diff options
| -rw-r--r-- | libthreads/malloc.c | 41 |
1 files changed, 32 insertions, 9 deletions
diff --git a/libthreads/malloc.c b/libthreads/malloc.c index 3a2109bd..961897d4 100644 --- a/libthreads/malloc.c +++ b/libthreads/malloc.c @@ -26,6 +26,14 @@ /* * HISTORY * $Log: malloc.c,v $ + * Revision 1.5 1996/03/06 23:51:04 miles + * [MCHECK] (struct header): New type. + * (union header): Only define if !MCHECK. + * (HEADER_SIZE, HEADER_NEXT, HEADER_FREE, HEADER_CHECK): New macros. + * [MCHECK] (MIN_SIZE): Add correct definition for this case. + * (more_memory, malloc, free, realloc): + * Use above macros, and add appropiate checks & frobs in MCHECK case. + * * Revision 1.4 1994/05/05 11:21:42 roland * entered into RCS * @@ -108,6 +116,7 @@ typedef struct header { #define HEADER_FREE(h) ((h)->u.fl) #define HEADER_CHECK(h) ((h)->check) #define MIN_SIZE 16 +#define LOG2_MIN_SIZE 4 #else /* ! MCHECK */ @@ -120,6 +129,7 @@ typedef union header { #define HEADER_NEXT(h) ((h)->next) #define HEADER_FREE(h) ((h)->fl) #define MIN_SIZE 8 /* minimum block size */ +#define LOG2_MIN_SIZE 3 #endif /* MCHECK */ @@ -132,10 +142,10 @@ typedef struct free_list { } *free_list_t; /* - * Free list with index i contains blocks of size 2^(i+3) including header. - * Smallest block size is 8, with 4 bytes available to user. - * Size argument to malloc is a signed integer for sanity checking, - * so largest block size is 2^31. + * Free list with index i contains blocks of size 2 ^ (i + LOG2_MIN_SIZE) + * including header. Smallest block size is MIN_SIZE, with MIN_SIZE - + * HEADER_SIZE bytes available to user. Size argument to malloc is a signed + * integer for sanity checking, so largest block size is 2^31. */ #define NBUCKETS 29 @@ -326,16 +336,29 @@ realloc(old_base, new_size) return 0; } /* - * Free list with index i contains blocks of size 2^(i+3) including header. + * Free list with index i contains blocks of size + * 2 ^ (i + * LOG2_MIN_SIZE) including header. */ - old_size = (1 << (i+3)) - HEADER_SIZE; + old_size = (1 << (i + LOG2_MIN_SIZE)) - HEADER_SIZE; + + if (new_size <= old_size + && new_size > (((old_size + HEADER_SIZE) >> 1) - HEADER_SIZE)) + /* The new size still fits in the same block, and wouldn't fit in + the next smaller block! */ + return old_base; + /* * Allocate new block, copy old bytes, and free old block. */ new_base = malloc(new_size); - if (new_base != 0) - bcopy(old_base, new_base, (int) (old_size < new_size ? old_size : new_size)); - free(old_base); + if (new_base) + bcopy(old_base, new_base, + (int) (old_size < new_size ? old_size : new_size)); + + if (new_base || new_size == 0) + /* Free OLD_BASE, but only if the malloc didn't fail. */ + free (old_base); + return new_base; } |