libgcc.texi revision 259563
1@c Copyright (C) 2003, 2004, 2005 Free Software Foundation, Inc.
2@c This is part of the GCC manual.
3@c For copying conditions, see the file gcc.texi.
4@c Contributed by Aldy Hernandez <aldy@quesejoda.com>
5
6@node Libgcc
7@chapter The GCC low-level runtime library
8
9GCC provides a low-level runtime library, @file{libgcc.a} or
10@file{libgcc_s.so.1} on some platforms.  GCC generates calls to
11routines in this library automatically, whenever it needs to perform
12some operation that is too complicated to emit inline code for.
13
14Most of the routines in @code{libgcc} handle arithmetic operations
15that the target processor cannot perform directly.  This includes
16integer multiply and divide on some machines, and all floating-point
17operations on other machines.  @code{libgcc} also includes routines
18for exception handling, and a handful of miscellaneous operations.
19
20Some of these routines can be defined in mostly machine-independent C@.
21Others must be hand-written in assembly language for each processor
22that needs them.
23
24GCC will also generate calls to C library routines, such as
25@code{memcpy} and @code{memset}, in some cases.  The set of routines
26that GCC may possibly use is documented in @ref{Other
27Builtins,,,gcc, Using the GNU Compiler Collection (GCC)}.
28
29These routines take arguments and return values of a specific machine
30mode, not a specific C type.  @xref{Machine Modes}, for an explanation
31of this concept.  For illustrative purposes, in this chapter the
32floating point type @code{float} is assumed to correspond to @code{SFmode};
33@code{double} to @code{DFmode}; and @code{@w{long double}} to both
34@code{TFmode} and @code{XFmode}.  Similarly, the integer types @code{int}
35and @code{@w{unsigned int}} correspond to @code{SImode}; @code{long} and
36@code{@w{unsigned long}} to @code{DImode}; and @code{@w{long long}} and
37@code{@w{unsigned long long}} to @code{TImode}.
38
39@menu
40* Integer library routines::
41* Soft float library routines::
42* Decimal float library routines::
43* Exception handling routines::
44* Miscellaneous routines::
45@end menu
46
47@node Integer library routines
48@section Routines for integer arithmetic
49
50The integer arithmetic routines are used on platforms that don't provide
51hardware support for arithmetic operations on some modes.
52
53@subsection Arithmetic functions
54
55@deftypefn {Runtime Function} int __ashlsi3 (int @var{a}, int @var{b})
56@deftypefnx {Runtime Function} long __ashldi3 (long @var{a}, int @var{b})
57@deftypefnx {Runtime Function} {long long} __ashlti3 (long long @var{a}, int @var{b})
58These functions return the result of shifting @var{a} left by @var{b} bits.
59@end deftypefn
60
61@deftypefn {Runtime Function} int __ashrsi3 (int @var{a}, int @var{b})
62@deftypefnx {Runtime Function} long __ashrdi3 (long @var{a}, int @var{b})
63@deftypefnx {Runtime Function} {long long} __ashrti3 (long long @var{a}, int @var{b})
64These functions return the result of arithmetically shifting @var{a} right
65by @var{b} bits.
66@end deftypefn
67
68@deftypefn {Runtime Function} int __divsi3 (int @var{a}, int @var{b})
69@deftypefnx {Runtime Function} long __divdi3 (long @var{a}, long @var{b})
70@deftypefnx {Runtime Function} {long long} __divti3 (long long @var{a}, long long @var{b})
71These functions return the quotient of the signed division of @var{a} and
72@var{b}.
73@end deftypefn
74
75@deftypefn {Runtime Function} int __lshrsi3 (int @var{a}, int @var{b})
76@deftypefnx {Runtime Function} long __lshrdi3 (long @var{a}, int @var{b})
77@deftypefnx {Runtime Function} {long long} __lshrti3 (long long @var{a}, int @var{b})
78These functions return the result of logically shifting @var{a} right by
79@var{b} bits.
80@end deftypefn
81
82@deftypefn {Runtime Function} int __modsi3 (int @var{a}, int @var{b})
83@deftypefnx {Runtime Function} long __moddi3 (long @var{a}, long @var{b})
84@deftypefnx {Runtime Function} {long long} __modti3 (long long @var{a}, long long @var{b})
85These functions return the remainder of the signed division of @var{a}
86and @var{b}.
87@end deftypefn
88
89@deftypefn {Runtime Function} int __mulsi3 (int @var{a}, int @var{b})
90@deftypefnx {Runtime Function} long __muldi3 (long @var{a}, long @var{b})
91@deftypefnx {Runtime Function} {long long} __multi3 (long long @var{a}, long long @var{b})
92These functions return the product of @var{a} and @var{b}.
93@end deftypefn
94
95@deftypefn {Runtime Function} long __negdi2 (long @var{a})
96@deftypefnx {Runtime Function} {long long} __negti2 (long long @var{a})
97These functions return the negation of @var{a}.
98@end deftypefn
99
100@deftypefn {Runtime Function} {unsigned int} __udivsi3 (unsigned int @var{a}, unsigned int @var{b})
101@deftypefnx {Runtime Function} {unsigned long} __udivdi3 (unsigned long @var{a}, unsigned long @var{b})
102@deftypefnx {Runtime Function} {unsigned long long} __udivti3 (unsigned long long @var{a}, unsigned long long @var{b})
103These functions return the quotient of the unsigned division of @var{a}
104and @var{b}.
105@end deftypefn
106
107@deftypefn {Runtime Function} {unsigned long} __udivmoddi3 (unsigned long @var{a}, unsigned long @var{b}, unsigned long *@var{c})
108@deftypefnx {Runtime Function} {unsigned long long} __udivti3 (unsigned long long @var{a}, unsigned long long @var{b}, unsigned long long *@var{c})
109These functions calculate both the quotient and remainder of the unsigned
110division of @var{a} and @var{b}.  The return value is the quotient, and
111the remainder is placed in variable pointed to by @var{c}.
112@end deftypefn
113
114@deftypefn {Runtime Function} {unsigned int} __umodsi3 (unsigned int @var{a}, unsigned int @var{b})
115@deftypefnx {Runtime Function} {unsigned long} __umoddi3 (unsigned long @var{a}, unsigned long @var{b})
116@deftypefnx {Runtime Function} {unsigned long long} __umodti3 (unsigned long long @var{a}, unsigned long long @var{b})
117These functions return the remainder of the unsigned division of @var{a}
118and @var{b}.
119@end deftypefn
120
121@subsection Comparison functions
122
123The following functions implement integral comparisons.  These functions
124implement a low-level compare, upon which the higher level comparison
125operators (such as less than and greater than or equal to) can be
126constructed.  The returned values lie in the range zero to two, to allow
127the high-level operators to be implemented by testing the returned
128result using either signed or unsigned comparison.
129
130@deftypefn {Runtime Function} int __cmpdi2 (long @var{a}, long @var{b})
131@deftypefnx {Runtime Function} int __cmpti2 (long long @var{a}, long long @var{b})
132These functions perform a signed comparison of @var{a} and @var{b}.  If
133@var{a} is less than @var{b}, they return 0; if @var{a} is greater than
134@var{b}, they return 2; and if @var{a} and @var{b} are equal they return 1.
135@end deftypefn
136
137@deftypefn {Runtime Function} int __ucmpdi2 (unsigned long @var{a}, unsigned long @var{b})
138@deftypefnx {Runtime Function} int __ucmpti2 (unsigned long long @var{a}, unsigned long long @var{b})
139These functions perform an unsigned comparison of @var{a} and @var{b}.
140If @var{a} is less than @var{b}, they return 0; if @var{a} is greater than
141@var{b}, they return 2; and if @var{a} and @var{b} are equal they return 1.
142@end deftypefn
143
144@subsection Trapping arithmetic functions
145
146The following functions implement trapping arithmetic.  These functions
147call the libc function @code{abort} upon signed arithmetic overflow.
148
149@deftypefn {Runtime Function} int __absvsi2 (int @var{a})
150@deftypefnx {Runtime Function} long __absvdi2 (long @var{a})
151These functions return the absolute value of @var{a}.
152@end deftypefn
153
154@deftypefn {Runtime Function} int __addvsi3 (int @var{a}, int @var{b})
155@deftypefnx {Runtime Function} long __addvdi3 (long @var{a}, long @var{b})
156These functions return the sum of @var{a} and @var{b}; that is
157@code{@var{a} + @var{b}}.
158@end deftypefn
159
160@deftypefn {Runtime Function} int __mulvsi3 (int @var{a}, int @var{b})
161@deftypefnx {Runtime Function} long __mulvdi3 (long @var{a}, long @var{b})
162The functions return the product of @var{a} and @var{b}; that is
163@code{@var{a} * @var{b}}.
164@end deftypefn
165
166@deftypefn {Runtime Function} int __negvsi2 (int @var{a})
167@deftypefnx {Runtime Function} long __negvdi2 (long @var{a})
168These functions return the negation of @var{a}; that is @code{-@var{a}}.
169@end deftypefn
170
171@deftypefn {Runtime Function} int __subvsi3 (int @var{a}, int @var{b})
172@deftypefnx {Runtime Function} long __subvdi3 (long @var{a}, long @var{b})
173These functions return the difference between @var{b} and @var{a};
174that is @code{@var{a} - @var{b}}.
175@end deftypefn
176
177@subsection Bit operations
178
179@deftypefn {Runtime Function} int __clzsi2 (int @var{a})
180@deftypefnx {Runtime Function} int __clzdi2 (long @var{a})
181@deftypefnx {Runtime Function} int __clzti2 (long long @var{a})
182These functions return the number of leading 0-bits in @var{a}, starting
183at the most significant bit position.  If @var{a} is zero, the result is
184undefined.
185@end deftypefn
186
187@deftypefn {Runtime Function} int __ctzsi2 (int @var{a})
188@deftypefnx {Runtime Function} int __ctzdi2 (long @var{a})
189@deftypefnx {Runtime Function} int __ctzti2 (long long @var{a})
190These functions return the number of trailing 0-bits in @var{a}, starting
191at the least significant bit position.  If @var{a} is zero, the result is
192undefined.
193@end deftypefn
194
195@deftypefn {Runtime Function} int __ffsdi2 (long @var{a})
196@deftypefnx {Runtime Function} int __ffsti2 (long long @var{a})
197These functions return the index of the least significant 1-bit in @var{a},
198or the value zero if @var{a} is zero.  The least significant bit is index
199one.
200@end deftypefn
201
202@deftypefn {Runtime Function} int __paritysi2 (int @var{a})
203@deftypefnx {Runtime Function} int __paritydi2 (long @var{a})
204@deftypefnx {Runtime Function} int __parityti2 (long long @var{a})
205These functions return the value zero if the number of bits set in
206@var{a} is even, and the value one otherwise.
207@end deftypefn
208
209@deftypefn {Runtime Function} int __popcountsi2 (int @var{a})
210@deftypefnx {Runtime Function} int __popcountdi2 (long @var{a})
211@deftypefnx {Runtime Function} int __popcountti2 (long long @var{a})
212These functions return the number of bits set in @var{a}.
213@end deftypefn
214
215@deftypefn {Runtime Function} int32_t __bswapsi2 (int32_t @var{a})
216@deftypefnx {Runtime Function} int64_t __bswapdi2 (int64_t @var{a})
217These functions return the @var{a} byteswapped.
218@end deftypefn
219
220@node Soft float library routines
221@section Routines for floating point emulation
222@cindex soft float library
223@cindex arithmetic library
224@cindex math library
225@opindex msoft-float
226
227The software floating point library is used on machines which do not
228have hardware support for floating point.  It is also used whenever
229@option{-msoft-float} is used to disable generation of floating point
230instructions.  (Not all targets support this switch.)
231
232For compatibility with other compilers, the floating point emulation
233routines can be renamed with the @code{DECLARE_LIBRARY_RENAMES} macro
234(@pxref{Library Calls}).  In this section, the default names are used.
235
236Presently the library does not support @code{XFmode}, which is used
237for @code{long double} on some architectures.
238
239@subsection Arithmetic functions
240
241@deftypefn {Runtime Function} float __addsf3 (float @var{a}, float @var{b})
242@deftypefnx {Runtime Function} double __adddf3 (double @var{a}, double @var{b})
243@deftypefnx {Runtime Function} {long double} __addtf3 (long double @var{a}, long double @var{b})
244@deftypefnx {Runtime Function} {long double} __addxf3 (long double @var{a}, long double @var{b})
245These functions return the sum of @var{a} and @var{b}.
246@end deftypefn
247
248@deftypefn {Runtime Function} float __subsf3 (float @var{a}, float @var{b})
249@deftypefnx {Runtime Function} double __subdf3 (double @var{a}, double @var{b})
250@deftypefnx {Runtime Function} {long double} __subtf3 (long double @var{a}, long double @var{b})
251@deftypefnx {Runtime Function} {long double} __subxf3 (long double @var{a}, long double @var{b})
252These functions return the difference between @var{b} and @var{a};
253that is, @w{@math{@var{a} - @var{b}}}.
254@end deftypefn
255
256@deftypefn {Runtime Function} float __mulsf3 (float @var{a}, float @var{b})
257@deftypefnx {Runtime Function} double __muldf3 (double @var{a}, double @var{b})
258@deftypefnx {Runtime Function} {long double} __multf3 (long double @var{a}, long double @var{b})
259@deftypefnx {Runtime Function} {long double} __mulxf3 (long double @var{a}, long double @var{b})
260These functions return the product of @var{a} and @var{b}.
261@end deftypefn
262
263@deftypefn {Runtime Function} float __divsf3 (float @var{a}, float @var{b})
264@deftypefnx {Runtime Function} double __divdf3 (double @var{a}, double @var{b})
265@deftypefnx {Runtime Function} {long double} __divtf3 (long double @var{a}, long double @var{b})
266@deftypefnx {Runtime Function} {long double} __divxf3 (long double @var{a}, long double @var{b})
267These functions return the quotient of @var{a} and @var{b}; that is,
268@w{@math{@var{a} / @var{b}}}.
269@end deftypefn
270
271@deftypefn {Runtime Function} float __negsf2 (float @var{a})
272@deftypefnx {Runtime Function} double __negdf2 (double @var{a})
273@deftypefnx {Runtime Function} {long double} __negtf2 (long double @var{a})
274@deftypefnx {Runtime Function} {long double} __negxf2 (long double @var{a})
275These functions return the negation of @var{a}.  They simply flip the
276sign bit, so they can produce negative zero and negative NaN@.
277@end deftypefn
278
279@subsection Conversion functions
280
281@deftypefn {Runtime Function} double __extendsfdf2 (float @var{a})
282@deftypefnx {Runtime Function} {long double} __extendsftf2 (float @var{a})
283@deftypefnx {Runtime Function} {long double} __extendsfxf2 (float @var{a})
284@deftypefnx {Runtime Function} {long double} __extenddftf2 (double @var{a})
285@deftypefnx {Runtime Function} {long double} __extenddfxf2 (double @var{a})
286These functions extend @var{a} to the wider mode of their return
287type.
288@end deftypefn
289
290@deftypefn {Runtime Function} double __truncxfdf2 (long double @var{a})
291@deftypefnx {Runtime Function} double __trunctfdf2 (long double @var{a})
292@deftypefnx {Runtime Function} float __truncxfsf2 (long double @var{a})
293@deftypefnx {Runtime Function} float __trunctfsf2 (long double @var{a})
294@deftypefnx {Runtime Function} float __truncdfsf2 (double @var{a})
295These functions truncate @var{a} to the narrower mode of their return
296type, rounding toward zero.
297@end deftypefn
298
299@deftypefn {Runtime Function} int __fixsfsi (float @var{a})
300@deftypefnx {Runtime Function} int __fixdfsi (double @var{a})
301@deftypefnx {Runtime Function} int __fixtfsi (long double @var{a})
302@deftypefnx {Runtime Function} int __fixxfsi (long double @var{a})
303These functions convert @var{a} to a signed integer, rounding toward zero.
304@end deftypefn
305
306@deftypefn {Runtime Function} long __fixsfdi (float @var{a})
307@deftypefnx {Runtime Function} long __fixdfdi (double @var{a})
308@deftypefnx {Runtime Function} long __fixtfdi (long double @var{a})
309@deftypefnx {Runtime Function} long __fixxfdi (long double @var{a})
310These functions convert @var{a} to a signed long, rounding toward zero.
311@end deftypefn
312
313@deftypefn {Runtime Function} {long long} __fixsfti (float @var{a})
314@deftypefnx {Runtime Function} {long long} __fixdfti (double @var{a})
315@deftypefnx {Runtime Function} {long long} __fixtfti (long double @var{a})
316@deftypefnx {Runtime Function} {long long} __fixxfti (long double @var{a})
317These functions convert @var{a} to a signed long long, rounding toward zero.
318@end deftypefn
319
320@deftypefn {Runtime Function} {unsigned int} __fixunssfsi (float @var{a})
321@deftypefnx {Runtime Function} {unsigned int} __fixunsdfsi (double @var{a})
322@deftypefnx {Runtime Function} {unsigned int} __fixunstfsi (long double @var{a})
323@deftypefnx {Runtime Function} {unsigned int} __fixunsxfsi (long double @var{a})
324These functions convert @var{a} to an unsigned integer, rounding
325toward zero.  Negative values all become zero.
326@end deftypefn
327
328@deftypefn {Runtime Function} {unsigned long} __fixunssfdi (float @var{a})
329@deftypefnx {Runtime Function} {unsigned long} __fixunsdfdi (double @var{a})
330@deftypefnx {Runtime Function} {unsigned long} __fixunstfdi (long double @var{a})
331@deftypefnx {Runtime Function} {unsigned long} __fixunsxfdi (long double @var{a})
332These functions convert @var{a} to an unsigned long, rounding
333toward zero.  Negative values all become zero.
334@end deftypefn
335
336@deftypefn {Runtime Function} {unsigned long long} __fixunssfti (float @var{a})
337@deftypefnx {Runtime Function} {unsigned long long} __fixunsdfti (double @var{a})
338@deftypefnx {Runtime Function} {unsigned long long} __fixunstfti (long double @var{a})
339@deftypefnx {Runtime Function} {unsigned long long} __fixunsxfti (long double @var{a})
340These functions convert @var{a} to an unsigned long long, rounding
341toward zero.  Negative values all become zero.
342@end deftypefn
343
344@deftypefn {Runtime Function} float __floatsisf (int @var{i})
345@deftypefnx {Runtime Function} double __floatsidf (int @var{i})
346@deftypefnx {Runtime Function} {long double} __floatsitf (int @var{i})
347@deftypefnx {Runtime Function} {long double} __floatsixf (int @var{i})
348These functions convert @var{i}, a signed integer, to floating point.
349@end deftypefn
350
351@deftypefn {Runtime Function} float __floatdisf (long @var{i})
352@deftypefnx {Runtime Function} double __floatdidf (long @var{i})
353@deftypefnx {Runtime Function} {long double} __floatditf (long @var{i})
354@deftypefnx {Runtime Function} {long double} __floatdixf (long @var{i})
355These functions convert @var{i}, a signed long, to floating point.
356@end deftypefn
357
358@deftypefn {Runtime Function} float __floattisf (long long @var{i})
359@deftypefnx {Runtime Function} double __floattidf (long long @var{i})
360@deftypefnx {Runtime Function} {long double} __floattitf (long long @var{i})
361@deftypefnx {Runtime Function} {long double} __floattixf (long long @var{i})
362These functions convert @var{i}, a signed long long, to floating point.
363@end deftypefn
364
365@deftypefn {Runtime Function} float __floatunsisf (unsigned int @var{i})
366@deftypefnx {Runtime Function} double __floatunsidf (unsigned int @var{i})
367@deftypefnx {Runtime Function} {long double} __floatunsitf (unsigned int @var{i})
368@deftypefnx {Runtime Function} {long double} __floatunsixf (unsigned int @var{i})
369These functions convert @var{i}, an unsigned integer, to floating point.
370@end deftypefn
371
372@deftypefn {Runtime Function} float __floatundisf (unsigned long @var{i})
373@deftypefnx {Runtime Function} double __floatundidf (unsigned long @var{i})
374@deftypefnx {Runtime Function} {long double} __floatunditf (unsigned long @var{i})
375@deftypefnx {Runtime Function} {long double} __floatundixf (unsigned long @var{i})
376These functions convert @var{i}, an unsigned long, to floating point.
377@end deftypefn
378
379@deftypefn {Runtime Function} float __floatuntisf (unsigned long long @var{i})
380@deftypefnx {Runtime Function} double __floatuntidf (unsigned long long @var{i})
381@deftypefnx {Runtime Function} {long double} __floatuntitf (unsigned long long @var{i})
382@deftypefnx {Runtime Function} {long double} __floatuntixf (unsigned long long @var{i})
383These functions convert @var{i}, an unsigned long long, to floating point.
384@end deftypefn
385
386@subsection Comparison functions
387
388There are two sets of basic comparison functions.
389
390@deftypefn {Runtime Function} int __cmpsf2 (float @var{a}, float @var{b})
391@deftypefnx {Runtime Function} int __cmpdf2 (double @var{a}, double @var{b})
392@deftypefnx {Runtime Function} int __cmptf2 (long double @var{a}, long double @var{b})
393These functions calculate @math{a <=> b}.  That is, if @var{a} is less
394than @var{b}, they return @minus{}1; if @var{a} is greater than @var{b}, they
395return 1; and if @var{a} and @var{b} are equal they return 0.  If
396either argument is NaN they return 1, but you should not rely on this;
397if NaN is a possibility, use one of the higher-level comparison
398functions.
399@end deftypefn
400
401@deftypefn {Runtime Function} int __unordsf2 (float @var{a}, float @var{b})
402@deftypefnx {Runtime Function} int __unorddf2 (double @var{a}, double @var{b})
403@deftypefnx {Runtime Function} int __unordtf2 (long double @var{a}, long double @var{b})
404These functions return a nonzero value if either argument is NaN, otherwise 0.
405@end deftypefn
406
407There is also a complete group of higher level functions which
408correspond directly to comparison operators.  They implement the ISO C
409semantics for floating-point comparisons, taking NaN into account.
410Pay careful attention to the return values defined for each set.
411Under the hood, all of these routines are implemented as
412
413@smallexample
414  if (__unord@var{X}f2 (a, b))
415    return @var{E};
416  return __cmp@var{X}f2 (a, b);
417@end smallexample
418
419@noindent
420where @var{E} is a constant chosen to give the proper behavior for
421NaN@.  Thus, the meaning of the return value is different for each set.
422Do not rely on this implementation; only the semantics documented
423below are guaranteed.
424
425@deftypefn {Runtime Function} int __eqsf2 (float @var{a}, float @var{b})
426@deftypefnx {Runtime Function} int __eqdf2 (double @var{a}, double @var{b})
427@deftypefnx {Runtime Function} int __eqtf2 (long double @var{a}, long double @var{b})
428These functions return zero if neither argument is NaN, and @var{a} and
429@var{b} are equal.
430@end deftypefn
431
432@deftypefn {Runtime Function} int __nesf2 (float @var{a}, float @var{b})
433@deftypefnx {Runtime Function} int __nedf2 (double @var{a}, double @var{b})
434@deftypefnx {Runtime Function} int __netf2 (long double @var{a}, long double @var{b})
435These functions return a nonzero value if either argument is NaN, or
436if @var{a} and @var{b} are unequal.
437@end deftypefn
438
439@deftypefn {Runtime Function} int __gesf2 (float @var{a}, float @var{b})
440@deftypefnx {Runtime Function} int __gedf2 (double @var{a}, double @var{b})
441@deftypefnx {Runtime Function} int __getf2 (long double @var{a}, long double @var{b})
442These functions return a value greater than or equal to zero if
443neither argument is NaN, and @var{a} is greater than or equal to
444@var{b}.
445@end deftypefn
446
447@deftypefn {Runtime Function} int __ltsf2 (float @var{a}, float @var{b})
448@deftypefnx {Runtime Function} int __ltdf2 (double @var{a}, double @var{b})
449@deftypefnx {Runtime Function} int __lttf2 (long double @var{a}, long double @var{b})
450These functions return a value less than zero if neither argument is
451NaN, and @var{a} is strictly less than @var{b}.
452@end deftypefn
453
454@deftypefn {Runtime Function} int __lesf2 (float @var{a}, float @var{b})
455@deftypefnx {Runtime Function} int __ledf2 (double @var{a}, double @var{b})
456@deftypefnx {Runtime Function} int __letf2 (long double @var{a}, long double @var{b})
457These functions return a value less than or equal to zero if neither
458argument is NaN, and @var{a} is less than or equal to @var{b}.
459@end deftypefn
460
461@deftypefn {Runtime Function} int __gtsf2 (float @var{a}, float @var{b})
462@deftypefnx {Runtime Function} int __gtdf2 (double @var{a}, double @var{b})
463@deftypefnx {Runtime Function} int __gttf2 (long double @var{a}, long double @var{b})
464These functions return a value greater than zero if neither argument
465is NaN, and @var{a} is strictly greater than @var{b}.
466@end deftypefn
467
468@subsection Other floating-point functions
469
470@deftypefn {Runtime Function} float __powisf2 (float @var{a}, int @var{b})
471@deftypefnx {Runtime Function} double __powidf2 (double @var{a}, int @var{b})
472@deftypefnx {Runtime Function} {long double} __powitf2 (long double @var{a}, int @var{b})
473@deftypefnx {Runtime Function} {long double} __powixf2 (long double @var{a}, int @var{b})
474These functions convert raise @var{a} to the power @var{b}.
475@end deftypefn
476
477@deftypefn {Runtime Function} {complex float} __mulsc3 (float @var{a}, float @var{b}, float @var{c}, float @var{d})
478@deftypefnx {Runtime Function} {complex double} __muldc3 (double @var{a}, double @var{b}, double @var{c}, double @var{d})
479@deftypefnx {Runtime Function} {complex long double} __multc3 (long double @var{a}, long double @var{b}, long double @var{c}, long double @var{d})
480@deftypefnx {Runtime Function} {complex long double} __mulxc3 (long double @var{a}, long double @var{b}, long double @var{c}, long double @var{d})
481These functions return the product of @math{@var{a} + i@var{b}} and
482@math{@var{c} + i@var{d}}, following the rules of C99 Annex G@.
483@end deftypefn
484
485@deftypefn {Runtime Function} {complex float} __divsc3 (float @var{a}, float @var{b}, float @var{c}, float @var{d})
486@deftypefnx {Runtime Function} {complex double} __divdc3 (double @var{a}, double @var{b}, double @var{c}, double @var{d})
487@deftypefnx {Runtime Function} {complex long double} __divtc3 (long double @var{a}, long double @var{b}, long double @var{c}, long double @var{d})
488@deftypefnx {Runtime Function} {complex long double} __divxc3 (long double @var{a}, long double @var{b}, long double @var{c}, long double @var{d})
489These functions return the quotient of @math{@var{a} + i@var{b}} and
490@math{@var{c} + i@var{d}} (i.e., @math{(@var{a} + i@var{b}) / (@var{c}
491+ i@var{d})}), following the rules of C99 Annex G@.
492@end deftypefn
493
494@node Decimal float library routines
495@section Routines for decimal floating point emulation
496@cindex decimal float library
497@cindex IEEE-754R
498
499The software decimal floating point library implements IEEE 754R
500decimal floating point arithmetic and is only activated on selected
501targets.
502
503@subsection Arithmetic functions
504
505@deftypefn {Runtime Function} _Decimal32 __addsd3 (_Decimal32 @var{a}, _Decimal32 @var{b})
506@deftypefnx {Runtime Function} _Decimal64 __adddd3 (_Decimal64 @var{a}, _Decimal64 @var{b})
507@deftypefnx {Runtime Function} _Decimal128 __addtd3 (_Decimal128 @var{a}, _Decimal128 @var{b})
508These functions return the sum of @var{a} and @var{b}.
509@end deftypefn
510
511@deftypefn {Runtime Function} _Decimal32 __subsd3 (_Decimal32 @var{a}, _Decimal32 @var{b})
512@deftypefnx {Runtime Function} _Decimal64 __subdd3 (_Decimal64 @var{a}, _Decimal64 @var{b})
513@deftypefnx {Runtime Function} _Decimal128 __subtd3 (_Decimal128 @var{a}, _Decimal128 @var{b})
514These functions return the difference between @var{b} and @var{a};
515that is, @w{@math{@var{a} - @var{b}}}.
516@end deftypefn
517
518@deftypefn {Runtime Function} _Decimal32 __mulsd3 (_Decimal32 @var{a}, _Decimal32 @var{b})
519@deftypefnx {Runtime Function} _Decimal64 __muldd3 (_Decimal64 @var{a}, _Decimal64 @var{b})
520@deftypefnx {Runtime Function} _Decimal128 __multd3 (_Decimal128 @var{a}, _Decimal128 @var{b})
521These functions return the product of @var{a} and @var{b}.
522@end deftypefn
523
524@deftypefn {Runtime Function} _Decimal32 __divsd3 (_Decimal32 @var{a}, _Decimal32 @var{b})
525@deftypefnx {Runtime Function} _Decimal64 __divdd3 (_Decimal64 @var{a}, _Decimal64 @var{b})
526@deftypefnx {Runtime Function} _Decimal128 __divtd3 (_Decimal128 @var{a}, _Decimal128 @var{b})
527These functions return the quotient of @var{a} and @var{b}; that is,
528@w{@math{@var{a} / @var{b}}}.
529@end deftypefn
530
531@deftypefn {Runtime Function} _Decimal32 __negsd2 (_Decimal32 @var{a})
532@deftypefnx {Runtime Function} _Decimal64 __negdd2 (_Decimal64 @var{a})
533@deftypefnx {Runtime Function} _Decimal128 __negtd2 (_Decimal128 @var{a})
534These functions return the negation of @var{a}.  They simply flip the
535sign bit, so they can produce negative zero and negative NaN@.
536@end deftypefn
537
538@subsection Conversion functions
539
540@c DFP/DFP conversions
541@deftypefn {Runtime Function} _Decimal64 __extendsddd2 (_Decimal32 @var{a})
542@deftypefnx {Runtime Function} _Decimal128 __extendsdtd2 (_Decimal32 @var{a})
543@deftypefnx {Runtime Function} _Decimal128 __extendddtd2 (_Decimal64 @var{a})
544@c DFP/binary FP conversions
545@deftypefnx {Runtime Function} _Decimal32 __extendsfsd (float @var{a})
546@deftypefnx {Runtime Function} double __extendsddf (_Decimal32 @var{a})
547@deftypefnx {Runtime Function} {long double} __extendsdxf (_Decimal32 @var{a})
548@deftypefnx {Runtime Function} _Decimal64 __extendsfdd (float @var{a})
549@deftypefnx {Runtime Function} _Decimal64 __extenddfdd (double @var{a})
550@deftypefnx {Runtime Function} {long double} __extendddxf (_Decimal64 @var{a})
551@deftypefnx {Runtime Function} _Decimal128 __extendsftd (float @var{a})
552@deftypefnx {Runtime Function} _Decimal128 __extenddftd (double @var{a})
553@deftypefnx {Runtime Function} _Decimal128 __extendxftd ({long double} @var{a})
554These functions extend @var{a} to the wider mode of their return type.
555@end deftypefn
556
557@c DFP/DFP conversions
558@deftypefn {Runtime Function} _Decimal32 __truncddsd2 (_Decimal64 @var{a})
559@deftypefnx {Runtime Function} _Decimal32 __trunctdsd2 (_Decimal128 @var{a})
560@deftypefnx {Runtime Function} _Decimal64 __trunctddd2 (_Decimal128 @var{a})
561@c DFP/binary FP conversions
562@deftypefnx {Runtime Function} float __truncsdsf (_Decimal32 @var{a})
563@deftypefnx {Runtime Function} _Decimal32 __truncdfsd (double @var{a})
564@deftypefnx {Runtime Function} _Decimal32 __truncxfsd ({long double} @var{a})
565@deftypefnx {Runtime Function} float __truncddsf (_Decimal64 @var{a})
566@deftypefnx {Runtime Function} double __truncdddf (_Decimal64 @var{a})
567@deftypefnx {Runtime Function} _Decimal64 __truncxfdd ({long double} @var{a})
568@deftypefnx {Runtime Function} float __trunctdsf (_Decimal128 @var{a})
569@deftypefnx {Runtime Function} double __trunctddf (_Decimal128 @var{a})
570@deftypefnx {Runtime Function} {long double} __trunctdxf (_Decimal128 @var{a})
571These functions truncate @var{a} to the narrower mode of their return
572type.
573@end deftypefn
574
575@deftypefn {Runtime Function} int __fixsdsi (_Decimal32 @var{a})
576@deftypefnx {Runtime Function} int __fixddsi (_Decimal64 @var{a})
577@deftypefnx {Runtime Function} int __fixtdsi (_Decimal128 @var{a})
578These functions convert @var{a} to a signed integer.
579@end deftypefn
580
581@deftypefn {Runtime Function} long __fixsddi (_Decimal32 @var{a})
582@deftypefnx {Runtime Function} long __fixdddi (_Decimal64 @var{a})
583@deftypefnx {Runtime Function} long __fixtddi (_Decimal128 @var{a})
584These functions convert @var{a} to a signed long.
585@end deftypefn
586
587@deftypefn {Runtime Function} {unsigned int} __fixunssdsi (_Decimal32 @var{a})
588@deftypefnx {Runtime Function} {unsigned int} __fixunsddsi (_Decimal64 @var{a})
589@deftypefnx {Runtime Function} {unsigned int} __fixunstdsi (_Decimal128 @var{a})
590These functions convert @var{a} to an unsigned integer.  Negative values all become zero.
591@end deftypefn
592
593@deftypefn {Runtime Function} {unsigned long} __fixunssddi (_Decimal32 @var{a})
594@deftypefnx {Runtime Function} {unsigned long} __fixunsdddi (_Decimal64 @var{a})
595@deftypefnx {Runtime Function} {unsigned long} __fixunstddi (_Decimal128 @var{a})
596These functions convert @var{a} to an unsigned long.  Negative values
597all become zero.
598@end deftypefn
599
600@deftypefn {Runtime Function} _Decimal32 __floatsisd (int @var{i})
601@deftypefnx {Runtime Function} _Decimal64 __floatsidd (int @var{i})
602@deftypefnx {Runtime Function} _Decimal128 __floatsitd (int @var{i})
603These functions convert @var{i}, a signed integer, to decimal floating point.
604@end deftypefn
605
606@deftypefn {Runtime Function} _Decimal32 __floatdisd (long @var{i})
607@deftypefnx {Runtime Function} _Decimal64 __floatdidd (long @var{i})
608@deftypefnx {Runtime Function} _Decimal128 __floatditd (long @var{i})
609These functions convert @var{i}, a signed long, to decimal floating point.
610@end deftypefn
611
612@deftypefn {Runtime Function} _Decimal32 __floatunssisd (unsigned int @var{i})
613@deftypefnx {Runtime Function} _Decimal64 __floatunssidd (unsigned int @var{i})
614@deftypefnx {Runtime Function} _Decimal128 __floatunssitd (unsigned int @var{i})
615These functions convert @var{i}, an unsigned integer, to decimal floating point.
616@end deftypefn
617
618@deftypefn {Runtime Function} _Decimal32 __floatunsdisd (unsigned long @var{i})
619@deftypefnx {Runtime Function} _Decimal64 __floatunsdidd (unsigned long @var{i})
620@deftypefnx {Runtime Function} _Decimal128 __floatunsditd (unsigned long @var{i})
621These functions convert @var{i}, an unsigned long, to decimal floating point.
622@end deftypefn
623
624@subsection Comparison functions
625
626@deftypefn {Runtime Function} int __unordsd2 (_Decimal32 @var{a}, _Decimal32 @var{b})
627@deftypefnx {Runtime Function} int __unorddd2 (_Decimal64 @var{a}, _Decimal64 @var{b})
628@deftypefnx {Runtime Function} int __unordtd2 (_Decimal128 @var{a}, _Decimal128 @var{b})
629These functions return a nonzero value if either argument is NaN, otherwise 0.
630@end deftypefn
631
632There is also a complete group of higher level functions which
633correspond directly to comparison operators.  They implement the ISO C
634semantics for floating-point comparisons, taking NaN into account.
635Pay careful attention to the return values defined for each set.
636Under the hood, all of these routines are implemented as
637
638@smallexample
639  if (__unord@var{X}d2 (a, b))
640    return @var{E};
641  return __cmp@var{X}d2 (a, b);
642@end smallexample
643
644@noindent
645where @var{E} is a constant chosen to give the proper behavior for
646NaN@.  Thus, the meaning of the return value is different for each set.
647Do not rely on this implementation; only the semantics documented
648below are guaranteed.
649
650@deftypefn {Runtime Function} int __eqsd2 (_Decimal32 @var{a}, _Decimal32 @var{b})
651@deftypefnx {Runtime Function} int __eqdd2 (_Decimal64 @var{a}, _Decimal64 @var{b})
652@deftypefnx {Runtime Function} int __eqtd2 (_Decimal128 @var{a}, _Decimal128 @var{b})
653These functions return zero if neither argument is NaN, and @var{a} and
654@var{b} are equal.
655@end deftypefn
656
657@deftypefn {Runtime Function} int __nesd2 (_Decimal32 @var{a}, _Decimal32 @var{b})
658@deftypefnx {Runtime Function} int __nedd2 (_Decimal64 @var{a}, _Decimal64 @var{b})
659@deftypefnx {Runtime Function} int __netd2 (_Decimal128 @var{a}, _Decimal128 @var{b})
660These functions return a nonzero value if either argument is NaN, or
661if @var{a} and @var{b} are unequal.
662@end deftypefn
663
664@deftypefn {Runtime Function} int __gesd2 (_Decimal32 @var{a}, _Decimal32 @var{b})
665@deftypefnx {Runtime Function} int __gedd2 (_Decimal64 @var{a}, _Decimal64 @var{b})
666@deftypefnx {Runtime Function} int __getd2 (_Decimal128 @var{a}, _Decimal128 @var{b})
667These functions return a value greater than or equal to zero if
668neither argument is NaN, and @var{a} is greater than or equal to
669@var{b}.
670@end deftypefn
671
672@deftypefn {Runtime Function} int __ltsd2 (_Decimal32 @var{a}, _Decimal32 @var{b})
673@deftypefnx {Runtime Function} int __ltdd2 (_Decimal64 @var{a}, _Decimal64 @var{b})
674@deftypefnx {Runtime Function} int __lttd2 (_Decimal128 @var{a}, _Decimal128 @var{b})
675These functions return a value less than zero if neither argument is
676NaN, and @var{a} is strictly less than @var{b}.
677@end deftypefn
678
679@deftypefn {Runtime Function} int __lesd2 (_Decimal32 @var{a}, _Decimal32 @var{b})
680@deftypefnx {Runtime Function} int __ledd2 (_Decimal64 @var{a}, _Decimal64 @var{b})
681@deftypefnx {Runtime Function} int __letd2 (_Decimal128 @var{a}, _Decimal128 @var{b})
682These functions return a value less than or equal to zero if neither
683argument is NaN, and @var{a} is less than or equal to @var{b}.
684@end deftypefn
685
686@deftypefn {Runtime Function} int __gtsd2 (_Decimal32 @var{a}, _Decimal32 @var{b})
687@deftypefnx {Runtime Function} int __gtdd2 (_Decimal64 @var{a}, _Decimal64 @var{b})
688@deftypefnx {Runtime Function} int __gttd2 (_Decimal128 @var{a}, _Decimal128 @var{b})
689These functions return a value greater than zero if neither argument
690is NaN, and @var{a} is strictly greater than @var{b}.
691@end deftypefn
692
693@node Exception handling routines
694@section Language-independent routines for exception handling
695
696document me!
697
698@smallexample
699  _Unwind_DeleteException
700  _Unwind_Find_FDE
701  _Unwind_ForcedUnwind
702  _Unwind_GetGR
703  _Unwind_GetIP
704  _Unwind_GetLanguageSpecificData
705  _Unwind_GetRegionStart
706  _Unwind_GetTextRelBase
707  _Unwind_GetDataRelBase
708  _Unwind_RaiseException
709  _Unwind_Resume
710  _Unwind_SetGR
711  _Unwind_SetIP
712  _Unwind_FindEnclosingFunction
713  _Unwind_SjLj_Register
714  _Unwind_SjLj_Unregister
715  _Unwind_SjLj_RaiseException
716  _Unwind_SjLj_ForcedUnwind
717  _Unwind_SjLj_Resume
718  __deregister_frame
719  __deregister_frame_info
720  __deregister_frame_info_bases
721  __register_frame
722  __register_frame_info
723  __register_frame_info_bases
724  __register_frame_info_table
725  __register_frame_info_table_bases
726  __register_frame_table
727@end smallexample
728
729@node Miscellaneous routines
730@section Miscellaneous runtime library routines
731
732@subsection Cache control functions
733@deftypefn {Runtime Function} void __clear_cache (char *@var{beg}, char *@var{end})
734This function clears the instruction cache between @var{beg} and @var{end}.
735@end deftypefn
736