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Revision 1.38 by sf-exg, Thu Aug 25 16:06:08 2011 UTC vs.
Revision 1.45 by root, Tue May 29 14:35:43 2012 UTC

… …
53C<uint32_t>, then the corresponding function works only with that type. If 53C<uint32_t>, then the corresponding function works only with that type. If
54only a generic name is used (C<expr>, C<cond>, C<value> and so on), then 54only a generic name is used (C<expr>, C<cond>, C<value> and so on), then
55the corresponding function relies on C to implement the correct types, and 55the corresponding function relies on C to implement the correct types, and
56is usually implemented as a macro. Specifically, a "bool" in this manual 56is usually implemented as a macro. Specifically, a "bool" in this manual
57refers to any kind of boolean value, not a specific type. 57refers to any kind of boolean value, not a specific type.
58
59=head2 TYPES / TYPE SUPPORT
60
61ecb.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 ptrdiff_t
66
67The macro C<ECB_PTRSIZE> is defined to the size of a pointer on this
68platform (currently C<4> or C<8>) and can be used in preprocessor
69expressions.
70
71=head2 LANGUAGE/COMPILER VERSIONS
72
73All the following symbols expand to an expressionb that cna be tested in
74preprocessor instructions as well as treated as a boolean (use C<!!> to
75ensure it's either C<0> or C<1> if you need that).
76
77=over 4
78
79=item ECB_C
80
81True if the implementation defines the C<__STDC__> macro to a true value,
82which is typically true for both C and C++ compilers.
83
84=item ECB_C99
85
86True if the implementation claims to be C99 compliant.
87
88=item ECB_C11
89
90True if the implementation claims to be C11 compliant.
91
92=item ECB_CPP
93
94True if the implementation defines the C<__cplusplus__> macro to a true
95value, which is typically true for C++ compilers.
96
97=item ECB_CPP98
98
99True if the implementation claims to be compliant to ISO/IEC 14882:1998
100(the first C++ ISO standard) or any later vwersion. Typically true for all
101C++ compilers.
102
103=item ECB_CPP11
104
105True if the implementation claims to be compliant to ISO/IEC 14882:2011
106(C++11) or any later vwersion.
107
108=item ECB_GCC_VERSION(major,minor)
109
110Expands to a true value (suitable for testing in by the preprocessor)
111if the compiler used is GNU C and the version is the givne version, or
112higher.
113
114This macro tries to return false on compilers that claim to be GCC
115compatible but aren't.
116
117=back
58 118
59=head2 GCC ATTRIBUTES 119=head2 GCC ATTRIBUTES
60 120
61A major part of libecb deals with GCC attributes. These are additional 121A major part of libecb deals with GCC attributes. These are additional
62attributes that you can assign to functions, variables and sometimes even 122attributes that you can assign to functions, variables and sometimes even
… …
425For example: 485For example:
426 486
427 ecb_ctz32 (3) = 0 487 ecb_ctz32 (3) = 0
428 ecb_ctz32 (6) = 1 488 ecb_ctz32 (6) = 1
429 489
490=item bool ecb_is_pot32 (uint32_t x)
491
492=item bool ecb_is_pot64 (uint32_t x)
493
494Return true iff C<x> is a power of two or C<x == 0>.
495
496For smaller types then C<uint32_t> you can safely use C<ecb_is_pot32>.
497
430=item int ecb_ld32 (uint32_t x) 498=item int ecb_ld32 (uint32_t x)
431 499
432=item int ecb_ld64 (uint64_t x) 500=item int ecb_ld64 (uint64_t x)
433 501
434Returns the index of the most significant bit set in C<x>, or the number 502Returns the index of the most significant bit set in C<x>, or the number
… …
454 522
455For example: 523For example:
456 524
457 ecb_popcount32 (7) = 3 525 ecb_popcount32 (7) = 3
458 ecb_popcount32 (255) = 8 526 ecb_popcount32 (255) = 8
527
528=item uint8_t ecb_bitrev8 (uint8_t x)
529
530=item uint16_t ecb_bitrev16 (uint16_t x)
531
532=item uint32_t ecb_bitrev32 (uint32_t x)
533
534Reverses the bits in x, i.e. the MSB becomes the LSB, MSB-1 becomes LSB+1
535and so on.
536
537Example:
538
539 ecb_bitrev8 (0xa7) = 0xea
540 ecb_bitrev32 (0xffcc4411) = 0x882233ff
459 541
460=item uint32_t ecb_bswap16 (uint32_t x) 542=item uint32_t ecb_bswap16 (uint32_t x)
461 543
462=item uint32_t ecb_bswap32 (uint32_t x) 544=item uint32_t ecb_bswap32 (uint32_t x)
463 545
… …
548 for (i = 0; i < ecb_array_length (primes); i++) 630 for (i = 0; i < ecb_array_length (primes); i++)
549 sum += primes [i]; 631 sum += primes [i];
550 632
551=back 633=back
552 634
635=head2 SYMBOLS GOVERNING COMPILATION OF ECB.H ITSELF
553 636
637These symbols need to be defined before including F<ecb.h> the first time.
638
639=over 4
640
641=item ECB_NO_THRADS
642
643If F<ecb.h> is never used from multiple threads, then this symbol can
644be defined, in which case memory fences (and similar constructs) are
645completely removed, leading to more efficient code and fewer dependencies.
646
647Setting this symbol to a true value implies C<ECB_NO_SMP>.
648
649=item ECB_NO_SMP
650
651The weaker version of C<ECB_NO_THREADS> - if F<ecb.h> is used from
652multiple threads, but never concurrently (e.g. if the system the program
653runs on has only a single CPU with a single core, no hyperthreading and so
654on), then this symbol can be defined, leading to more efficient code and
655fewer dependencies.
656
657=back
658
659

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