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

Comparing libecb/ecb.pod (file contents):
Revision 1.76 by root, Mon Jan 20 13:13:56 2020 UTC vs.
Revision 1.90 by root, Tue Jun 22 00:01:15 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
…		…
80		80
81	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
82	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
83	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).
84		84
85	=over 4	85	=over
86		86
87	=item ECB_C	87	=item ECB_C
88		88
89	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,
90	while not claiming to be C++.	90	while not claiming to be C++, i..e C, but not C++.
91		91
92	=item ECB_C99	92	=item ECB_C99
93		93
94	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
95	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++.
…		…
110	=item ECB_CPP11, ECB_CPP14, ECB_CPP17	110	=item ECB_CPP11, ECB_CPP14, ECB_CPP17
111		111
112	True if the implementation claims to be compliant to C++11/C++14/C++17	112	True if the implementation claims to be compliant to C++11/C++14/C++17
113	(ISO/IEC 14882:2011, :2014, :2017) or any later version.	113	(ISO/IEC 14882:2011, :2014, :2017) or any later version.
114		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.
		123
115	=item ECB_GCC_VERSION (major, minor)	124	=item ECB_GCC_VERSION (major, minor)
116		125
117	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
118	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.
119	higher.
120		128
121	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
122	compatible but aren't.	130	compatible but aren't.
123		131
124	=item ECB_EXTERN_C	132	=item ECB_EXTERN_C
…		…
143		151
144	ECB_EXTERN_C_END	152	ECB_EXTERN_C_END
145		153
146	=item ECB_STDFP	154	=item ECB_STDFP
147		155
148	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
149	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
150	and double/binary64 representations internally I<and> the endianness of	158	and double/binary64 representations internally I<and> the endianness of
151	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>.
152		160
153	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
…		…
155	without having to think about format or endianness.	163	without having to think about format or endianness.
156		164
157	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
158	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
159	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.
160		176
161	=item ECB_AMD64, ECB_AMD64_X32	177	=item ECB_AMD64, ECB_AMD64_X32
162		178
163	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
164	ABI, respectively, and undefined elsewhere.	180	ABI, respectively, and undefined elsewhere.
…		…
171		187
172	=back	188	=back
173		189
174	=head2 MACRO TRICKERY	190	=head2 MACRO TRICKERY
175		191
176	=over 4	192	=over
177		193
178	=item ECB_CONCAT (a, b)	194	=item ECB_CONCAT (a, b)
179		195
180	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
181	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,
…		…
222	declarations must be put before the whole declaration:	238	declarations must be put before the whole declaration:
223		239
224	ecb_const int mysqrt (int a);	240	ecb_const int mysqrt (int a);
225	ecb_unused int i;	241	ecb_unused int i;
226		242
227	=over 4	243	=over
228		244
229	=item ecb_unused	245	=item ecb_unused
230		246
231	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
232	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
233	declare a variable but do not always use it:	249	you e.g. declare a variable but do not always use it:
234		250
235	{	251	{
236	ecb_unused int var;	252	ecb_unused int var;
237		253
238	#ifdef SOMECONDITION	254	#ifdef SOMECONDITION
…		…
406		422
407	=back	423	=back
408		424
409	=head2 OPTIMISATION HINTS	425	=head2 OPTIMISATION HINTS
410		426
411	=over 4	427	=over
412
413	=item ECB_OPTIMIZE_SIZE
414
415	Is C<1> when the compiler optimizes for size, C<0> otherwise. This symbol
416	can also be defined before including F<ecb.h>, in which case it will be
417	unchanged.
418		428
419	=item bool ecb_is_constant (expr)	429	=item bool ecb_is_constant (expr)
420		430
421	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
422	constant, and false otherwise.	432	constant, and false otherwise.
…		…
579		589
580	=back	590	=back
581		591
582	=head2 BIT FIDDLING / BIT WIZARDRY	592	=head2 BIT FIDDLING / BIT WIZARDRY
583		593
584	=over 4	594	=over
585		595
586	=item bool ecb_big_endian ()	596	=item bool ecb_big_endian ()
587		597
588	=item bool ecb_little_endian ()	598	=item bool ecb_little_endian ()
589		599
…		…
595		605
596	=item int ecb_ctz32 (uint32_t x)	606	=item int ecb_ctz32 (uint32_t x)
597		607
598	=item int ecb_ctz64 (uint64_t x)	608	=item int ecb_ctz64 (uint64_t x)
599		609
		610	=item int ecb_ctz (T x) [C++]
		611
600	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
601	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
602	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.
603		615
604	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>.
605		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
606	For example:	621	For example:
607		622
608	ecb_ctz32 (3) = 0	623	ecb_ctz32 (3) = 0
609	ecb_ctz32 (6) = 1	624	ecb_ctz32 (6) = 1
610		625
611	=item bool ecb_is_pot32 (uint32_t x)	626	=item bool ecb_is_pot32 (uint32_t x)
612		627
613	=item bool ecb_is_pot64 (uint32_t x)	628	=item bool ecb_is_pot64 (uint32_t x)
614		629
		630	=item bool ecb_is_pot (T x) [C++]
		631
615	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>.
616		633
617	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>.
618		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
619	=item int ecb_ld32 (uint32_t x)	639	=item int ecb_ld32 (uint32_t x)
620		640
621	=item int ecb_ld64 (uint64_t x)	641	=item int ecb_ld64 (uint64_t x)
		642
		643	=item int ecb_ld64 (T x) [C++]
622		644
623	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
624	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 <
625	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
626	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
…		…
631	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
632	itself requires.	654	itself requires.
633		655
634	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>.
635		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
636	=item int ecb_popcount32 (uint32_t x)	661	=item int ecb_popcount32 (uint32_t x)
637		662
638	=item int ecb_popcount64 (uint64_t x)	663	=item int ecb_popcount64 (uint64_t x)
639		664
		665	=item int ecb_popcount (T x) [C++]
		666
640	Returns the number of bits set to 1 in C<x>.	667	Returns the number of bits set to 1 in C<x>.
641		668
642	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.
643		673
644	For example:	674	For example:
645		675
646	ecb_popcount32 (7) = 3	676	ecb_popcount32 (7) = 3
647	ecb_popcount32 (255) = 8	677	ecb_popcount32 (255) = 8
…		…
650		680
651	=item uint16_t ecb_bitrev16 (uint16_t x)	681	=item uint16_t ecb_bitrev16 (uint16_t x)
652		682
653	=item uint32_t ecb_bitrev32 (uint32_t x)	683	=item uint32_t ecb_bitrev32 (uint32_t x)
654		684
		685	=item T ecb_bitrev (T x) [C++]
		686
655	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
656	and so on.	688	and so on.
657		689
		690	The overloaded C++ C<ecb_bitrev> function supports C<uint8_t>, C<uint16_t> and C<uint32_t> types.
		691
658	Example:	692	Example:
659		693
660	ecb_bitrev8 (0xa7) = 0xea	694	ecb_bitrev8 (0xa7) = 0xea
661	ecb_bitrev32 (0xffcc4411) = 0x882233ff	695	ecb_bitrev32 (0xffcc4411) = 0x882233ff
662		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
663	=item uint32_t ecb_bswap16 (uint32_t x)	703	=item uint32_t ecb_bswap16 (uint32_t x)
664		704
665	=item uint32_t ecb_bswap32 (uint32_t x)	705	=item uint32_t ecb_bswap32 (uint32_t x)
666		706
667	=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)
668		710
669	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
670	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
671	C<ecb_bswap32>).	713	C<ecb_bswap32>).
672		714
673	=item T ecb_bswap (T x) [C++]	715	The overloaded C++ C<ecb_bswap> function supports C<uint8_t>, C<uint16_t>,
674		716	C<uint32_t> and C<uint64_t> types.
675	For C++, an additional generic bswap function is provided. It supports
676	C<uint8_t>, C<uint16_t>, C<uint32_t> and C<uint64_t>.
677		717
678	=item uint8_t ecb_rotl8 (uint8_t x, unsigned int count)	718	=item uint8_t ecb_rotl8 (uint8_t x, unsigned int count)
679		719
680	=item uint16_t ecb_rotl16 (uint16_t x, unsigned int count)	720	=item uint16_t ecb_rotl16 (uint16_t x, unsigned int count)
681		721
…		…
693		733
694	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
695	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
696	(C<ecb_rotl>).	736	(C<ecb_rotl>).
697		737
698	Current GCC versions understand these functions and usually compile them	738	Current GCC/clang versions understand these functions and usually compile
699	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>
700	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>.
701		749
702	=back	750	=back
703		751
704	=head2 HOST ENDIANNESS CONVERSION	752	=head2 HOST ENDIANNESS CONVERSION
705		753
706	=over 4	754	=over
707		755
708	=item uint_fast16_t ecb_be_u16_to_host (uint_fast16_t v)	756	=item uint_fast16_t ecb_be_u16_to_host (uint_fast16_t v)
709		757
710	=item uint_fast32_t ecb_be_u32_to_host (uint_fast32_t v)	758	=item uint_fast32_t ecb_be_u32_to_host (uint_fast32_t v)
711		759
…		…
718	=item uint_fast64_t ecb_le_u64_to_host (uint_fast64_t v)	766	=item uint_fast64_t ecb_le_u64_to_host (uint_fast64_t v)
719		767
720	Convert an unsigned 16, 32 or 64 bit value from big or little endian to host byte order.	768	Convert an unsigned 16, 32 or 64 bit value from big or little endian to host byte order.
721		769
722	The naming convention is C<ecb_>(C<be>\|C<le>)C<_u>C<16\|32\|64>C<_to_host>,	770	The naming convention is C<ecb_>(C<be>\|C<le>)C<_u>C<16\|32\|64>C<_to_host>,
723	where be and le stand for big endian and little endian, respectively.	771	where C<be> and C<le> stand for big endian and little endian, respectively.
724		772
725	=item uint_fast16_t ecb_host_to_be_u16 (uint_fast16_t v)	773	=item uint_fast16_t ecb_host_to_be_u16 (uint_fast16_t v)
726		774
727	=item uint_fast32_t ecb_host_to_be_u32 (uint_fast32_t v)	775	=item uint_fast32_t ecb_host_to_be_u32 (uint_fast32_t v)
728		776
…		…
737	Like above, but converts I<from> host byte order to the specified	785	Like above, but converts I<from> host byte order to the specified
738	endianness.	786	endianness.
739		787
740	=back	788	=back
741		789
742	In C++ the following additional functions are supported:	790	In C++ the following additional template functions are supported:
743		791
744	=over 4	792	=over
745		793
746	=item T ecb_be_to_host (T v)	794	=item T ecb_be_to_host (T v)
747		795
748	=item T ecb_le_to_host (T v)	796	=item T ecb_le_to_host (T v)
749		797
750	=item T ecb_host_to_be (T v)	798	=item T ecb_host_to_be (T v)
751		799
752	=item T ecb_host_to_le (T v)	800	=item T ecb_host_to_le (T v)
753		801
		802	=back
		803
754	These work like their C counterparts, above, but use templates for the	804	These functions work like their C counterparts, above, but use templates,
755	type, which make them useful in generic code.	805	which make them useful in generic code.
756		806
757	C<T> must be one of C<uint8_t>, C<uint16_t>, C<uint32_t> or C<uint64_t>	807	C<T> must be one of C<uint8_t>, C<uint16_t>, C<uint32_t> or C<uint64_t>
758	(so unlike their C counterparts, there is a version for C<uint8_t>, which	808	(so unlike their C counterparts, there is a version for C<uint8_t>, which
759	again can be useful in generic code).	809	again can be useful in generic code).
760		810
761	=head2 UNALIGNED LOAD/STORE	811	=head2 UNALIGNED LOAD/STORE
762		812
763	These function load or store unaligned multi-byte values.	813	These function load or store unaligned multi-byte values.
764		814
765	=over 4	815	=over
766		816
767	=item uint_fast16_t ecb_peek_u16_u (const void *ptr)	817	=item uint_fast16_t ecb_peek_u16_u (const void *ptr)
768		818
769	=item uint_fast32_t ecb_peek_u32_u (const void *ptr)	819	=item uint_fast32_t ecb_peek_u32_u (const void *ptr)
770		820
…		…
812	Like above, but additionally convert from host byte order to big endian	862	Like above, but additionally convert from host byte order to big endian
813	(C<be>) or little endian (C<le>) byte order while doing so.	863	(C<be>) or little endian (C<le>) byte order while doing so.
814		864
815	=back	865	=back
816		866
817	In C++ the following additional functions are supported:	867	In C++ the following additional template functions are supported:
818		868
819	=over 4	869	=over
820		870
821	=item T ecb_peek (const void *ptr)	871	=item T ecb_peek<T> (const void *ptr)
822		872
823	=item T ecb_peek_be (const void *ptr)	873	=item T ecb_peek_be<T> (const void *ptr)
824		874
825	=item T ecb_peek_le (const void *ptr)	875	=item T ecb_peek_le<T> (const void *ptr)
826		876
827	=item T ecb_peek_u (const void *ptr)	877	=item T ecb_peek_u<T> (const void *ptr)
828		878
829	=item T ecb_peek_be_u (const void *ptr)	879	=item T ecb_peek_be_u<T> (const void *ptr)
830		880
831	=item T ecb_peek_le_u (const void *ptr)	881	=item T ecb_peek_le_u<T> (const void *ptr)
832		882
833	Similarly to their C counterparts, these functions load an unsigned 8, 16,	883	Similarly to their C counterparts, these functions load an unsigned 8, 16,
834	32 or 64 bit value from memory, with optional conversion from big/little	884	32 or 64 bit value from memory, with optional conversion from big/little
835	endian.	885	endian.
836		886
837	Since the type cannot be deduced, it has top be specified explicitly, e.g.	887	Since the type cannot be deduced, it has to be specified explicitly, e.g.
838		888
839	uint_fast16_t v = ecb_peek<uint16_t> (ptr);	889	uint_fast16_t v = ecb_peek<uint16_t> (ptr);
840		890
841	C<T> must be one of C<uint8_t>, C<uint16_t>, C<uint32_t> or C<uint64_t>.	891	C<T> must be one of C<uint8_t>, C<uint16_t>, C<uint32_t> or C<uint64_t>.
842		892
…		…
866	(C<uint8_t>) and also have an aligned version (without the C<_u> prefix),	916	(C<uint8_t>) and also have an aligned version (without the C<_u> prefix),
867	all of which hopefully makes them more useful in generic code.	917	all of which hopefully makes them more useful in generic code.
868		918
869	=back	919	=back
870		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	=over
		940
		941	=item ECB_I2A_I32_DIGITS (=11)
		942
		943	=item char ecb_i2a_u32 (char ptr, uint32_t value)
		944
		945	Takes an C<uint32_t> I<value> and formats it as a decimal number starting
		946	at I<ptr>, using at most C<ECB_I2A_I32_DIGITS> characters. Returns a
		947	pointer to just after the generated string, where you would normally put
		948	the temrinating C<0> character. This function outputs the minimum number
		949	of digits.
		950
		951	=item ECB_I2A_U32_DIGITS (=10)
		952
		953	=item char ecb_i2a_i32 (char ptr, int32_t value)
		954
		955	Same as C<ecb_i2a_u32>, but formats a C<int32_t> value, including a minus
		956	sign if needed.
		957
		958	=item ECB_I2A_I64_DIGITS (=20)
		959
		960	=item char ecb_i2a_u64 (char ptr, uint64_t value)
		961
		962	=item ECB_I2A_U64_DIGITS (=21)
		963
		964	=item char ecb_i2a_i64 (char ptr, int64_t value)
		965
		966	Similar to their 32 bit counterparts, these take a 64 bit argument.
		967
		968	=item ECB_I2A_MAX_DIGITS (=21)
		969
		970	Instead of using a type specific length macro, youi can just use
		971	C<ECB_I2A_MAX_DIGITS>, which is good enough for any C<ecb_i2a> function.
		972
		973	=back
		974
		975	=head3 LOW-LEVEL API
		976
		977	The functions above use a number of low-level APIs which have some strict
		978	limitaitons, but cna be used as building blocks (study of C<ecb_i2a_i32>
		979	and related cunctions is recommended).
		980
		981	There are three families of functions: functions that convert a number
		982	to a fixed number of digits with leading zeroes (C<ecb_i2a_0N>, C<0>
		983	for "leading zeroes"), functions that generate up to N digits, skipping
		984	leading zeroes (C<_N>), and functions that can generate more digits, but
		985	the leading digit has limited range (C<_xN>).
		986
		987	None of the functions deal with negative numbera.
		988
		989	=over
		990
		991	=item char ecb_i2a_02 (char ptr, uint32_t value) // 32 bit
		992
		993	=item char ecb_i2a_03 (char ptr, uint32_t value) // 32 bit
		994
		995	=item char ecb_i2a_04 (char ptr, uint32_t value) // 32 bit
		996
		997	=item char ecb_i2a_05 (char ptr, uint32_t value) // 64 bit
		998
		999	=item char ecb_i2a_06 (char ptr, uint32_t value) // 64 bit
		1000
		1001	=item char ecb_i2a_07 (char ptr, uint32_t value) // 64 bit
		1002
		1003	=item char ecb_i2a_08 (char ptr, uint32_t value) // 64 bit
		1004
		1005	=item char ecb_i2a_09 (char ptr, uint32_t value) // 64 bit
		1006
		1007	The C<< ecb_i2a_0I<N> > functions take an unsigned I<value> and convert
		1008	them to exactly I<N> digits, returning a pointer to the first character
		1009	after the digits. The I<value> must be in range. The functions marked with
		1010	I<32 bit> do their calculations internally in 32 bit, the ones marked with
		1011	I<64 bit> internally use 64 bit integers, which might be slow on 32 bit
		1012	architectures (the high level API decides on 32 vs. 64 bit versions using
		1013	C<ECB_64BIT_NATIVE>).
		1014
		1015	=item char ecb_i2a_2 (char ptr, uint32_t value) // 32 bit
		1016
		1017	=item char ecb_i2a_3 (char ptr, uint32_t value) // 32 bit
		1018
		1019	=item char ecb_i2a_4 (char ptr, uint32_t value) // 32 bit
		1020
		1021	=item char ecb_i2a_5 (char ptr, uint32_t value) // 64 bit
		1022
		1023	=item char ecb_i2a_6 (char ptr, uint32_t value) // 64 bit
		1024
		1025	=item char ecb_i2a_7 (char ptr, uint32_t value) // 64 bit
		1026
		1027	=item char ecb_i2a_8 (char ptr, uint32_t value) // 64 bit
		1028
		1029	=item char ecb_i2a_9 (char ptr, uint32_t value) // 64 bit
		1030
		1031	Similarly, the C<< ecb_i2a_I<N> > functions take an unsigned I<value>
		1032	and convert them to at most I<N> digits, suppressing leading zeroes, and
		1033	returning a pointer to the first character after the digits.
		1034
		1035	=item ECB_I2A_MAX_X5 (=59074)
		1036
		1037	=item char ecb_i2a_x5 (char ptr, uint32_t value) // 32 bit
		1038
		1039	=item ECB_I2A_MAX_X10 (=2932500665)
		1040
		1041	=item char ecb_i2a_x10 (char ptr, uint32_t value) // 64 bit
		1042
		1043	The C<< ecb_i2a_xI<N> >> functions are similar to the C<< ecb_i2a_I<N> >
		1044	functions, but they can generate one digit more, as long as the number
		1045	is within range, which is given by the symbols C<ECB_I2A_MAX_X5> (almost
		1046	16 bit range) and C<ECB_I2A_MAX_X10> (a bit more than 31 bit range),
		1047	respectively.
		1048
		1049	For example, the sigit part of a 32 bit signed integer just fits into the
		1050	C<ECB_I2A_MAX_X10> range, so while C<ecb_i2a_x10> cannot convert a 10
		1051	digit number, it can convert all 32 bit signed numbers. Sadly, it's not
		1052	good enough for 32 bit unsigned numbers.
		1053
		1054	=back
		1055
871	=head2 FLOATING POINT FIDDLING	1056	=head2 FLOATING POINT FIDDLING
872		1057
873	=over 4	1058	=over
874		1059
875	=item ECB_INFINITY [-UECB_NO_LIBM]	1060	=item ECB_INFINITY [-UECB_NO_LIBM]
876		1061
877	Evaluates to positive infinity if supported by the platform, otherwise to	1062	Evaluates to positive infinity if supported by the platform, otherwise to
878	a truly huge number.	1063	a truly huge number.
…		…
956		1141
957	=back	1142	=back
958		1143
959	=head2 ARITHMETIC	1144	=head2 ARITHMETIC
960		1145
961	=over 4	1146	=over
962		1147
963	=item x = ecb_mod (m, n)	1148	=item x = ecb_mod (m, n)
964		1149
965	Returns C<m> modulo C<n>, which is the same as the positive remainder	1150	Returns C<m> modulo C<n>, which is the same as the positive remainder
966	of the division operation between C<m> and C<n>, using floored	1151	of the division operation between C<m> and C<n>, using floored
…		…
973	C<n> must be strictly positive (i.e. C<< >= 1 >>), while C<m> must be	1158	C<n> must be strictly positive (i.e. C<< >= 1 >>), while C<m> must be
974	negatable, that is, both C<m> and C<-m> must be representable in its	1159	negatable, that is, both C<m> and C<-m> must be representable in its
975	type (this typically excludes the minimum signed integer value, the same	1160	type (this typically excludes the minimum signed integer value, the same
976	limitation as for C</> and C<%> in C).	1161	limitation as for C</> and C<%> in C).
977		1162
978	Current GCC versions compile this into an efficient branchless sequence on	1163	Current GCC/clang versions compile this into an efficient branchless
979	almost all CPUs.	1164	sequence on almost all CPUs.
980		1165
981	For example, when you want to rotate forward through the members of an	1166	For example, when you want to rotate forward through the members of an
982	array for increasing C<m> (which might be negative), then you should use	1167	array for increasing C<m> (which might be negative), then you should use
983	C<ecb_mod>, as the C<%> operator might give either negative results, or	1168	C<ecb_mod>, as the C<%> operator might give either negative results, or
984	change direction for negative values:	1169	change direction for negative values:
…		…
997		1182
998	=back	1183	=back
999		1184
1000	=head2 UTILITY	1185	=head2 UTILITY
1001		1186
1002	=over 4	1187	=over
1003		1188
1004	=item element_count = ecb_array_length (name)	1189	=item element_count = ecb_array_length (name)
1005		1190
1006	Returns the number of elements in the array C<name>. For example:	1191	Returns the number of elements in the array C<name>. For example:
1007		1192
…		…
1015		1200
1016	=head2 SYMBOLS GOVERNING COMPILATION OF ECB.H ITSELF	1201	=head2 SYMBOLS GOVERNING COMPILATION OF ECB.H ITSELF
1017		1202
1018	These symbols need to be defined before including F<ecb.h> the first time.	1203	These symbols need to be defined before including F<ecb.h> the first time.
1019		1204
1020	=over 4	1205	=over
1021		1206
1022	=item ECB_NO_THREADS	1207	=item ECB_NO_THREADS
1023		1208
1024	If F<ecb.h> is never used from multiple threads, then this symbol can	1209	If F<ecb.h> is never used from multiple threads, then this symbol can
1025	be defined, in which case memory fences (and similar constructs) are	1210	be defined, in which case memory fences (and similar constructs) are

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Comparing libecb/ecb.pod (file contents): Revision 1.76 by root, Mon Jan 20 13:13:56 2020 UTC vs. Revision 1.90 by root, Tue Jun 22 00:01:15 2021 UTC

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Comparing libecb/ecb.pod (file contents):
Revision 1.76 by root, Mon Jan 20 13:13:56 2020 UTC vs.
Revision 1.90 by root, Tue Jun 22 00:01:15 2021 UTC