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

Comparing libecb/ecb.pod (file contents):
Revision 1.55 by root, Thu Jan 9 05:16:12 2014 UTC vs.
Revision 1.81 by root, Mon Jan 20 21:01:29 2020 UTC

…		…
58		58
59	=head2 TYPES / TYPE SUPPORT	59	=head2 TYPES / TYPE SUPPORT
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_
64	int32_t uint32_t int64_t uint64_t	64	int16_t uint16_t
		65	int32_t uint32_
		66	int64_t uint64_t
		67	int_fast8_t uint_fast8_t
		68	int_fast16_t uint_fast16_t
		69	int_fast32_t uint_fast32_t
		70	int_fast64_t uint_fast64_t
65	intptr_t uintptr_t	71	intptr_t uintptr_t
66		72
67	The macro C<ECB_PTRSIZE> is defined to the size of a pointer on this	73	The macro C<ECB_PTRSIZE> is defined to the size of a pointer on this
68	platform (currently C<4> or C<8>) and can be used in preprocessor	74	platform (currently C<4> or C<8>) and can be used in preprocessor
69	expressions.	75	expressions.
70		76
71	For C<ptrdiff_t> and C<size_t> use C<stddef.h>.	77	For C<ptrdiff_t> and C<size_t> use C<stddef.h>/C<cstddef>.
72		78
73	=head2 LANGUAGE/COMPILER VERSIONS	79	=head2 LANGUAGE/ENVIRONMENT/COMPILER VERSIONS
74		80
75	All the following symbols expand to an expression that can be tested in	81	All the following symbols expand to an expression that can be tested in
76	preprocessor instructions as well as treated as a boolean (use C<!!> to	82	preprocessor instructions as well as treated as a boolean (use C<!!> to
77	ensure it's either C<0> or C<1> if you need that).	83	ensure it's either C<0> or C<1> if you need that).
78		84
…		…
89	9899:1999) or any later version, while not claiming to be C++.	95	9899:1999) or any later version, while not claiming to be C++.
90		96
91	Note that later versions (ECB_C11) remove core features again (for	97	Note that later versions (ECB_C11) remove core features again (for
92	example, variable length arrays).	98	example, variable length arrays).
93		99
94	=item ECB_C11	100	=item ECB_C11, ECB_C17
95		101
96	True if the implementation claims to be compliant to C11 (ISO/IEC	102	True if the implementation claims to be compliant to C11/C17 (ISO/IEC
97	9899:2011) or any later version, while not claiming to be C++.	103	9899:2011, :20187) or any later version, while not claiming to be C++.
98		104
99	=item ECB_CPP	105	=item ECB_CPP
100		106
101	True if the implementation defines the C<__cplusplus__> macro to a true	107	True if the implementation defines the C<__cplusplus__> macro to a true
102	value, which is typically true for C++ compilers.	108	value, which is typically true for C++ compilers.
103		109
104	=item ECB_CPP11	110	=item ECB_CPP11, ECB_CPP14, ECB_CPP17
105		111
106	True if the implementation claims to be compliant to ISO/IEC 14882:2011	112	True if the implementation claims to be compliant to C++11/C++14/C++17
107	(C++11) or any later version.	113	(ISO/IEC 14882:2011, :2014, :2017) or any later version.
108		114
		115	=item ECB_OPTIMIZE_SIZE
		116
		117	Is C<1> when the compiler optimizes for size, C<0> otherwise. This symbol
		118	can also be defined before including F<ecb.h>, in which case it will be
		119	unchanged.
		120
109	=item ECB_GCC_VERSION(major,minor)	121	=item ECB_GCC_VERSION (major, minor)
110		122
111	Expands to a true value (suitable for testing in by the preprocessor)	123	Expands to a true value (suitable for testing in by the preprocessor)
112	if the compiler used is GNU C and the version is the given version, or	124	if the compiler used is GNU C and the version is the given version, or
113	higher.	125	higher.
114		126
…		…
163	C<__x86_64> stands for, well, the x86-64 ABI, making these macros	175	C<__x86_64> stands for, well, the x86-64 ABI, making these macros
164	necessary.	176	necessary.
165		177
166	=back	178	=back
167		179
		180	=head2 MACRO TRICKERY
		181
		182	=over 4
		183
		184	=item ECB_CONCAT (a, b)
		185
		186	Expands any macros in C<a> and C<b>, then concatenates the result to form
		187	a single token. This is mainly useful to form identifiers from components,
		188	e.g.:
		189
		190	#define S1 str
		191	#define S2 cpy
		192
		193	ECB_CONCAT (S1, S2)(dst, src); // == strcpy (dst, src);
		194
		195	=item ECB_STRINGIFY (arg)
		196
		197	Expands any macros in C<arg> and returns the stringified version of
		198	it. This is mainly useful to get the contents of a macro in string form,
		199	e.g.:
		200
		201	#define SQL_LIMIT 100
		202	sql_exec ("select * from table limit " ECB_STRINGIFY (SQL_LIMIT));
		203
		204	=item ECB_STRINGIFY_EXPR (expr)
		205
		206	Like C<ECB_STRINGIFY>, but additionally evaluates C<expr> to make sure it
		207	is a valid expression. This is useful to catch typos or cases where the
		208	macro isn't available:
		209
		210	#include <errno.h>
		211
		212	ECB_STRINGIFY (EDOM); // "33" (on my system at least)
		213	ECB_STRINGIFY_EXPR (EDOM); // "33"
		214
		215	// now imagine we had a typo:
		216
		217	ECB_STRINGIFY (EDAM); // "EDAM"
		218	ECB_STRINGIFY_EXPR (EDAM); // error: EDAM undefined
		219
		220	=back
		221
168	=head2 GCC ATTRIBUTES	222	=head2 ATTRIBUTES
169		223
170	A major part of libecb deals with GCC attributes. These are additional	224	A major part of libecb deals with additional attributes that can be
171	attributes that you can assign to functions, variables and sometimes even	225	assigned to functions, variables and sometimes even types - much like
172	types - much like C<const> or C<volatile> in C.	226	C<const> or C<volatile> in C. They are implemented using either GCC
173		227	attributes or other compiler/language specific features. Attributes
174	While GCC allows declarations to show up in many surprising places,
175	but not in many expected places, the safest way is to put attribute
176	declarations before the whole declaration:	228	declarations must be put before the whole declaration:
177		229
178	ecb_const int mysqrt (int a);	230	ecb_const int mysqrt (int a);
179	ecb_unused int i;	231	ecb_unused int i;
180		232
181	For variables, it is often nicer to put the attribute after the name, and
182	avoid multiple declarations using commas:
183
184	int i ecb_unused;
185
186	=over 4	233	=over 4
187
188	=item ecb_attribute ((attrs...))
189
190	A simple wrapper that expands to C<__attribute__((attrs))> on GCC, and to
191	nothing on other compilers, so the effect is that only GCC sees these.
192
193	Example: use the C<deprecated> attribute on a function.
194
195	ecb_attribute((__deprecated__)) void
196	do_not_use_me_anymore (void);
197		234
198	=item ecb_unused	235	=item ecb_unused
199		236
200	Marks a function or a variable as "unused", which simply suppresses a	237	Marks a function or a variable as "unused", which simply suppresses a
201	warning by GCC when it detects it as unused. This is useful when you e.g.	238	warning by GCC when it detects it as unused. This is useful when you e.g.
202	declare a variable but do not always use it:	239	declare a variable but do not always use it:
203		240
204	{	241	{
205	int var ecb_unused;	242	ecb_unused int var;
206		243
207	#ifdef SOMECONDITION	244	#ifdef SOMECONDITION
208	var = ...;	245	var = ...;
209	return var;	246	return var;
210	#else	247	#else
211	return 0;	248	return 0;
212	#endif	249	#endif
213	}	250	}
214		251
		252	=item ecb_deprecated
		253
		254	Similar to C<ecb_unused>, but marks a function, variable or type as
		255	deprecated. This makes some compilers warn when the type is used.
		256
		257	=item ecb_deprecated_message (message)
		258
		259	Same as C<ecb_deprecated>, but if possible, the specified diagnostic is
		260	used instead of a generic depreciation message when the object is being
		261	used.
		262
215	=item ecb_inline	263	=item ecb_inline
216		264
217	This is not actually an attribute, but you use it like one. It expands	265	Expands either to (a compiler-specific equivalent of) C<static inline> or
218	either to C<static inline> or to just C<static>, if inline isn't	266	to just C<static>, if inline isn't supported. It should be used to declare
219	supported. It should be used to declare functions that should be inlined,	267	functions that should be inlined, for code size or speed reasons.
220	for code size or speed reasons.
221		268
222	Example: inline this function, it surely will reduce codesize.	269	Example: inline this function, it surely will reduce codesize.
223		270
224	ecb_inline int	271	ecb_inline int
225	negmul (int a, int b)	272	negmul (int a, int b)
…		…
227	return - (a * b);	274	return - (a * b);
228	}	275	}
229		276
230	=item ecb_noinline	277	=item ecb_noinline
231		278
232	Prevent a function from being inlined - it might be optimised away, but	279	Prevents a function from being inlined - it might be optimised away, but
233	not inlined into other functions. This is useful if you know your function	280	not inlined into other functions. This is useful if you know your function
234	is rarely called and large enough for inlining not to be helpful.	281	is rarely called and large enough for inlining not to be helpful.
235		282
236	=item ecb_noreturn	283	=item ecb_noreturn
237		284
…		…
258		305
259	Example: multiply a vector, and allow the compiler to parallelise the	306	Example: multiply a vector, and allow the compiler to parallelise the
260	loop, because it knows it doesn't overwrite input values.	307	loop, because it knows it doesn't overwrite input values.
261		308
262	void	309	void
263	multiply (float *ecb_restrict src,	310	multiply (ecb_restrict float *src,
264	float *ecb_restrict dst,	311	ecb_restrict float *dst,
265	int len, float factor)	312	int len, float factor)
266	{	313	{
267	int i;	314	int i;
268		315
269	for (i = 0; i < len; ++i)	316	for (i = 0; i < len; ++i)
…		…
367		414
368	=head2 OPTIMISATION HINTS	415	=head2 OPTIMISATION HINTS
369		416
370	=over 4	417	=over 4
371		418
372	=item bool ecb_is_constant(expr)	419	=item bool ecb_is_constant (expr)
373		420
374	Returns true iff the expression can be deduced to be a compile-time	421	Returns true iff the expression can be deduced to be a compile-time
375	constant, and false otherwise.	422	constant, and false otherwise.
376		423
377	For example, when you have a C<rndm16> function that returns a 16 bit	424	For example, when you have a C<rndm16> function that returns a 16 bit
…		…
395	return is_constant (n) && !(n & (n - 1))	442	return is_constant (n) && !(n & (n - 1))
396	? rndm16 () & (num - 1)	443	? rndm16 () & (num - 1)
397	: (n * (uint32_t)rndm16 ()) >> 16;	444	: (n * (uint32_t)rndm16 ()) >> 16;
398	}	445	}
399		446
400	=item bool ecb_expect (expr, value)	447	=item ecb_expect (expr, value)
401		448
402	Evaluates C<expr> and returns it. In addition, it tells the compiler that	449	Evaluates C<expr> and returns it. In addition, it tells the compiler that
403	the C<expr> evaluates to C<value> a lot, which can be used for static	450	the C<expr> evaluates to C<value> a lot, which can be used for static
404	branch optimisations.	451	branch optimisations.
405		452
…		…
452	{	499	{
453	if (ecb_expect_false (current + size > end))	500	if (ecb_expect_false (current + size > end))
454	real_reserve_method (size); /* presumably noinline */	501	real_reserve_method (size); /* presumably noinline */
455	}	502	}
456		503
457	=item bool ecb_assume (cond)	504	=item ecb_assume (cond)
458		505
459	Try to tell the compiler that some condition is true, even if it's not	506	Tries to tell the compiler that some condition is true, even if it's not
460	obvious.	507	obvious. This is not a function, but a statement: it cannot be used in
		508	another expression.
461		509
462	This can be used to teach the compiler about invariants or other	510	This can be used to teach the compiler about invariants or other
463	conditions that might improve code generation, but which are impossible to	511	conditions that might improve code generation, but which are impossible to
464	deduce form the code itself.	512	deduce form the code itself.
465		513
…		…
482		530
483	Then the compiler I<might> be able to optimise out the second call	531	Then the compiler I<might> be able to optimise out the second call
484	completely, as it knows that C<< current + 1 > end >> is false and the	532	completely, as it knows that C<< current + 1 > end >> is false and the
485	call will never be executed.	533	call will never be executed.
486		534
487	=item bool ecb_unreachable ()	535	=item ecb_unreachable ()
488		536
489	This function does nothing itself, except tell the compiler that it will	537	This function does nothing itself, except tell the compiler that it will
490	never be executed. Apart from suppressing a warning in some cases, this	538	never be executed. Apart from suppressing a warning in some cases, this
491	function can be used to implement C<ecb_assume> or similar functions.	539	function can be used to implement C<ecb_assume> or similar functionality.
492		540
493	=item bool ecb_prefetch (addr, rw, locality)	541	=item ecb_prefetch (addr, rw, locality)
494		542
495	Tells the compiler to try to prefetch memory at the given C<addr>ess	543	Tells the compiler to try to prefetch memory at the given C<addr>ess
496	for either reading (C<rw> = 0) or writing (C<rw> = 1). A C<locality> of	544	for either reading (C<rw> = 0) or writing (C<rw> = 1). A C<locality> of
497	C<0> means that there will only be one access later, C<3> means that	545	C<0> means that there will only be one access later, C<3> means that
498	the data will likely be accessed very often, and values in between mean	546	the data will likely be accessed very often, and values in between mean
499	something... in between. The memory pointed to by the address does not	547	something... in between. The memory pointed to by the address does not
500	need to be accessible (it could be a null pointer for example), but C<rw>	548	need to be accessible (it could be a null pointer for example), but C<rw>
501	and C<locality> must be compile-time constants.	549	and C<locality> must be compile-time constants.
502		550
		551	This is a statement, not a function: you cannot use it as part of an
		552	expression.
		553
503	An obvious way to use this is to prefetch some data far away, in a big	554	An obvious way to use this is to prefetch some data far away, in a big
504	array you loop over. This prefetches memory some 128 array elements later,	555	array you loop over. This prefetches memory some 128 array elements later,
505	in the hope that it will be ready when the CPU arrives at that location.	556	in the hope that it will be ready when the CPU arrives at that location.
506		557
507	int sum = 0;	558	int sum = 0;
…		…
544		595
545	=item int ecb_ctz32 (uint32_t x)	596	=item int ecb_ctz32 (uint32_t x)
546		597
547	=item int ecb_ctz64 (uint64_t x)	598	=item int ecb_ctz64 (uint64_t x)
548		599
		600	=item int ecb_ctz (T x) [C++]
		601
549	Returns the index of the least significant bit set in C<x> (or	602	Returns the index of the least significant bit set in C<x> (or
550	equivalently the number of bits set to 0 before the least significant bit	603	equivalently the number of bits set to 0 before the least significant bit
551	set), starting from 0. If C<x> is 0 the result is undefined.	604	set), starting from 0. If C<x> is 0 the result is undefined.
552		605
553	For smaller types than C<uint32_t> you can safely use C<ecb_ctz32>.	606	For smaller types than C<uint32_t> you can safely use C<ecb_ctz32>.
554		607
		608	The overloaded C++ C<ecb_ctz> function supports C<uint8_t>, C<uint16_t>,
		609	C<uint32_t> and C<uint64_t> types.
		610
555	For example:	611	For example:
556		612
557	ecb_ctz32 (3) = 0	613	ecb_ctz32 (3) = 0
558	ecb_ctz32 (6) = 1	614	ecb_ctz32 (6) = 1
559		615
560	=item bool ecb_is_pot32 (uint32_t x)	616	=item bool ecb_is_pot32 (uint32_t x)
561		617
562	=item bool ecb_is_pot64 (uint32_t x)	618	=item bool ecb_is_pot64 (uint32_t x)
563		619
		620	=item bool ecb_is_pot (T x) [C++]
		621
564	Return true iff C<x> is a power of two or C<x == 0>.	622	Returns true iff C<x> is a power of two or C<x == 0>.
565		623
566	For smaller types then C<uint32_t> you can safely use C<ecb_is_pot32>.	624	For smaller types than C<uint32_t> you can safely use C<ecb_is_pot32>.
		625
		626	The overloaded C++ C<ecb_is_pot> function supports C<uint8_t>, C<uint16_t>,
		627	C<uint32_t> and C<uint64_t> types.
567		628
568	=item int ecb_ld32 (uint32_t x)	629	=item int ecb_ld32 (uint32_t x)
569		630
570	=item int ecb_ld64 (uint64_t x)	631	=item int ecb_ld64 (uint64_t x)
		632
		633	=item int ecb_ld64 (T x) [C++]
571		634
572	Returns the index of the most significant bit set in C<x>, or the number	635	Returns the index of the most significant bit set in C<x>, or the number
573	of digits the number requires in binary (so that C<< 2**ld <= x <	636	of digits the number requires in binary (so that C<< 2**ld <= x <
574	2**(ld+1) >>). If C<x> is 0 the result is undefined. A common use case is	637	2**(ld+1) >>). If C<x> is 0 the result is undefined. A common use case is
575	to compute the integer binary logarithm, i.e. C<floor (log2 (n))>, for	638	to compute the integer binary logarithm, i.e. C<floor (log2 (n))>, for
…		…
580	the given data type), while C<ecb_ld> returns how many bits the number	643	the given data type), while C<ecb_ld> returns how many bits the number
581	itself requires.	644	itself requires.
582		645
583	For smaller types than C<uint32_t> you can safely use C<ecb_ld32>.	646	For smaller types than C<uint32_t> you can safely use C<ecb_ld32>.
584		647
		648	The overloaded C++ C<ecb_ld> function supports C<uint8_t>, C<uint16_t>,
		649	C<uint32_t> and C<uint64_t> types.
		650
585	=item int ecb_popcount32 (uint32_t x)	651	=item int ecb_popcount32 (uint32_t x)
586		652
587	=item int ecb_popcount64 (uint64_t x)	653	=item int ecb_popcount64 (uint64_t x)
588		654
		655	=item int ecb_popcount (T x) [C++]
		656
589	Returns the number of bits set to 1 in C<x>.	657	Returns the number of bits set to 1 in C<x>.
590		658
591	For smaller types than C<uint32_t> you can safely use C<ecb_popcount32>.	659	For smaller types than C<uint32_t> you can safely use C<ecb_popcount32>.
		660
		661	The overloaded C++ C<ecb_popcount> function supports C<uint8_t>, C<uint16_t>,
		662	C<uint32_t> and C<uint64_t> types.
592		663
593	For example:	664	For example:
594		665
595	ecb_popcount32 (7) = 3	666	ecb_popcount32 (7) = 3
596	ecb_popcount32 (255) = 8	667	ecb_popcount32 (255) = 8
…		…
599		670
600	=item uint16_t ecb_bitrev16 (uint16_t x)	671	=item uint16_t ecb_bitrev16 (uint16_t x)
601		672
602	=item uint32_t ecb_bitrev32 (uint32_t x)	673	=item uint32_t ecb_bitrev32 (uint32_t x)
603		674
		675	=item T ecb_bitrev (T x) [C++]
		676
604	Reverses the bits in x, i.e. the MSB becomes the LSB, MSB-1 becomes LSB+1	677	Reverses the bits in x, i.e. the MSB becomes the LSB, MSB-1 becomes LSB+1
605	and so on.	678	and so on.
606		679
		680	The overloaded C++ C<ecb_bitrev> function supports C<uint8_t>, C<uint16_t> and C<uint32_t> types.
		681
607	Example:	682	Example:
608		683
609	ecb_bitrev8 (0xa7) = 0xea	684	ecb_bitrev8 (0xa7) = 0xea
610	ecb_bitrev32 (0xffcc4411) = 0x882233ff	685	ecb_bitrev32 (0xffcc4411) = 0x882233ff
611		686
		687	=item T ecb_bitrev (T x) [C++]
		688
		689	Overloaded C++ bitrev function.
		690
		691	C<T> must be one of C<uint8_t>, C<uint16_t> or C<uint32_t>.
		692
612	=item uint32_t ecb_bswap16 (uint32_t x)	693	=item uint32_t ecb_bswap16 (uint32_t x)
613		694
614	=item uint32_t ecb_bswap32 (uint32_t x)	695	=item uint32_t ecb_bswap32 (uint32_t x)
615		696
616	=item uint64_t ecb_bswap64 (uint64_t x)	697	=item uint64_t ecb_bswap64 (uint64_t x)
		698
		699	=item T ecb_bswap (T x)
617		700
618	These functions return the value of the 16-bit (32-bit, 64-bit) value	701	These functions return the value of the 16-bit (32-bit, 64-bit) value
619	C<x> after reversing the order of bytes (0x11223344 becomes 0x44332211 in	702	C<x> after reversing the order of bytes (0x11223344 becomes 0x44332211 in
620	C<ecb_bswap32>).	703	C<ecb_bswap32>).
621		704
		705	The overloaded C++ C<ecb_bswap> function supports C<uint8_t>, C<uint16_t>,
		706	C<uint32_t> and C<uint64_t> types.
		707
622	=item uint8_t ecb_rotl8 (uint8_t x, unsigned int count)	708	=item uint8_t ecb_rotl8 (uint8_t x, unsigned int count)
623		709
624	=item uint16_t ecb_rotl16 (uint16_t x, unsigned int count)	710	=item uint16_t ecb_rotl16 (uint16_t x, unsigned int count)
625		711
626	=item uint32_t ecb_rotl32 (uint32_t x, unsigned int count)	712	=item uint32_t ecb_rotl32 (uint32_t x, unsigned int count)
…		…
641		727
642	Current GCC versions understand these functions and usually compile them	728	Current GCC versions understand these functions and usually compile them
643	to "optimal" code (e.g. a single C<rol> or a combination of C<shld> on	729	to "optimal" code (e.g. a single C<rol> or a combination of C<shld> on
644	x86).	730	x86).
645		731
		732	=item T ecb_rotl (T x, unsigned int count) [C++]
		733
		734	=item T ecb_rotr (T x, unsigned int count) [C++]
		735
		736	Overloaded C++ rotl/rotr functions.
		737
		738	C<T> must be one of C<uint8_t>, C<uint16_t>, C<uint32_t> or C<uint64_t>.
		739
646	=back	740	=back
647		741
		742	=head2 HOST ENDIANNESS CONVERSION
		743
		744	=over 4
		745
		746	=item uint_fast16_t ecb_be_u16_to_host (uint_fast16_t v)
		747
		748	=item uint_fast32_t ecb_be_u32_to_host (uint_fast32_t v)
		749
		750	=item uint_fast64_t ecb_be_u64_to_host (uint_fast64_t v)
		751
		752	=item uint_fast16_t ecb_le_u16_to_host (uint_fast16_t v)
		753
		754	=item uint_fast32_t ecb_le_u32_to_host (uint_fast32_t v)
		755
		756	=item uint_fast64_t ecb_le_u64_to_host (uint_fast64_t v)
		757
		758	Convert an unsigned 16, 32 or 64 bit value from big or little endian to host byte order.
		759
		760	The naming convention is C<ecb_>(C<be>\|C<le>)C<_u>C<16\|32\|64>C<_to_host>,
		761	where C<be> and C<le> stand for big endian and little endian, respectively.
		762
		763	=item uint_fast16_t ecb_host_to_be_u16 (uint_fast16_t v)
		764
		765	=item uint_fast32_t ecb_host_to_be_u32 (uint_fast32_t v)
		766
		767	=item uint_fast64_t ecb_host_to_be_u64 (uint_fast64_t v)
		768
		769	=item uint_fast16_t ecb_host_to_le_u16 (uint_fast16_t v)
		770
		771	=item uint_fast32_t ecb_host_to_le_u32 (uint_fast32_t v)
		772
		773	=item uint_fast64_t ecb_host_to_le_u64 (uint_fast64_t v)
		774
		775	Like above, but converts I<from> host byte order to the specified
		776	endianness.
		777
		778	=back
		779
		780	In C++ the following additional template functions are supported:
		781
		782	=over 4
		783
		784	=item T ecb_be_to_host (T v)
		785
		786	=item T ecb_le_to_host (T v)
		787
		788	=item T ecb_host_to_be (T v)
		789
		790	=item T ecb_host_to_le (T v)
		791
		792	These functions work like their C counterparts, above, but use templates,
		793	which make them useful in generic code.
		794
		795	C<T> must be one of C<uint8_t>, C<uint16_t>, C<uint32_t> or C<uint64_t>
		796	(so unlike their C counterparts, there is a version for C<uint8_t>, which
		797	again can be useful in generic code).
		798
		799	=head2 UNALIGNED LOAD/STORE
		800
		801	These function load or store unaligned multi-byte values.
		802
		803	=over 4
		804
		805	=item uint_fast16_t ecb_peek_u16_u (const void *ptr)
		806
		807	=item uint_fast32_t ecb_peek_u32_u (const void *ptr)
		808
		809	=item uint_fast64_t ecb_peek_u64_u (const void *ptr)
		810
		811	These functions load an unaligned, unsigned 16, 32 or 64 bit value from
		812	memory.
		813
		814	=item uint_fast16_t ecb_peek_be_u16_u (const void *ptr)
		815
		816	=item uint_fast32_t ecb_peek_be_u32_u (const void *ptr)
		817
		818	=item uint_fast64_t ecb_peek_be_u64_u (const void *ptr)
		819
		820	=item uint_fast16_t ecb_peek_le_u16_u (const void *ptr)
		821
		822	=item uint_fast32_t ecb_peek_le_u32_u (const void *ptr)
		823
		824	=item uint_fast64_t ecb_peek_le_u64_u (const void *ptr)
		825
		826	Like above, but additionally convert from big endian (C<be>) or little
		827	endian (C<le>) byte order to host byte order while doing so.
		828
		829	=item ecb_poke_u16_u (void *ptr, uint16_t v)
		830
		831	=item ecb_poke_u32_u (void *ptr, uint32_t v)
		832
		833	=item ecb_poke_u64_u (void *ptr, uint64_t v)
		834
		835	These functions store an unaligned, unsigned 16, 32 or 64 bit value to
		836	memory.
		837
		838	=item ecb_poke_be_u16_u (void *ptr, uint_fast16_t v)
		839
		840	=item ecb_poke_be_u32_u (void *ptr, uint_fast32_t v)
		841
		842	=item ecb_poke_be_u64_u (void *ptr, uint_fast64_t v)
		843
		844	=item ecb_poke_le_u16_u (void *ptr, uint_fast16_t v)
		845
		846	=item ecb_poke_le_u32_u (void *ptr, uint_fast32_t v)
		847
		848	=item ecb_poke_le_u64_u (void *ptr, uint_fast64_t v)
		849
		850	Like above, but additionally convert from host byte order to big endian
		851	(C<be>) or little endian (C<le>) byte order while doing so.
		852
		853	=back
		854
		855	In C++ the following additional template functions are supported:
		856
		857	=over 4
		858
		859	=item T ecb_peek<T> (const void *ptr)
		860
		861	=item T ecb_peek_be<T> (const void *ptr)
		862
		863	=item T ecb_peek_le<T> (const void *ptr)
		864
		865	=item T ecb_peek_u<T> (const void *ptr)
		866
		867	=item T ecb_peek_be_u<T> (const void *ptr)
		868
		869	=item T ecb_peek_le_u<T> (const void *ptr)
		870
		871	Similarly to their C counterparts, these functions load an unsigned 8, 16,
		872	32 or 64 bit value from memory, with optional conversion from big/little
		873	endian.
		874
		875	Since the type cannot be deduced, it has to be specified explicitly, e.g.
		876
		877	uint_fast16_t v = ecb_peek<uint16_t> (ptr);
		878
		879	C<T> must be one of C<uint8_t>, C<uint16_t>, C<uint32_t> or C<uint64_t>.
		880
		881	Unlike their C counterparts, these functions support 8 bit quantities
		882	(C<uint8_t>) and also have an aligned version (without the C<_u> prefix),
		883	all of which hopefully makes them more useful in generic code.
		884
		885	=item ecb_poke (void *ptr, T v)
		886
		887	=item ecb_poke_be (void *ptr, T v)
		888
		889	=item ecb_poke_le (void *ptr, T v)
		890
		891	=item ecb_poke_u (void *ptr, T v)
		892
		893	=item ecb_poke_be_u (void *ptr, T v)
		894
		895	=item ecb_poke_le_u (void *ptr, T v)
		896
		897	Again, similarly to their C counterparts, these functions store an
		898	unsigned 8, 16, 32 or z64 bit value to memory, with optional conversion to
		899	big/little endian.
		900
		901	C<T> must be one of C<uint8_t>, C<uint16_t>, C<uint32_t> or C<uint64_t>.
		902
		903	Unlike their C counterparts, these functions support 8 bit quantities
		904	(C<uint8_t>) and also have an aligned version (without the C<_u> prefix),
		905	all of which hopefully makes them more useful in generic code.
		906
		907	=back
		908
648	=head2 FLOATING POINT FIDDLING	909	=head2 FLOATING POINT FIDDLING
649		910
650	=over 4	911	=over 4
651		912
		913	=item ECB_INFINITY [-UECB_NO_LIBM]
		914
		915	Evaluates to positive infinity if supported by the platform, otherwise to
		916	a truly huge number.
		917
		918	=item ECB_NAN [-UECB_NO_LIBM]
		919
		920	Evaluates to a quiet NAN if supported by the platform, otherwise to
		921	C<ECB_INFINITY>.
		922
		923	=item float ecb_ldexpf (float x, int exp) [-UECB_NO_LIBM]
		924
		925	Same as C<ldexpf>, but always available.
		926
		927	=item uint32_t ecb_float_to_binary16 (float x) [-UECB_NO_LIBM]
		928
652	=item uint32_t ecb_float_to_binary32 (float x) [-UECB_NO_LIBM]	929	=item uint32_t ecb_float_to_binary32 (float x) [-UECB_NO_LIBM]
653		930
654	=item uint64_t ecb_double_to_binary64 (double x) [-UECB_NO_LIBM]	931	=item uint64_t ecb_double_to_binary64 (double x) [-UECB_NO_LIBM]
655		932
656	These functions each take an argument in the native C<float> or C<double>	933	These functions each take an argument in the native C<float> or C<double>
657	type and return the IEEE 754 bit representation of it.	934	type and return the IEEE 754 bit representation of it (binary16/half,
		935	binary32/single or binary64/double precision).
658		936
659	The bit representation is just as IEEE 754 defines it, i.e. the sign bit	937	The bit representation is just as IEEE 754 defines it, i.e. the sign bit
660	will be the most significant bit, followed by exponent and mantissa.	938	will be the most significant bit, followed by exponent and mantissa.
661		939
662	This function should work even when the native floating point format isn't	940	This function should work even when the native floating point format isn't
…		…
666		944
667	On all modern platforms (where C<ECB_STDFP> is true), the compiler should	945	On all modern platforms (where C<ECB_STDFP> is true), the compiler should
668	be able to optimise away this function completely.	946	be able to optimise away this function completely.
669		947
670	These functions can be helpful when serialising floats to the network - you	948	These functions can be helpful when serialising floats to the network - you
671	can serialise the return value like a normal uint32_t/uint64_t.	949	can serialise the return value like a normal uint16_t/uint32_t/uint64_t.
672		950
673	Another use for these functions is to manipulate floating point values	951	Another use for these functions is to manipulate floating point values
674	directly.	952	directly.
675		953
676	Silly example: toggle the sign bit of a float.	954	Silly example: toggle the sign bit of a float.
…		…
679	/* this results in a single add instruction to toggle the bit, and 4 extra */	957	/* this results in a single add instruction to toggle the bit, and 4 extra */
680	/* instructions to move the float value to an integer register and back. */	958	/* instructions to move the float value to an integer register and back. */
681		959
682	x = ecb_binary32_to_float (ecb_float_to_binary32 (x) ^ 0x80000000U)	960	x = ecb_binary32_to_float (ecb_float_to_binary32 (x) ^ 0x80000000U)
683		961
		962	=item float ecb_binary16_to_float (uint16_t x) [-UECB_NO_LIBM]
		963
684	=item float ecb_binary32_to_float (uint32_t x) [-UECB_NO_LIBM]	964	=item float ecb_binary32_to_float (uint32_t x) [-UECB_NO_LIBM]
685		965
686	=item double ecb_binary32_to_double (uint64_t x) [-UECB_NO_LIBM]	966	=item double ecb_binary64_to_double (uint64_t x) [-UECB_NO_LIBM]
687		967
688	The reverse operation of the previos function - takes the bit representation	968	The reverse operation of the previous function - takes the bit
689	of an IEEE binary32 or binary64 number and converts it to the native C<float>	969	representation of an IEEE binary16, binary32 or binary64 number (half,
		970	single or double precision) and converts it to the native C<float> or
690	or C<double> format.	971	C<double> format.
691		972
692	This function should work even when the native floating point format isn't	973	This function should work even when the native floating point format isn't
693	IEEE compliant, of course at a speed and code size penalty, and of course	974	IEEE compliant, of course at a speed and code size penalty, and of course
694	also within reasonable limits (it tries to convert normals and denormals,	975	also within reasonable limits (it tries to convert normals and denormals,
695	and might be lucky for infinities, and with extraordinary luck, also for	976	and might be lucky for infinities, and with extraordinary luck, also for
696	negative zero).	977	negative zero).
697		978
698	On all modern platforms (where C<ECB_STDFP> is true), the compiler should	979	On all modern platforms (where C<ECB_STDFP> is true), the compiler should
699	be able to optimise away this function completely.	980	be able to optimise away this function completely.
		981
		982	=item uint16_t ecb_binary32_to_binary16 (uint32_t x)
		983
		984	=item uint32_t ecb_binary16_to_binary32 (uint16_t x)
		985
		986	Convert a IEEE binary32/single precision to binary16/half format, and vice
		987	versa, handling all details (round-to-nearest-even, subnormals, infinity
		988	and NaNs) correctly.
		989
		990	These are functions are available under C<-DECB_NO_LIBM>, since
		991	they do not rely on the platform floating point format. The
		992	C<ecb_float_to_binary16> and C<ecb_binary16_to_float> functions are
		993	usually what you want.
700		994
701	=back	995	=back
702		996
703	=head2 ARITHMETIC	997	=head2 ARITHMETIC
704		998
…		…
785	dependencies on the math library (usually called F<-lm>) - these are	1079	dependencies on the math library (usually called F<-lm>) - these are
786	marked with [-UECB_NO_LIBM].	1080	marked with [-UECB_NO_LIBM].
787		1081
788	=back	1082	=back
789		1083
		1084	=head1 UNDOCUMENTED FUNCTIONALITY
790		1085
		1086	F<ecb.h> is full of undocumented functionality as well, some of which is
		1087	intended to be internal-use only, some of which we forgot to document, and
		1088	some of which we hide because we are not sure we will keep the interface
		1089	stable.
		1090
		1091	While you are welcome to rummage around and use whatever you find useful
		1092	(we can't stop you), keep in mind that we will change undocumented
		1093	functionality in incompatible ways without thinking twice, while we are
		1094	considerably more conservative with documented things.
		1095
		1096	=head1 AUTHORS
		1097
		1098	C<libecb> is designed and maintained by:
		1099
		1100	Emanuele Giaquinta <e.giaquinta@glauco.it>
		1101	Marc Alexander Lehmann <schmorp@schmorp.de>
		1102
		1103

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Comparing libecb/ecb.pod (file contents): Revision 1.55 by root, Thu Jan 9 05:16:12 2014 UTC vs. Revision 1.81 by root, Mon Jan 20 21:01:29 2020 UTC

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Comparing libecb/ecb.pod (file contents):
Revision 1.55 by root, Thu Jan 9 05:16:12 2014 UTC vs.
Revision 1.81 by root, Mon Jan 20 21:01:29 2020 UTC