binalloc, bingrow, binfree – grouped memory allocation


#include <u.h>
#include <libc.h>
#include <bin.h>

typedef struct Bin Bin;

void *binalloc(Bin **bp, ulong size, int clr);

void *bingrow(Bin **bp, void *op, ulong osize,
ulong size, int clr);

void binfree(Bin **bp);


These routines provide simple grouped memory allocation and deallocation. Items allocated with binalloc are added to the Bin pointed to by bp. All items in a bin may be freed with one call to binfree; there is no way to free a single item.

Binalloc returns a pointer to a new block of at least size bytes. The block is suitably aligned for storage of any type of object. No two active pointers from binalloc will have the same value. The call binalloc(0) returns a valid pointer rather than null. If clr is non-zero, the allocated memory is set to 0; otherwise, the contents are undefined.

Bingrow is used to extend the size of a block of memory returned by binalloc. Bp must point to the same bin group used to allocate the original block, and osize must be the last size used to allocate or grow the block. A pointer to a block of at least size bytes is returned, with the same contents in the first osize locations. If clr is non-zero, the remaining bytes are set to 0, and are undefined otherwise. If op is nil, it and osize are ignored, and the result is the same as calling binalloc.

Binalloc and bingrow allocate large chunks of memory using malloc(2) and return pieces of these chunks. The chunks are free’d upon a call to binfree.






binalloc and bingrow return 0 if there is no available memory.