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

Comparing libecb/ecb.pod (file contents):
Revision 1.25 by root, Tue May 31 21:52:31 2011 UTC vs.
Revision 1.53 by root, Wed Dec 5 16:31:27 2012 UTC

…		…
54	only a generic name is used (C<expr>, C<cond>, C<value> and so on), then	54	only a generic name is used (C<expr>, C<cond>, C<value> and so on), then
55	the corresponding function relies on C to implement the correct types, and	55	the corresponding function relies on C to implement the correct types, and
56	is usually implemented as a macro. Specifically, a "bool" in this manual	56	is usually implemented as a macro. Specifically, a "bool" in this manual
57	refers to any kind of boolean value, not a specific type.	57	refers to any kind of boolean value, not a specific type.
58		58
		59	=head2 TYPES / TYPE SUPPORT
		60
		61	ecb.h makes sure that the following types are defined (in the expected way):
		62
		63	int8_t uint8_t int16_t uint16_t
		64	int32_t uint32_t int64_t uint64_t
		65	intptr_t uintptr_t
		66
		67	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
		69	expressions.
		70
		71	For C<ptrdiff_t> and C<size_t> use C<stddef.h>.
		72
		73	=head2 LANGUAGE/COMPILER VERSIONS
		74
		75	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
		77	ensure it's either C<0> or C<1> if you need that).
		78
		79	=over 4
		80
		81	=item ECB_C
		82
		83	True if the implementation defines the C<__STDC__> macro to a true value,
		84	which is typically true for both C and C++ compilers.
		85
		86	=item ECB_C99
		87
		88	True if the implementation claims to be compliant to C99 (ISO/IEC
		89	9899:1999) or any later version.
		90
		91	Note that later versions (ECB_C11) remove core features again (for
		92	example, variable length arrays).
		93
		94	=item ECB_C11
		95
		96	True if the implementation claims to be compliant to C11 (ISO/IEC
		97	9899:2011) or any later version.
		98
		99	=item ECB_CPP
		100
		101	True if the implementation defines the C<__cplusplus__> macro to a true
		102	value, which is typically true for C++ compilers.
		103
		104	=item ECB_CPP11
		105
		106	True if the implementation claims to be compliant to ISO/IEC 14882:2011
		107	(C++11) or any later version.
		108
		109	=item ECB_GCC_VERSION(major,minor)
		110
		111	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
		113	higher.
		114
		115	This macro tries to return false on compilers that claim to be GCC
		116	compatible but aren't.
		117
		118	=item ECB_EXTERN_C
		119
		120	Expands to C<extern "C"> in C++, and a simple C<extern> in C.
		121
		122	This can be used to declare a single external C function:
		123
		124	ECB_EXTERN_C int printf (const char *format, ...);
		125
		126	=item ECB_EXTERN_C_BEG / ECB_EXTERN_C_END
		127
		128	These two macros can be used to wrap multiple C<extern "C"> definitions -
		129	they expand to nothing in C.
		130
		131	They are most useful in header files:
		132
		133	ECB_EXTERN_C_BEG
		134
		135	int mycfun1 (int x);
		136	int mycfun2 (int x);
		137
		138	ECB_EXTERN_C_END
		139
		140	=item ECB_STDFP
		141
		142	If this evaluates to a true value (suitable for testing in by the
		143	preprocessor), then C<float> and C<double> use IEEE 754 single/binary32
		144	and double/binary64 representations internally I<and> the endianness of
		145	both types match the endianness of C<uint32_t> and C<uint64_t>.
		146
		147	This means you can just copy the bits of a C<float> (or C<double>) to an
		148	C<uint32_t> (or C<uint64_t>) and get the raw IEEE 754 bit representation
		149	without having to think about format or endianness.
		150
		151	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
		153	side.
		154
		155	=back
		156
59	=head2 GCC ATTRIBUTES	157	=head2 GCC ATTRIBUTES
60		158
61	A major part of libecb deals with GCC attributes. These are additional	159	A major part of libecb deals with GCC attributes. These are additional
62	attributes that you cna assign to functions, variables and sometimes even	160	attributes that you can assign to functions, variables and sometimes even
63	types - much like C<const> or C<volatile> in C.	161	types - much like C<const> or C<volatile> in C.
64		162
65	While GCC allows declarations to show up in many surprising places,	163	While GCC allows declarations to show up in many surprising places,
66	but not in many expeted places, the safest way is to put attribute	164	but not in many expected places, the safest way is to put attribute
67	declarations before the whole declaration:	165	declarations before the whole declaration:
68		166
69	ecb_const int mysqrt (int a);	167	ecb_const int mysqrt (int a);
70	ecb_unused int i;	168	ecb_unused int i;
71		169
…		…
101	#else	199	#else
102	return 0;	200	return 0;
103	#endif	201	#endif
104	}	202	}
105		203
		204	=item ecb_inline
		205
		206	This is not actually an attribute, but you use it like one. It expands
		207	either to C<static inline> or to just C<static>, if inline isn't
		208	supported. It should be used to declare functions that should be inlined,
		209	for code size or speed reasons.
		210
		211	Example: inline this function, it surely will reduce codesize.
		212
		213	ecb_inline int
		214	negmul (int a, int b)
		215	{
		216	return - (a * b);
		217	}
		218
106	=item ecb_noinline	219	=item ecb_noinline
107		220
108	Prevent a function from being inlined - it might be optimised away, but	221	Prevent a function from being inlined - it might be optimised away, but
109	not inlined into other functions. This is useful if you know your function	222	not inlined into other functions. This is useful if you know your function
110	is rarely called and large enough for inlining not to be helpful.	223	is rarely called and large enough for inlining not to be helpful.
…		…
123	}	236	}
124		237
125	In this case, the compiler would probably be smart enough to deduce it on	238	In this case, the compiler would probably be smart enough to deduce it on
126	its own, so this is mainly useful for declarations.	239	its own, so this is mainly useful for declarations.
127		240
		241	=item ecb_restrict
		242
		243	Expands to the C<restrict> keyword or equivalent on compilers that support
		244	them, and to nothing on others. Must be specified on a pointer type or
		245	an array index to indicate that the memory doesn't alias with any other
		246	restricted pointer in the same scope.
		247
		248	Example: multiply a vector, and allow the compiler to parallelise the
		249	loop, because it knows it doesn't overwrite input values.
		250
		251	void
		252	multiply (float *ecb_restrict src,
		253	float *ecb_restrict dst,
		254	int len, float factor)
		255	{
		256	int i;
		257
		258	for (i = 0; i < len; ++i)
		259	dst [i] = src [i] * factor;
		260	}
		261
128	=item ecb_const	262	=item ecb_const
129		263
130	Declares that the function only depends on the values of its arguments,	264	Declares that the function only depends on the values of its arguments,
131	much like a mathematical function. It specifically does not read or write	265	much like a mathematical function. It specifically does not read or write
132	any memory any arguments might point to, global variables, or call any	266	any memory any arguments might point to, global variables, or call any
…		…
184		318
185	In addition to placing cold functions together (or at least away from hot	319	In addition to placing cold functions together (or at least away from hot
186	functions), this knowledge can be used in other ways, for example, the	320	functions), this knowledge can be used in other ways, for example, the
187	function will be optimised for size, as opposed to speed, and codepaths	321	function will be optimised for size, as opposed to speed, and codepaths
188	leading to calls to those functions can automatically be marked as if	322	leading to calls to those functions can automatically be marked as if
189	C<ecb_unlikely> had been used to reach them.	323	C<ecb_expect_false> had been used to reach them.
190		324
191	Good examples for such functions would be error reporting functions, or	325	Good examples for such functions would be error reporting functions, or
192	functions only called in exceptional or rare cases.	326	functions only called in exceptional or rare cases.
193		327
194	=item ecb_artificial	328	=item ecb_artificial
195		329
196	Declares the function as "artificial", in this case meaning that this	330	Declares the function as "artificial", in this case meaning that this
197	function is not really mean to be a function, but more like an accessor	331	function is not really meant to be a function, but more like an accessor
198	- many methods in C++ classes are mere accessor functions, and having a	332	- many methods in C++ classes are mere accessor functions, and having a
199	crash reported in such a method, or single-stepping through them, is not	333	crash reported in such a method, or single-stepping through them, is not
200	usually so helpful, especially when it's inlined to just a few instructions.	334	usually so helpful, especially when it's inlined to just a few instructions.
201		335
202	Marking them as artificial will instruct the debugger about just this,	336	Marking them as artificial will instruct the debugger about just this,
…		…
256		390
257	Evaluates C<expr> and returns it. In addition, it tells the compiler that	391	Evaluates C<expr> and returns it. In addition, it tells the compiler that
258	the C<expr> evaluates to C<value> a lot, which can be used for static	392	the C<expr> evaluates to C<value> a lot, which can be used for static
259	branch optimisations.	393	branch optimisations.
260		394
261	Usually, you want to use the more intuitive C<ecb_likely> and	395	Usually, you want to use the more intuitive C<ecb_expect_true> and
262	C<ecb_unlikely> functions instead.	396	C<ecb_expect_false> functions instead.
263		397
		398	=item bool ecb_expect_true (cond)
		399
264	=item bool ecb_likely (cond)	400	=item bool ecb_expect_false (cond)
265
266	=item bool ecb_unlikely (cond)
267		401
268	These two functions expect a expression that is true or false and return	402	These two functions expect a expression that is true or false and return
269	C<1> or C<0>, respectively, so when used in the condition of an C<if> or	403	C<1> or C<0>, respectively, so when used in the condition of an C<if> or
270	other conditional statement, it will not change the program:	404	other conditional statement, it will not change the program:
271		405
272	/* these two do the same thing */	406	/* these two do the same thing */
273	if (some_condition) ...;	407	if (some_condition) ...;
274	if (ecb_likely (some_condition)) ...;	408	if (ecb_expect_true (some_condition)) ...;
275		409
276	However, by using C<ecb_likely>, you tell the compiler that the condition	410	However, by using C<ecb_expect_true>, you tell the compiler that the
277	is likely to be true (and for C<ecb_unlikely>, that it is unlikely to be	411	condition is likely to be true (and for C<ecb_expect_false>, that it is
278	true).	412	unlikely to be true).
279		413
280	For example, when you check for a null pointer and expect this to be a	414	For example, when you check for a null pointer and expect this to be a
281	rare, exceptional, case, then use C<ecb_unlikely>:	415	rare, exceptional, case, then use C<ecb_expect_false>:
282		416
283	void my_free (void *ptr)	417	void my_free (void *ptr)
284	{	418	{
285	if (ecb_unlikely (ptr == 0))	419	if (ecb_expect_false (ptr == 0))
286	return;	420	return;
287	}	421	}
288		422
289	Consequent use of these functions to mark away exceptional cases or to	423	Consequent use of these functions to mark away exceptional cases or to
290	tell the compiler what the hot path through a function is can increase	424	tell the compiler what the hot path through a function is can increase
291	performance considerably.	425	performance considerably.
		426
		427	You might know these functions under the name C<likely> and C<unlikely>
		428	- while these are common aliases, we find that the expect name is easier
		429	to understand when quickly skimming code. If you wish, you can use
		430	C<ecb_likely> instead of C<ecb_expect_true> and C<ecb_unlikely> instead of
		431	C<ecb_expect_false> - these are simply aliases.
292		432
293	A very good example is in a function that reserves more space for some	433	A very good example is in a function that reserves more space for some
294	memory block (for example, inside an implementation of a string stream) -	434	memory block (for example, inside an implementation of a string stream) -
295	each time something is added, you have to check for a buffer overrun, but	435	each time something is added, you have to check for a buffer overrun, but
296	you expect that most checks will turn out to be false:	436	you expect that most checks will turn out to be false:
297		437
298	/* make sure we have "size" extra room in our buffer */	438	/* make sure we have "size" extra room in our buffer */
299	ecb_inline void	439	ecb_inline void
300	reserve (int size)	440	reserve (int size)
301	{	441	{
302	if (ecb_unlikely (current + size > end))	442	if (ecb_expect_false (current + size > end))
303	real_reserve_method (size); /* presumably noinline */	443	real_reserve_method (size); /* presumably noinline */
304	}	444	}
305		445
306	=item bool ecb_assume (cond)	446	=item bool ecb_assume (cond)
307		447
…		…
310		450
311	This can be used to teach the compiler about invariants or other	451	This can be used to teach the compiler about invariants or other
312	conditions that might improve code generation, but which are impossible to	452	conditions that might improve code generation, but which are impossible to
313	deduce form the code itself.	453	deduce form the code itself.
314		454
315	For example, the example reservation function from the C<ecb_unlikely>	455	For example, the example reservation function from the C<ecb_expect_false>
316	description could be written thus (only C<ecb_assume> was added):	456	description could be written thus (only C<ecb_assume> was added):
317		457
318	ecb_inline void	458	ecb_inline void
319	reserve (int size)	459	reserve (int size)
320	{	460	{
321	if (ecb_unlikely (current + size > end))	461	if (ecb_expect_false (current + size > end))
322	real_reserve_method (size); /* presumably noinline */	462	real_reserve_method (size); /* presumably noinline */
323		463
324	ecb_assume (current + size <= end);	464	ecb_assume (current + size <= end);
325	}	465	}
326		466
…		…
375	After processing the node, (part of) the next node might already be in	515	After processing the node, (part of) the next node might already be in
376	cache.	516	cache.
377		517
378	=back	518	=back
379		519
380	=head2 BIT FIDDLING / BITSTUFFS	520	=head2 BIT FIDDLING / BIT WIZARDRY
381		521
382	=over 4	522	=over 4
383		523
384	=item bool ecb_big_endian ()	524	=item bool ecb_big_endian ()
385		525
…		…
391		531
392	On systems that are neither, their return values are unspecified.	532	On systems that are neither, their return values are unspecified.
393		533
394	=item int ecb_ctz32 (uint32_t x)	534	=item int ecb_ctz32 (uint32_t x)
395		535
		536	=item int ecb_ctz64 (uint64_t x)
		537
396	Returns the index of the least significant bit set in C<x> (or	538	Returns the index of the least significant bit set in C<x> (or
397	equivalently the number of bits set to 0 before the least significant bit	539	equivalently the number of bits set to 0 before the least significant bit
398	set), starting from 0. If C<x> is 0 the result is undefined. A common use	540	set), starting from 0. If C<x> is 0 the result is undefined.
399	case is to compute the integer binary logarithm, i.e., C<floor (log2	541
		542	For smaller types than C<uint32_t> you can safely use C<ecb_ctz32>.
		543
400	(n))>. For example:	544	For example:
401		545
402	ecb_ctz32 (3) = 0	546	ecb_ctz32 (3) = 0
403	ecb_ctz32 (6) = 1	547	ecb_ctz32 (6) = 1
404		548
		549	=item bool ecb_is_pot32 (uint32_t x)
		550
		551	=item bool ecb_is_pot64 (uint32_t x)
		552
		553	Return true iff C<x> is a power of two or C<x == 0>.
		554
		555	For smaller types then C<uint32_t> you can safely use C<ecb_is_pot32>.
		556
		557	=item int ecb_ld32 (uint32_t x)
		558
		559	=item int ecb_ld64 (uint64_t x)
		560
		561	Returns the index of the most significant bit set in C<x>, or the number
		562	of digits the number requires in binary (so that C<< 2**ld <= x <
		563	2**(ld+1) >>). If C<x> is 0 the result is undefined. A common use case is
		564	to compute the integer binary logarithm, i.e. C<floor (log2 (n))>, for
		565	example to see how many bits a certain number requires to be encoded.
		566
		567	This function is similar to the "count leading zero bits" function, except
		568	that that one returns how many zero bits are "in front" of the number (in
		569	the given data type), while C<ecb_ld> returns how many bits the number
		570	itself requires.
		571
		572	For smaller types than C<uint32_t> you can safely use C<ecb_ld32>.
		573
405	=item int ecb_popcount32 (uint32_t x)	574	=item int ecb_popcount32 (uint32_t x)
406		575
		576	=item int ecb_popcount64 (uint64_t x)
		577
407	Returns the number of bits set to 1 in C<x>. For example:	578	Returns the number of bits set to 1 in C<x>.
		579
		580	For smaller types than C<uint32_t> you can safely use C<ecb_popcount32>.
		581
		582	For example:
408		583
409	ecb_popcount32 (7) = 3	584	ecb_popcount32 (7) = 3
410	ecb_popcount32 (255) = 8	585	ecb_popcount32 (255) = 8
411		586
		587	=item uint8_t ecb_bitrev8 (uint8_t x)
		588
		589	=item uint16_t ecb_bitrev16 (uint16_t x)
		590
		591	=item uint32_t ecb_bitrev32 (uint32_t x)
		592
		593	Reverses the bits in x, i.e. the MSB becomes the LSB, MSB-1 becomes LSB+1
		594	and so on.
		595
		596	Example:
		597
		598	ecb_bitrev8 (0xa7) = 0xea
		599	ecb_bitrev32 (0xffcc4411) = 0x882233ff
		600
412	=item uint32_t ecb_bswap16 (uint32_t x)	601	=item uint32_t ecb_bswap16 (uint32_t x)
413		602
414	=item uint32_t ecb_bswap32 (uint32_t x)	603	=item uint32_t ecb_bswap32 (uint32_t x)
415		604
		605	=item uint64_t ecb_bswap64 (uint64_t x)
		606
416	These two functions return the value of the 16-bit (32-bit) value C<x>	607	These functions return the value of the 16-bit (32-bit, 64-bit) value
417	after reversing the order of bytes (0x11223344 becomes 0x44332211).	608	C<x> after reversing the order of bytes (0x11223344 becomes 0x44332211 in
		609	C<ecb_bswap32>).
		610
		611	=item uint8_t ecb_rotl8 (uint8_t x, unsigned int count)
		612
		613	=item uint16_t ecb_rotl16 (uint16_t x, unsigned int count)
		614
		615	=item uint32_t ecb_rotl32 (uint32_t x, unsigned int count)
		616
		617	=item uint64_t ecb_rotl64 (uint64_t x, unsigned int count)
		618
		619	=item uint8_t ecb_rotr8 (uint8_t x, unsigned int count)
		620
		621	=item uint16_t ecb_rotr16 (uint16_t x, unsigned int count)
418		622
419	=item uint32_t ecb_rotr32 (uint32_t x, unsigned int count)	623	=item uint32_t ecb_rotr32 (uint32_t x, unsigned int count)
420		624
421	=item uint32_t ecb_rotl32 (uint32_t x, unsigned int count)	625	=item uint64_t ecb_rotr64 (uint64_t x, unsigned int count)
422		626
423	These two functions return the value of C<x> after rotating all the bits	627	These two families of functions return the value of C<x> after rotating
424	by C<count> positions to the right or left respectively.	628	all the bits by C<count> positions to the right (C<ecb_rotr>) or left
		629	(C<ecb_rotl>).
425		630
426	Current GCC versions understand these functions and usually compile them	631	Current GCC versions understand these functions and usually compile them
427	to "optimal" code (e.g. a single C<roll> on x86).	632	to "optimal" code (e.g. a single C<rol> or a combination of C<shld> on
		633	x86).
		634
		635	=back
		636
		637	=head2 FLOATING POINT FIDDLING
		638
		639	=over 4
		640
		641	=item uint32_t ecb_float_to_binary32 (float x) [-UECB_NO_LIBM]
		642
		643	=item uint64_t ecb_double_to_binary64 (double x) [-UECB_NO_LIBM]
		644
		645	These functions each take an argument in the native C<float> or C<double>
		646	type and return the IEEE 754 bit representation of it.
		647
		648	The bit representation is just as IEEE 754 defines it, i.e. the sign bit
		649	will be the most significant bit, followed by exponent and mantissa.
		650
		651	This function should work even when the native floating point format isn't
		652	IEEE compliant, of course at a speed and code size penalty, and of course
		653	also within reasonable limits (it tries to convert NaNs, infinities and
		654	denormals, but will likely convert negative zero to positive zero).
		655
		656	On all modern platforms (where C<ECB_STDFP> is true), the compiler should
		657	be able to optimise away this function completely.
		658
		659	These functions can be helpful when serialising floats to the network - you
		660	can serialise the return value like a normal uint32_t/uint64_t.
		661
		662	Another use for these functions is to manipulate floating point values
		663	directly.
		664
		665	Silly example: toggle the sign bit of a float.
		666
		667	/* On gcc-4.7 on amd64, */
		668	/* this results in a single add instruction to toggle the bit, and 4 extra */
		669	/* instructions to move the float value to an integer register and back. */
		670
		671	x = ecb_binary32_to_float (ecb_float_to_binary32 (x) ^ 0x80000000U)
		672
		673	=item float ecb_binary32_to_float (uint32_t x) [-UECB_NO_LIBM]
		674
		675	=item double ecb_binary32_to_double (uint64_t x) [-UECB_NO_LIBM]
		676
		677	The reverse operation of the previos function - takes the bit representation
		678	of an IEEE binary32 or binary64 number and converts it to the native C<float>
		679	or C<double> format.
		680
		681	This function should work even when the native floating point format isn't
		682	IEEE compliant, of course at a speed and code size penalty, and of course
		683	also within reasonable limits (it tries to convert normals and denormals,
		684	and might be lucky for infinities, and with extraordinary luck, also for
		685	negative zero).
		686
		687	On all modern platforms (where C<ECB_STDFP> is true), the compiler should
		688	be able to optimise away this function completely.
428		689
429	=back	690	=back
430		691
431	=head2 ARITHMETIC	692	=head2 ARITHMETIC
432		693
…		…
442	C<ecb_mod> implements the mathematical modulo operation, which is missing	703	C<ecb_mod> implements the mathematical modulo operation, which is missing
443	in the language.	704	in the language.
444		705
445	C<n> must be strictly positive (i.e. C<< >= 1 >>), while C<m> must be	706	C<n> must be strictly positive (i.e. C<< >= 1 >>), while C<m> must be
446	negatable, that is, both C<m> and C<-m> must be representable in its	707	negatable, that is, both C<m> and C<-m> must be representable in its
447	type (this typically includes the minimum signed integer value, the same	708	type (this typically excludes the minimum signed integer value, the same
448	limitation as for C</> and C<%> in C).	709	limitation as for C</> and C<%> in C).
449		710
450	Current GCC versions compile this into an efficient branchless sequence on	711	Current GCC versions compile this into an efficient branchless sequence on
451	many systems.	712	almost all CPUs.
452		713
453	For example, when you want to rotate forward through the members of an	714	For example, when you want to rotate forward through the members of an
454	array for increasing C<m> (which might be negative), then you should use	715	array for increasing C<m> (which might be negative), then you should use
455	C<ecb_mod>, as the C<%> operator might give either negative results, or	716	C<ecb_mod>, as the C<%> operator might give either negative results, or
456	change direction for negative values:	717	change direction for negative values:
457		718
458	for (m = -100; m <= 100; ++m)	719	for (m = -100; m <= 100; ++m)
459	int elem = myarray [ecb_mod (m, ecb_array_length (myarray))];	720	int elem = myarray [ecb_mod (m, ecb_array_length (myarray))];
460		721
		722	=item x = ecb_div_rd (val, div)
		723
		724	=item x = ecb_div_ru (val, div)
		725
		726	Returns C<val> divided by C<div> rounded down or up, respectively.
		727	C<val> and C<div> must have integer types and C<div> must be strictly
		728	positive. Note that these functions are implemented with macros in C
		729	and with function templates in C++.
		730
461	=back	731	=back
462		732
463	=head2 UTILITY	733	=head2 UTILITY
464		734
465	=over 4	735	=over 4
…		…
474	for (i = 0; i < ecb_array_length (primes); i++)	744	for (i = 0; i < ecb_array_length (primes); i++)
475	sum += primes [i];	745	sum += primes [i];
476		746
477	=back	747	=back
478		748
		749	=head2 SYMBOLS GOVERNING COMPILATION OF ECB.H ITSELF
479		750
		751	These symbols need to be defined before including F<ecb.h> the first time.
		752
		753	=over 4
		754
		755	=item ECB_NO_THREADS
		756
		757	If F<ecb.h> is never used from multiple threads, then this symbol can
		758	be defined, in which case memory fences (and similar constructs) are
		759	completely removed, leading to more efficient code and fewer dependencies.
		760
		761	Setting this symbol to a true value implies C<ECB_NO_SMP>.
		762
		763	=item ECB_NO_SMP
		764
		765	The weaker version of C<ECB_NO_THREADS> - if F<ecb.h> is used from
		766	multiple threads, but never concurrently (e.g. if the system the program
		767	runs on has only a single CPU with a single core, no hyperthreading and so
		768	on), then this symbol can be defined, leading to more efficient code and
		769	fewer dependencies.
		770
		771	=item ECB_NO_LIBM
		772
		773	When defined to C<1>, do not export any functions that might introduce
		774	dependencies on the math library (usually called F<-lm>) - these are
		775	marked with [-UECB_NO_LIBM].
		776
		777	=back
		778
		779

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Comparing libecb/ecb.pod (file contents): Revision 1.25 by root, Tue May 31 21:52:31 2011 UTC vs. Revision 1.53 by root, Wed Dec 5 16:31:27 2012 UTC

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Comparing libecb/ecb.pod (file contents):
Revision 1.25 by root, Tue May 31 21:52:31 2011 UTC vs.
Revision 1.53 by root, Wed Dec 5 16:31:27 2012 UTC