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

Comparing cvsroot/libecb/ecb.pod (file contents):
Revision 1.70 by root, Tue Sep 1 16:14:42 2015 UTC vs.
Revision 1.93 by root, Sat Jul 31 14:39:16 2021 UTC

…		…
10		10
11	Its homepage can be found here:	11	Its homepage can be found here:
12		12
13	http://software.schmorp.de/pkg/libecb	13	http://software.schmorp.de/pkg/libecb
14		14
15	It mainly provides a number of wrappers around GCC built-ins, together	15	It mainly provides a number of wrappers around many compiler built-ins,
16	with replacement functions for other compilers. In addition to this,	16	together with replacement functions for other compilers. In addition
17	it provides a number of other lowlevel C utilities, such as endianness	17	to this, it provides a number of other lowlevel C utilities, such as
18	detection, byte swapping or bit rotations.	18	endianness detection, byte swapping or bit rotations.
19		19
20	Or in other words, things that should be built into any standard C system,	20	Or in other words, things that should be built into any standard C
21	but aren't, implemented as efficient as possible with GCC, and still	21	system, but aren't, implemented as efficient as possible with GCC (clang,
22	correct with other compilers.	22	msvc...), and still correct with other compilers.
23		23
24	More might come.	24	More might come.
25		25
26	=head2 ABOUT THE HEADER	26	=head2 ABOUT THE HEADER
27		27
…		…
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/ENVIRONMENT/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
79	=over 4	85	=over
80		86
81	=item ECB_C	87	=item ECB_C
82		88
83	True if the implementation defines the C<__STDC__> macro to a true value,	89	True if the implementation defines the C<__STDC__> macro to a true value,
84	while not claiming to be C++.	90	while not claiming to be C++, i..e C, but not C++.
85		91
86	=item ECB_C99	92	=item ECB_C99
87		93
88	True if the implementation claims to be compliant to C99 (ISO/IEC	94	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++.	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.
		114
		115	Note that many C++20 features will likely have their own feature test
		116	macros (see e.g. L<http://eel.is/c++draft/cpp.predefined#1.8>).
		117
		118	=item ECB_OPTIMIZE_SIZE
		119
		120	Is C<1> when the compiler optimizes for size, C<0> otherwise. This symbol
		121	can also be defined before including F<ecb.h>, in which case it will be
		122	unchanged.
108		123
109	=item ECB_GCC_VERSION (major, minor)	124	=item ECB_GCC_VERSION (major, minor)
110		125
111	Expands to a true value (suitable for testing in by the preprocessor)	126	Expands to a true value (suitable for testing by the preprocessor) if the
112	if the compiler used is GNU C and the version is the given version, or	127	compiler used is GNU C and the version is the given version, or higher.
113	higher.
114		128
115	This macro tries to return false on compilers that claim to be GCC	129	This macro tries to return false on compilers that claim to be GCC
116	compatible but aren't.	130	compatible but aren't.
117		131
118	=item ECB_EXTERN_C	132	=item ECB_EXTERN_C
…		…
137		151
138	ECB_EXTERN_C_END	152	ECB_EXTERN_C_END
139		153
140	=item ECB_STDFP	154	=item ECB_STDFP
141		155
142	If this evaluates to a true value (suitable for testing in by the	156	If this evaluates to a true value (suitable for testing by the
143	preprocessor), then C<float> and C<double> use IEEE 754 single/binary32	157	preprocessor), then C<float> and C<double> use IEEE 754 single/binary32
144	and double/binary64 representations internally I<and> the endianness of	158	and double/binary64 representations internally I<and> the endianness of
145	both types match the endianness of C<uint32_t> and C<uint64_t>.	159	both types match the endianness of C<uint32_t> and C<uint64_t>.
146		160
147	This means you can just copy the bits of a C<float> (or C<double>) to an	161	This means you can just copy the bits of a C<float> (or C<double>) to an
…		…
149	without having to think about format or endianness.	163	without having to think about format or endianness.
150		164
151	This is true for basically all modern platforms, although F<ecb.h> might	165	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	166	not be able to deduce this correctly everywhere and might err on the safe
153	side.	167	side.
		168
		169	=item ECB_64BIT_NATIVE
		170
		171	Evaluates to a true value (suitable for both preprocessor and C code
		172	testing) if 64 bit integer types on this architecture are evaluated
		173	"natively", that is, with similar speeds as 32 bit integers. While 64 bit
		174	integer support is very common (and in fact required by libecb), 32 bit
		175	cpus have to emulate operations on them, so you might want to avoid them.
154		176
155	=item ECB_AMD64, ECB_AMD64_X32	177	=item ECB_AMD64, ECB_AMD64_X32
156		178
157	These two macros are defined to C<1> on the x86_64/amd64 ABI and the X32	179	These two macros are defined to C<1> on the x86_64/amd64 ABI and the X32
158	ABI, respectively, and undefined elsewhere.	180	ABI, respectively, and undefined elsewhere.
…		…
165		187
166	=back	188	=back
167		189
168	=head2 MACRO TRICKERY	190	=head2 MACRO TRICKERY
169		191
170	=over 4	192	=over
171		193
172	=item ECB_CONCAT (a, b)	194	=item ECB_CONCAT (a, b)
173		195
174	Expands any macros in C<a> and C<b>, then concatenates the result to form	196	Expands any macros in C<a> and C<b>, then concatenates the result to form
175	a single token. This is mainly useful to form identifiers from components,	197	a single token. This is mainly useful to form identifiers from components,
…		…
216	declarations must be put before the whole declaration:	238	declarations must be put before the whole declaration:
217		239
218	ecb_const int mysqrt (int a);	240	ecb_const int mysqrt (int a);
219	ecb_unused int i;	241	ecb_unused int i;
220		242
221	=over 4	243	=over
222		244
223	=item ecb_unused	245	=item ecb_unused
224		246
225	Marks a function or a variable as "unused", which simply suppresses a	247	Marks a function or a variable as "unused", which simply suppresses a
226	warning by GCC when it detects it as unused. This is useful when you e.g.	248	warning by the compiler when it detects it as unused. This is useful when
227	declare a variable but do not always use it:	249	you e.g. declare a variable but do not always use it:
228		250
229	{	251	{
230	ecb_unused int var;	252	ecb_unused int var;
231		253
232	#ifdef SOMECONDITION	254	#ifdef SOMECONDITION
…		…
248	used instead of a generic depreciation message when the object is being	270	used instead of a generic depreciation message when the object is being
249	used.	271	used.
250		272
251	=item ecb_inline	273	=item ecb_inline
252		274
253	Expands either to C<static inline> or to just C<static>, if inline	275	Expands either to (a compiler-specific equivalent of) C<static inline> or
254	isn't supported. It should be used to declare functions that should be	276	to just C<static>, if inline isn't supported. It should be used to declare
255	inlined, for code size or speed reasons.	277	functions that should be inlined, for code size or speed reasons.
256		278
257	Example: inline this function, it surely will reduce codesize.	279	Example: inline this function, it surely will reduce codesize.
258		280
259	ecb_inline int	281	ecb_inline int
260	negmul (int a, int b)	282	negmul (int a, int b)
…		…
400		422
401	=back	423	=back
402		424
403	=head2 OPTIMISATION HINTS	425	=head2 OPTIMISATION HINTS
404		426
405	=over 4	427	=over
406		428
407	=item bool ecb_is_constant (expr)	429	=item bool ecb_is_constant (expr)
408		430
409	Returns true iff the expression can be deduced to be a compile-time	431	Returns true iff the expression can be deduced to be a compile-time
410	constant, and false otherwise.	432	constant, and false otherwise.
…		…
567		589
568	=back	590	=back
569		591
570	=head2 BIT FIDDLING / BIT WIZARDRY	592	=head2 BIT FIDDLING / BIT WIZARDRY
571		593
572	=over 4	594	=over
573		595
574	=item bool ecb_big_endian ()	596	=item bool ecb_big_endian ()
575		597
576	=item bool ecb_little_endian ()	598	=item bool ecb_little_endian ()
577		599
…		…
583		605
584	=item int ecb_ctz32 (uint32_t x)	606	=item int ecb_ctz32 (uint32_t x)
585		607
586	=item int ecb_ctz64 (uint64_t x)	608	=item int ecb_ctz64 (uint64_t x)
587		609
		610	=item int ecb_ctz (T x) [C++]
		611
588	Returns the index of the least significant bit set in C<x> (or	612	Returns the index of the least significant bit set in C<x> (or
589	equivalently the number of bits set to 0 before the least significant bit	613	equivalently the number of bits set to 0 before the least significant bit
590	set), starting from 0. If C<x> is 0 the result is undefined.	614	set), starting from 0. If C<x> is 0 the result is undefined.
591		615
592	For smaller types than C<uint32_t> you can safely use C<ecb_ctz32>.	616	For smaller types than C<uint32_t> you can safely use C<ecb_ctz32>.
593		617
		618	The overloaded C++ C<ecb_ctz> function supports C<uint8_t>, C<uint16_t>,
		619	C<uint32_t> and C<uint64_t> types.
		620
594	For example:	621	For example:
595		622
596	ecb_ctz32 (3) = 0	623	ecb_ctz32 (3) = 0
597	ecb_ctz32 (6) = 1	624	ecb_ctz32 (6) = 1
598		625
599	=item bool ecb_is_pot32 (uint32_t x)	626	=item bool ecb_is_pot32 (uint32_t x)
600		627
601	=item bool ecb_is_pot64 (uint32_t x)	628	=item bool ecb_is_pot64 (uint32_t x)
602		629
		630	=item bool ecb_is_pot (T x) [C++]
		631
603	Returns true iff C<x> is a power of two or C<x == 0>.	632	Returns true iff C<x> is a power of two or C<x == 0>.
604		633
605	For smaller types than C<uint32_t> you can safely use C<ecb_is_pot32>.	634	For smaller types than C<uint32_t> you can safely use C<ecb_is_pot32>.
606		635
		636	The overloaded C++ C<ecb_is_pot> function supports C<uint8_t>, C<uint16_t>,
		637	C<uint32_t> and C<uint64_t> types.
		638
607	=item int ecb_ld32 (uint32_t x)	639	=item int ecb_ld32 (uint32_t x)
608		640
609	=item int ecb_ld64 (uint64_t x)	641	=item int ecb_ld64 (uint64_t x)
		642
		643	=item int ecb_ld64 (T x) [C++]
610		644
611	Returns the index of the most significant bit set in C<x>, or the number	645	Returns the index of the most significant bit set in C<x>, or the number
612	of digits the number requires in binary (so that C<< 2**ld <= x <	646	of digits the number requires in binary (so that C<< 2**ld <= x <
613	2**(ld+1) >>). If C<x> is 0 the result is undefined. A common use case is	647	2**(ld+1) >>). If C<x> is 0 the result is undefined. A common use case is
614	to compute the integer binary logarithm, i.e. C<floor (log2 (n))>, for	648	to compute the integer binary logarithm, i.e. C<floor (log2 (n))>, for
…		…
619	the given data type), while C<ecb_ld> returns how many bits the number	653	the given data type), while C<ecb_ld> returns how many bits the number
620	itself requires.	654	itself requires.
621		655
622	For smaller types than C<uint32_t> you can safely use C<ecb_ld32>.	656	For smaller types than C<uint32_t> you can safely use C<ecb_ld32>.
623		657
		658	The overloaded C++ C<ecb_ld> function supports C<uint8_t>, C<uint16_t>,
		659	C<uint32_t> and C<uint64_t> types.
		660
624	=item int ecb_popcount32 (uint32_t x)	661	=item int ecb_popcount32 (uint32_t x)
625		662
626	=item int ecb_popcount64 (uint64_t x)	663	=item int ecb_popcount64 (uint64_t x)
627		664
		665	=item int ecb_popcount (T x) [C++]
		666
628	Returns the number of bits set to 1 in C<x>.	667	Returns the number of bits set to 1 in C<x>.
629		668
630	For smaller types than C<uint32_t> you can safely use C<ecb_popcount32>.	669	For smaller types than C<uint32_t> you can safely use C<ecb_popcount32>.
		670
		671	The overloaded C++ C<ecb_popcount> function supports C<uint8_t>, C<uint16_t>,
		672	C<uint32_t> and C<uint64_t> types.
631		673
632	For example:	674	For example:
633		675
634	ecb_popcount32 (7) = 3	676	ecb_popcount32 (7) = 3
635	ecb_popcount32 (255) = 8	677	ecb_popcount32 (255) = 8
…		…
638		680
639	=item uint16_t ecb_bitrev16 (uint16_t x)	681	=item uint16_t ecb_bitrev16 (uint16_t x)
640		682
641	=item uint32_t ecb_bitrev32 (uint32_t x)	683	=item uint32_t ecb_bitrev32 (uint32_t x)
642		684
		685	=item T ecb_bitrev (T x) [C++]
		686
643	Reverses the bits in x, i.e. the MSB becomes the LSB, MSB-1 becomes LSB+1	687	Reverses the bits in x, i.e. the MSB becomes the LSB, MSB-1 becomes LSB+1
644	and so on.	688	and so on.
645		689
		690	The overloaded C++ C<ecb_bitrev> function supports C<uint8_t>, C<uint16_t> and C<uint32_t> types.
		691
646	Example:	692	Example:
647		693
648	ecb_bitrev8 (0xa7) = 0xea	694	ecb_bitrev8 (0xa7) = 0xea
649	ecb_bitrev32 (0xffcc4411) = 0x882233ff	695	ecb_bitrev32 (0xffcc4411) = 0x882233ff
650		696
		697	=item T ecb_bitrev (T x) [C++]
		698
		699	Overloaded C++ bitrev function.
		700
		701	C<T> must be one of C<uint8_t>, C<uint16_t> or C<uint32_t>.
		702
651	=item uint32_t ecb_bswap16 (uint32_t x)	703	=item uint32_t ecb_bswap16 (uint32_t x)
652		704
653	=item uint32_t ecb_bswap32 (uint32_t x)	705	=item uint32_t ecb_bswap32 (uint32_t x)
654		706
655	=item uint64_t ecb_bswap64 (uint64_t x)	707	=item uint64_t ecb_bswap64 (uint64_t x)
		708
		709	=item T ecb_bswap (T x)
656		710
657	These functions return the value of the 16-bit (32-bit, 64-bit) value	711	These functions return the value of the 16-bit (32-bit, 64-bit) value
658	C<x> after reversing the order of bytes (0x11223344 becomes 0x44332211 in	712	C<x> after reversing the order of bytes (0x11223344 becomes 0x44332211 in
659	C<ecb_bswap32>).	713	C<ecb_bswap32>).
660		714
		715	The overloaded C++ C<ecb_bswap> function supports C<uint8_t>, C<uint16_t>,
		716	C<uint32_t> and C<uint64_t> types.
		717
661	=item uint8_t ecb_rotl8 (uint8_t x, unsigned int count)	718	=item uint8_t ecb_rotl8 (uint8_t x, unsigned int count)
662		719
663	=item uint16_t ecb_rotl16 (uint16_t x, unsigned int count)	720	=item uint16_t ecb_rotl16 (uint16_t x, unsigned int count)
664		721
665	=item uint32_t ecb_rotl32 (uint32_t x, unsigned int count)	722	=item uint32_t ecb_rotl32 (uint32_t x, unsigned int count)
…		…
676		733
677	These two families of functions return the value of C<x> after rotating	734	These two families of functions return the value of C<x> after rotating
678	all the bits by C<count> positions to the right (C<ecb_rotr>) or left	735	all the bits by C<count> positions to the right (C<ecb_rotr>) or left
679	(C<ecb_rotl>).	736	(C<ecb_rotl>).
680		737
		738	The valid range for C<count> is C<1> to the number of bits in the
		739	underlying datatype minus one (7/15/31/63). If you need a rotate count
		740	of zero you need to add an extra check before calling these functions
		741	currently.
		742
681	Current GCC versions understand these functions and usually compile them	743	Current GCC/clang versions understand these functions and usually compile
682	to "optimal" code (e.g. a single C<rol> or a combination of C<shld> on	744	them to "optimal" code (e.g. a single C<rol> or a combination of C<shld>
683	x86).	745	on x86).
		746
		747	=item T ecb_rotl (T x, unsigned int count) [C++]
		748
		749	=item T ecb_rotr (T x, unsigned int count) [C++]
		750
		751	Overloaded C++ rotl/rotr functions.
		752
		753	C<T> must be one of C<uint8_t>, C<uint16_t>, C<uint32_t> or C<uint64_t>.
		754
		755	=back
		756
		757	=head2 HOST ENDIANNESS CONVERSION
		758
		759	=over
		760
		761	=item uint_fast16_t ecb_be_u16_to_host (uint_fast16_t v)
		762
		763	=item uint_fast32_t ecb_be_u32_to_host (uint_fast32_t v)
		764
		765	=item uint_fast64_t ecb_be_u64_to_host (uint_fast64_t v)
		766
		767	=item uint_fast16_t ecb_le_u16_to_host (uint_fast16_t v)
		768
		769	=item uint_fast32_t ecb_le_u32_to_host (uint_fast32_t v)
		770
		771	=item uint_fast64_t ecb_le_u64_to_host (uint_fast64_t v)
		772
		773	Convert an unsigned 16, 32 or 64 bit value from big or little endian to host byte order.
		774
		775	The naming convention is C<ecb_>(C<be>\|C<le>)C<_u>C<16\|32\|64>C<_to_host>,
		776	where C<be> and C<le> stand for big endian and little endian, respectively.
		777
		778	=item uint_fast16_t ecb_host_to_be_u16 (uint_fast16_t v)
		779
		780	=item uint_fast32_t ecb_host_to_be_u32 (uint_fast32_t v)
		781
		782	=item uint_fast64_t ecb_host_to_be_u64 (uint_fast64_t v)
		783
		784	=item uint_fast16_t ecb_host_to_le_u16 (uint_fast16_t v)
		785
		786	=item uint_fast32_t ecb_host_to_le_u32 (uint_fast32_t v)
		787
		788	=item uint_fast64_t ecb_host_to_le_u64 (uint_fast64_t v)
		789
		790	Like above, but converts I<from> host byte order to the specified
		791	endianness.
		792
		793	=back
		794
		795	In C++ the following additional template functions are supported:
		796
		797	=over
		798
		799	=item T ecb_be_to_host (T v)
		800
		801	=item T ecb_le_to_host (T v)
		802
		803	=item T ecb_host_to_be (T v)
		804
		805	=item T ecb_host_to_le (T v)
		806
		807	=back
		808
		809	These functions work like their C counterparts, above, but use templates,
		810	which make them useful in generic code.
		811
		812	C<T> must be one of C<uint8_t>, C<uint16_t>, C<uint32_t> or C<uint64_t>
		813	(so unlike their C counterparts, there is a version for C<uint8_t>, which
		814	again can be useful in generic code).
		815
		816	=head2 UNALIGNED LOAD/STORE
		817
		818	These function load or store unaligned multi-byte values.
		819
		820	=over
		821
		822	=item uint_fast16_t ecb_peek_u16_u (const void *ptr)
		823
		824	=item uint_fast32_t ecb_peek_u32_u (const void *ptr)
		825
		826	=item uint_fast64_t ecb_peek_u64_u (const void *ptr)
		827
		828	These functions load an unaligned, unsigned 16, 32 or 64 bit value from
		829	memory.
		830
		831	=item uint_fast16_t ecb_peek_be_u16_u (const void *ptr)
		832
		833	=item uint_fast32_t ecb_peek_be_u32_u (const void *ptr)
		834
		835	=item uint_fast64_t ecb_peek_be_u64_u (const void *ptr)
		836
		837	=item uint_fast16_t ecb_peek_le_u16_u (const void *ptr)
		838
		839	=item uint_fast32_t ecb_peek_le_u32_u (const void *ptr)
		840
		841	=item uint_fast64_t ecb_peek_le_u64_u (const void *ptr)
		842
		843	Like above, but additionally convert from big endian (C<be>) or little
		844	endian (C<le>) byte order to host byte order while doing so.
		845
		846	=item ecb_poke_u16_u (void *ptr, uint16_t v)
		847
		848	=item ecb_poke_u32_u (void *ptr, uint32_t v)
		849
		850	=item ecb_poke_u64_u (void *ptr, uint64_t v)
		851
		852	These functions store an unaligned, unsigned 16, 32 or 64 bit value to
		853	memory.
		854
		855	=item ecb_poke_be_u16_u (void *ptr, uint_fast16_t v)
		856
		857	=item ecb_poke_be_u32_u (void *ptr, uint_fast32_t v)
		858
		859	=item ecb_poke_be_u64_u (void *ptr, uint_fast64_t v)
		860
		861	=item ecb_poke_le_u16_u (void *ptr, uint_fast16_t v)
		862
		863	=item ecb_poke_le_u32_u (void *ptr, uint_fast32_t v)
		864
		865	=item ecb_poke_le_u64_u (void *ptr, uint_fast64_t v)
		866
		867	Like above, but additionally convert from host byte order to big endian
		868	(C<be>) or little endian (C<le>) byte order while doing so.
		869
		870	=back
		871
		872	In C++ the following additional template functions are supported:
		873
		874	=over
		875
		876	=item T ecb_peek<T> (const void *ptr)
		877
		878	=item T ecb_peek_be<T> (const void *ptr)
		879
		880	=item T ecb_peek_le<T> (const void *ptr)
		881
		882	=item T ecb_peek_u<T> (const void *ptr)
		883
		884	=item T ecb_peek_be_u<T> (const void *ptr)
		885
		886	=item T ecb_peek_le_u<T> (const void *ptr)
		887
		888	Similarly to their C counterparts, these functions load an unsigned 8, 16,
		889	32 or 64 bit value from memory, with optional conversion from big/little
		890	endian.
		891
		892	Since the type cannot be deduced, it has to be specified explicitly, e.g.
		893
		894	uint_fast16_t v = ecb_peek<uint16_t> (ptr);
		895
		896	C<T> must be one of C<uint8_t>, C<uint16_t>, C<uint32_t> or C<uint64_t>.
		897
		898	Unlike their C counterparts, these functions support 8 bit quantities
		899	(C<uint8_t>) and also have an aligned version (without the C<_u> prefix),
		900	all of which hopefully makes them more useful in generic code.
		901
		902	=item ecb_poke (void *ptr, T v)
		903
		904	=item ecb_poke_be (void *ptr, T v)
		905
		906	=item ecb_poke_le (void *ptr, T v)
		907
		908	=item ecb_poke_u (void *ptr, T v)
		909
		910	=item ecb_poke_be_u (void *ptr, T v)
		911
		912	=item ecb_poke_le_u (void *ptr, T v)
		913
		914	Again, similarly to their C counterparts, these functions store an
		915	unsigned 8, 16, 32 or z64 bit value to memory, with optional conversion to
		916	big/little endian.
		917
		918	C<T> must be one of C<uint8_t>, C<uint16_t>, C<uint32_t> or C<uint64_t>.
		919
		920	Unlike their C counterparts, these functions support 8 bit quantities
		921	(C<uint8_t>) and also have an aligned version (without the C<_u> prefix),
		922	all of which hopefully makes them more useful in generic code.
		923
		924	=back
		925
		926	=head2 FAST INTEGER TO STRING
		927
		928	Libecb defines a set of very fast integer to decimal string (or integer
		929	to ascii, short C<i2a>) functions. These work by converting the integer
		930	to a fixed point representation and then successively multiplying out
		931	the topmost digits. Unlike some other, also very fast, libraries, ecb's
		932	algorithm should be completely branchless per digit, and does not rely on
		933	the presence of special cpu functions (such as clz).
		934
		935	There is a high level API that takes an C<int32_t>, C<uint32_t>,
		936	C<int64_t> or C<uint64_t> as argument, and a low-level API, which is
		937	harder to use but supports slightly more formatting options.
		938
		939	=head3 HIGH LEVEL API
		940
		941	The high level API consists of four functions, one each for C<int32_t>,
		942	C<uint32_t>, C<int64_t> and C<uint64_t>:
		943
		944	Example:
		945
		946	char buf[ECB_I2A_MAX_DIGITS + 1];
		947	char *end = ecb_i2a_i32 (buf, 17262);
		948	*end = 0;
		949	// buf now contains "17262"
		950
		951	=over
		952
		953	=item ECB_I2A_I32_DIGITS (=11)
		954
		955	=item char ecb_i2a_u32 (char ptr, uint32_t value)
		956
		957	Takes an C<uint32_t> I<value> and formats it as a decimal number starting
		958	at I<ptr>, using at most C<ECB_I2A_I32_DIGITS> characters. Returns a
		959	pointer to just after the generated string, where you would normally put
		960	the terminating C<0> character. This function outputs the minimum number
		961	of digits.
		962
		963	=item ECB_I2A_U32_DIGITS (=10)
		964
		965	=item char ecb_i2a_i32 (char ptr, int32_t value)
		966
		967	Same as C<ecb_i2a_u32>, but formats a C<int32_t> value, including a minus
		968	sign if needed.
		969
		970	=item ECB_I2A_I64_DIGITS (=20)
		971
		972	=item char ecb_i2a_u64 (char ptr, uint64_t value)
		973
		974	=item ECB_I2A_U64_DIGITS (=21)
		975
		976	=item char ecb_i2a_i64 (char ptr, int64_t value)
		977
		978	Similar to their 32 bit counterparts, these take a 64 bit argument.
		979
		980	=item ECB_I2A_MAX_DIGITS (=21)
		981
		982	Instead of using a type specific length macro, youi can just use
		983	C<ECB_I2A_MAX_DIGITS>, which is good enough for any C<ecb_i2a> function.
		984
		985	=back
		986
		987	=head3 LOW-LEVEL API
		988
		989	The functions above use a number of low-level APIs which have some strict
		990	limitations, but can be used as building blocks (study of C<ecb_i2a_i32>
		991	and related functions is recommended).
		992
		993	There are three families of functions: functions that convert a number
		994	to a fixed number of digits with leading zeroes (C<ecb_i2a_0N>, C<0>
		995	for "leading zeroes"), functions that generate up to N digits, skipping
		996	leading zeroes (C<_N>), and functions that can generate more digits, but
		997	the leading digit has limited range (C<_xN>).
		998
		999	None of the functions deal with negative numbers.
		1000
		1001	Example: convert an IP address in an u32 into dotted-quad:
		1002
		1003	uint32_t ip = 0x0a000164; // 10.0.1.100
		1004	char ips[3 * 4 + 3 + 1];
		1005	char *ptr = ips;
		1006	ptr = ecb_i2a_3 (ptr, ip >> 24 ); *ptr++ = '.';
		1007	ptr = ecb_i2a_3 (ptr, (ip >> 16) & 0xff); *ptr++ = '.';
		1008	ptr = ecb_i2a_3 (ptr, (ip >> 8) & 0xff); *ptr++ = '.';
		1009	ptr = ecb_i2a_3 (ptr, ip & 0xff); *ptr++ = 0;
		1010	printf ("ip: %s\n", ips); // prints "ip: 10.0.1.100"
		1011
		1012	=over
		1013
		1014	=item char ecb_i2a_02 (char ptr, uint32_t value) // 32 bit
		1015
		1016	=item char ecb_i2a_03 (char ptr, uint32_t value) // 32 bit
		1017
		1018	=item char ecb_i2a_04 (char ptr, uint32_t value) // 32 bit
		1019
		1020	=item char ecb_i2a_05 (char ptr, uint32_t value) // 64 bit
		1021
		1022	=item char ecb_i2a_06 (char ptr, uint32_t value) // 64 bit
		1023
		1024	=item char ecb_i2a_07 (char ptr, uint32_t value) // 64 bit
		1025
		1026	=item char ecb_i2a_08 (char ptr, uint32_t value) // 64 bit
		1027
		1028	=item char ecb_i2a_09 (char ptr, uint32_t value) // 64 bit
		1029
		1030	The C<< ecb_i2a_0I<N> > functions take an unsigned I<value> and convert
		1031	them to exactly I<N> digits, returning a pointer to the first character
		1032	after the digits. The I<value> must be in range. The functions marked with
		1033	I<32 bit> do their calculations internally in 32 bit, the ones marked with
		1034	I<64 bit> internally use 64 bit integers, which might be slow on 32 bit
		1035	architectures (the high level API decides on 32 vs. 64 bit versions using
		1036	C<ECB_64BIT_NATIVE>).
		1037
		1038	=item char ecb_i2a_2 (char ptr, uint32_t value) // 32 bit
		1039
		1040	=item char ecb_i2a_3 (char ptr, uint32_t value) // 32 bit
		1041
		1042	=item char ecb_i2a_4 (char ptr, uint32_t value) // 32 bit
		1043
		1044	=item char ecb_i2a_5 (char ptr, uint32_t value) // 64 bit
		1045
		1046	=item char ecb_i2a_6 (char ptr, uint32_t value) // 64 bit
		1047
		1048	=item char ecb_i2a_7 (char ptr, uint32_t value) // 64 bit
		1049
		1050	=item char ecb_i2a_8 (char ptr, uint32_t value) // 64 bit
		1051
		1052	=item char ecb_i2a_9 (char ptr, uint32_t value) // 64 bit
		1053
		1054	Similarly, the C<< ecb_i2a_I<N> > functions take an unsigned I<value>
		1055	and convert them to at most I<N> digits, suppressing leading zeroes, and
		1056	returning a pointer to the first character after the digits.
		1057
		1058	=item ECB_I2A_MAX_X5 (=59074)
		1059
		1060	=item char ecb_i2a_x5 (char ptr, uint32_t value) // 32 bit
		1061
		1062	=item ECB_I2A_MAX_X10 (=2932500665)
		1063
		1064	=item char ecb_i2a_x10 (char ptr, uint32_t value) // 64 bit
		1065
		1066	The C<< ecb_i2a_xI<N> >> functions are similar to the C<< ecb_i2a_I<N> >
		1067	functions, but they can generate one digit more, as long as the number
		1068	is within range, which is given by the symbols C<ECB_I2A_MAX_X5> (almost
		1069	16 bit range) and C<ECB_I2A_MAX_X10> (a bit more than 31 bit range),
		1070	respectively.
		1071
		1072	For example, the digit part of a 32 bit signed integer just fits into the
		1073	C<ECB_I2A_MAX_X10> range, so while C<ecb_i2a_x10> cannot convert a 10
		1074	digit number, it can convert all 32 bit signed numbers. Sadly, it's not
		1075	good enough for 32 bit unsigned numbers.
684		1076
685	=back	1077	=back
686		1078
687	=head2 FLOATING POINT FIDDLING	1079	=head2 FLOATING POINT FIDDLING
688		1080
689	=over 4	1081	=over
690		1082
691	=item ECB_INFINITY	1083	=item ECB_INFINITY [-UECB_NO_LIBM]
692		1084
693	Evaluates to positive infinity if supported by the platform, otherwise to	1085	Evaluates to positive infinity if supported by the platform, otherwise to
694	a truly huge number.	1086	a truly huge number.
695		1087
696	=item ECB_NAN	1088	=item ECB_NAN [-UECB_NO_LIBM]
697		1089
698	Evaluates to a quiet NAN if supported by the platform, otherwise to	1090	Evaluates to a quiet NAN if supported by the platform, otherwise to
699	C<ECB_INFINITY>.	1091	C<ECB_INFINITY>.
700		1092
701	=item float ecb_ldexpf (float x, int exp)	1093	=item float ecb_ldexpf (float x, int exp) [-UECB_NO_LIBM]
702		1094
703	Same as C<ldexpf>, but always available.	1095	Same as C<ldexpf>, but always available.
704		1096
		1097	=item uint32_t ecb_float_to_binary16 (float x) [-UECB_NO_LIBM]
		1098
705	=item uint32_t ecb_float_to_binary32 (float x) [-UECB_NO_LIBM]	1099	=item uint32_t ecb_float_to_binary32 (float x) [-UECB_NO_LIBM]
706		1100
707	=item uint64_t ecb_double_to_binary64 (double x) [-UECB_NO_LIBM]	1101	=item uint64_t ecb_double_to_binary64 (double x) [-UECB_NO_LIBM]
708		1102
709	These functions each take an argument in the native C<float> or C<double>	1103	These functions each take an argument in the native C<float> or C<double>
710	type and return the IEEE 754 bit representation of it.	1104	type and return the IEEE 754 bit representation of it (binary16/half,
		1105	binary32/single or binary64/double precision).
711		1106
712	The bit representation is just as IEEE 754 defines it, i.e. the sign bit	1107	The bit representation is just as IEEE 754 defines it, i.e. the sign bit
713	will be the most significant bit, followed by exponent and mantissa.	1108	will be the most significant bit, followed by exponent and mantissa.
714		1109
715	This function should work even when the native floating point format isn't	1110	This function should work even when the native floating point format isn't
…		…
719		1114
720	On all modern platforms (where C<ECB_STDFP> is true), the compiler should	1115	On all modern platforms (where C<ECB_STDFP> is true), the compiler should
721	be able to optimise away this function completely.	1116	be able to optimise away this function completely.
722		1117
723	These functions can be helpful when serialising floats to the network - you	1118	These functions can be helpful when serialising floats to the network - you
724	can serialise the return value like a normal uint32_t/uint64_t.	1119	can serialise the return value like a normal uint16_t/uint32_t/uint64_t.
725		1120
726	Another use for these functions is to manipulate floating point values	1121	Another use for these functions is to manipulate floating point values
727	directly.	1122	directly.
728		1123
729	Silly example: toggle the sign bit of a float.	1124	Silly example: toggle the sign bit of a float.
…		…
739	=item float ecb_binary32_to_float (uint32_t x) [-UECB_NO_LIBM]	1134	=item float ecb_binary32_to_float (uint32_t x) [-UECB_NO_LIBM]
740		1135
741	=item double ecb_binary64_to_double (uint64_t x) [-UECB_NO_LIBM]	1136	=item double ecb_binary64_to_double (uint64_t x) [-UECB_NO_LIBM]
742		1137
743	The reverse operation of the previous function - takes the bit	1138	The reverse operation of the previous function - takes the bit
744	representation of an IEEE binary16, binary32 or binary64 number and	1139	representation of an IEEE binary16, binary32 or binary64 number (half,
745	converts it to the native C<float> or C<double> format.	1140	single or double precision) and converts it to the native C<float> or
		1141	C<double> format.
746		1142
747	This function should work even when the native floating point format isn't	1143	This function should work even when the native floating point format isn't
748	IEEE compliant, of course at a speed and code size penalty, and of course	1144	IEEE compliant, of course at a speed and code size penalty, and of course
749	also within reasonable limits (it tries to convert normals and denormals,	1145	also within reasonable limits (it tries to convert normals and denormals,
750	and might be lucky for infinities, and with extraordinary luck, also for	1146	and might be lucky for infinities, and with extraordinary luck, also for
751	negative zero).	1147	negative zero).
752		1148
753	On all modern platforms (where C<ECB_STDFP> is true), the compiler should	1149	On all modern platforms (where C<ECB_STDFP> is true), the compiler should
754	be able to optimise away this function completely.	1150	be able to optimise away this function completely.
755		1151
		1152	=item uint16_t ecb_binary32_to_binary16 (uint32_t x)
		1153
		1154	=item uint32_t ecb_binary16_to_binary32 (uint16_t x)
		1155
		1156	Convert a IEEE binary32/single precision to binary16/half format, and vice
		1157	versa, handling all details (round-to-nearest-even, subnormals, infinity
		1158	and NaNs) correctly.
		1159
		1160	These are functions are available under C<-DECB_NO_LIBM>, since
		1161	they do not rely on the platform floating point format. The
		1162	C<ecb_float_to_binary16> and C<ecb_binary16_to_float> functions are
		1163	usually what you want.
		1164
756	=back	1165	=back
757		1166
758	=head2 ARITHMETIC	1167	=head2 ARITHMETIC
759		1168
760	=over 4	1169	=over
761		1170
762	=item x = ecb_mod (m, n)	1171	=item x = ecb_mod (m, n)
763		1172
764	Returns C<m> modulo C<n>, which is the same as the positive remainder	1173	Returns C<m> modulo C<n>, which is the same as the positive remainder
765	of the division operation between C<m> and C<n>, using floored	1174	of the division operation between C<m> and C<n>, using floored
…		…
772	C<n> must be strictly positive (i.e. C<< >= 1 >>), while C<m> must be	1181	C<n> must be strictly positive (i.e. C<< >= 1 >>), while C<m> must be
773	negatable, that is, both C<m> and C<-m> must be representable in its	1182	negatable, that is, both C<m> and C<-m> must be representable in its
774	type (this typically excludes the minimum signed integer value, the same	1183	type (this typically excludes the minimum signed integer value, the same
775	limitation as for C</> and C<%> in C).	1184	limitation as for C</> and C<%> in C).
776		1185
777	Current GCC versions compile this into an efficient branchless sequence on	1186	Current GCC/clang versions compile this into an efficient branchless
778	almost all CPUs.	1187	sequence on almost all CPUs.
779		1188
780	For example, when you want to rotate forward through the members of an	1189	For example, when you want to rotate forward through the members of an
781	array for increasing C<m> (which might be negative), then you should use	1190	array for increasing C<m> (which might be negative), then you should use
782	C<ecb_mod>, as the C<%> operator might give either negative results, or	1191	C<ecb_mod>, as the C<%> operator might give either negative results, or
783	change direction for negative values:	1192	change direction for negative values:
…		…
796		1205
797	=back	1206	=back
798		1207
799	=head2 UTILITY	1208	=head2 UTILITY
800		1209
801	=over 4	1210	=over
802		1211
803	=item element_count = ecb_array_length (name)	1212	=item element_count = ecb_array_length (name)
804		1213
805	Returns the number of elements in the array C<name>. For example:	1214	Returns the number of elements in the array C<name>. For example:
806		1215
…		…
814		1223
815	=head2 SYMBOLS GOVERNING COMPILATION OF ECB.H ITSELF	1224	=head2 SYMBOLS GOVERNING COMPILATION OF ECB.H ITSELF
816		1225
817	These symbols need to be defined before including F<ecb.h> the first time.	1226	These symbols need to be defined before including F<ecb.h> the first time.
818		1227
819	=over 4	1228	=over
820		1229
821	=item ECB_NO_THREADS	1230	=item ECB_NO_THREADS
822		1231
823	If F<ecb.h> is never used from multiple threads, then this symbol can	1232	If F<ecb.h> is never used from multiple threads, then this symbol can
824	be defined, in which case memory fences (and similar constructs) are	1233	be defined, in which case memory fences (and similar constructs) are

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Comparing cvsroot/libecb/ecb.pod (file contents): Revision 1.70 by root, Tue Sep 1 16:14:42 2015 UTC vs. Revision 1.93 by root, Sat Jul 31 14:39:16 2021 UTC

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Comparing cvsroot/libecb/ecb.pod (file contents):
Revision 1.70 by root, Tue Sep 1 16:14:42 2015 UTC vs.
Revision 1.93 by root, Sat Jul 31 14:39:16 2021 UTC