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.
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  24  * Contributor(s):
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  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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  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 /*
  44  * JS number (IEEE double) interface.
  45  *
  46  * JS numbers are optimistically stored in the top 31 bits of 32-bit integers,
  47  * but floating point literals, results that overflow 31 bits, and division and
  48  * modulus operands and results require a 64-bit IEEE double.  These are GC'ed
  49  * and pointed to by 32-bit jsvals on the stack and in object properties.
  50  */
  51
  52 JS_BEGIN_EXTERN_C
  53
  54 /*
  55  * The ARM architecture supports two floating point models: VFP and FPA. When
  56  * targetting FPA, doubles are mixed-endian on little endian ARMs (meaning that
  57  * the high and low words are in big endian order).
  58  */
  59 #if defined(__arm) || defined(__arm32__) || defined(__arm26__) || defined(__arm__)
  60 #if !defined(__VFP_FP__)
  61 #define FPU_IS_ARM_FPA
  62 #endif
  63 #endif
  64
  65 typedef union jsdpun {
  66     struct {
  67 #if defined(IS_LITTLE_ENDIAN) && !defined(FPU_IS_ARM_FPA)
  68         uint32 lo, hi;
  69 #else
  70         uint32 hi, lo;
  71 #endif
  72     } s;
  73     uint64   u64;
  74     jsdouble d;
  75 } jsdpun;
  76
  77 #if (__GNUC__ == 2 && __GNUC_MINOR__ > 95) || __GNUC__ > 2
  78 /*
  79  * This version of the macros is safe for the alias optimizations that gcc
  80  * does, but uses gcc-specific extensions.
  81  */
  82
  83 #define JSDOUBLE_HI32(x) (__extension__ ({ jsdpun u; u.d = (x); u.s.hi; }))
  84 #define JSDOUBLE_LO32(x) (__extension__ ({ jsdpun u; u.d = (x); u.s.lo; }))
  85 #define JSDOUBLE_SET_HI32(x, y) \
  86     (__extension__ ({ jsdpun u; u.d = (x); u.s.hi = (y); (x) = u.d; }))
  87 #define JSDOUBLE_SET_LO32(x, y) \
  88     (__extension__ ({ jsdpun u; u.d = (x); u.s.lo = (y); (x) = u.d; }))
  89
  90 #else /* not or old GNUC */
  91
  92 /*
  93  * We don't know of any non-gcc compilers that perform alias optimization,
  94  * so this code should work.
  95  */
  96
  97 #if defined(IS_LITTLE_ENDIAN) && !defined(FPU_IS_ARM_FPA)
  98 #define JSDOUBLE_HI32(x)        (((uint32 *)&(x))[1])
  99 #define JSDOUBLE_LO32(x)        (((uint32 *)&(x))[0])
 100 #else
 101 #define JSDOUBLE_HI32(x)        (((uint32 *)&(x))[0])
 102 #define JSDOUBLE_LO32(x)        (((uint32 *)&(x))[1])
 103 #endif
 104
 105 #define JSDOUBLE_SET_HI32(x, y) (JSDOUBLE_HI32(x)=(y))
 106 #define JSDOUBLE_SET_LO32(x, y) (JSDOUBLE_LO32(x)=(y))
 107
 108 #endif /* not or old GNUC */
 109
 110 #define JSDOUBLE_HI32_SIGNBIT   0x80000000
 111 #define JSDOUBLE_HI32_EXPMASK   0x7ff00000
 112 #define JSDOUBLE_HI32_MANTMASK  0x000fffff
 113
 114 #define JSDOUBLE_IS_NaN(x)                                                    \
 115     ((JSDOUBLE_HI32(x) & JSDOUBLE_HI32_EXPMASK) == JSDOUBLE_HI32_EXPMASK &&   \
 116      (JSDOUBLE_LO32(x) || (JSDOUBLE_HI32(x) & JSDOUBLE_HI32_MANTMASK)))
 117
 118 #define JSDOUBLE_IS_INFINITE(x)                                               \
 119     ((JSDOUBLE_HI32(x) & ~JSDOUBLE_HI32_SIGNBIT) == JSDOUBLE_HI32_EXPMASK &&  \
 120      !JSDOUBLE_LO32(x))
 121
 122 #define JSDOUBLE_IS_FINITE(x)                                                 \
 123     ((JSDOUBLE_HI32(x) & JSDOUBLE_HI32_EXPMASK) != JSDOUBLE_HI32_EXPMASK)
 124
 125 #define JSDOUBLE_IS_NEGZERO(d)  (JSDOUBLE_HI32(d) == JSDOUBLE_HI32_SIGNBIT && \
 126                                  JSDOUBLE_LO32(d) == 0)
 127
 128 /*
 129  * JSDOUBLE_IS_INT first checks that d is neither NaN nor infinite, to avoid
 130  * raising SIGFPE on platforms such as Alpha Linux, then (only if the cast is
 131  * safe) leaves i as (jsint)d.  This also avoid anomalous NaN floating point
 132  * comparisons under MSVC.
 133  */
 134 #define JSDOUBLE_IS_INT(d, i) (JSDOUBLE_IS_FINITE(d)                          \
 135                                && !JSDOUBLE_IS_NEGZERO(d)                     \
 136                                && ((d) == (i = (jsint)(d))))
 137
 138 #if defined(XP_WIN)
 139 #define JSDOUBLE_COMPARE(LVAL, OP, RVAL, IFNAN)                               \
 140     ((JSDOUBLE_IS_NaN(LVAL) || JSDOUBLE_IS_NaN(RVAL))                         \
 141      ? (IFNAN)                                                                \
 142      : (LVAL) OP (RVAL))
 143 #else
 144 #define JSDOUBLE_COMPARE(LVAL, OP, RVAL, IFNAN) ((LVAL) OP (RVAL))
 145 #endif
 146
 147 extern jsdouble js_NaN;
 148
 149 /* Initialize number constants and runtime state for the first context. */
 150 extern JSBool
 151 js_InitRuntimeNumberState(JSContext *cx);
 152
 153 extern void
 154 js_TraceRuntimeNumberState(JSTracer *trc);
 155
 156 extern void
 157 js_FinishRuntimeNumberState(JSContext *cx);
 158
 159 /* Initialize the Number class, returning its prototype object. */
 160 extern JSClass js_NumberClass;
 161
 162 extern JSObject *
 163 js_InitNumberClass(JSContext *cx, JSObject *obj);
 164
 165 /*
 166  * String constants for global function names, used in jsapi.c and jsnum.c.
 167  */
 168 extern const char js_Infinity_str[];
 169 extern const char js_NaN_str[];
 170 extern const char js_isNaN_str[];
 171 extern const char js_isFinite_str[];
 172 extern const char js_parseFloat_str[];
 173 extern const char js_parseInt_str[];
 174
 175 /*
 176  * vp must be a root.
 177  */
 178 extern JSBool
 179 js_NewNumberInRootedValue(JSContext *cx, jsdouble d, jsval *vp);
 180
 181 /* Convert a number to a GC'ed string. */
 182 extern JSString * JS_FASTCALL
 183 js_NumberToString(JSContext *cx, jsdouble d);
 184
 185 /*
 186  * Convert int to C string. The buf must be big enough for MIN_INT to fit
 187  * including '-' and '\0'.
 188  */
 189 char *
 190 js_IntToCString(jsint i, jsint base, char *buf, size_t bufSize);
 191
 192 /*
 193  * Convert a number to C string. The buf must be at least
 194  * DTOSTR_STANDARD_BUFFER_SIZE.
 195  */
 196 char *
 197 js_NumberToCString(JSContext *cx, jsdouble d, jsint base, char *buf, size_t bufSize);
 198
 199 /*
 200  * Convert a value to a number. On exit JSVAL_IS_NULL(*vp) iff there was an
 201  * error. If on exit JSVAL_IS_NUMBER(*vp), then *vp holds the jsval that
 202  * matches the result. Otherwise *vp is JSVAL_TRUE indicating that the jsval
 203  * for result has to be created explicitly using, for example, the
 204  * js_NewNumberInRootedValue function.
 205  */
 206 extern jsdouble
 207 js_ValueToNumber(JSContext *cx, jsval* vp);
 208
 209 /*
 210  * Convert a value to an int32 or uint32, according to the ECMA rules for
 211  * ToInt32 and ToUint32. On exit JSVAL_IS_NULL(*vp) iff there was an error. If
 212  * on exit JSVAL_IS_INT(*vp), then *vp holds the jsval matching the result.
 213  * Otherwise *vp is JSVAL_TRUE indicating that the jsval for result has to be
 214  * created explicitly using, for example, the js_NewNumberInRootedValue
 215  * function.
 216  */
 217 extern int32
 218 js_ValueToECMAInt32(JSContext *cx, jsval *vp);
 219
 220 extern uint32
 221 js_ValueToECMAUint32(JSContext *cx, jsval *vp);
 222
 223 /*
 224  * Specialized ToInt32 and ToUint32 converters for doubles.
 225  */
 226 extern int32
 227 js_DoubleToECMAInt32(jsdouble d);
 228
 229 extern uint32
 230 js_DoubleToECMAUint32(jsdouble d);
 231
 232 /*
 233  * Convert a value to a number, then to an int32 if it fits by rounding to
 234  * nearest; but failing with an error report if the double is out of range
 235  * or unordered. On exit JSVAL_IS_NULL(*vp) iff there was an error. If on exit
 236  * JSVAL_IS_INT(*vp), then *vp holds the jsval matching the result. Otherwise
 237  * *vp is JSVAL_TRUE indicating that the jsval for result has to be created
 238  * explicitly using, for example, the js_NewNumberInRootedValue function.
 239  */
 240 extern int32
 241 js_ValueToInt32(JSContext *cx, jsval *vp);
 242
 243 /*
 244  * Convert a value to a number, then to a uint16 according to the ECMA rules
 245  * for ToUint16. On exit JSVAL_IS_NULL(*vp) iff there was an error, otherwise
 246  * vp is jsval matching the result.
 247  */
 248 extern uint16
 249 js_ValueToUint16(JSContext *cx, jsval *vp);
 250
 251 /*
 252  * Convert a jsdouble to an integral number, stored in a jsdouble.
 253  * If d is NaN, return 0.  If d is an infinity, return it without conversion.
 254  */
 255 extern jsdouble
 256 js_DoubleToInteger(jsdouble d);
 257
 258 /*
 259  * Similar to strtod except that it replaces overflows with infinities of the
 260  * correct sign, and underflows with zeros of the correct sign.  Guaranteed to
 261  * return the closest double number to the given input in dp.
 262  *
 263  * Also allows inputs of the form [+|-]Infinity, which produce an infinity of
 264  * the appropriate sign.  The case of the "Infinity" string must match exactly.
 265  * If the string does not contain a number, set *ep to s and return 0.0 in dp.
 266  * Return false if out of memory.
 267  */
 268 extern JSBool
 269 js_strtod(JSContext *cx, const jschar *s, const jschar *send,
 270           const jschar **ep, jsdouble *dp);
 271
 272 /*
 273  * Similar to strtol except that it handles integers of arbitrary size.
 274  * Guaranteed to return the closest double number to the given input when radix
 275  * is 10 or a power of 2.  Callers may see round-off errors for very large
 276  * numbers of a different radix than 10 or a power of 2.
 277  *
 278  * If the string does not contain a number, set *ep to s and return 0.0 in dp.
 279  * Return false if out of memory.
 280  */
 281 extern JSBool
 282 js_strtointeger(JSContext *cx, const jschar *s, const jschar *send,
 283                 const jschar **ep, jsint radix, jsdouble *dp);
 284
 285 JS_END_EXTERN_C
 286
 287 #endif /* jsnum_h___ */