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diff --git a/libiberty/obstacks.texi b/libiberty/obstacks.texi new file mode 100644 index 00000000000..9bddf7caf30 --- /dev/null +++ b/libiberty/obstacks.texi @@ -0,0 +1,758 @@ +@node Obstacks,Licenses,Functions,Top +@chapter Obstacks +@cindex obstacks + +An @dfn{obstack} is a pool of memory containing a stack of objects. You +can create any number of separate obstacks, and then allocate objects in +specified obstacks. Within each obstack, the last object allocated must +always be the first one freed, but distinct obstacks are independent of +each other. + +Aside from this one constraint of order of freeing, obstacks are totally +general: an obstack can contain any number of objects of any size. They +are implemented with macros, so allocation is usually very fast as long as +the objects are usually small. And the only space overhead per object is +the padding needed to start each object on a suitable boundary. + +@menu +* Creating Obstacks:: How to declare an obstack in your program. +* Preparing for Obstacks:: Preparations needed before you can + use obstacks. +* Allocation in an Obstack:: Allocating objects in an obstack. +* Freeing Obstack Objects:: Freeing objects in an obstack. +* Obstack Functions:: The obstack functions are both + functions and macros. +* Growing Objects:: Making an object bigger by stages. +* Extra Fast Growing:: Extra-high-efficiency (though more + complicated) growing objects. +* Status of an Obstack:: Inquiries about the status of an obstack. +* Obstacks Data Alignment:: Controlling alignment of objects in obstacks. +* Obstack Chunks:: How obstacks obtain and release chunks; + efficiency considerations. +* Summary of Obstacks:: +@end menu + +@node Creating Obstacks +@section Creating Obstacks + +The utilities for manipulating obstacks are declared in the header +file @file{obstack.h}. +@pindex obstack.h + +@comment obstack.h +@comment GNU +@deftp {Data Type} {struct obstack} +An obstack is represented by a data structure of type @code{struct +obstack}. This structure has a small fixed size; it records the status +of the obstack and how to find the space in which objects are allocated. +It does not contain any of the objects themselves. You should not try +to access the contents of the structure directly; use only the functions +described in this chapter. +@end deftp + +You can declare variables of type @code{struct obstack} and use them as +obstacks, or you can allocate obstacks dynamically like any other kind +of object. Dynamic allocation of obstacks allows your program to have a +variable number of different stacks. (You can even allocate an +obstack structure in another obstack, but this is rarely useful.) + +All the functions that work with obstacks require you to specify which +obstack to use. You do this with a pointer of type @code{struct obstack +*}. In the following, we often say ``an obstack'' when strictly +speaking the object at hand is such a pointer. + +The objects in the obstack are packed into large blocks called +@dfn{chunks}. The @code{struct obstack} structure points to a chain of +the chunks currently in use. + +The obstack library obtains a new chunk whenever you allocate an object +that won't fit in the previous chunk. Since the obstack library manages +chunks automatically, you don't need to pay much attention to them, but +you do need to supply a function which the obstack library should use to +get a chunk. Usually you supply a function which uses @code{malloc} +directly or indirectly. You must also supply a function to free a chunk. +These matters are described in the following section. + +@node Preparing for Obstacks +@section Preparing for Using Obstacks + +Each source file in which you plan to use the obstack functions +must include the header file @file{obstack.h}, like this: + +@smallexample +#include <obstack.h> +@end smallexample + +@findex obstack_chunk_alloc +@findex obstack_chunk_free +Also, if the source file uses the macro @code{obstack_init}, it must +declare or define two functions or macros that will be called by the +obstack library. One, @code{obstack_chunk_alloc}, is used to allocate +the chunks of memory into which objects are packed. The other, +@code{obstack_chunk_free}, is used to return chunks when the objects in +them are freed. These macros should appear before any use of obstacks +in the source file. + +Usually these are defined to use @code{malloc} via the intermediary +@code{xmalloc} (@pxref{Unconstrained Allocation, , , libc, The GNU C Library Reference Manual}). This is done with +the following pair of macro definitions: + +@smallexample +#define obstack_chunk_alloc xmalloc +#define obstack_chunk_free free +@end smallexample + +@noindent +Though the memory you get using obstacks really comes from @code{malloc}, +using obstacks is faster because @code{malloc} is called less often, for +larger blocks of memory. @xref{Obstack Chunks}, for full details. + +At run time, before the program can use a @code{struct obstack} object +as an obstack, it must initialize the obstack by calling +@code{obstack_init}. + +@comment obstack.h +@comment GNU +@deftypefun int obstack_init (struct obstack *@var{obstack-ptr}) +Initialize obstack @var{obstack-ptr} for allocation of objects. This +function calls the obstack's @code{obstack_chunk_alloc} function. If +allocation of memory fails, the function pointed to by +@code{obstack_alloc_failed_handler} is called. The @code{obstack_init} +function always returns 1 (Compatibility notice: Former versions of +obstack returned 0 if allocation failed). +@end deftypefun + +Here are two examples of how to allocate the space for an obstack and +initialize it. First, an obstack that is a static variable: + +@smallexample +static struct obstack myobstack; +@dots{} +obstack_init (&myobstack); +@end smallexample + +@noindent +Second, an obstack that is itself dynamically allocated: + +@smallexample +struct obstack *myobstack_ptr + = (struct obstack *) xmalloc (sizeof (struct obstack)); + +obstack_init (myobstack_ptr); +@end smallexample + +@comment obstack.h +@comment GNU +@defvar obstack_alloc_failed_handler +The value of this variable is a pointer to a function that +@code{obstack} uses when @code{obstack_chunk_alloc} fails to allocate +memory. The default action is to print a message and abort. +You should supply a function that either calls @code{exit} +(@pxref{Program Termination, , , libc, The GNU C Library Reference Manual}) or @code{longjmp} (@pxref{Non-Local +Exits, , , libc, The GNU C Library Reference Manual}) and doesn't return. + +@smallexample +void my_obstack_alloc_failed (void) +@dots{} +obstack_alloc_failed_handler = &my_obstack_alloc_failed; +@end smallexample + +@end defvar + +@node Allocation in an Obstack +@section Allocation in an Obstack +@cindex allocation (obstacks) + +The most direct way to allocate an object in an obstack is with +@code{obstack_alloc}, which is invoked almost like @code{malloc}. + +@comment obstack.h +@comment GNU +@deftypefun {void *} obstack_alloc (struct obstack *@var{obstack-ptr}, int @var{size}) +This allocates an uninitialized block of @var{size} bytes in an obstack +and returns its address. Here @var{obstack-ptr} specifies which obstack +to allocate the block in; it is the address of the @code{struct obstack} +object which represents the obstack. Each obstack function or macro +requires you to specify an @var{obstack-ptr} as the first argument. + +This function calls the obstack's @code{obstack_chunk_alloc} function if +it needs to allocate a new chunk of memory; it calls +@code{obstack_alloc_failed_handler} if allocation of memory by +@code{obstack_chunk_alloc} failed. +@end deftypefun + +For example, here is a function that allocates a copy of a string @var{str} +in a specific obstack, which is in the variable @code{string_obstack}: + +@smallexample +struct obstack string_obstack; + +char * +copystring (char *string) +@{ + size_t len = strlen (string) + 1; + char *s = (char *) obstack_alloc (&string_obstack, len); + memcpy (s, string, len); + return s; +@} +@end smallexample + +To allocate a block with specified contents, use the function +@code{obstack_copy}, declared like this: + +@comment obstack.h +@comment GNU +@deftypefun {void *} obstack_copy (struct obstack *@var{obstack-ptr}, void *@var{address}, int @var{size}) +This allocates a block and initializes it by copying @var{size} +bytes of data starting at @var{address}. It calls +@code{obstack_alloc_failed_handler} if allocation of memory by +@code{obstack_chunk_alloc} failed. +@end deftypefun + +@comment obstack.h +@comment GNU +@deftypefun {void *} obstack_copy0 (struct obstack *@var{obstack-ptr}, void *@var{address}, int @var{size}) +Like @code{obstack_copy}, but appends an extra byte containing a null +character. This extra byte is not counted in the argument @var{size}. +@end deftypefun + +The @code{obstack_copy0} function is convenient for copying a sequence +of characters into an obstack as a null-terminated string. Here is an +example of its use: + +@smallexample +char * +obstack_savestring (char *addr, int size) +@{ + return obstack_copy0 (&myobstack, addr, size); +@} +@end smallexample + +@noindent +Contrast this with the previous example of @code{savestring} using +@code{malloc} (@pxref{Basic Allocation, , , libc, The GNU C Library Reference Manual}). + +@node Freeing Obstack Objects +@section Freeing Objects in an Obstack +@cindex freeing (obstacks) + +To free an object allocated in an obstack, use the function +@code{obstack_free}. Since the obstack is a stack of objects, freeing +one object automatically frees all other objects allocated more recently +in the same obstack. + +@comment obstack.h +@comment GNU +@deftypefun void obstack_free (struct obstack *@var{obstack-ptr}, void *@var{object}) +If @var{object} is a null pointer, everything allocated in the obstack +is freed. Otherwise, @var{object} must be the address of an object +allocated in the obstack. Then @var{object} is freed, along with +everything allocated in @var{obstack} since @var{object}. +@end deftypefun + +Note that if @var{object} is a null pointer, the result is an +uninitialized obstack. To free all memory in an obstack but leave it +valid for further allocation, call @code{obstack_free} with the address +of the first object allocated on the obstack: + +@smallexample +obstack_free (obstack_ptr, first_object_allocated_ptr); +@end smallexample + +Recall that the objects in an obstack are grouped into chunks. When all +the objects in a chunk become free, the obstack library automatically +frees the chunk (@pxref{Preparing for Obstacks}). Then other +obstacks, or non-obstack allocation, can reuse the space of the chunk. + +@node Obstack Functions +@section Obstack Functions and Macros +@cindex macros + +The interfaces for using obstacks may be defined either as functions or +as macros, depending on the compiler. The obstack facility works with +all C compilers, including both @w{ISO C} and traditional C, but there are +precautions you must take if you plan to use compilers other than GNU C. + +If you are using an old-fashioned @w{non-ISO C} compiler, all the obstack +``functions'' are actually defined only as macros. You can call these +macros like functions, but you cannot use them in any other way (for +example, you cannot take their address). + +Calling the macros requires a special precaution: namely, the first +operand (the obstack pointer) may not contain any side effects, because +it may be computed more than once. For example, if you write this: + +@smallexample +obstack_alloc (get_obstack (), 4); +@end smallexample + +@noindent +you will find that @code{get_obstack} may be called several times. +If you use @code{*obstack_list_ptr++} as the obstack pointer argument, +you will get very strange results since the incrementation may occur +several times. + +In @w{ISO C}, each function has both a macro definition and a function +definition. The function definition is used if you take the address of the +function without calling it. An ordinary call uses the macro definition by +default, but you can request the function definition instead by writing the +function name in parentheses, as shown here: + +@smallexample +char *x; +void *(*funcp) (); +/* @r{Use the macro}. */ +x = (char *) obstack_alloc (obptr, size); +/* @r{Call the function}. */ +x = (char *) (obstack_alloc) (obptr, size); +/* @r{Take the address of the function}. */ +funcp = obstack_alloc; +@end smallexample + +@noindent +This is the same situation that exists in @w{ISO C} for the standard library +functions. @xref{Macro Definitions, , , libc, The GNU C Library Reference Manual}. + +@strong{Warning:} When you do use the macros, you must observe the +precaution of avoiding side effects in the first operand, even in @w{ISO C}. + +If you use the GNU C compiler, this precaution is not necessary, because +various language extensions in GNU C permit defining the macros so as to +compute each argument only once. + +@node Growing Objects +@section Growing Objects +@cindex growing objects (in obstacks) +@cindex changing the size of a block (obstacks) + +Because memory in obstack chunks is used sequentially, it is possible to +build up an object step by step, adding one or more bytes at a time to the +end of the object. With this technique, you do not need to know how much +data you will put in the object until you come to the end of it. We call +this the technique of @dfn{growing objects}. The special functions +for adding data to the growing object are described in this section. + +You don't need to do anything special when you start to grow an object. +Using one of the functions to add data to the object automatically +starts it. However, it is necessary to say explicitly when the object is +finished. This is done with the function @code{obstack_finish}. + +The actual address of the object thus built up is not known until the +object is finished. Until then, it always remains possible that you will +add so much data that the object must be copied into a new chunk. + +While the obstack is in use for a growing object, you cannot use it for +ordinary allocation of another object. If you try to do so, the space +already added to the growing object will become part of the other object. + +@comment obstack.h +@comment GNU +@deftypefun void obstack_blank (struct obstack *@var{obstack-ptr}, int @var{size}) +The most basic function for adding to a growing object is +@code{obstack_blank}, which adds space without initializing it. +@end deftypefun + +@comment obstack.h +@comment GNU +@deftypefun void obstack_grow (struct obstack *@var{obstack-ptr}, void *@var{data}, int @var{size}) +To add a block of initialized space, use @code{obstack_grow}, which is +the growing-object analogue of @code{obstack_copy}. It adds @var{size} +bytes of data to the growing object, copying the contents from +@var{data}. +@end deftypefun + +@comment obstack.h +@comment GNU +@deftypefun void obstack_grow0 (struct obstack *@var{obstack-ptr}, void *@var{data}, int @var{size}) +This is the growing-object analogue of @code{obstack_copy0}. It adds +@var{size} bytes copied from @var{data}, followed by an additional null +character. +@end deftypefun + +@comment obstack.h +@comment GNU +@deftypefun void obstack_1grow (struct obstack *@var{obstack-ptr}, char @var{c}) +To add one character at a time, use the function @code{obstack_1grow}. +It adds a single byte containing @var{c} to the growing object. +@end deftypefun + +@comment obstack.h +@comment GNU +@deftypefun void obstack_ptr_grow (struct obstack *@var{obstack-ptr}, void *@var{data}) +Adding the value of a pointer one can use the function +@code{obstack_ptr_grow}. It adds @code{sizeof (void *)} bytes +containing the value of @var{data}. +@end deftypefun + +@comment obstack.h +@comment GNU +@deftypefun void obstack_int_grow (struct obstack *@var{obstack-ptr}, int @var{data}) +A single value of type @code{int} can be added by using the +@code{obstack_int_grow} function. It adds @code{sizeof (int)} bytes to +the growing object and initializes them with the value of @var{data}. +@end deftypefun + +@comment obstack.h +@comment GNU +@deftypefun {void *} obstack_finish (struct obstack *@var{obstack-ptr}) +When you are finished growing the object, use the function +@code{obstack_finish} to close it off and return its final address. + +Once you have finished the object, the obstack is available for ordinary +allocation or for growing another object. + +This function can return a null pointer under the same conditions as +@code{obstack_alloc} (@pxref{Allocation in an Obstack}). +@end deftypefun + +When you build an object by growing it, you will probably need to know +afterward how long it became. You need not keep track of this as you grow +the object, because you can find out the length from the obstack just +before finishing the object with the function @code{obstack_object_size}, +declared as follows: + +@comment obstack.h +@comment GNU +@deftypefun int obstack_object_size (struct obstack *@var{obstack-ptr}) +This function returns the current size of the growing object, in bytes. +Remember to call this function @emph{before} finishing the object. +After it is finished, @code{obstack_object_size} will return zero. +@end deftypefun + +If you have started growing an object and wish to cancel it, you should +finish it and then free it, like this: + +@smallexample +obstack_free (obstack_ptr, obstack_finish (obstack_ptr)); +@end smallexample + +@noindent +This has no effect if no object was growing. + +@cindex shrinking objects +You can use @code{obstack_blank} with a negative size argument to make +the current object smaller. Just don't try to shrink it beyond zero +length---there's no telling what will happen if you do that. + +@node Extra Fast Growing +@section Extra Fast Growing Objects +@cindex efficiency and obstacks + +The usual functions for growing objects incur overhead for checking +whether there is room for the new growth in the current chunk. If you +are frequently constructing objects in small steps of growth, this +overhead can be significant. + +You can reduce the overhead by using special ``fast growth'' +functions that grow the object without checking. In order to have a +robust program, you must do the checking yourself. If you do this checking +in the simplest way each time you are about to add data to the object, you +have not saved anything, because that is what the ordinary growth +functions do. But if you can arrange to check less often, or check +more efficiently, then you make the program faster. + +The function @code{obstack_room} returns the amount of room available +in the current chunk. It is declared as follows: + +@comment obstack.h +@comment GNU +@deftypefun int obstack_room (struct obstack *@var{obstack-ptr}) +This returns the number of bytes that can be added safely to the current +growing object (or to an object about to be started) in obstack +@var{obstack} using the fast growth functions. +@end deftypefun + +While you know there is room, you can use these fast growth functions +for adding data to a growing object: + +@comment obstack.h +@comment GNU +@deftypefun void obstack_1grow_fast (struct obstack *@var{obstack-ptr}, char @var{c}) +The function @code{obstack_1grow_fast} adds one byte containing the +character @var{c} to the growing object in obstack @var{obstack-ptr}. +@end deftypefun + +@comment obstack.h +@comment GNU +@deftypefun void obstack_ptr_grow_fast (struct obstack *@var{obstack-ptr}, void *@var{data}) +The function @code{obstack_ptr_grow_fast} adds @code{sizeof (void *)} +bytes containing the value of @var{data} to the growing object in +obstack @var{obstack-ptr}. +@end deftypefun + +@comment obstack.h +@comment GNU +@deftypefun void obstack_int_grow_fast (struct obstack *@var{obstack-ptr}, int @var{data}) +The function @code{obstack_int_grow_fast} adds @code{sizeof (int)} bytes +containing the value of @var{data} to the growing object in obstack +@var{obstack-ptr}. +@end deftypefun + +@comment obstack.h +@comment GNU +@deftypefun void obstack_blank_fast (struct obstack *@var{obstack-ptr}, int @var{size}) +The function @code{obstack_blank_fast} adds @var{size} bytes to the +growing object in obstack @var{obstack-ptr} without initializing them. +@end deftypefun + +When you check for space using @code{obstack_room} and there is not +enough room for what you want to add, the fast growth functions +are not safe. In this case, simply use the corresponding ordinary +growth function instead. Very soon this will copy the object to a +new chunk; then there will be lots of room available again. + +So, each time you use an ordinary growth function, check afterward for +sufficient space using @code{obstack_room}. Once the object is copied +to a new chunk, there will be plenty of space again, so the program will +start using the fast growth functions again. + +Here is an example: + +@smallexample +@group +void +add_string (struct obstack *obstack, const char *ptr, int len) +@{ + while (len > 0) + @{ + int room = obstack_room (obstack); + if (room == 0) + @{ + /* @r{Not enough room. Add one character slowly,} + @r{which may copy to a new chunk and make room.} */ + obstack_1grow (obstack, *ptr++); + len--; + @} + else + @{ + if (room > len) + room = len; + /* @r{Add fast as much as we have room for.} */ + len -= room; + while (room-- > 0) + obstack_1grow_fast (obstack, *ptr++); + @} + @} +@} +@end group +@end smallexample + +@node Status of an Obstack +@section Status of an Obstack +@cindex obstack status +@cindex status of obstack + +Here are functions that provide information on the current status of +allocation in an obstack. You can use them to learn about an object while +still growing it. + +@comment obstack.h +@comment GNU +@deftypefun {void *} obstack_base (struct obstack *@var{obstack-ptr}) +This function returns the tentative address of the beginning of the +currently growing object in @var{obstack-ptr}. If you finish the object +immediately, it will have that address. If you make it larger first, it +may outgrow the current chunk---then its address will change! + +If no object is growing, this value says where the next object you +allocate will start (once again assuming it fits in the current +chunk). +@end deftypefun + +@comment obstack.h +@comment GNU +@deftypefun {void *} obstack_next_free (struct obstack *@var{obstack-ptr}) +This function returns the address of the first free byte in the current +chunk of obstack @var{obstack-ptr}. This is the end of the currently +growing object. If no object is growing, @code{obstack_next_free} +returns the same value as @code{obstack_base}. +@end deftypefun + +@comment obstack.h +@comment GNU +@deftypefun int obstack_object_size (struct obstack *@var{obstack-ptr}) +This function returns the size in bytes of the currently growing object. +This is equivalent to + +@smallexample +obstack_next_free (@var{obstack-ptr}) - obstack_base (@var{obstack-ptr}) +@end smallexample +@end deftypefun + +@node Obstacks Data Alignment +@section Alignment of Data in Obstacks +@cindex alignment (in obstacks) + +Each obstack has an @dfn{alignment boundary}; each object allocated in +the obstack automatically starts on an address that is a multiple of the +specified boundary. By default, this boundary is 4 bytes. + +To access an obstack's alignment boundary, use the macro +@code{obstack_alignment_mask}, whose function prototype looks like +this: + +@comment obstack.h +@comment GNU +@deftypefn Macro int obstack_alignment_mask (struct obstack *@var{obstack-ptr}) +The value is a bit mask; a bit that is 1 indicates that the corresponding +bit in the address of an object should be 0. The mask value should be one +less than a power of 2; the effect is that all object addresses are +multiples of that power of 2. The default value of the mask is 3, so that +addresses are multiples of 4. A mask value of 0 means an object can start +on any multiple of 1 (that is, no alignment is required). + +The expansion of the macro @code{obstack_alignment_mask} is an lvalue, +so you can alter the mask by assignment. For example, this statement: + +@smallexample +obstack_alignment_mask (obstack_ptr) = 0; +@end smallexample + +@noindent +has the effect of turning off alignment processing in the specified obstack. +@end deftypefn + +Note that a change in alignment mask does not take effect until +@emph{after} the next time an object is allocated or finished in the +obstack. If you are not growing an object, you can make the new +alignment mask take effect immediately by calling @code{obstack_finish}. +This will finish a zero-length object and then do proper alignment for +the next object. + +@node Obstack Chunks +@section Obstack Chunks +@cindex efficiency of chunks +@cindex chunks + +Obstacks work by allocating space for themselves in large chunks, and +then parceling out space in the chunks to satisfy your requests. Chunks +are normally 4096 bytes long unless you specify a different chunk size. +The chunk size includes 8 bytes of overhead that are not actually used +for storing objects. Regardless of the specified size, longer chunks +will be allocated when necessary for long objects. + +The obstack library allocates chunks by calling the function +@code{obstack_chunk_alloc}, which you must define. When a chunk is no +longer needed because you have freed all the objects in it, the obstack +library frees the chunk by calling @code{obstack_chunk_free}, which you +must also define. + +These two must be defined (as macros) or declared (as functions) in each +source file that uses @code{obstack_init} (@pxref{Creating Obstacks}). +Most often they are defined as macros like this: + +@smallexample +#define obstack_chunk_alloc malloc +#define obstack_chunk_free free +@end smallexample + +Note that these are simple macros (no arguments). Macro definitions with +arguments will not work! It is necessary that @code{obstack_chunk_alloc} +or @code{obstack_chunk_free}, alone, expand into a function name if it is +not itself a function name. + +If you allocate chunks with @code{malloc}, the chunk size should be a +power of 2. The default chunk size, 4096, was chosen because it is long +enough to satisfy many typical requests on the obstack yet short enough +not to waste too much memory in the portion of the last chunk not yet used. + +@comment obstack.h +@comment GNU +@deftypefn Macro int obstack_chunk_size (struct obstack *@var{obstack-ptr}) +This returns the chunk size of the given obstack. +@end deftypefn + +Since this macro expands to an lvalue, you can specify a new chunk size by +assigning it a new value. Doing so does not affect the chunks already +allocated, but will change the size of chunks allocated for that particular +obstack in the future. It is unlikely to be useful to make the chunk size +smaller, but making it larger might improve efficiency if you are +allocating many objects whose size is comparable to the chunk size. Here +is how to do so cleanly: + +@smallexample +if (obstack_chunk_size (obstack_ptr) < @var{new-chunk-size}) + obstack_chunk_size (obstack_ptr) = @var{new-chunk-size}; +@end smallexample + +@node Summary of Obstacks +@section Summary of Obstack Functions + +Here is a summary of all the functions associated with obstacks. Each +takes the address of an obstack (@code{struct obstack *}) as its first +argument. + +@table @code +@item void obstack_init (struct obstack *@var{obstack-ptr}) +Initialize use of an obstack. @xref{Creating Obstacks}. + +@item void *obstack_alloc (struct obstack *@var{obstack-ptr}, int @var{size}) +Allocate an object of @var{size} uninitialized bytes. +@xref{Allocation in an Obstack}. + +@item void *obstack_copy (struct obstack *@var{obstack-ptr}, void *@var{address}, int @var{size}) +Allocate an object of @var{size} bytes, with contents copied from +@var{address}. @xref{Allocation in an Obstack}. + +@item void *obstack_copy0 (struct obstack *@var{obstack-ptr}, void *@var{address}, int @var{size}) +Allocate an object of @var{size}+1 bytes, with @var{size} of them copied +from @var{address}, followed by a null character at the end. +@xref{Allocation in an Obstack}. + +@item void obstack_free (struct obstack *@var{obstack-ptr}, void *@var{object}) +Free @var{object} (and everything allocated in the specified obstack +more recently than @var{object}). @xref{Freeing Obstack Objects}. + +@item void obstack_blank (struct obstack *@var{obstack-ptr}, int @var{size}) +Add @var{size} uninitialized bytes to a growing object. +@xref{Growing Objects}. + +@item void obstack_grow (struct obstack *@var{obstack-ptr}, void *@var{address}, int @var{size}) +Add @var{size} bytes, copied from @var{address}, to a growing object. +@xref{Growing Objects}. + +@item void obstack_grow0 (struct obstack *@var{obstack-ptr}, void *@var{address}, int @var{size}) +Add @var{size} bytes, copied from @var{address}, to a growing object, +and then add another byte containing a null character. @xref{Growing +Objects}. + +@item void obstack_1grow (struct obstack *@var{obstack-ptr}, char @var{data-char}) +Add one byte containing @var{data-char} to a growing object. +@xref{Growing Objects}. + +@item void *obstack_finish (struct obstack *@var{obstack-ptr}) +Finalize the object that is growing and return its permanent address. +@xref{Growing Objects}. + +@item int obstack_object_size (struct obstack *@var{obstack-ptr}) +Get the current size of the currently growing object. @xref{Growing +Objects}. + +@item void obstack_blank_fast (struct obstack *@var{obstack-ptr}, int @var{size}) +Add @var{size} uninitialized bytes to a growing object without checking +that there is enough room. @xref{Extra Fast Growing}. + +@item void obstack_1grow_fast (struct obstack *@var{obstack-ptr}, char @var{data-char}) +Add one byte containing @var{data-char} to a growing object without +checking that there is enough room. @xref{Extra Fast Growing}. + +@item int obstack_room (struct obstack *@var{obstack-ptr}) +Get the amount of room now available for growing the current object. +@xref{Extra Fast Growing}. + +@item int obstack_alignment_mask (struct obstack *@var{obstack-ptr}) +The mask used for aligning the beginning of an object. This is an +lvalue. @xref{Obstacks Data Alignment}. + +@item int obstack_chunk_size (struct obstack *@var{obstack-ptr}) +The size for allocating chunks. This is an lvalue. @xref{Obstack Chunks}. + +@item void *obstack_base (struct obstack *@var{obstack-ptr}) +Tentative starting address of the currently growing object. +@xref{Status of an Obstack}. + +@item void *obstack_next_free (struct obstack *@var{obstack-ptr}) +Address just after the end of the currently growing object. +@xref{Status of an Obstack}. +@end table + |