… | |
… | |
53 | C<uint32_t>, then the corresponding function works only with that type. If |
53 | C<uint32_t>, then the corresponding function works only with that type. If |
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 | |
|
|
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 ptrdiff_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 | =head2 LANGUAGE/COMPILER VERSIONS |
|
|
72 | |
|
|
73 | All the following symbols expand to an expression that can be tested in |
|
|
74 | preprocessor instructions as well as treated as a boolean (use C<!!> to |
|
|
75 | ensure it's either C<0> or C<1> if you need that). |
|
|
76 | |
|
|
77 | =over 4 |
|
|
78 | |
|
|
79 | =item ECB_C |
|
|
80 | |
|
|
81 | True if the implementation defines the C<__STDC__> macro to a true value, |
|
|
82 | which is typically true for both C and C++ compilers. |
|
|
83 | |
|
|
84 | =item ECB_C99 |
|
|
85 | |
|
|
86 | True if the implementation claims to be C99 compliant. |
|
|
87 | |
|
|
88 | =item ECB_C11 |
|
|
89 | |
|
|
90 | True if the implementation claims to be C11 compliant. |
|
|
91 | |
|
|
92 | =item ECB_CPP |
|
|
93 | |
|
|
94 | True if the implementation defines the C<__cplusplus__> macro to a true |
|
|
95 | value, which is typically true for C++ compilers. |
|
|
96 | |
|
|
97 | =item ECB_CPP98 |
|
|
98 | |
|
|
99 | True if the implementation claims to be compliant to ISO/IEC 14882:1998 |
|
|
100 | (the first C++ ISO standard) or any later version. Typically true for all |
|
|
101 | C++ compilers. |
|
|
102 | |
|
|
103 | =item ECB_CPP11 |
|
|
104 | |
|
|
105 | True if the implementation claims to be compliant to ISO/IEC 14882:2011 |
|
|
106 | (C++11) or any later version. |
|
|
107 | |
|
|
108 | =item ECB_GCC_VERSION(major,minor) |
|
|
109 | |
|
|
110 | Expands to a true value (suitable for testing in by the preprocessor) |
|
|
111 | if the compiler used is GNU C and the version is the given version, or |
|
|
112 | higher. |
|
|
113 | |
|
|
114 | This macro tries to return false on compilers that claim to be GCC |
|
|
115 | compatible but aren't. |
|
|
116 | |
|
|
117 | =back |
58 | |
118 | |
59 | =head2 GCC ATTRIBUTES |
119 | =head2 GCC ATTRIBUTES |
60 | |
120 | |
61 | A major part of libecb deals with GCC attributes. These are additional |
121 | A major part of libecb deals with GCC attributes. These are additional |
62 | attributes that you can assign to functions, variables and sometimes even |
122 | attributes that you can assign to functions, variables and sometimes even |
… | |
… | |
425 | For example: |
485 | For 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 | |
|
|
494 | Return true iff C<x> is a power of two or C<x == 0>. |
|
|
495 | |
|
|
496 | For 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 | |
434 | Returns the index of the most significant bit set in C<x>, or the number |
502 | Returns the index of the most significant bit set in C<x>, or the number |
… | |
… | |
454 | |
522 | |
455 | For example: |
523 | For 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 | |
|
|
534 | Reverses the bits in x, i.e. the MSB becomes the LSB, MSB-1 becomes LSB+1 |
|
|
535 | and so on. |
|
|
536 | |
|
|
537 | Example: |
|
|
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 | |
… | |
… | |
527 | |
609 | |
528 | =item x = ecb_div_ru (val, div) |
610 | =item x = ecb_div_ru (val, div) |
529 | |
611 | |
530 | Returns C<val> divided by C<div> rounded down or up, respectively. |
612 | Returns C<val> divided by C<div> rounded down or up, respectively. |
531 | C<val> and C<div> must have integer types and C<div> must be strictly |
613 | C<val> and C<div> must have integer types and C<div> must be strictly |
532 | positive. |
614 | positive. Note that these functions are implemented with macros in C |
|
|
615 | and with function templates in C++. |
533 | |
616 | |
534 | =back |
617 | =back |
535 | |
618 | |
536 | =head2 UTILITY |
619 | =head2 UTILITY |
537 | |
620 | |
… | |
… | |
547 | for (i = 0; i < ecb_array_length (primes); i++) |
630 | for (i = 0; i < ecb_array_length (primes); i++) |
548 | sum += primes [i]; |
631 | sum += primes [i]; |
549 | |
632 | |
550 | =back |
633 | =back |
551 | |
634 | |
|
|
635 | =head2 SYMBOLS GOVERNING COMPILATION OF ECB.H ITSELF |
552 | |
636 | |
|
|
637 | These symbols need to be defined before including F<ecb.h> the first time. |
|
|
638 | |
|
|
639 | =over 4 |
|
|
640 | |
|
|
641 | =item ECB_NO_THRADS |
|
|
642 | |
|
|
643 | If F<ecb.h> is never used from multiple threads, then this symbol can |
|
|
644 | be defined, in which case memory fences (and similar constructs) are |
|
|
645 | completely removed, leading to more efficient code and fewer dependencies. |
|
|
646 | |
|
|
647 | Setting this symbol to a true value implies C<ECB_NO_SMP>. |
|
|
648 | |
|
|
649 | =item ECB_NO_SMP |
|
|
650 | |
|
|
651 | The weaker version of C<ECB_NO_THREADS> - if F<ecb.h> is used from |
|
|
652 | multiple threads, but never concurrently (e.g. if the system the program |
|
|
653 | runs on has only a single CPU with a single core, no hyperthreading and so |
|
|
654 | on), then this symbol can be defined, leading to more efficient code and |
|
|
655 | fewer dependencies. |
|
|
656 | |
|
|
657 | =back |
|
|
658 | |
|
|
659 | |