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

Comparing libecb/ecb.pod (file contents):
Revision 1.52 by root, Sun Sep 23 22:32:33 2012 UTC vs.
Revision 1.76 by root, Mon Jan 20 13:13:56 2020 UTC

…		…
58		58
59	=head2 TYPES / TYPE SUPPORT	59	=head2 TYPES / TYPE SUPPORT
60		60
61	ecb.h makes sure that the following types are defined (in the expected way):	61	ecb.h makes sure that the following types are defined (in the expected way):
62		62
63	int8_t uint8_t int16_t uint16_t	63	int8_t uint8_
64	int32_t uint32_t int64_t uint64_t	64	int16_t uint16_t
		65	int32_t uint32_
		66	int64_t uint64_t
		67	int_fast8_t uint_fast8_t
		68	int_fast16_t uint_fast16_t
		69	int_fast32_t uint_fast32_t
		70	int_fast64_t uint_fast64_t
65	intptr_t uintptr_t	71	intptr_t uintptr_t
66		72
67	The macro C<ECB_PTRSIZE> is defined to the size of a pointer on this	73	The macro C<ECB_PTRSIZE> is defined to the size of a pointer on this
68	platform (currently C<4> or C<8>) and can be used in preprocessor	74	platform (currently C<4> or C<8>) and can be used in preprocessor
69	expressions.	75	expressions.
70		76
71	For C<ptrdiff_t> and C<size_t> use C<stddef.h>.	77	For C<ptrdiff_t> and C<size_t> use C<stddef.h>/C<cstddef>.
72		78
73	=head2 LANGUAGE/COMPILER VERSIONS	79	=head2 LANGUAGE/ENVIRONMENT/COMPILER VERSIONS
74		80
75	All the following symbols expand to an expression that can be tested in	81	All the following symbols expand to an expression that can be tested in
76	preprocessor instructions as well as treated as a boolean (use C<!!> to	82	preprocessor instructions as well as treated as a boolean (use C<!!> to
77	ensure it's either C<0> or C<1> if you need that).	83	ensure it's either C<0> or C<1> if you need that).
78		84
79	=over 4	85	=over 4
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	which is typically true for both C and C++ compilers.	90	while not claiming to be 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.	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.	103	9899:2011, :20187) or any later version, while not claiming to be C++.
98		104
99	=item ECB_CPP	105	=item ECB_CPP
100		106
101	True if the implementation defines the C<__cplusplus__> macro to a true	107	True if the implementation defines the C<__cplusplus__> macro to a true
102	value, which is typically true for C++ compilers.	108	value, which is typically true for C++ compilers.
103		109
104	=item ECB_CPP11	110	=item ECB_CPP11, ECB_CPP14, ECB_CPP17
105		111
106	True if the implementation claims to be compliant to ISO/IEC 14882:2011	112	True if the implementation claims to be compliant to C++11/C++14/C++17
107	(C++11) or any later version.	113	(ISO/IEC 14882:2011, :2014, :2017) or any later version.
108		114
109	=item ECB_GCC_VERSION(major,minor)	115	=item ECB_GCC_VERSION (major, minor)
110		116
111	Expands to a true value (suitable for testing in by the preprocessor)	117	Expands to a true value (suitable for testing in by the preprocessor)
112	if the compiler used is GNU C and the version is the given version, or	118	if the compiler used is GNU C and the version is the given version, or
113	higher.	119	higher.
114		120
…		…
150		156
151	This is true for basically all modern platforms, although F<ecb.h> might	157	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	158	not be able to deduce this correctly everywhere and might err on the safe
153	side.	159	side.
154		160
155	=back	161	=item ECB_AMD64, ECB_AMD64_X32
156		162
		163	These two macros are defined to C<1> on the x86_64/amd64 ABI and the X32
		164	ABI, respectively, and undefined elsewhere.
		165
		166	The designers of the new X32 ABI for some inexplicable reason decided to
		167	make it look exactly like amd64, even though it's completely incompatible
		168	to that ABI, breaking about every piece of software that assumed that
		169	C<__x86_64> stands for, well, the x86-64 ABI, making these macros
		170	necessary.
		171
		172	=back
		173
		174	=head2 MACRO TRICKERY
		175
		176	=over 4
		177
		178	=item ECB_CONCAT (a, b)
		179
		180	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,
		182	e.g.:
		183
		184	#define S1 str
		185	#define S2 cpy
		186
		187	ECB_CONCAT (S1, S2)(dst, src); // == strcpy (dst, src);
		188
		189	=item ECB_STRINGIFY (arg)
		190
		191	Expands any macros in C<arg> and returns the stringified version of
		192	it. This is mainly useful to get the contents of a macro in string form,
		193	e.g.:
		194
		195	#define SQL_LIMIT 100
		196	sql_exec ("select * from table limit " ECB_STRINGIFY (SQL_LIMIT));
		197
		198	=item ECB_STRINGIFY_EXPR (expr)
		199
		200	Like C<ECB_STRINGIFY>, but additionally evaluates C<expr> to make sure it
		201	is a valid expression. This is useful to catch typos or cases where the
		202	macro isn't available:
		203
		204	#include <errno.h>
		205
		206	ECB_STRINGIFY (EDOM); // "33" (on my system at least)
		207	ECB_STRINGIFY_EXPR (EDOM); // "33"
		208
		209	// now imagine we had a typo:
		210
		211	ECB_STRINGIFY (EDAM); // "EDAM"
		212	ECB_STRINGIFY_EXPR (EDAM); // error: EDAM undefined
		213
		214	=back
		215
157	=head2 GCC ATTRIBUTES	216	=head2 ATTRIBUTES
158		217
159	A major part of libecb deals with GCC attributes. These are additional	218	A major part of libecb deals with additional attributes that can be
160	attributes that you can assign to functions, variables and sometimes even	219	assigned to functions, variables and sometimes even types - much like
161	types - much like C<const> or C<volatile> in C.	220	C<const> or C<volatile> in C. They are implemented using either GCC
162		221	attributes or other compiler/language specific features. Attributes
163	While GCC allows declarations to show up in many surprising places,
164	but not in many expected places, the safest way is to put attribute
165	declarations before the whole declaration:	222	declarations must be put before the whole declaration:
166		223
167	ecb_const int mysqrt (int a);	224	ecb_const int mysqrt (int a);
168	ecb_unused int i;	225	ecb_unused int i;
169		226
170	For variables, it is often nicer to put the attribute after the name, and
171	avoid multiple declarations using commas:
172
173	int i ecb_unused;
174
175	=over 4	227	=over 4
176
177	=item ecb_attribute ((attrs...))
178
179	A simple wrapper that expands to C<__attribute__((attrs))> on GCC, and to
180	nothing on other compilers, so the effect is that only GCC sees these.
181
182	Example: use the C<deprecated> attribute on a function.
183
184	ecb_attribute((__deprecated__)) void
185	do_not_use_me_anymore (void);
186		228
187	=item ecb_unused	229	=item ecb_unused
188		230
189	Marks a function or a variable as "unused", which simply suppresses a	231	Marks a function or a variable as "unused", which simply suppresses a
190	warning by GCC when it detects it as unused. This is useful when you e.g.	232	warning by GCC when it detects it as unused. This is useful when you e.g.
191	declare a variable but do not always use it:	233	declare a variable but do not always use it:
192		234
193	{	235	{
194	int var ecb_unused;	236	ecb_unused int var;
195		237
196	#ifdef SOMECONDITION	238	#ifdef SOMECONDITION
197	var = ...;	239	var = ...;
198	return var;	240	return var;
199	#else	241	#else
200	return 0;	242	return 0;
201	#endif	243	#endif
202	}	244	}
203		245
		246	=item ecb_deprecated
		247
		248	Similar to C<ecb_unused>, but marks a function, variable or type as
		249	deprecated. This makes some compilers warn when the type is used.
		250
		251	=item ecb_deprecated_message (message)
		252
		253	Same as C<ecb_deprecated>, but if possible, the specified diagnostic is
		254	used instead of a generic depreciation message when the object is being
		255	used.
		256
204	=item ecb_inline	257	=item ecb_inline
205		258
206	This is not actually an attribute, but you use it like one. It expands	259	Expands either to (a compiler-specific equivalent of) C<static inline> or
207	either to C<static inline> or to just C<static>, if inline isn't	260	to just C<static>, if inline isn't supported. It should be used to declare
208	supported. It should be used to declare functions that should be inlined,	261	functions that should be inlined, for code size or speed reasons.
209	for code size or speed reasons.
210		262
211	Example: inline this function, it surely will reduce codesize.	263	Example: inline this function, it surely will reduce codesize.
212		264
213	ecb_inline int	265	ecb_inline int
214	negmul (int a, int b)	266	negmul (int a, int b)
…		…
216	return - (a * b);	268	return - (a * b);
217	}	269	}
218		270
219	=item ecb_noinline	271	=item ecb_noinline
220		272
221	Prevent a function from being inlined - it might be optimised away, but	273	Prevents a function from being inlined - it might be optimised away, but
222	not inlined into other functions. This is useful if you know your function	274	not inlined into other functions. This is useful if you know your function
223	is rarely called and large enough for inlining not to be helpful.	275	is rarely called and large enough for inlining not to be helpful.
224		276
225	=item ecb_noreturn	277	=item ecb_noreturn
226		278
…		…
236	}	288	}
237		289
238	In this case, the compiler would probably be smart enough to deduce it on	290	In this case, the compiler would probably be smart enough to deduce it on
239	its own, so this is mainly useful for declarations.	291	its own, so this is mainly useful for declarations.
240		292
		293	=item ecb_restrict
		294
		295	Expands to the C<restrict> keyword or equivalent on compilers that support
		296	them, and to nothing on others. Must be specified on a pointer type or
		297	an array index to indicate that the memory doesn't alias with any other
		298	restricted pointer in the same scope.
		299
		300	Example: multiply a vector, and allow the compiler to parallelise the
		301	loop, because it knows it doesn't overwrite input values.
		302
		303	void
		304	multiply (ecb_restrict float *src,
		305	ecb_restrict float *dst,
		306	int len, float factor)
		307	{
		308	int i;
		309
		310	for (i = 0; i < len; ++i)
		311	dst [i] = src [i] * factor;
		312	}
		313
241	=item ecb_const	314	=item ecb_const
242		315
243	Declares that the function only depends on the values of its arguments,	316	Declares that the function only depends on the values of its arguments,
244	much like a mathematical function. It specifically does not read or write	317	much like a mathematical function. It specifically does not read or write
245	any memory any arguments might point to, global variables, or call any	318	any memory any arguments might point to, global variables, or call any
…		…
335		408
336	=head2 OPTIMISATION HINTS	409	=head2 OPTIMISATION HINTS
337		410
338	=over 4	411	=over 4
339		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
340	=item bool ecb_is_constant(expr)	419	=item bool ecb_is_constant (expr)
341		420
342	Returns true iff the expression can be deduced to be a compile-time	421	Returns true iff the expression can be deduced to be a compile-time
343	constant, and false otherwise.	422	constant, and false otherwise.
344		423
345	For example, when you have a C<rndm16> function that returns a 16 bit	424	For example, when you have a C<rndm16> function that returns a 16 bit
…		…
363	return is_constant (n) && !(n & (n - 1))	442	return is_constant (n) && !(n & (n - 1))
364	? rndm16 () & (num - 1)	443	? rndm16 () & (num - 1)
365	: (n * (uint32_t)rndm16 ()) >> 16;	444	: (n * (uint32_t)rndm16 ()) >> 16;
366	}	445	}
367		446
368	=item bool ecb_expect (expr, value)	447	=item ecb_expect (expr, value)
369		448
370	Evaluates C<expr> and returns it. In addition, it tells the compiler that	449	Evaluates C<expr> and returns it. In addition, it tells the compiler that
371	the C<expr> evaluates to C<value> a lot, which can be used for static	450	the C<expr> evaluates to C<value> a lot, which can be used for static
372	branch optimisations.	451	branch optimisations.
373		452
…		…
420	{	499	{
421	if (ecb_expect_false (current + size > end))	500	if (ecb_expect_false (current + size > end))
422	real_reserve_method (size); /* presumably noinline */	501	real_reserve_method (size); /* presumably noinline */
423	}	502	}
424		503
425	=item bool ecb_assume (cond)	504	=item ecb_assume (cond)
426		505
427	Try to tell the compiler that some condition is true, even if it's not	506	Tries to tell the compiler that some condition is true, even if it's not
428	obvious.	507	obvious. This is not a function, but a statement: it cannot be used in
		508	another expression.
429		509
430	This can be used to teach the compiler about invariants or other	510	This can be used to teach the compiler about invariants or other
431	conditions that might improve code generation, but which are impossible to	511	conditions that might improve code generation, but which are impossible to
432	deduce form the code itself.	512	deduce form the code itself.
433		513
…		…
450		530
451	Then the compiler I<might> be able to optimise out the second call	531	Then the compiler I<might> be able to optimise out the second call
452	completely, as it knows that C<< current + 1 > end >> is false and the	532	completely, as it knows that C<< current + 1 > end >> is false and the
453	call will never be executed.	533	call will never be executed.
454		534
455	=item bool ecb_unreachable ()	535	=item ecb_unreachable ()
456		536
457	This function does nothing itself, except tell the compiler that it will	537	This function does nothing itself, except tell the compiler that it will
458	never be executed. Apart from suppressing a warning in some cases, this	538	never be executed. Apart from suppressing a warning in some cases, this
459	function can be used to implement C<ecb_assume> or similar functions.	539	function can be used to implement C<ecb_assume> or similar functionality.
460		540
461	=item bool ecb_prefetch (addr, rw, locality)	541	=item ecb_prefetch (addr, rw, locality)
462		542
463	Tells the compiler to try to prefetch memory at the given C<addr>ess	543	Tells the compiler to try to prefetch memory at the given C<addr>ess
464	for either reading (C<rw> = 0) or writing (C<rw> = 1). A C<locality> of	544	for either reading (C<rw> = 0) or writing (C<rw> = 1). A C<locality> of
465	C<0> means that there will only be one access later, C<3> means that	545	C<0> means that there will only be one access later, C<3> means that
466	the data will likely be accessed very often, and values in between mean	546	the data will likely be accessed very often, and values in between mean
467	something... in between. The memory pointed to by the address does not	547	something... in between. The memory pointed to by the address does not
468	need to be accessible (it could be a null pointer for example), but C<rw>	548	need to be accessible (it could be a null pointer for example), but C<rw>
469	and C<locality> must be compile-time constants.	549	and C<locality> must be compile-time constants.
470		550
		551	This is a statement, not a function: you cannot use it as part of an
		552	expression.
		553
471	An obvious way to use this is to prefetch some data far away, in a big	554	An obvious way to use this is to prefetch some data far away, in a big
472	array you loop over. This prefetches memory some 128 array elements later,	555	array you loop over. This prefetches memory some 128 array elements later,
473	in the hope that it will be ready when the CPU arrives at that location.	556	in the hope that it will be ready when the CPU arrives at that location.
474		557
475	int sum = 0;	558	int sum = 0;
…		…
527		610
528	=item bool ecb_is_pot32 (uint32_t x)	611	=item bool ecb_is_pot32 (uint32_t x)
529		612
530	=item bool ecb_is_pot64 (uint32_t x)	613	=item bool ecb_is_pot64 (uint32_t x)
531		614
532	Return true iff C<x> is a power of two or C<x == 0>.	615	Returns true iff C<x> is a power of two or C<x == 0>.
533		616
534	For smaller types then C<uint32_t> you can safely use C<ecb_is_pot32>.	617	For smaller types than C<uint32_t> you can safely use C<ecb_is_pot32>.
535		618
536	=item int ecb_ld32 (uint32_t x)	619	=item int ecb_ld32 (uint32_t x)
537		620
538	=item int ecb_ld64 (uint64_t x)	621	=item int ecb_ld64 (uint64_t x)
539		622
…		…
585		668
586	These functions return the value of the 16-bit (32-bit, 64-bit) value	669	These functions return the value of the 16-bit (32-bit, 64-bit) value
587	C<x> after reversing the order of bytes (0x11223344 becomes 0x44332211 in	670	C<x> after reversing the order of bytes (0x11223344 becomes 0x44332211 in
588	C<ecb_bswap32>).	671	C<ecb_bswap32>).
589		672
		673	=item T ecb_bswap (T x) [C++]
		674
		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
590	=item uint8_t ecb_rotl8 (uint8_t x, unsigned int count)	678	=item uint8_t ecb_rotl8 (uint8_t x, unsigned int count)
591		679
592	=item uint16_t ecb_rotl16 (uint16_t x, unsigned int count)	680	=item uint16_t ecb_rotl16 (uint16_t x, unsigned int count)
593		681
594	=item uint32_t ecb_rotl32 (uint32_t x, unsigned int count)	682	=item uint32_t ecb_rotl32 (uint32_t x, unsigned int count)
…		…
611	to "optimal" code (e.g. a single C<rol> or a combination of C<shld> on	699	to "optimal" code (e.g. a single C<rol> or a combination of C<shld> on
612	x86).	700	x86).
613		701
614	=back	702	=back
615		703
		704	=head2 HOST ENDIANNESS CONVERSION
		705
		706	=over 4
		707
		708	=item uint_fast16_t ecb_be_u16_to_host (uint_fast16_t v)
		709
		710	=item uint_fast32_t ecb_be_u32_to_host (uint_fast32_t v)
		711
		712	=item uint_fast64_t ecb_be_u64_to_host (uint_fast64_t v)
		713
		714	=item uint_fast16_t ecb_le_u16_to_host (uint_fast16_t v)
		715
		716	=item uint_fast32_t ecb_le_u32_to_host (uint_fast32_t v)
		717
		718	=item uint_fast64_t ecb_le_u64_to_host (uint_fast64_t v)
		719
		720	Convert an unsigned 16, 32 or 64 bit value from big or little endian to host byte order.
		721
		722	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.
		724
		725	=item uint_fast16_t ecb_host_to_be_u16 (uint_fast16_t v)
		726
		727	=item uint_fast32_t ecb_host_to_be_u32 (uint_fast32_t v)
		728
		729	=item uint_fast64_t ecb_host_to_be_u64 (uint_fast64_t v)
		730
		731	=item uint_fast16_t ecb_host_to_le_u16 (uint_fast16_t v)
		732
		733	=item uint_fast32_t ecb_host_to_le_u32 (uint_fast32_t v)
		734
		735	=item uint_fast64_t ecb_host_to_le_u64 (uint_fast64_t v)
		736
		737	Like above, but converts I<from> host byte order to the specified
		738	endianness.
		739
		740	=back
		741
		742	In C++ the following additional functions are supported:
		743
		744	=over 4
		745
		746	=item T ecb_be_to_host (T v)
		747
		748	=item T ecb_le_to_host (T v)
		749
		750	=item T ecb_host_to_be (T v)
		751
		752	=item T ecb_host_to_le (T v)
		753
		754	These work like their C counterparts, above, but use templates for the
		755	type, which make them useful in generic code.
		756
		757	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
		759	again can be useful in generic code).
		760
		761	=head2 UNALIGNED LOAD/STORE
		762
		763	These function load or store unaligned multi-byte values.
		764
		765	=over 4
		766
		767	=item uint_fast16_t ecb_peek_u16_u (const void *ptr)
		768
		769	=item uint_fast32_t ecb_peek_u32_u (const void *ptr)
		770
		771	=item uint_fast64_t ecb_peek_u64_u (const void *ptr)
		772
		773	These functions load an unaligned, unsigned 16, 32 or 64 bit value from
		774	memory.
		775
		776	=item uint_fast16_t ecb_peek_be_u16_u (const void *ptr)
		777
		778	=item uint_fast32_t ecb_peek_be_u32_u (const void *ptr)
		779
		780	=item uint_fast64_t ecb_peek_be_u64_u (const void *ptr)
		781
		782	=item uint_fast16_t ecb_peek_le_u16_u (const void *ptr)
		783
		784	=item uint_fast32_t ecb_peek_le_u32_u (const void *ptr)
		785
		786	=item uint_fast64_t ecb_peek_le_u64_u (const void *ptr)
		787
		788	Like above, but additionally convert from big endian (C<be>) or little
		789	endian (C<le>) byte order to host byte order while doing so.
		790
		791	=item ecb_poke_u16_u (void *ptr, uint16_t v)
		792
		793	=item ecb_poke_u32_u (void *ptr, uint32_t v)
		794
		795	=item ecb_poke_u64_u (void *ptr, uint64_t v)
		796
		797	These functions store an unaligned, unsigned 16, 32 or 64 bit value to
		798	memory.
		799
		800	=item ecb_poke_be_u16_u (void *ptr, uint_fast16_t v)
		801
		802	=item ecb_poke_be_u32_u (void *ptr, uint_fast32_t v)
		803
		804	=item ecb_poke_be_u64_u (void *ptr, uint_fast64_t v)
		805
		806	=item ecb_poke_le_u16_u (void *ptr, uint_fast16_t v)
		807
		808	=item ecb_poke_le_u32_u (void *ptr, uint_fast32_t v)
		809
		810	=item ecb_poke_le_u64_u (void *ptr, uint_fast64_t v)
		811
		812	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.
		814
		815	=back
		816
		817	In C++ the following additional functions are supported:
		818
		819	=over 4
		820
		821	=item T ecb_peek (const void *ptr)
		822
		823	=item T ecb_peek_be (const void *ptr)
		824
		825	=item T ecb_peek_le (const void *ptr)
		826
		827	=item T ecb_peek_u (const void *ptr)
		828
		829	=item T ecb_peek_be_u (const void *ptr)
		830
		831	=item T ecb_peek_le_u (const void *ptr)
		832
		833	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
		835	endian.
		836
		837	Since the type cannot be deduced, it has top be specified explicitly, e.g.
		838
		839	uint_fast16_t v = ecb_peek<uint16_t> (ptr);
		840
		841	C<T> must be one of C<uint8_t>, C<uint16_t>, C<uint32_t> or C<uint64_t>.
		842
		843	Unlike their C counterparts, these functions support 8 bit quantities
		844	(C<uint8_t>) and also have an aligned version (without the C<_u> prefix),
		845	all of which hopefully makes them more useful in generic code.
		846
		847	=item ecb_poke (void *ptr, T v)
		848
		849	=item ecb_poke_be (void *ptr, T v)
		850
		851	=item ecb_poke_le (void *ptr, T v)
		852
		853	=item ecb_poke_u (void *ptr, T v)
		854
		855	=item ecb_poke_be_u (void *ptr, T v)
		856
		857	=item ecb_poke_le_u (void *ptr, T v)
		858
		859	Again, similarly to their C counterparts, these functions store an
		860	unsigned 8, 16, 32 or z64 bit value to memory, with optional conversion to
		861	big/little endian.
		862
		863	C<T> must be one of C<uint8_t>, C<uint16_t>, C<uint32_t> or C<uint64_t>.
		864
		865	Unlike their C counterparts, these functions support 8 bit quantities
		866	(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.
		868
		869	=back
		870
616	=head2 FLOATING POINT FIDDLING	871	=head2 FLOATING POINT FIDDLING
617		872
618	=over 4	873	=over 4
619		874
		875	=item ECB_INFINITY [-UECB_NO_LIBM]
		876
		877	Evaluates to positive infinity if supported by the platform, otherwise to
		878	a truly huge number.
		879
		880	=item ECB_NAN [-UECB_NO_LIBM]
		881
		882	Evaluates to a quiet NAN if supported by the platform, otherwise to
		883	C<ECB_INFINITY>.
		884
		885	=item float ecb_ldexpf (float x, int exp) [-UECB_NO_LIBM]
		886
		887	Same as C<ldexpf>, but always available.
		888
		889	=item uint32_t ecb_float_to_binary16 (float x) [-UECB_NO_LIBM]
		890
620	=item uint32_t ecb_float_to_binary32 (float x) [-UECB_NO_LIBM]	891	=item uint32_t ecb_float_to_binary32 (float x) [-UECB_NO_LIBM]
621		892
622	=item uint64_t ecb_double_to_binary64 (double x) [-UECB_NO_LIBM]	893	=item uint64_t ecb_double_to_binary64 (double x) [-UECB_NO_LIBM]
623		894
624	These functions each take an argument in the native C<float> or C<double>	895	These functions each take an argument in the native C<float> or C<double>
625	type and return the IEEE 754 bit representation of it.	896	type and return the IEEE 754 bit representation of it (binary16/half,
		897	binary32/single or binary64/double precision).
626		898
627	The bit representation is just as IEEE 754 defines it, i.e. the sign bit	899	The bit representation is just as IEEE 754 defines it, i.e. the sign bit
628	will be the most significant bit, followed by exponent and mantissa.	900	will be the most significant bit, followed by exponent and mantissa.
629		901
630	This function should work even when the native floating point format isn't	902	This function should work even when the native floating point format isn't
…		…
634		906
635	On all modern platforms (where C<ECB_STDFP> is true), the compiler should	907	On all modern platforms (where C<ECB_STDFP> is true), the compiler should
636	be able to optimise away this function completely.	908	be able to optimise away this function completely.
637		909
638	These functions can be helpful when serialising floats to the network - you	910	These functions can be helpful when serialising floats to the network - you
639	can serialise the return value like a normal uint32_t/uint64_t.	911	can serialise the return value like a normal uint16_t/uint32_t/uint64_t.
640		912
641	Another use for these functions is to manipulate floating point values	913	Another use for these functions is to manipulate floating point values
642	directly.	914	directly.
643		915
644	Silly example: toggle the sign bit of a float.	916	Silly example: toggle the sign bit of a float.
…		…
647	/* this results in a single add instruction to toggle the bit, and 4 extra */	919	/* this results in a single add instruction to toggle the bit, and 4 extra */
648	/* instructions to move the float value to an integer register and back. */	920	/* instructions to move the float value to an integer register and back. */
649		921
650	x = ecb_binary32_to_float (ecb_float_to_binary32 (x) ^ 0x80000000U)	922	x = ecb_binary32_to_float (ecb_float_to_binary32 (x) ^ 0x80000000U)
651		923
		924	=item float ecb_binary16_to_float (uint16_t x) [-UECB_NO_LIBM]
		925
652	=item float ecb_binary32_to_float (uint32_t x) [-UECB_NO_LIBM]	926	=item float ecb_binary32_to_float (uint32_t x) [-UECB_NO_LIBM]
653		927
654	=item double ecb_binary32_to_double (uint64_t x) [-UECB_NO_LIBM]	928	=item double ecb_binary64_to_double (uint64_t x) [-UECB_NO_LIBM]
655		929
656	The reverse operation of the previos function - takes the bit representation	930	The reverse operation of the previous function - takes the bit
657	of an IEEE binary32 or binary64 number and converts it to the native C<float>	931	representation of an IEEE binary16, binary32 or binary64 number (half,
		932	single or double precision) and converts it to the native C<float> or
658	or C<double> format.	933	C<double> format.
659		934
660	This function should work even when the native floating point format isn't	935	This function should work even when the native floating point format isn't
661	IEEE compliant, of course at a speed and code size penalty, and of course	936	IEEE compliant, of course at a speed and code size penalty, and of course
662	also within reasonable limits (it tries to convert normals and denormals,	937	also within reasonable limits (it tries to convert normals and denormals,
663	and might be lucky for infinities, and with extraordinary luck, also for	938	and might be lucky for infinities, and with extraordinary luck, also for
664	negative zero).	939	negative zero).
665		940
666	On all modern platforms (where C<ECB_STDFP> is true), the compiler should	941	On all modern platforms (where C<ECB_STDFP> is true), the compiler should
667	be able to optimise away this function completely.	942	be able to optimise away this function completely.
		943
		944	=item uint16_t ecb_binary32_to_binary16 (uint32_t x)
		945
		946	=item uint32_t ecb_binary16_to_binary32 (uint16_t x)
		947
		948	Convert a IEEE binary32/single precision to binary16/half format, and vice
		949	versa, handling all details (round-to-nearest-even, subnormals, infinity
		950	and NaNs) correctly.
		951
		952	These are functions are available under C<-DECB_NO_LIBM>, since
		953	they do not rely on the platform floating point format. The
		954	C<ecb_float_to_binary16> and C<ecb_binary16_to_float> functions are
		955	usually what you want.
668		956
669	=back	957	=back
670		958
671	=head2 ARITHMETIC	959	=head2 ARITHMETIC
672		960
…		…
753	dependencies on the math library (usually called F<-lm>) - these are	1041	dependencies on the math library (usually called F<-lm>) - these are
754	marked with [-UECB_NO_LIBM].	1042	marked with [-UECB_NO_LIBM].
755		1043
756	=back	1044	=back
757		1045
		1046	=head1 UNDOCUMENTED FUNCTIONALITY
758		1047
		1048	F<ecb.h> is full of undocumented functionality as well, some of which is
		1049	intended to be internal-use only, some of which we forgot to document, and
		1050	some of which we hide because we are not sure we will keep the interface
		1051	stable.
		1052
		1053	While you are welcome to rummage around and use whatever you find useful
		1054	(we can't stop you), keep in mind that we will change undocumented
		1055	functionality in incompatible ways without thinking twice, while we are
		1056	considerably more conservative with documented things.
		1057
		1058	=head1 AUTHORS
		1059
		1060	C<libecb> is designed and maintained by:
		1061
		1062	Emanuele Giaquinta <e.giaquinta@glauco.it>
		1063	Marc Alexander Lehmann <schmorp@schmorp.de>
		1064
		1065

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Comparing libecb/ecb.pod (file contents): Revision 1.52 by root, Sun Sep 23 22:32:33 2012 UTC vs. Revision 1.76 by root, Mon Jan 20 13:13:56 2020 UTC

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Comparing libecb/ecb.pod (file contents):
Revision 1.52 by root, Sun Sep 23 22:32:33 2012 UTC vs.
Revision 1.76 by root, Mon Jan 20 13:13:56 2020 UTC