mirror of
https://github.com/DarkPlacesEngine/gmqcc.git
synced 2024-11-24 04:41:25 +00:00
More work on buddy allocator
This commit is contained in:
Dale Weiler
parent
01b619d53d
commit
baaa6407d5
1 changed files with 220 additions and 16 deletions
220
mem.c
220
mem.c
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@ -1,4 +1,5 @@
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#include "gmqcc.h"
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#include <assert.h>
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/*
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* GMQCC does a lot of allocations on shortly lived objects all of which
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* call down to malloc/free internally. The overhead involved with these
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@ -12,6 +13,19 @@
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#define GMQCC_MEM_CORE 0x00000000000000AA
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#define GMQCC_MEM_BSL -1
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#define GMQCC_MEM_BSR 1
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#define GMQCC_MEM_DEBUG 1
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#ifdef GMQCC_MEM_DEBUG
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# include <stdio.h>
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# define GMQCC_MEM_TRACE(TAG, ...) \
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do { \
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printf("[mem:%s]: %s ", TAG, __func__); \
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printf(__VA_ARGS__); \
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printf("\n"); \
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} while (0)
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#else
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# define GMQCC_MEM_TRACE(TAG, ...)
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#endif
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typedef unsigned long int mem_addr;
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@ -25,7 +39,7 @@ static size_t mem_size = 0; /* heap size */
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/* read of write first block to heap */
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#define GMQCC_MEM_WRITEFBA(SIZE, ADDR) GMQCC_MEM_WRITEHEAP(mem_look + (SIZE) * sizeof(mem_addr), mem_addr, ADDR)
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#define GMQCC_MEM_READFBA(SIZE) GMQCC_MEM_READHEAP (mem_look + (SIZE) * sizeof(mem_addr), ADDR)
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#define GMQCC_MEM_READFBA(SIZE) GMQCC_MEM_READHEAP (mem_look + (SIZE) * sizeof(mem_addr), mem_addr)
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/* read and write block sizes from heap */
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#define GMQCC_MEM_WRITEBS(ADDR, SIZE) GMQCC_MEM_WRITEHEAP(ADDR, mem_addr, (SIZE))
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@ -44,7 +58,11 @@ static size_t mem_size = 0; /* heap size */
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#define GMQCC_MEM_MARKUSED(ADDR) GMQCC_MEM_WRITEHEAP((ADDR) + 1 * sizeof(mem_addr), mem_addr, GMQCC_MEM_USED)
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#define GMQCC_MEM_MARKFREE(ADDR) GMQCC_MEM_WRITEHEAP((ADDR) + 1 * sizeof(mem_addr), mem_addr, GMQCC_MEM_FREE)
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/* Has block? */
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#define GMQCC_MEM_HASBLOCK(SIZE) (GMQCC_MEM_READFBA(size) != 0)
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static void mem_init_table(size_t size) {
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GMQCC_MEM_TRACE("flow", "(%lu)", size);
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size_t i;
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mem_look = 8 * ((mem_addr)1 << (size - 1)) + sizeof(mem_addr);
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@ -58,7 +76,7 @@ static void mem_init_table(size_t size) {
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GMQCC_MEM_WRITEHEAP(mem_look + sizeof(mem_addr) * size, mem_addr, sizeof(mem_addr));
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GMQCC_MEM_WRITEHEAP(sizeof(mem_addr), mem_addr, size);
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GMQCC_MEM_MARKFREE (sizeof(mem_addr) << 1);
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GMQCC_MEM_MARKFREE (sizeof(mem_addr) * 2);
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GMQCC_MEM_WRITEHEAP(sizeof(mem_addr) * 3, mem_addr, 0);
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GMQCC_MEM_WRITEHEAP(sizeof(mem_addr) * 4, mem_addr, 0);
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}
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@ -69,33 +87,171 @@ static size_t mem_getnbs(const size_t need) {
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size_t s = 1;
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while (need > b) {
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b >>= 1;
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b *= 2;
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s ++;
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}
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return s;
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}
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static void mem_removeblock(mem_addr a, size_t size) {
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mem_addr p = GMQCC_MEM_GETADDROFPS(a);
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mem_addr n = GMQCC_MEM_GETADDROFFS(a);
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GMQCC_MEM_SETADDROFPS(a, ~((mem_addr)0));
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GMQCC_MEM_SETADDROFFS(a, ~((mem_addr)0));
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/* handle singles in list */
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if ((p == 0) && (n == 0)) {
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GMQCC_MEM_WRITEFBA(size, 0);
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return;
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}
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/* first in list has different sibling semantics */
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if (p == 0) {
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GMQCC_MEM_WRITEFBA (size, n);
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GMQCC_MEM_SETADDROFPS(n, 0);
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return;
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}
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/* last item also has special meaning :) */
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if (n == 0) {
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GMQCC_MEM_SETADDROFFS(p, 0);
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return;
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}
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/* middle of list */
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GMQCC_MEM_SETADDROFPS(n, p);
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GMQCC_MEM_SETADDROFFS(p, n);
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}
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static int mem_createblock(const size_t size) {
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mem_addr parent;
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int test;
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GMQCC_MEM_TRACE("flow", "(%lu)", size);
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if (GMQCC_MEM_HASBLOCK(size))
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return 0;
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if (size > GMQCC_MEM_READHEAP(mem_look, mem_addr))
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abort();
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/* recrusive ... */
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if ((test = mem_createblock(size + 1)) != 0)
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return test;
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/* safe splits assured */
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parent = GMQCC_MEM_READFBA(size + 1);
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mem_removeblock(parent, size + 1);
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/* split it */
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GMQCC_MEM_WRITEFBA(size, parent);
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{
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/* find center and split */
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mem_addr block = parent + 8 * ((mem_addr)1 << (size - 1));
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mem_addr left = parent;
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mem_addr right = block;
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GMQCC_MEM_TRACE(
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"dump",
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"block info:\n left addr: %lu\n right addr: %lu\n prev addr: %lu",
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left, right, parent
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);
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/* left half */
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GMQCC_MEM_WRITEHEAP (left, mem_addr, size);
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GMQCC_MEM_MARKFREE (left);
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GMQCC_MEM_SETADDROFPS(left, 0);
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GMQCC_MEM_SETADDROFFS(left, right);
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/* right half */
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GMQCC_MEM_WRITEHEAP (right, mem_addr, size);
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GMQCC_MEM_MARKFREE (right);
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GMQCC_MEM_SETADDROFPS(right, left);
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GMQCC_MEM_SETADDROFPS(right, 0);
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}
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return 0;
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}
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static mem_addr mem_allocblock(const size_t size) {
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GMQCC_MEM_TRACE("flow", "(%lu)", size);
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int test = mem_createblock(size);
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mem_addr first;
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mem_addr next;
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if (test != 0)
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return 0;
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/* first free one */
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first = GMQCC_MEM_READFBA (size);
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next = GMQCC_MEM_GETADDROFFS(first);
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mem_removeblock(first, size);
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GMQCC_MEM_WRITEFBA(next, size);
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GMQCC_MEM_MARKUSED(first);
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return first;
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}
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static int mem_getside(mem_addr addr, const size_t size) {
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size_t real = addr - sizeof(mem_addr);
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size_t next = ((mem_addr)1 << (size));
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assert((real % 8) == 0); /* blow up */
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real /= 8;
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return ((real % next) == 0)? GMQCC_MEM_BSL : GMQCC_MEM_BSR;
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}
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static mem_addr mem_getaddr(mem_addr start, const size_t size) {
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size_t length = (((mem_addr)1 << (size - 1)) * 8);
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switch (mem_getside(start, size)) {
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case GMQCC_MEM_BSL: return start + length;
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case GMQCC_MEM_BSR: return start - length;
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}
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/* if reached blow up */
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return (abort(), 1);
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}
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static void mem_addblock(mem_addr a, size_t s) {
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mem_addr first = GMQCC_MEM_READFBA(s);
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if (first == 0) {
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/* only block */
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GMQCC_MEM_WRITEFBA (s, a);
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GMQCC_MEM_SETADDROFPS(a, 0);
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GMQCC_MEM_SETADDROFFS(a, 0);
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} else {
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/* add to front */
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GMQCC_MEM_WRITEFBA (s, a);
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GMQCC_MEM_SETADDROFPS(a, 0);
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GMQCC_MEM_SETADDROFFS(a, first);
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GMQCC_MEM_SETADDROFPS(first, a);
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}
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}
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void mem_init(size_t size) {
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size_t alloc = 0;
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size_t alloc = size;
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size_t count = 1;
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size_t block = 1;
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/* blow up if too small */
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assert (sizeof(void*) == sizeof(mem_addr));
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if (!(mem_heap = malloc(size)))
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abort();
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memset(mem_heap, GMQCC_MEM_CORE, size);
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mem_size = size;
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alloc = size - (2 * sizeof(mem_addr));
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alloc -= 2 * sizeof(mem_addr);
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while (alloc + sizeof(mem_addr) > 8 * block) {
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alloc -= sizeof(mem_addr);
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block <<= 1;
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block *= 2;
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count ++;
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}
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/* over shot ? */
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block >>= 1;
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block /= 2;
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count --;
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mem_init_table(count);
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@ -108,10 +264,58 @@ void mem_destroy() {
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}
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void *mem_alloc(size_t amount) {
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GMQCC_MEM_TRACE("flow", "(%lu)", amount);
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size_t need = amount + 4 * sizeof(mem_addr);
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size_t size = mem_getnbs (need);
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mem_addr block = mem_allocblock(size);
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if (!block) return NULL;
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GMQCC_MEM_TRACE("dump", "will allocate %lu size block", size);
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/* standard behaviour */
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if (block == 0)
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return NULL;
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GMQCC_MEM_TRACE("dump", "returning offset %lu", block);
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return mem_heap + block + 4 * sizeof(mem_addr);
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}
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void mem_free(void *ptr) {
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mem_addr start = (mem_addr)(ptr - mem_heap) - 4 * sizeof(mem_addr);
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size_t size = GMQCC_MEM_READHEAP(start, mem_addr);
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mem_addr addr = mem_getaddr(start, size);
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int side = mem_getside(start, size);
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GMQCC_MEM_TRACE (
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"dump",
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"deallocating %s buddy (neighbour at %lu)",
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(side == GMQCC_MEM_BSL) ? "left" : "right",
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addr
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);
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GMQCC_MEM_MARKFREE(start);
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/* while free block merge */
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while ((GMQCC_MEM_READHEAP(addr + 1 * sizeof(mem_addr), mem_addr)) == (mem_addr)GMQCC_MEM_FREE) {
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GMQCC_MEM_TRACE("dump", "merging ...");
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mem_removeblock(addr, size);
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/* find new start */
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start = addr < start ? addr : start;
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size ++;
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if (size == GMQCC_MEM_READHEAP(mem_look, mem_addr))
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break; /* blow up */
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addr = mem_getaddr(start, size);
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GMQCC_MEM_TRACE("dump", "new block start is %lu, buddy at %lu", start, addr);
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}
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/* add it */
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GMQCC_MEM_WRITEBS(start, size);
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mem_addblock (start, size);
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}
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#include <stdio.h>
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int main() {
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mem_init(1330);
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char *p = mem_alloc(sizeof(char) * 5);
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/* blows up on second alloc, why? char *x = mem_alloc(200); */
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}
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