diff options
Diffstat (limited to 'doc/info')
| -rw-r--r-- | doc/info/chap/memory-allocation.texinfo | 201 |
1 files changed, 192 insertions, 9 deletions
diff --git a/doc/info/chap/memory-allocation.texinfo b/doc/info/chap/memory-allocation.texinfo index d9d2e86..44a9198 100644 --- a/doc/info/chap/memory-allocation.texinfo +++ b/doc/info/chap/memory-allocation.texinfo @@ -495,7 +495,7 @@ This function is a @sc{GNU} extension and requires @code{_GNU_SOURCE}. @end table -@hfindex{slibc-alloc.h} +@hfindex slibc-alloc.h @command{slibc} provides a number of additional methods for memory management. These are defined in the header file @file{<slibc-alloc.h>}. They @@ -736,8 +736,65 @@ p = aligned_alloc(sizeof(*p), n) @end table -@c TODO @item void* rememalign(void* ptr, size_t boundary, size_t size, enum rememalign_mode mode) -@c @fnindex rememalign +@hfindex slibc-alloc.h +@command{slibc} provides a number of additional +methods for memory management. These are defined +in the header file @file{<slibc-alloc.h>}. They +are available even if @code{_SLIBC_SOURCE} is not +defined, but it is required that neither +@code{_PORTABLE_SOURCE} nor @code{_LIBRARY_HEADER} +is defined. + +@table @code +@item void* rememalign(void* ptr, size_t boundary, size_t size, enum rememalign_mode mode) +@fnindex rememalign +@tpindex rememalign_mode +@tpindex enum rememalign_mode +@cpindex Reallocating memory +@cpindex Memory, reallocation +@cpindex Resizing memory allocations +@cpindex Memory, resize allocations +This function is similar to @code{realloc}, however its +behaviour and pointer alignment can be tuned. + +The pointer's alignment is specified by the parameter +@code{boundary}. It must be a power of two, lest the +function fail with @code{errno} set to @code{EINVAL}. +@code{boundary} is not validated before it is necessary, +that is, it will only be validated if a new allocation +is created. + +The function's behaviour is tuned with the @code{mode} +paarameter. It may be any combination of +@table @code +@item REMEMALIGN_CLEAR +If the allocation shrunk, the disowned memory is cleared. +If @code{ptr} is deallocated, it will be cleared. +@item REMEMALIGN_INIT +If the allocation growed, the newly available memory +is zero-initialised. If @code{REMEMALIGN_MEMCPY} is not +used but a new allocation was created, the entire +allocation is zero-initialised. +@item REMEMALIGN_MEMCPY +If a new allocation is created, and @code{ptr} is not +@code{NULL}, the data from the old allocation is copied +over to the new allocation. +@end table + +If @code{mode} contains any other set bit that those +set by @code{REMEMALIGN_CLEAR}, @code{REMEMALIGN_INIT}, +or @code{REMEMALIGN_MEMCPY}, the function fails with +@code{errno} set to @code{EINVAL}. + +Upon successful completion, @code{errno} is set to zero +if @code{NULL} is returned. + +@item void* naive_realloc(void* ptr, size_t boundary, size_t size) +This function is discussed in @ref{Resizing memory allocations}. + +@item void* falloc(void* ptr, size_t* ptrshift, size_t boundary, size_t old_size, size_t new_size, enum falloc_mode mode) +This function is discussed in @ref{Resizing memory allocations}. +@end table @@ -756,7 +813,7 @@ it simplifies to the program code. @table @code @item void* realloc(void* ptr, size_t size) -@hfindex stdilb.h +@hfindex stdlib.h @hfindex malloc.h @sc{ANSI}@tie{}C defines this function to be defined in the header file @file{<stdlib.h>}, @@ -824,7 +881,7 @@ is returned, and thus, the behaviour is also identical to that of @code{free}. @end table -@hfindex{slibc-alloc.h} +@hfindex slibc-alloc.h @command{slibc} provides a number of additional methods for memory management. These are defined in the header file @file{<slibc-alloc.h>}. They @@ -887,23 +944,149 @@ not be cleared. @item void* extalloc(void* ptr, size_t size, enum extalloc_mode mode) @fnindex extalloc -TODO +@tpindex extalloc_mode +@tpindex enum extalloc_mode +This function is similar to @code{realloc}, but if it +creates a new allocation, data is not copied over from +the old allocation to the new allocation. If it is +necessary to create a new allocation, @code{errno} is +set to zero and @code{NULL} is returned, unless +@code{mode & EXTALLOC_MALLOC}. This funtion will not +initialise new memory, additionally, it will only clear +old memory --- disowned, or the old allocation --- if +@code{mode & EXTALLOC_CLEAR}. @code{EXTALLOC_MALLOC} +and @code{EXTALLOC_CLEAR} can be combined freely. @item void* naive_realloc(void* ptr, size_t boundary, size_t size) @fnindex naive_realloc -TODO +This is a naïve bare-bones version of @code{realloc}, +intended to be used to implement @code{realloc}-functions. +It behaviour is identical to that if @code{fast_realloc}, +with a new exceptions: +@itemize @bullet{} +@item +Its behaviour is undefined if @code{ptr} is @code{NULL}. +@item +Its behaviour is undefined if @code{size} equals the old +allocation size. +@item +Its behaviour is undefined if @code{size} is zero. +@item +It will never free @code{ptr}. +@item +The alignment of new pointers can be specified. +If and only if, a new allocation is created, the +returned pointer's alignment will be @code{boundary}. +@end itemize @item void* naive_extalloc(void* ptr, size_t size) @fnindex naive_extalloc -TODO +This is a naïve bare-bones version of @code{extalloc}, +intended to be used to implement @code{extalloc}-functions. +This fucntion is identical to that of @code{naive_realloc}, +except it will return @code{NULL} with @code{errno} set to +zero, if it is not possible to perform the shrink or grow +without creating new pointer. @item void* falloc(void* ptr, size_t* ptrshift, size_t boundary, size_t old_size, size_t new_size, enum falloc_mode mode) @fnindex falloc +@tpindex falloc_mode +@tpindex enum falloc_mode @cpindex Memory alignment @cpindex Pointer alignment @cpindex Aligned pointers -TODO +This function is similar to @code{realloc}, but it does +not do internal bookkeeping. It can allocates, deallocates, +or reallocates memory. The created allocation may not be +inspected, deallocated, or reallocated with any other +function than this function. @code{falloc} can be used to +minimise the memory footprint. + +This function has six parameters: +@table @code +@item void* ptr +The old pointer, @code{NULL} if a new shall be created. +@item size_t* ptrshift +Pointer that is used to keep track of the pointer's +shift for alignment. @code{NULL} if the shift shall not +be tracked. If this is the case, @code{falloc} cannot +be used to reallocate or deallocate an allocation, +unless the pointer is unaligned (@code{alignment} is +zero or one). +@item size_t boundary +The aligment of both the new and old pointer, zero +or one if it should not be aligned. +@item size_t old_size +The old allocation size, zero if a new shall be created. +@item size_t new_size +The new allocation size, zero if it shall be freed. +@item enum falloc_mode mode +Any combination of +@table @code +@item FALLOC_CLEAR +If the allocation shrunk, the disowned memory is cleared. +If @code{ptr} is deallocated, it will be cleared. +@item FALLOC_INIT +If the allocation growed, the newly available memory +is zero-initialised. If @code{FALLOC_MEMCPY} is not +used but a new allocation was created, the entire +allocation is zero-initialised. +@item FALLOC_MEMCPY +If a new allocation is created, and @code{ptr} is not +@code{NULL}, the data from the old allocation is copied +over to the new allocation. +@end table +@end table +The function will return the old pointer if it has been +shrunk or grown, a new pointer if a new allocation was +required (the allocation is deallocated and @code{ptr} +has become an invalid pointer,) @code{NULL}, with +@code{errno} set to zero, if the @code{ptr} is deallocated +and no new allocation was created (@code{new_size} is zero), +or if @code{new_size} and @code{old_size} is zero and +@code{ptr} is @code{NULL}, or @code{NULL} with errno set +to describe the error on failure. + +On error, @code{errno} is set to either @code{EINVAL}, +if the input arguments invalid, or @code{ENOMEM} if the +process could not allocate the requested memory. + +If @code{new_size} is zero and @code{ptr} is @code{NULL}, +nothing happens, but @code{errno} is set to zero and +@code{NULL} is returned. + +If @code{new_size} is non-zero, @code{old_size} is zero, +and @code{ptr} is not @code{NULL} or if @code{new_size} +and @code{old_size} is non-zero, and @code{ptr} is +@code{NULL}, @code{errno} is set to @code{EINVAL} and +@code{NULL} is returned. + +If @code{new_size} and @code{old_size} is zero and +@code{ptr} is not @code{NULL}, @code{errno} is set to +@code{EINVAL} and @code{NULL} is returned. + +If @code{new_size} is zero, @code{old_size} is non-zero, +and @code{ptr} is not @code{NULL}, @code{ptr} is deallocated, +and @code{NULL} is returned with @code{errno} set to zero. +The memory cleared before it is deallocated if +@code{mode & FALLOC_CLEAR}. + +If @code{new_size} is non-zero, @code{old_size} is zero, +and @code{ptr} is @code{NULL}, a new allocation is created +of @code{new_size} bytes. It will be zero-initialised if +@code{mode & FALLOC_INIT}. + +If @code{new_size} and @code{old_size} is non-zero and +@code{ptr} is not @code{NULL}, @code{ptr} is reallocated. +if the allocation is shrunk, the disowned area is cleared +if @code{mode & FALLOC_CLEAR}. Newly available memory is +zero-initialised if @code{mode & FALLOC_INIT}. If a new +allocation is required, the data from the old allocation +is only copied over to the new allocation if +@code{mode & FALLOC_MEMCPY}. If +@code{(mode & FALLOC_INIT) && !(mode & FALLOC_MEMCPY)}, +the entire allocation will be cleared. @end table |