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242 | Similar to C<ecb_unused>, but marks a function, variable or type as |
242 | Similar to C<ecb_unused>, but marks a function, variable or type as |
243 | deprecated. This makes some compilers warn when the type is used. |
243 | deprecated. This makes some compilers warn when the type is used. |
244 | |
244 | |
245 | =item ecb_deprecated_message (message) |
245 | =item ecb_deprecated_message (message) |
246 | |
246 | |
247 | Same as C<ecb_deprecated>, but if possible, supply a diagnostic that is |
247 | Same as C<ecb_deprecated>, but if possible, the specified diagnostic is |
248 | used instead of a generic depreciation message when the object is being |
248 | used instead of a generic depreciation message when the object is being |
249 | used. |
249 | used. |
250 | |
250 | |
251 | =item ecb_inline |
251 | =item ecb_inline |
252 | |
252 | |
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262 | return - (a * b); |
262 | return - (a * b); |
263 | } |
263 | } |
264 | |
264 | |
265 | =item ecb_noinline |
265 | =item ecb_noinline |
266 | |
266 | |
267 | Prevent a function from being inlined - it might be optimised away, but |
267 | Prevents a function from being inlined - it might be optimised away, but |
268 | not inlined into other functions. This is useful if you know your function |
268 | not inlined into other functions. This is useful if you know your function |
269 | is rarely called and large enough for inlining not to be helpful. |
269 | is rarely called and large enough for inlining not to be helpful. |
270 | |
270 | |
271 | =item ecb_noreturn |
271 | =item ecb_noreturn |
272 | |
272 | |
… | |
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489 | real_reserve_method (size); /* presumably noinline */ |
489 | real_reserve_method (size); /* presumably noinline */ |
490 | } |
490 | } |
491 | |
491 | |
492 | =item ecb_assume (cond) |
492 | =item ecb_assume (cond) |
493 | |
493 | |
494 | Try to tell the compiler that some condition is true, even if it's not |
494 | Tries to tell the compiler that some condition is true, even if it's not |
495 | obvious. |
495 | obvious. This is not a function, but a statement: it cannot be used in |
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496 | another expression. |
496 | |
497 | |
497 | This can be used to teach the compiler about invariants or other |
498 | This can be used to teach the compiler about invariants or other |
498 | conditions that might improve code generation, but which are impossible to |
499 | conditions that might improve code generation, but which are impossible to |
499 | deduce form the code itself. |
500 | deduce form the code itself. |
500 | |
501 | |
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521 | |
522 | |
522 | =item ecb_unreachable () |
523 | =item ecb_unreachable () |
523 | |
524 | |
524 | This function does nothing itself, except tell the compiler that it will |
525 | This function does nothing itself, except tell the compiler that it will |
525 | never be executed. Apart from suppressing a warning in some cases, this |
526 | never be executed. Apart from suppressing a warning in some cases, this |
526 | function can be used to implement C<ecb_assume> or similar functions. |
527 | function can be used to implement C<ecb_assume> or similar functionality. |
527 | |
528 | |
528 | =item ecb_prefetch (addr, rw, locality) |
529 | =item ecb_prefetch (addr, rw, locality) |
529 | |
530 | |
530 | Tells the compiler to try to prefetch memory at the given C<addr>ess |
531 | Tells the compiler to try to prefetch memory at the given C<addr>ess |
531 | for either reading (C<rw> = 0) or writing (C<rw> = 1). A C<locality> of |
532 | for either reading (C<rw> = 0) or writing (C<rw> = 1). A C<locality> of |
… | |
… | |
533 | the data will likely be accessed very often, and values in between mean |
534 | the data will likely be accessed very often, and values in between mean |
534 | something... in between. The memory pointed to by the address does not |
535 | something... in between. The memory pointed to by the address does not |
535 | need to be accessible (it could be a null pointer for example), but C<rw> |
536 | need to be accessible (it could be a null pointer for example), but C<rw> |
536 | and C<locality> must be compile-time constants. |
537 | and C<locality> must be compile-time constants. |
537 | |
538 | |
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539 | This is a statement, not a function: you cannot use it as part of an |
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540 | expression. |
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541 | |
538 | An obvious way to use this is to prefetch some data far away, in a big |
542 | An obvious way to use this is to prefetch some data far away, in a big |
539 | array you loop over. This prefetches memory some 128 array elements later, |
543 | array you loop over. This prefetches memory some 128 array elements later, |
540 | in the hope that it will be ready when the CPU arrives at that location. |
544 | in the hope that it will be ready when the CPU arrives at that location. |
541 | |
545 | |
542 | int sum = 0; |
546 | int sum = 0; |
… | |
… | |
594 | |
598 | |
595 | =item bool ecb_is_pot32 (uint32_t x) |
599 | =item bool ecb_is_pot32 (uint32_t x) |
596 | |
600 | |
597 | =item bool ecb_is_pot64 (uint32_t x) |
601 | =item bool ecb_is_pot64 (uint32_t x) |
598 | |
602 | |
599 | Return true iff C<x> is a power of two or C<x == 0>. |
603 | Returns true iff C<x> is a power of two or C<x == 0>. |
600 | |
604 | |
601 | For smaller types then C<uint32_t> you can safely use C<ecb_is_pot32>. |
605 | For smaller types than C<uint32_t> you can safely use C<ecb_is_pot32>. |
602 | |
606 | |
603 | =item int ecb_ld32 (uint32_t x) |
607 | =item int ecb_ld32 (uint32_t x) |
604 | |
608 | |
605 | =item int ecb_ld64 (uint64_t x) |
609 | =item int ecb_ld64 (uint64_t x) |
606 | |
610 | |
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836 | dependencies on the math library (usually called F<-lm>) - these are |
840 | dependencies on the math library (usually called F<-lm>) - these are |
837 | marked with [-UECB_NO_LIBM]. |
841 | marked with [-UECB_NO_LIBM]. |
838 | |
842 | |
839 | =back |
843 | =back |
840 | |
844 | |
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845 | =head1 UNDOCUMENTED FUNCTIONALITY |
841 | |
846 | |
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847 | F<ecb.h> is full of undocumented functionality as well, some of which is |
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848 | intended to be internal-use only, some of which we forgot to document, and |
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849 | some of which we hide because we are not sure we will keep the interface |
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850 | stable. |
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851 | |
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852 | While you are welcome to rummage around and use whatever you find useful |
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853 | (we can't stop you), keep in mind that we will change undocumented |
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854 | functionality in incompatible ways without thinking twice, while we are |
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855 | considerably more conservative with documented things. |
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856 | |
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857 | =head1 AUTHORS |
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858 | |
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859 | C<libecb> is designed and maintained by: |
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860 | |
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861 | Emanuele Giaquinta <e.giaquinta@glauco.it> |
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862 | Marc Alexander Lehmann <schmorp@schmorp.de> |
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863 | |
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864 | |