buflib: Optimize away the BSIZE metadata field

Now that allocations are unnamed, BSIZE is a constant.

Change-Id: Iab52cbebe426ea0d12f428582347e20ed243367f
This commit is contained in:
Aidan MacDonald 2022-10-15 23:45:31 +01:00
parent 1e9ad3ca0d
commit 31f03d9433

View file

@ -127,15 +127,14 @@ enum {
#ifdef BUFLIB_HAS_CRC
bidx_CRC, /* CRC, protects all metadata behind it */
#endif
bidx_BSIZE, /* total size of the block header */
};
/* Number of fields in the block header. Note that bidx_USER is not an
* actual field so it is not included in the count. */
#ifdef BUFLIB_HAS_CRC
# define BUFLIB_NUM_FIELDS 6
#else
# define BUFLIB_NUM_FIELDS 5
#else
# define BUFLIB_NUM_FIELDS 4
#endif
struct buflib_callbacks buflib_ops_locked = {
@ -339,7 +338,7 @@ union buflib_data* handle_to_block(struct buflib_context* ctx, int handle)
return NULL;
union buflib_data *data = ALIGN_DOWN(ptr, sizeof(*data));
return data - data[-bidx_BSIZE].val;
return data - BUFLIB_NUM_FIELDS;
}
/* Get the block end pointer from a handle table entry */
@ -740,10 +739,8 @@ buffer_alloc:
block[fidx_HANDLE].handle = handle;
block[fidx_OPS].ops = ops;
size_t bsize = BUFLIB_NUM_FIELDS;
union buflib_data *block_end = block + bsize;
union buflib_data *block_end = block + BUFLIB_NUM_FIELDS;
block_end[-bidx_PIN].pincount = 0;
block_end[-bidx_BSIZE].val = bsize;
update_block_crc(ctx, block, block_end);
handle->alloc = (char*)&block_end[-bidx_USER];