
  77  * This version of the macros is safe for the alias optimizations that gcc
  78  * does, but uses gcc-specific extensions.
  79  */
  80
  81 #define JSDOUBLE_HI32(x) (__extension__ ({ jsdpun u; u.d = (x); u.s.hi; }))
  82 #define JSDOUBLE_LO32(x) (__extension__ ({ jsdpun u; u.d = (x); u.s.lo; }))
  83 #define JSDOUBLE_SET_HI32(x, y) \
  84     (__extension__ ({ jsdpun u; u.d = (x); u.s.hi = (y); (x) = u.d; }))
  85 #define JSDOUBLE_SET_LO32(x, y) \
  86     (__extension__ ({ jsdpun u; u.d = (x); u.s.lo = (y); (x) = u.d; }))
  87
  88 #else /* not or old GNUC */
  89
  90 /*
  91  * We don't know of any non-gcc compilers that perform alias optimization,
  92  * so this code should work.
  93  */
  94
  95 #if defined(IS_LITTLE_ENDIAN) && !defined(FPU_IS_ARM_FPA)
  96 #define JSDOUBLE_HI32(x)        (((uint32 *)&(x))[1])
  97 #define JSDOUBLE_LO32(x)        (((uint32 *)&(x))[0])
  98 #else
  99 #define JSDOUBLE_HI32(x)        (((uint32 *)&(x))[0])
 100 #define JSDOUBLE_LO32(x)        (((uint32 *)&(x))[1])
 101 #endif
 102
 103 #define JSDOUBLE_SET_HI32(x, y) (JSDOUBLE_HI32(x)=(y))
 104 #define JSDOUBLE_SET_LO32(x, y) (JSDOUBLE_LO32(x)=(y))
 105
 106 #endif /* not or old GNUC */
 107
 108 #define JSDOUBLE_HI32_SIGNBIT   0x80000000
 109 #define JSDOUBLE_HI32_EXPMASK   0x7ff00000
 110 #define JSDOUBLE_HI32_MANTMASK  0x000fffff
 111
 112 #define JSDOUBLE_IS_NaN(x)                                                    \
 113     ((JSDOUBLE_HI32(x) & JSDOUBLE_HI32_EXPMASK) == JSDOUBLE_HI32_EXPMASK &&   \
 114      (JSDOUBLE_LO32(x) || (JSDOUBLE_HI32(x) & JSDOUBLE_HI32_MANTMASK)))
 115
 116 #define JSDOUBLE_IS_INFINITE(x)                                               \
 117     ((JSDOUBLE_HI32(x) & ~JSDOUBLE_HI32_SIGNBIT) == JSDOUBLE_HI32_EXPMASK &&  \
 118      !JSDOUBLE_LO32(x))
 119
 120 #define JSDOUBLE_IS_FINITE(x)                                                 \
 121     ((JSDOUBLE_HI32(x) & JSDOUBLE_HI32_EXPMASK) != JSDOUBLE_HI32_EXPMASK)
 122
 123 #define JSDOUBLE_IS_NEGZERO(d)  (JSDOUBLE_HI32(d) == JSDOUBLE_HI32_SIGNBIT && \
 124                                  JSDOUBLE_LO32(d) == 0)
 125
 126 /*
 127  * JSDOUBLE_IS_INT first checks that d is neither NaN nor infinite, to avoid
 128  * raising SIGFPE on platforms such as Alpha Linux, then (only if the cast is
 129  * safe) leaves i as (jsint)d.  This also avoid anomalous NaN floating point
 130  * comparisons under MSVC.
 131  */
 132 #define JSDOUBLE_IS_INT(d, i) (JSDOUBLE_IS_FINITE(d)                          \
 133                                && !JSDOUBLE_IS_NEGZERO(d)                     \
 134                                && ((d) == (i = (jsint)(d))))
 135
 136 #if defined(XP_WIN)
 137 #define JSDOUBLE_COMPARE(LVAL, OP, RVAL, IFNAN)                               \
 138     ((JSDOUBLE_IS_NaN(LVAL) || JSDOUBLE_IS_NaN(RVAL))                         \
 139      ? (IFNAN)                                                                \
 140      : (LVAL) OP (RVAL))
 141 #else
 142 #define JSDOUBLE_COMPARE(LVAL, OP, RVAL, IFNAN) ((LVAL) OP (RVAL))
 143 #endif
 144
 145 /* Initialize number constants and runtime state for the first context. */
 146 extern JSBool
 147 js_InitRuntimeNumberState(JSContext *cx);
 148
 149 extern void
 150 js_FinishRuntimeNumberState(JSContext *cx);
 151
 152 /* Initialize the Number class, returning its prototype object. */
 153 extern JSClass js_NumberClass;
 154
 155 extern JSObject *
 156 js_InitNumberClass(JSContext *cx, JSObject *obj);
 157
 158 /*
 159  * String constants for global function names, used in jsapi.c and jsnum.c.
 160  */
 161 extern const char js_Infinity_str[];
 162 extern const char js_NaN_str[];
 163 extern const char js_isNaN_str[];
 164 extern const char js_isFinite_str[];
 165 extern const char js_parseFloat_str[];
 166 extern const char js_parseInt_str[];
 167
 168 /* GC-allocate a new JS number. */
 169 extern jsdouble *
 170 js_NewDouble(JSContext *cx, jsdouble d, uintN gcflag);
 171
 172 extern void
 173 js_FinalizeDouble(JSContext *cx, jsdouble *dp);
 174
 175 extern JSBool
 176 js_NewDoubleValue(JSContext *cx, jsdouble d, jsval *rval);
 177
 178 extern JSBool
 179 js_NewNumberValue(JSContext *cx, jsdouble d, jsval *rval);
 180
 181 /* Convert a number to a GC'ed string. */
 182 extern JSString *
 183 js_NumberToString(JSContext *cx, jsdouble d);
 184
 185 /*
 186  * Convert a value to a number, returning false after reporting any error,
 187  * otherwise returning true with *dp set.
 188  */
 189 extern JSBool
 190 js_ValueToNumber(JSContext *cx, jsval v, jsdouble *dp);
 191
 192 /*
 193  * Convert a value or a double to an int32, according to the ECMA rules
 194  * for ToInt32.
 195  */
 196 extern JSBool
 197 js_ValueToECMAInt32(JSContext *cx, jsval v, int32 *ip);
 198
 199 extern JSBool
 200 js_DoubleToECMAInt32(JSContext *cx, jsdouble d, int32 *ip);
 201
 202 /*
 203  * Convert a value or a double to a uint32, according to the ECMA rules
 204  * for ToUint32.
 205  */
 206 extern JSBool
 207 js_ValueToECMAUint32(JSContext *cx, jsval v, uint32 *ip);
 208
 209 extern JSBool
 210 js_DoubleToECMAUint32(JSContext *cx, jsdouble d, uint32 *ip);
 211
 212 /*
 213  * Convert a value to a number, then to an int32 if it fits by rounding to
 214  * nearest; but failing with an error report if the double is out of range
 215  * or unordered.
 216  */
 217 extern JSBool
 218 js_ValueToInt32(JSContext *cx, jsval v, int32 *ip);
 219
 220 /*
 221  * Convert a value to a number, then to a uint16 according to the ECMA rules
 222  * for ToUint16.
 223  */
 224 extern JSBool
 225 js_ValueToUint16(JSContext *cx, jsval v, uint16 *ip);
 226
 227 /*
 228  * Convert a jsdouble to an integral number, stored in a jsdouble.
 229  * If d is NaN, return 0.  If d is an infinity, return it without conversion.
 230  */
 231 extern jsdouble
 232 js_DoubleToInteger(jsdouble d);
 233
 234 /*
 235  * Similar to strtod except that it replaces overflows with infinities of the
 236  * correct sign, and underflows with zeros of the correct sign.  Guaranteed to
 237  * return the closest double number to the given input in dp.
 238  *
 239  * Also allows inputs of the form [+|-]Infinity, which produce an infinity of
 240  * the appropriate sign.  The case of the "Infinity" string must match exactly.
 241  * If the string does not contain a number, set *ep to s and return 0.0 in dp.
 242  * Return false if out of memory.
 243  */
 244 extern JSBool
 245 js_strtod(JSContext *cx, const jschar *s, const jschar *send,
 246           const jschar **ep, jsdouble *dp);
 247
 248 /*
 249  * Similar to strtol except that it handles integers of arbitrary size.
 250  * Guaranteed to return the closest double number to the given input when radix
 251  * is 10 or a power of 2.  Callers may see round-off errors for very large
 252  * numbers of a different radix than 10 or a power of 2.
 253  *
 254  * If the string does not contain a number, set *ep to s and return 0.0 in dp.
 255  * Return false if out of memory.
 256  */
 257 extern JSBool
 258 js_strtointeger(JSContext *cx, const jschar *s, const jschar *send,
 259                 const jschar **ep, jsint radix, jsdouble *dp);
 260
 261 JS_END_EXTERN_C
 262
 263 #endif /* jsnum_h___ */