3 * GMQCC does a lot of allocations on shortly lived objects all of which
4 * call down to malloc/free internally. The overhead involved with these
5 * allocations makes GMQCC slow. To combat this, a special allocator was
6 * in need. This is an implementation of a user-space buddy allocator
7 * that sits ontop of malloc/free. I'd like to thank Lee Salzman for
8 * guiding me in the right direction for designing this.
10 #define GMQCC_MEM_USED 0xEDCA10A1EDCA10A1
11 #define GMQCC_MEM_FREE 0xEEF8EEF8EEF8EEF8
12 #define GMQCC_MEM_CORE 0x00000000000000AA
13 #define GMQCC_MEM_BSL -1
14 #define GMQCC_MEM_BSR 1
16 typedef unsigned long int mem_addr;
18 static void *mem_heap = NULL;
19 static size_t mem_look = 0; /* lookup table offset */
20 static size_t mem_size = 0; /* heap size */
22 /* read or write to heap */
23 #define GMQCC_MEM_WRITEHEAP(OFFSET, TYPE, VALUE) *((TYPE *) ((unsigned char*)mem_heap + (OFFSET))) = (VALUE)
24 #define GMQCC_MEM_READHEAP (OFFSET, TYPE) ((TYPE)*((TYPE *)(((unsigned char*)mem_heap + (OFFSET)))))
26 /* read of write first block to heap */
27 #define GMQCC_MEM_WRITEFBA(SIZE, ADDR) GMQCC_MEM_WRITEHEAP(mem_look + (SIZE) * sizeof(mem_addr), mem_addr, ADDR)
28 #define GMQCC_MEM_READFBA(SIZE) GMQCC_MEM_READHEAP (mem_look + (SIZE) * sizeof(mem_addr), ADDR)
30 /* read and write block sizes from heap */
31 #define GMQCC_MEM_WRITEBS(ADDR, SIZE) GMQCC_MEM_WRITEHEAP(ADDR, mem_addr, (SIZE))
32 #define GMQCC_MEM_READBS(ADDR) GMQCC_MEM_READHEAP (ADDR, mem_addr);
35 * Getting address of previous/following siblings, as well as
36 * setting address of previous/following siblings.
38 #define GMQCC_MEM_GETADDROFPS(ADDR) GMQCC_MEM_READHEAP ((ADDR) + 2 * sizeof(mem_addr), mem_addr)
39 #define GMQCC_MEM_GETADDROFFS(ADDR) GMQCC_MEM_READHEAP ((ADDR) + 3 * sizeof(mem_addr), mem_addr)
40 #define GMQCC_MEM_SETADDROFPS(ADDR,V) GMQCC_MEM_WRITEHEAP((ADDR) + 2 * sizeof(mem_addr), mem_addr, V)
41 #define GMQCC_MEM_SETADDROFFS(ADDR,V) GMQCC_MEM_WRITEHEAP((ADDR) + 3 * sizeof(mem_addr), mem_addr, V)
43 /* Marking blocks as used or free */
44 #define GMQCC_MEM_MARKUSED(ADDR) GMQCC_MEM_WRITEHEAP((ADDR) + 1 * sizeof(mem_addr), mem_addr, GMQCC_MEM_USED)
45 #define GMQCC_MEM_MARKFREE(ADDR) GMQCC_MEM_WRITEHEAP((ADDR) + 1 * sizeof(mem_addr), mem_addr, GMQCC_MEM_FREE)
47 static void mem_init_table(size_t size) {
50 mem_look = 8 * ((mem_addr)1 << (size - 1)) + sizeof(mem_addr);
52 GMQCC_MEM_WRITEHEAP(0, mem_addr, mem_look);
53 GMQCC_MEM_WRITEHEAP(mem_look, mem_addr, size);
55 /* write pointers to first free bock of said size */
56 for (i = 1; i < size; i++)
57 GMQCC_MEM_WRITEHEAP(mem_look + sizeof(mem_addr) * i, mem_addr, 0);
59 GMQCC_MEM_WRITEHEAP(mem_look + sizeof(mem_addr) * size, mem_addr, sizeof(mem_addr));
60 GMQCC_MEM_WRITEHEAP(sizeof(mem_addr), mem_addr, size);
61 GMQCC_MEM_MARKFREE (sizeof(mem_addr) << 1);
62 GMQCC_MEM_WRITEHEAP(sizeof(mem_addr) * 3, mem_addr, 0);
63 GMQCC_MEM_WRITEHEAP(sizeof(mem_addr) * 4, mem_addr, 0);
66 /* get needed block size */
67 static size_t mem_getnbs(const size_t need) {
79 void mem_init(size_t size) {
84 if (!(mem_heap = malloc(size)))
87 memset(mem_heap, GMQCC_MEM_CORE, size);
89 alloc = size - (2 * sizeof(mem_addr));
91 while (alloc + sizeof(mem_addr) > 8 * block) {
92 alloc -= sizeof(mem_addr);
101 mem_init_table(count);
104 /* doesn't get any simpler :-) */
110 void *mem_alloc(size_t amount) {
111 size_t need = amount + 4 * sizeof(mem_addr);
112 size_t size = mem_getnbs (need);
113 mem_addr block = mem_allocblock(size);
114 if (!block) return NULL;
116 return mem_heap + block + 4 * sizeof(mem_addr);