Mercurial > hg > octave-lyh > gnulib-hg
changeset 4817:7c67f04e1c19
Add x2realloc, x2nrealloc. Port to C99 inline.
author | Paul Eggert <eggert@cs.ucla.edu> |
---|---|
date | Mon, 27 Oct 2003 07:28:24 +0000 |
parents | 07ab22e0779a |
children | 167a92276385 |
files | lib/xalloc.h lib/xmalloc.c |
diffstat | 2 files changed, 124 insertions(+), 6 deletions(-) [+] |
line wrap: on
line diff
--- a/lib/xalloc.h +++ b/lib/xalloc.h @@ -54,6 +54,8 @@ void *xcalloc (size_t n, size_t s); void *xrealloc (void *p, size_t s); void *xnrealloc (void *p, size_t n, size_t s); +void *x2realloc (void *p, size_t *pn); +void *x2nrealloc (void *p, size_t *pn, size_t s); void *xclone (void const *p, size_t s); char *xstrdup (const char *str);
--- a/lib/xmalloc.c +++ b/lib/xmalloc.c @@ -77,8 +77,8 @@ /* Allocate an array of N objects, each with S bytes of memory, dynamically, with error checking. S must be nonzero. */ -inline void * -xnmalloc (size_t n, size_t s) +static inline void * +xnmalloc_inline (size_t n, size_t s) { void *p; if (array_size_overflow (n, s) || ! (p = malloc (n * s))) @@ -86,32 +86,148 @@ return p; } +void * +xnmalloc (size_t n, size_t s) +{ + return xnmalloc_inline (n, s); +} + /* Allocate N bytes of memory dynamically, with error checking. */ void * xmalloc (size_t n) { - return xnmalloc (n, 1); + return xnmalloc_inline (n, 1); } /* Change the size of an allocated block of memory P to an array of N objects each of S bytes, with error checking. S must be nonzero. */ -inline void * -xnrealloc (void *p, size_t n, size_t s) +static inline void * +xnrealloc_inline (void *p, size_t n, size_t s) { if (array_size_overflow (n, s) || ! (p = realloc (p, n * s))) xalloc_die (); return p; } +void * +xnrealloc (void *p, size_t n, size_t s) +{ + return xnrealloc_inline (p, n, s); +} + /* Change the size of an allocated block of memory P to N bytes, with error checking. */ void * xrealloc (void *p, size_t n) { - return xnrealloc (p, n, 1); + return xnrealloc_inline (p, n, 1); +} + + +/* If P is null, allocate a block of at least *PN such objects; + otherwise, reallocate P so that it contains more than *PN objects + each of S bytes. *PN must be nonzero unless P is null, and S must + be nonzero. Set *PN to the new number of objects, and return the + pointer to the new block. *PN is never set to zero, and the + returned pointer is never null. + + Repeated reallocations are guaranteed to make progress, either by + allocating an initial block with a nonzero size, or by allocating a + larger block. + + In the following implementation, nonzero sizes are doubled so that + repeated reallocations have O(N log N) overall cost rather than + O(N**2) cost, but the specification for this function does not + guarantee that sizes are doubled. + + Here is an example of use: + + int *p = NULL; + size used = 0; + size allocated = 0; + + void + append_int (int value) + { + if (used == allocated) + p = x2nrealloc (p, &allocated, sizeof *p); + p[used++] = value; + } + + This causes x2nrealloc to allocate a block of some nonzero size the + first time it is called. + + To have finer-grained control over the initial size, set *PN to a + nonzero value before calling this function with P == NULL. For + example: + + int *p = NULL; + size used = 0; + size allocated = 0; + size allocated1 = 1000; + + void + append_int (int value) + { + if (used == allocated) + { + p = x2nrealloc (p, &allocated1, sizeof *p); + allocated = allocated1; + } + p[used++] = value; + } + + */ + +static inline void * +x2nrealloc_inline (void *p, size_t *pn, size_t s) +{ + size_t n = *pn; + + if (! p) + { + if (! n) + { + /* The approximate size to use for initial small allocation + requests, when the invoking code specifies an old size of + zero. 64 bytes is the largest "small" request for the + GNU C library malloc. */ + enum { DEFAULT_MXFAST = 64 }; + + n = DEFAULT_MXFAST / s; + n += !n; + } + } + else + { + if (SIZE_MAX / 2 / s < n) + xalloc_die (); + n *= 2; + } + + *pn = n; + return xrealloc (p, n * s); +} + +void * +x2nrealloc (void *p, size_t *pn, size_t s) +{ + return x2nrealloc_inline (p, pn, s); +} + +/* If P is null, allocate a block of at least *PN bytes; otherwise, + reallocate P so that it contains more than *PN bytes. *PN must be + nonzero unless P is null. Set *PN to the new block's size, and + return the pointer to the new block. *PN is never set to zero, and + the returned pointer is never null. */ + +void * +x2realloc (void *p, size_t *pn) +{ + return x2nrealloc_inline (p, pn, 1); } /* Allocate S bytes of zeroed memory dynamically, with error checking.