[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 1.91 by root, Tue Jun 22 01:07:29 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 integerss. While 64 bit
		174	integer support is very common (and in fatc 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
681	Current GCC versions understand these functions and usually compile them	738	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	739	them to "optimal" code (e.g. a single C<rol> or a combination of C<shld>
683	x86).	740	on x86).
		741
		742	=item T ecb_rotl (T x, unsigned int count) [C++]
		743
		744	=item T ecb_rotr (T x, unsigned int count) [C++]
		745
		746	Overloaded C++ rotl/rotr functions.
		747
		748	C<T> must be one of C<uint8_t>, C<uint16_t>, C<uint32_t> or C<uint64_t>.
		749
		750	=back
		751
		752	=head2 HOST ENDIANNESS CONVERSION
		753
		754	=over
		755
		756	=item uint_fast16_t ecb_be_u16_to_host (uint_fast16_t v)
		757
		758	=item uint_fast32_t ecb_be_u32_to_host (uint_fast32_t v)
		759
		760	=item uint_fast64_t ecb_be_u64_to_host (uint_fast64_t v)
		761
		762	=item uint_fast16_t ecb_le_u16_to_host (uint_fast16_t v)
		763
		764	=item uint_fast32_t ecb_le_u32_to_host (uint_fast32_t v)
		765
		766	=item uint_fast64_t ecb_le_u64_to_host (uint_fast64_t v)
		767
		768	Convert an unsigned 16, 32 or 64 bit value from big or little endian to host byte order.
		769
		770	The naming convention is C<ecb_>(C<be>\|C<le>)C<_u>C<16\|32\|64>C<_to_host>,
		771	where C<be> and C<le> stand for big endian and little endian, respectively.
		772
		773	=item uint_fast16_t ecb_host_to_be_u16 (uint_fast16_t v)
		774
		775	=item uint_fast32_t ecb_host_to_be_u32 (uint_fast32_t v)
		776
		777	=item uint_fast64_t ecb_host_to_be_u64 (uint_fast64_t v)
		778
		779	=item uint_fast16_t ecb_host_to_le_u16 (uint_fast16_t v)
		780
		781	=item uint_fast32_t ecb_host_to_le_u32 (uint_fast32_t v)
		782
		783	=item uint_fast64_t ecb_host_to_le_u64 (uint_fast64_t v)
		784
		785	Like above, but converts I<from> host byte order to the specified
		786	endianness.
		787
		788	=back
		789
		790	In C++ the following additional template functions are supported:
		791
		792	=over
		793
		794	=item T ecb_be_to_host (T v)
		795
		796	=item T ecb_le_to_host (T v)
		797
		798	=item T ecb_host_to_be (T v)
		799
		800	=item T ecb_host_to_le (T v)
		801
		802	=back
		803
		804	These functions work like their C counterparts, above, but use templates,
		805	which make them useful in generic code.
		806
		807	C<T> must be one of C<uint8_t>, C<uint16_t>, C<uint32_t> or C<uint64_t>
		808	(so unlike their C counterparts, there is a version for C<uint8_t>, which
		809	again can be useful in generic code).
		810
		811	=head2 UNALIGNED LOAD/STORE
		812
		813	These function load or store unaligned multi-byte values.
		814
		815	=over
		816
		817	=item uint_fast16_t ecb_peek_u16_u (const void *ptr)
		818
		819	=item uint_fast32_t ecb_peek_u32_u (const void *ptr)
		820
		821	=item uint_fast64_t ecb_peek_u64_u (const void *ptr)
		822
		823	These functions load an unaligned, unsigned 16, 32 or 64 bit value from
		824	memory.
		825
		826	=item uint_fast16_t ecb_peek_be_u16_u (const void *ptr)
		827
		828	=item uint_fast32_t ecb_peek_be_u32_u (const void *ptr)
		829
		830	=item uint_fast64_t ecb_peek_be_u64_u (const void *ptr)
		831
		832	=item uint_fast16_t ecb_peek_le_u16_u (const void *ptr)
		833
		834	=item uint_fast32_t ecb_peek_le_u32_u (const void *ptr)
		835
		836	=item uint_fast64_t ecb_peek_le_u64_u (const void *ptr)
		837
		838	Like above, but additionally convert from big endian (C<be>) or little
		839	endian (C<le>) byte order to host byte order while doing so.
		840
		841	=item ecb_poke_u16_u (void *ptr, uint16_t v)
		842
		843	=item ecb_poke_u32_u (void *ptr, uint32_t v)
		844
		845	=item ecb_poke_u64_u (void *ptr, uint64_t v)
		846
		847	These functions store an unaligned, unsigned 16, 32 or 64 bit value to
		848	memory.
		849
		850	=item ecb_poke_be_u16_u (void *ptr, uint_fast16_t v)
		851
		852	=item ecb_poke_be_u32_u (void *ptr, uint_fast32_t v)
		853
		854	=item ecb_poke_be_u64_u (void *ptr, uint_fast64_t v)
		855
		856	=item ecb_poke_le_u16_u (void *ptr, uint_fast16_t v)
		857
		858	=item ecb_poke_le_u32_u (void *ptr, uint_fast32_t v)
		859
		860	=item ecb_poke_le_u64_u (void *ptr, uint_fast64_t v)
		861
		862	Like above, but additionally convert from host byte order to big endian
		863	(C<be>) or little endian (C<le>) byte order while doing so.
		864
		865	=back
		866
		867	In C++ the following additional template functions are supported:
		868
		869	=over
		870
		871	=item T ecb_peek<T> (const void *ptr)
		872
		873	=item T ecb_peek_be<T> (const void *ptr)
		874
		875	=item T ecb_peek_le<T> (const void *ptr)
		876
		877	=item T ecb_peek_u<T> (const void *ptr)
		878
		879	=item T ecb_peek_be_u<T> (const void *ptr)
		880
		881	=item T ecb_peek_le_u<T> (const void *ptr)
		882
		883	Similarly to their C counterparts, these functions load an unsigned 8, 16,
		884	32 or 64 bit value from memory, with optional conversion from big/little
		885	endian.
		886
		887	Since the type cannot be deduced, it has to be specified explicitly, e.g.
		888
		889	uint_fast16_t v = ecb_peek<uint16_t> (ptr);
		890
		891	C<T> must be one of C<uint8_t>, C<uint16_t>, C<uint32_t> or C<uint64_t>.
		892
		893	Unlike their C counterparts, these functions support 8 bit quantities
		894	(C<uint8_t>) and also have an aligned version (without the C<_u> prefix),
		895	all of which hopefully makes them more useful in generic code.
		896
		897	=item ecb_poke (void *ptr, T v)
		898
		899	=item ecb_poke_be (void *ptr, T v)
		900
		901	=item ecb_poke_le (void *ptr, T v)
		902
		903	=item ecb_poke_u (void *ptr, T v)
		904
		905	=item ecb_poke_be_u (void *ptr, T v)
		906
		907	=item ecb_poke_le_u (void *ptr, T v)
		908
		909	Again, similarly to their C counterparts, these functions store an
		910	unsigned 8, 16, 32 or z64 bit value to memory, with optional conversion to
		911	big/little endian.
		912
		913	C<T> must be one of C<uint8_t>, C<uint16_t>, C<uint32_t> or C<uint64_t>.
		914
		915	Unlike their C counterparts, these functions support 8 bit quantities
		916	(C<uint8_t>) and also have an aligned version (without the C<_u> prefix),
		917	all of which hopefully makes them more useful in generic code.
		918
		919	=back
		920
		921	=head2 FAST INTEGER TO STRING
		922
		923	Libecb defines a set of very fast integer to decimal string (or integer
		924	to ascii, short C<i2a>) functions. These work by converting the integer
		925	to a fixed point representation and then successively multiplying out
		926	the topmost digits. Unlike some other, also very fast, libraries, ecb's
		927	algorithm should be completely branchless per digit, and does not rely on
		928	the presence of special cpu functions (such as clz).
		929
		930	There is a high level API that takes an C<int32_t>, C<uint32_t>,
		931	C<int64_t> or C<uint64_t> as argument, and a low-level API, which is
		932	harder to use but supports slightly more formatting options.
		933
		934	=head3 HIGH LEVEL API
		935
		936	The high level API consists of four functions, one each for C<int32_t>,
		937	C<uint32_t>, C<int64_t> and C<uint64_t>:
		938
		939	Example:
		940
		941	char buf[ECB_I2A_MAX_DIGITS + 1];
		942	char *end = ecb_i2a_i32 (buf, 17262);
		943	*end = 0;
		944	// buf now contains "17262"
		945
		946	=over
		947
		948	=item ECB_I2A_I32_DIGITS (=11)
		949
		950	=item char ecb_i2a_u32 (char ptr, uint32_t value)
		951
		952	Takes an C<uint32_t> I<value> and formats it as a decimal number starting
		953	at I<ptr>, using at most C<ECB_I2A_I32_DIGITS> characters. Returns a
		954	pointer to just after the generated string, where you would normally put
		955	the temrinating C<0> character. This function outputs the minimum number
		956	of digits.
		957
		958	=item ECB_I2A_U32_DIGITS (=10)
		959
		960	=item char ecb_i2a_i32 (char ptr, int32_t value)
		961
		962	Same as C<ecb_i2a_u32>, but formats a C<int32_t> value, including a minus
		963	sign if needed.
		964
		965	=item ECB_I2A_I64_DIGITS (=20)
		966
		967	=item char ecb_i2a_u64 (char ptr, uint64_t value)
		968
		969	=item ECB_I2A_U64_DIGITS (=21)
		970
		971	=item char ecb_i2a_i64 (char ptr, int64_t value)
		972
		973	Similar to their 32 bit counterparts, these take a 64 bit argument.
		974
		975	=item ECB_I2A_MAX_DIGITS (=21)
		976
		977	Instead of using a type specific length macro, youi can just use
		978	C<ECB_I2A_MAX_DIGITS>, which is good enough for any C<ecb_i2a> function.
		979
		980	=back
		981
		982	=head3 LOW-LEVEL API
		983
		984	The functions above use a number of low-level APIs which have some strict
		985	limitaitons, but cna be used as building blocks (study of C<ecb_i2a_i32>
		986	and related cunctions is recommended).
		987
		988	There are three families of functions: functions that convert a number
		989	to a fixed number of digits with leading zeroes (C<ecb_i2a_0N>, C<0>
		990	for "leading zeroes"), functions that generate up to N digits, skipping
		991	leading zeroes (C<_N>), and functions that can generate more digits, but
		992	the leading digit has limited range (C<_xN>).
		993
		994	None of the functions deal with negative numbera.
		995
		996	Example: convert an IP address in an u32 into dotted-quad:
		997
		998	uint32_t ip = 0x0a000164; // 10.0.1.100
		999	char ips[3 * 4 + 3 + 1];
		1000	char *ptr = ips;
		1001	ptr = ecb_i2a_3 (ptr, ip >> 24 ); *ptr++ = '.';
		1002	ptr = ecb_i2a_3 (ptr, (ip >> 16) & 0xff); *ptr++ = '.';
		1003	ptr = ecb_i2a_3 (ptr, (ip >> 8) & 0xff); *ptr++ = '.';
		1004	ptr = ecb_i2a_3 (ptr, ip & 0xff); *ptr++ = 0;
		1005	printf ("ip: %s\n", ips); // prints "ip: 10.0.1.100"
		1006
		1007	=over
		1008
		1009	=item char ecb_i2a_02 (char ptr, uint32_t value) // 32 bit
		1010
		1011	=item char ecb_i2a_03 (char ptr, uint32_t value) // 32 bit
		1012
		1013	=item char ecb_i2a_04 (char ptr, uint32_t value) // 32 bit
		1014
		1015	=item char ecb_i2a_05 (char ptr, uint32_t value) // 64 bit
		1016
		1017	=item char ecb_i2a_06 (char ptr, uint32_t value) // 64 bit
		1018
		1019	=item char ecb_i2a_07 (char ptr, uint32_t value) // 64 bit
		1020
		1021	=item char ecb_i2a_08 (char ptr, uint32_t value) // 64 bit
		1022
		1023	=item char ecb_i2a_09 (char ptr, uint32_t value) // 64 bit
		1024
		1025	The C<< ecb_i2a_0I<N> > functions take an unsigned I<value> and convert
		1026	them to exactly I<N> digits, returning a pointer to the first character
		1027	after the digits. The I<value> must be in range. The functions marked with
		1028	I<32 bit> do their calculations internally in 32 bit, the ones marked with
		1029	I<64 bit> internally use 64 bit integers, which might be slow on 32 bit
		1030	architectures (the high level API decides on 32 vs. 64 bit versions using
		1031	C<ECB_64BIT_NATIVE>).
		1032
		1033	=item char ecb_i2a_2 (char ptr, uint32_t value) // 32 bit
		1034
		1035	=item char ecb_i2a_3 (char ptr, uint32_t value) // 32 bit
		1036
		1037	=item char ecb_i2a_4 (char ptr, uint32_t value) // 32 bit
		1038
		1039	=item char ecb_i2a_5 (char ptr, uint32_t value) // 64 bit
		1040
		1041	=item char ecb_i2a_6 (char ptr, uint32_t value) // 64 bit
		1042
		1043	=item char ecb_i2a_7 (char ptr, uint32_t value) // 64 bit
		1044
		1045	=item char ecb_i2a_8 (char ptr, uint32_t value) // 64 bit
		1046
		1047	=item char ecb_i2a_9 (char ptr, uint32_t value) // 64 bit
		1048
		1049	Similarly, the C<< ecb_i2a_I<N> > functions take an unsigned I<value>
		1050	and convert them to at most I<N> digits, suppressing leading zeroes, and
		1051	returning a pointer to the first character after the digits.
		1052
		1053	=item ECB_I2A_MAX_X5 (=59074)
		1054
		1055	=item char ecb_i2a_x5 (char ptr, uint32_t value) // 32 bit
		1056
		1057	=item ECB_I2A_MAX_X10 (=2932500665)
		1058
		1059	=item char ecb_i2a_x10 (char ptr, uint32_t value) // 64 bit
		1060
		1061	The C<< ecb_i2a_xI<N> >> functions are similar to the C<< ecb_i2a_I<N> >
		1062	functions, but they can generate one digit more, as long as the number
		1063	is within range, which is given by the symbols C<ECB_I2A_MAX_X5> (almost
		1064	16 bit range) and C<ECB_I2A_MAX_X10> (a bit more than 31 bit range),
		1065	respectively.
		1066
		1067	For example, the sigit part of a 32 bit signed integer just fits into the
		1068	C<ECB_I2A_MAX_X10> range, so while C<ecb_i2a_x10> cannot convert a 10
		1069	digit number, it can convert all 32 bit signed numbers. Sadly, it's not
		1070	good enough for 32 bit unsigned numbers.
684		1071
685	=back	1072	=back
686		1073
687	=head2 FLOATING POINT FIDDLING	1074	=head2 FLOATING POINT FIDDLING
688		1075
689	=over 4	1076	=over
690		1077
691	=item ECB_INFINITY	1078	=item ECB_INFINITY [-UECB_NO_LIBM]
692		1079
693	Evaluates to positive infinity if supported by the platform, otherwise to	1080	Evaluates to positive infinity if supported by the platform, otherwise to
694	a truly huge number.	1081	a truly huge number.
695		1082
696	=item ECB_NAN	1083	=item ECB_NAN [-UECB_NO_LIBM]
697		1084
698	Evaluates to a quiet NAN if supported by the platform, otherwise to	1085	Evaluates to a quiet NAN if supported by the platform, otherwise to
699	C<ECB_INFINITY>.	1086	C<ECB_INFINITY>.
700		1087
701	=item float ecb_ldexpf (float x, int exp)	1088	=item float ecb_ldexpf (float x, int exp) [-UECB_NO_LIBM]
702		1089
703	Same as C<ldexpf>, but always available.	1090	Same as C<ldexpf>, but always available.
704		1091
		1092	=item uint32_t ecb_float_to_binary16 (float x) [-UECB_NO_LIBM]
		1093
705	=item uint32_t ecb_float_to_binary32 (float x) [-UECB_NO_LIBM]	1094	=item uint32_t ecb_float_to_binary32 (float x) [-UECB_NO_LIBM]
706		1095
707	=item uint64_t ecb_double_to_binary64 (double x) [-UECB_NO_LIBM]	1096	=item uint64_t ecb_double_to_binary64 (double x) [-UECB_NO_LIBM]
708		1097
709	These functions each take an argument in the native C<float> or C<double>	1098	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.	1099	type and return the IEEE 754 bit representation of it (binary16/half,
		1100	binary32/single or binary64/double precision).
711		1101
712	The bit representation is just as IEEE 754 defines it, i.e. the sign bit	1102	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.	1103	will be the most significant bit, followed by exponent and mantissa.
714		1104
715	This function should work even when the native floating point format isn't	1105	This function should work even when the native floating point format isn't
…		…
719		1109
720	On all modern platforms (where C<ECB_STDFP> is true), the compiler should	1110	On all modern platforms (where C<ECB_STDFP> is true), the compiler should
721	be able to optimise away this function completely.	1111	be able to optimise away this function completely.
722		1112
723	These functions can be helpful when serialising floats to the network - you	1113	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.	1114	can serialise the return value like a normal uint16_t/uint32_t/uint64_t.
725		1115
726	Another use for these functions is to manipulate floating point values	1116	Another use for these functions is to manipulate floating point values
727	directly.	1117	directly.
728		1118
729	Silly example: toggle the sign bit of a float.	1119	Silly example: toggle the sign bit of a float.
…		…
739	=item float ecb_binary32_to_float (uint32_t x) [-UECB_NO_LIBM]	1129	=item float ecb_binary32_to_float (uint32_t x) [-UECB_NO_LIBM]
740		1130
741	=item double ecb_binary64_to_double (uint64_t x) [-UECB_NO_LIBM]	1131	=item double ecb_binary64_to_double (uint64_t x) [-UECB_NO_LIBM]
742		1132
743	The reverse operation of the previous function - takes the bit	1133	The reverse operation of the previous function - takes the bit
744	representation of an IEEE binary16, binary32 or binary64 number and	1134	representation of an IEEE binary16, binary32 or binary64 number (half,
745	converts it to the native C<float> or C<double> format.	1135	single or double precision) and converts it to the native C<float> or
		1136	C<double> format.
746		1137
747	This function should work even when the native floating point format isn't	1138	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	1139	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,	1140	also within reasonable limits (it tries to convert normals and denormals,
750	and might be lucky for infinities, and with extraordinary luck, also for	1141	and might be lucky for infinities, and with extraordinary luck, also for
751	negative zero).	1142	negative zero).
752		1143
753	On all modern platforms (where C<ECB_STDFP> is true), the compiler should	1144	On all modern platforms (where C<ECB_STDFP> is true), the compiler should
754	be able to optimise away this function completely.	1145	be able to optimise away this function completely.
755		1146
		1147	=item uint16_t ecb_binary32_to_binary16 (uint32_t x)
		1148
		1149	=item uint32_t ecb_binary16_to_binary32 (uint16_t x)
		1150
		1151	Convert a IEEE binary32/single precision to binary16/half format, and vice
		1152	versa, handling all details (round-to-nearest-even, subnormals, infinity
		1153	and NaNs) correctly.
		1154
		1155	These are functions are available under C<-DECB_NO_LIBM>, since
		1156	they do not rely on the platform floating point format. The
		1157	C<ecb_float_to_binary16> and C<ecb_binary16_to_float> functions are
		1158	usually what you want.
		1159
756	=back	1160	=back
757		1161
758	=head2 ARITHMETIC	1162	=head2 ARITHMETIC
759		1163
760	=over 4	1164	=over
761		1165
762	=item x = ecb_mod (m, n)	1166	=item x = ecb_mod (m, n)
763		1167
764	Returns C<m> modulo C<n>, which is the same as the positive remainder	1168	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	1169	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	1176	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	1177	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	1178	type (this typically excludes the minimum signed integer value, the same
775	limitation as for C</> and C<%> in C).	1179	limitation as for C</> and C<%> in C).
776		1180
777	Current GCC versions compile this into an efficient branchless sequence on	1181	Current GCC/clang versions compile this into an efficient branchless
778	almost all CPUs.	1182	sequence on almost all CPUs.
779		1183
780	For example, when you want to rotate forward through the members of an	1184	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	1185	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	1186	C<ecb_mod>, as the C<%> operator might give either negative results, or
783	change direction for negative values:	1187	change direction for negative values:
…		…
796		1200
797	=back	1201	=back
798		1202
799	=head2 UTILITY	1203	=head2 UTILITY
800		1204
801	=over 4	1205	=over
802		1206
803	=item element_count = ecb_array_length (name)	1207	=item element_count = ecb_array_length (name)
804		1208
805	Returns the number of elements in the array C<name>. For example:	1209	Returns the number of elements in the array C<name>. For example:
806		1210
…		…
814		1218
815	=head2 SYMBOLS GOVERNING COMPILATION OF ECB.H ITSELF	1219	=head2 SYMBOLS GOVERNING COMPILATION OF ECB.H ITSELF
816		1220
817	These symbols need to be defined before including F<ecb.h> the first time.	1221	These symbols need to be defined before including F<ecb.h> the first time.
818		1222
819	=over 4	1223	=over
820		1224
821	=item ECB_NO_THREADS	1225	=item ECB_NO_THREADS
822		1226
823	If F<ecb.h> is never used from multiple threads, then this symbol can	1227	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	1228	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 1.91 by root, Tue Jun 22 01:07:29 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 1.91 by root, Tue Jun 22 01:07:29 2021 UTC