[ViewVC] Diff of: cvs/libecb/ecb.pod

Comparing libecb/ecb.pod (file contents):
Revision 1.44 by root, Tue May 29 14:30:44 2012 UTC vs.
Revision 1.59 by sf-exg, Mon Jan 26 12:04:56 2015 UTC

…		…
60		60
61	ecb.h makes sure that the following types are defined (in the expected way):	61	ecb.h makes sure that the following types are defined (in the expected way):
62		62
63	int8_t uint8_t int16_t uint16_t	63	int8_t uint8_t int16_t uint16_t
64	int32_t uint32_t int64_t uint64_t	64	int32_t uint32_t int64_t uint64_t
65	intptr_t uintptr_t ptrdiff_t	65	intptr_t uintptr_t
66		66
67	The macro C<ECB_PTRSIZE> is defined to the size of a pointer on this	67	The macro C<ECB_PTRSIZE> is defined to the size of a pointer on this
68	platform (currently C<4> or C<8>).	68	platform (currently C<4> or C<8>) and can be used in preprocessor
		69	expressions.
		70
		71	For C<ptrdiff_t> and C<size_t> use C<stddef.h>.
69		72
70	=head2 LANGUAGE/COMPILER VERSIONS	73	=head2 LANGUAGE/COMPILER VERSIONS
71		74
72	All the following symbols expand to an expressionb that cna be tested in	75	All the following symbols expand to an expression that can be tested in
73	preprocessor instructions as well as treated as a boolean (use C<!!> to	76	preprocessor instructions as well as treated as a boolean (use C<!!> to
74	ensure it's either C<0> or C<1> if you need that).	77	ensure it's either C<0> or C<1> if you need that).
75		78
76	=over 4	79	=over 4
77		80
78	=item ECB_C	81	=item ECB_C
79		82
80	True if the implementation defines the C<__STDC__> macro to a true value,	83	True if the implementation defines the C<__STDC__> macro to a true value,
81	which is typically true for both C and C++ compilers.	84	while not claiming to be C++.
82		85
83	=item ECB_C99	86	=item ECB_C99
84		87
85	True if the implementation claims to be C99 compliant.	88	True if the implementation claims to be compliant to C99 (ISO/IEC
		89	9899:1999) or any later version, while not claiming to be C++.
		90
		91	Note that later versions (ECB_C11) remove core features again (for
		92	example, variable length arrays).
86		93
87	=item ECB_C11	94	=item ECB_C11
88		95
89	True if the implementation claims to be C11 compliant.	96	True if the implementation claims to be compliant to C11 (ISO/IEC
		97	9899:2011) or any later version, while not claiming to be C++.
90		98
91	=item ECB_CPP	99	=item ECB_CPP
92		100
93	True if the implementation defines the C<__cplusplus__> macro to a true	101	True if the implementation defines the C<__cplusplus__> macro to a true
94	value, which is typically true for C++ compilers.	102	value, which is typically true for C++ compilers.
95		103
96	=item ECB_CPP98
97
98	True if the implementation claims to be compliant to ISO/IEC 14882:1998
99	(the first C++ ISO standard) or any later vwersion. Typically true for all
100	C++ compilers.
101
102	=item ECB_CPP11	104	=item ECB_CPP11
103		105
104	True if the implementation claims to be compliant to ISO/IEC 14882:2011	106	True if the implementation claims to be compliant to ISO/IEC 14882:2011
105	(C++11) or any later vwersion.	107	(C++11) or any later version.
106		108
107	=item ECB_GCC_VERSION(major,minor)	109	=item ECB_GCC_VERSION (major, minor)
108		110
109	Expands to a true value (suitable for testing in by the preprocessor)	111	Expands to a true value (suitable for testing in by the preprocessor)
110	if the compiler used is GNU C and the version is the givne version, or	112	if the compiler used is GNU C and the version is the given version, or
111	higher.	113	higher.
112		114
113	This macro tries to return false on compilers that claim to be GCC	115	This macro tries to return false on compilers that claim to be GCC
114	compatible but aren't.	116	compatible but aren't.
		117
		118	=item ECB_EXTERN_C
		119
		120	Expands to C<extern "C"> in C++, and a simple C<extern> in C.
		121
		122	This can be used to declare a single external C function:
		123
		124	ECB_EXTERN_C int printf (const char *format, ...);
		125
		126	=item ECB_EXTERN_C_BEG / ECB_EXTERN_C_END
		127
		128	These two macros can be used to wrap multiple C<extern "C"> definitions -
		129	they expand to nothing in C.
		130
		131	They are most useful in header files:
		132
		133	ECB_EXTERN_C_BEG
		134
		135	int mycfun1 (int x);
		136	int mycfun2 (int x);
		137
		138	ECB_EXTERN_C_END
		139
		140	=item ECB_STDFP
		141
		142	If this evaluates to a true value (suitable for testing in by the
		143	preprocessor), then C<float> and C<double> use IEEE 754 single/binary32
		144	and double/binary64 representations internally I<and> the endianness of
		145	both types match the endianness of C<uint32_t> and C<uint64_t>.
		146
		147	This means you can just copy the bits of a C<float> (or C<double>) to an
		148	C<uint32_t> (or C<uint64_t>) and get the raw IEEE 754 bit representation
		149	without having to think about format or endianness.
		150
		151	This is true for basically all modern platforms, although F<ecb.h> might
		152	not be able to deduce this correctly everywhere and might err on the safe
		153	side.
		154
		155	=item ECB_AMD64, ECB_AMD64_X32
		156
		157	These two macros are defined to C<1> on the x86_64/amd64 ABI and the X32
		158	ABI, respectively, and undefined elsewhere.
		159
		160	The designers of the new X32 ABI for some inexplicable reason decided to
		161	make it look exactly like amd64, even though it's completely incompatible
		162	to that ABI, breaking about every piece of software that assumed that
		163	C<__x86_64> stands for, well, the x86-64 ABI, making these macros
		164	necessary.
115		165
116	=back	166	=back
117		167
118	=head2 GCC ATTRIBUTES	168	=head2 GCC ATTRIBUTES
119		169
…		…
135		185
136	=over 4	186	=over 4
137		187
138	=item ecb_attribute ((attrs...))	188	=item ecb_attribute ((attrs...))
139		189
140	A simple wrapper that expands to C<__attribute__((attrs))> on GCC, and to	190	A simple wrapper that expands to C<__attribute__((attrs))> on GCC 3.1+ and
141	nothing on other compilers, so the effect is that only GCC sees these.	191	Clang 2.8+, and to nothing on other compilers, so the effect is that only
		192	GCC and Clang see these.
142		193
143	Example: use the C<deprecated> attribute on a function.	194	Example: use the C<deprecated> attribute on a function.
144		195
145	ecb_attribute((__deprecated__)) void	196	ecb_attribute((__deprecated__)) void
146	do_not_use_me_anymore (void);	197	do_not_use_me_anymore (void);
…		…
160	#else	211	#else
161	return 0;	212	return 0;
162	#endif	213	#endif
163	}	214	}
164		215
		216	=item ecb_deprecated
		217
		218	Similar to C<ecb_unused>, but marks a function, variable or type as
		219	deprecated. This makes some compilers warn when the type is used.
		220
165	=item ecb_inline	221	=item ecb_inline
166		222
167	This is not actually an attribute, but you use it like one. It expands	223	This is not actually an attribute, but you use it like one. It expands
168	either to C<static inline> or to just C<static>, if inline isn't	224	either to C<static inline> or to just C<static>, if inline isn't
169	supported. It should be used to declare functions that should be inlined,	225	supported. It should be used to declare functions that should be inlined,
…		…
197	}	253	}
198		254
199	In this case, the compiler would probably be smart enough to deduce it on	255	In this case, the compiler would probably be smart enough to deduce it on
200	its own, so this is mainly useful for declarations.	256	its own, so this is mainly useful for declarations.
201		257
		258	=item ecb_restrict
		259
		260	Expands to the C<restrict> keyword or equivalent on compilers that support
		261	them, and to nothing on others. Must be specified on a pointer type or
		262	an array index to indicate that the memory doesn't alias with any other
		263	restricted pointer in the same scope.
		264
		265	Example: multiply a vector, and allow the compiler to parallelise the
		266	loop, because it knows it doesn't overwrite input values.
		267
		268	void
		269	multiply (float *ecb_restrict src,
		270	float *ecb_restrict dst,
		271	int len, float factor)
		272	{
		273	int i;
		274
		275	for (i = 0; i < len; ++i)
		276	dst [i] = src [i] * factor;
		277	}
		278
202	=item ecb_const	279	=item ecb_const
203		280
204	Declares that the function only depends on the values of its arguments,	281	Declares that the function only depends on the values of its arguments,
205	much like a mathematical function. It specifically does not read or write	282	much like a mathematical function. It specifically does not read or write
206	any memory any arguments might point to, global variables, or call any	283	any memory any arguments might point to, global variables, or call any
…		…
266	functions only called in exceptional or rare cases.	343	functions only called in exceptional or rare cases.
267		344
268	=item ecb_artificial	345	=item ecb_artificial
269		346
270	Declares the function as "artificial", in this case meaning that this	347	Declares the function as "artificial", in this case meaning that this
271	function is not really mean to be a function, but more like an accessor	348	function is not really meant to be a function, but more like an accessor
272	- many methods in C++ classes are mere accessor functions, and having a	349	- many methods in C++ classes are mere accessor functions, and having a
273	crash reported in such a method, or single-stepping through them, is not	350	crash reported in such a method, or single-stepping through them, is not
274	usually so helpful, especially when it's inlined to just a few instructions.	351	usually so helpful, especially when it's inlined to just a few instructions.
275		352
276	Marking them as artificial will instruct the debugger about just this,	353	Marking them as artificial will instruct the debugger about just this,
…		…
296		373
297	=head2 OPTIMISATION HINTS	374	=head2 OPTIMISATION HINTS
298		375
299	=over 4	376	=over 4
300		377
301	=item bool ecb_is_constant(expr)	378	=item bool ecb_is_constant (expr)
302		379
303	Returns true iff the expression can be deduced to be a compile-time	380	Returns true iff the expression can be deduced to be a compile-time
304	constant, and false otherwise.	381	constant, and false otherwise.
305		382
306	For example, when you have a C<rndm16> function that returns a 16 bit	383	For example, when you have a C<rndm16> function that returns a 16 bit
…		…
572	to "optimal" code (e.g. a single C<rol> or a combination of C<shld> on	649	to "optimal" code (e.g. a single C<rol> or a combination of C<shld> on
573	x86).	650	x86).
574		651
575	=back	652	=back
576		653
		654	=head2 FLOATING POINT FIDDLING
		655
		656	=over 4
		657
		658	=item uint32_t ecb_float_to_binary32 (float x) [-UECB_NO_LIBM]
		659
		660	=item uint64_t ecb_double_to_binary64 (double x) [-UECB_NO_LIBM]
		661
		662	These functions each take an argument in the native C<float> or C<double>
		663	type and return the IEEE 754 bit representation of it.
		664
		665	The bit representation is just as IEEE 754 defines it, i.e. the sign bit
		666	will be the most significant bit, followed by exponent and mantissa.
		667
		668	This function should work even when the native floating point format isn't
		669	IEEE compliant, of course at a speed and code size penalty, and of course
		670	also within reasonable limits (it tries to convert NaNs, infinities and
		671	denormals, but will likely convert negative zero to positive zero).
		672
		673	On all modern platforms (where C<ECB_STDFP> is true), the compiler should
		674	be able to optimise away this function completely.
		675
		676	These functions can be helpful when serialising floats to the network - you
		677	can serialise the return value like a normal uint32_t/uint64_t.
		678
		679	Another use for these functions is to manipulate floating point values
		680	directly.
		681
		682	Silly example: toggle the sign bit of a float.
		683
		684	/* On gcc-4.7 on amd64, */
		685	/* this results in a single add instruction to toggle the bit, and 4 extra */
		686	/* instructions to move the float value to an integer register and back. */
		687
		688	x = ecb_binary32_to_float (ecb_float_to_binary32 (x) ^ 0x80000000U)
		689
		690	=item float ecb_binary16_to_float (uint16_t x) [-UECB_NO_LIBM]
		691
		692	=item float ecb_binary32_to_float (uint32_t x) [-UECB_NO_LIBM]
		693
		694	=item double ecb_binary32_to_double (uint64_t x) [-UECB_NO_LIBM]
		695
		696	The reverse operation of the previous function - takes the bit
		697	representation of an IEEE binary16, binary32 or binary64 number and
		698	converts it to the native C<float> or C<double> format.
		699
		700	This function should work even when the native floating point format isn't
		701	IEEE compliant, of course at a speed and code size penalty, and of course
		702	also within reasonable limits (it tries to convert normals and denormals,
		703	and might be lucky for infinities, and with extraordinary luck, also for
		704	negative zero).
		705
		706	On all modern platforms (where C<ECB_STDFP> is true), the compiler should
		707	be able to optimise away this function completely.
		708
		709	=back
		710
577	=head2 ARITHMETIC	711	=head2 ARITHMETIC
578		712
579	=over 4	713	=over 4
580		714
581	=item x = ecb_mod (m, n)	715	=item x = ecb_mod (m, n)
…		…
635		769
636	These symbols need to be defined before including F<ecb.h> the first time.	770	These symbols need to be defined before including F<ecb.h> the first time.
637		771
638	=over 4	772	=over 4
639		773
640	=item ECB_NO_THRADS	774	=item ECB_NO_THREADS
641		775
642	If F<ecb.h> is never used from multiple threads, then this symbol can	776	If F<ecb.h> is never used from multiple threads, then this symbol can
643	be defined, in which case memory fences (and similar constructs) are	777	be defined, in which case memory fences (and similar constructs) are
644	completely removed, leading to more efficient code and fewer dependencies.	778	completely removed, leading to more efficient code and fewer dependencies.
645		779
…		…
651	multiple threads, but never concurrently (e.g. if the system the program	785	multiple threads, but never concurrently (e.g. if the system the program
652	runs on has only a single CPU with a single core, no hyperthreading and so	786	runs on has only a single CPU with a single core, no hyperthreading and so
653	on), then this symbol can be defined, leading to more efficient code and	787	on), then this symbol can be defined, leading to more efficient code and
654	fewer dependencies.	788	fewer dependencies.
655		789
		790	=item ECB_NO_LIBM
		791
		792	When defined to C<1>, do not export any functions that might introduce
		793	dependencies on the math library (usually called F<-lm>) - these are
		794	marked with [-UECB_NO_LIBM].
		795
656	=back	796	=back
657		797
658		798

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Comparing libecb/ecb.pod (file contents): Revision 1.44 by root, Tue May 29 14:30:44 2012 UTC vs. Revision 1.59 by sf-exg, Mon Jan 26 12:04:56 2015 UTC

Diff Legend

Comparing libecb/ecb.pod (file contents):
Revision 1.44 by root, Tue May 29 14:30:44 2012 UTC vs.
Revision 1.59 by sf-exg, Mon Jan 26 12:04:56 2015 UTC