1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/src/klibc/malloc.c	Fri May 27 12:05:38 2011 +0300
     1.3 @@ -0,0 +1,209 @@
     1.4 +#include <stdlib.h>
     1.5 +#include "intr.h"
     1.6 +#include "vm.h"
     1.7 +#include "panic.h"
     1.8 +
     1.9 +#define MAGIC	0xbaadbeef
    1.10 +
    1.11 +struct mem_range {
    1.12 +	uint32_t start;
    1.13 +	size_t size;
    1.14 +	struct mem_range *next;
    1.15 +};
    1.16 +
    1.17 +struct alloc_desc {
    1.18 +	size_t size;
    1.19 +	uint32_t magic;
    1.20 +};
    1.21 +
    1.22 +static void add_range(struct mem_range *rng);
    1.23 +static void coalesce(struct mem_range *low, struct mem_range *mid, struct mem_range *high);
    1.24 +static struct mem_range *alloc_node(void);
    1.25 +static void free_node(struct mem_range *node);
    1.26 +
    1.27 +struct mem_range *free_list;
    1.28 +struct mem_range *node_pool;
    1.29 +
    1.30 +
    1.31 +void *malloc(size_t sz)
    1.32 +{
    1.33 +	void *res = 0;
    1.34 +	struct mem_range *node, *prev, dummy;
    1.35 +	int intr_state;
    1.36 +	struct alloc_desc *desc;
    1.37 +	size_t alloc_size = sz + sizeof *desc;
    1.38 +
    1.39 +	if(!sz) {
    1.40 +		return 0;
    1.41 +	}
    1.42 +
    1.43 +	/* entering the critical section, do not disturb */
    1.44 +	intr_state = get_intr_state();
    1.45 +	disable_intr();
    1.46 +
    1.47 +find_range:
    1.48 +	prev = &dummy;
    1.49 +	dummy.next = node = free_list;
    1.50 +	while(node) {
    1.51 +		/* find a node in the free_list with enough space ... */
    1.52 +		if(node->size >= alloc_size) {
    1.53 +			/* insert the allocation descriptor at the beginning */
    1.54 +			desc = (void*)node->start;
    1.55 +			desc->size = alloc_size;
    1.56 +			desc->magic = MAGIC;
    1.57 +			res = desc + 1; /* that's what we'll return to the user */
    1.58 +
    1.59 +			/* modify the node to reflect the new range after we
    1.60 +			 * grabbed a part at the beginning...
    1.61 +			 */
    1.62 +			node->size -= alloc_size;
    1.63 +			node->start += alloc_size;
    1.64 +
    1.65 +			/* if the range represented by this node now has zero size,
    1.66 +			 * remove and free the node (it goes into the node_pool)
    1.67 +			 */
    1.68 +			if(!node->size) {
    1.69 +				prev->next = node->next;
    1.70 +				if(free_list == node) {
    1.71 +					free_list = node->next;
    1.72 +				}
    1.73 +				free_node(node);
    1.74 +			}
    1.75 +			break;
    1.76 +		}
    1.77 +		prev = node;
    1.78 +		node = node->next;
    1.79 +	}
    1.80 +
    1.81 +	/* we didn't find a range big enough in the free_list. In that case
    1.82 +	 * we need to allocate some pages, add them to the free_list and try
    1.83 +	 * again.
    1.84 +	 */
    1.85 +	if(!res) {
    1.86 +		struct mem_range *range;
    1.87 +		int pg, pgcount = (PGSIZE - 1 + alloc_size) / PGSIZE;
    1.88 +
    1.89 +		if((pg = pgalloc(pgcount, MEM_KERNEL)) == -1) {
    1.90 +			set_intr_state(intr_state);
    1.91 +			return 0;
    1.92 +		}
    1.93 +
    1.94 +		range = alloc_node();
    1.95 +		range->start = PAGE_TO_ADDR(pg);
    1.96 +		range->size = pg * PGSIZE;
    1.97 +		add_range(range);
    1.98 +		goto find_range;
    1.99 +	}
   1.100 +
   1.101 +	set_intr_state(intr_state);
   1.102 +	return res;
   1.103 +}
   1.104 +
   1.105 +void free(void *ptr)
   1.106 +{
   1.107 +	int intr_state;
   1.108 +	struct alloc_desc *desc;
   1.109 +	struct mem_range *rng;
   1.110 +
   1.111 +	if(!ptr) return;
   1.112 +
   1.113 +	intr_state = get_intr_state();
   1.114 +	disable_intr();
   1.115 +
   1.116 +	desc = (struct alloc_desc*)ptr - 1;
   1.117 +	if(desc->magic != MAGIC) {
   1.118 +		panic("free(%x) magic missmatch, invalid address.\n", (unsigned int)ptr);
   1.119 +	}
   1.120 +
   1.121 +	rng = alloc_node();
   1.122 +	rng->start = (uint32_t)desc;
   1.123 +	rng->size = desc->size;
   1.124 +	add_range(rng);
   1.125 +
   1.126 +	set_intr_state(intr_state);
   1.127 +}
   1.128 +
   1.129 +static void add_range(struct mem_range *rng)
   1.130 +{
   1.131 +	struct mem_range *node, *prev = 0;
   1.132 +
   1.133 +	if(!free_list || free_list->start > rng->start) {
   1.134 +		rng->next = free_list;
   1.135 +		free_list = rng;
   1.136 +
   1.137 +	} else {
   1.138 +		node = free_list;
   1.139 +
   1.140 +		while(node) {
   1.141 +			if(!node->next || node->next->start > rng->start) {
   1.142 +				rng->next = node->next;
   1.143 +				node->next = rng;
   1.144 +				prev = node;	/* needed by coalesce after the loop */
   1.145 +				break;
   1.146 +			}
   1.147 +
   1.148 +			prev = node;
   1.149 +			node = node->next;
   1.150 +		}
   1.151 +	}
   1.152 +
   1.153 +	coalesce(prev, rng, rng->next);
   1.154 +}
   1.155 +
   1.156 +static void coalesce(struct mem_range *low, struct mem_range *mid, struct mem_range *high)
   1.157 +{
   1.158 +	if(high) {
   1.159 +		if(mid->start + mid->size >= high->start) {
   1.160 +			mid->size = high->size - mid->start;
   1.161 +			mid->next = high->next;
   1.162 +			free_node(high);
   1.163 +		}
   1.164 +	}
   1.165 +
   1.166 +	if(low) {
   1.167 +		if(low->start + low->size >= mid->start) {
   1.168 +			low->size = mid->size - low->start;
   1.169 +			low->next = mid->next;
   1.170 +			free_node(mid);
   1.171 +		}
   1.172 +	}
   1.173 +}
   1.174 +
   1.175 +static struct mem_range *alloc_node(void)
   1.176 +{
   1.177 +	struct mem_range *node;
   1.178 +
   1.179 +	/* no nodes available for reuse...
   1.180 +	 * grab a page, slice it into nodes, link them up and hang them in the pool
   1.181 +	 */
   1.182 +	if(!node_pool) {
   1.183 +		int i, num_nodes, pg;
   1.184 +		struct mem_range *nodepage;
   1.185 +
   1.186 +		pg = pgalloc(1, MEM_KERNEL);
   1.187 +		if(pg == -1) {
   1.188 +			panic("failed to allocate page for the malloc node pool\n");
   1.189 +			return 0;	/* unreachable */
   1.190 +		}
   1.191 +
   1.192 +		nodepage = (struct mem_range*)PAGE_TO_ADDR(pg);
   1.193 +		num_nodes = PGSIZE / sizeof *nodepage;
   1.194 +
   1.195 +		for(i=1; i<num_nodes; i++) {
   1.196 +			nodepage[i - 1].next = nodepage + i;
   1.197 +		}
   1.198 +		nodepage[i - 1].next = 0;
   1.199 +		node_pool = nodepage;
   1.200 +	}
   1.201 +
   1.202 +	node = node_pool;
   1.203 +	node_pool = node->next;
   1.204 +	node->next = 0;
   1.205 +	return node;
   1.206 +}
   1.207 +
   1.208 +static void free_node(struct mem_range *node)
   1.209 +{
   1.210 +	node->next = node_pool;
   1.211 +	node_pool = node;
   1.212 +}

     2.1 --- a/src/klibc/stdlib.h	Sat Apr 09 07:22:27 2011 +0300
     2.2 +++ b/src/klibc/stdlib.h	Fri May 27 12:05:38 2011 +0300
     2.3 @@ -12,4 +12,8 @@
     2.4  void itoa(int val, char *buf, int base);
     2.5  void utoa(unsigned int val, char *buf, int base);
     2.6  
     2.7 +/* defined in malloc.c */
     2.8 +void *malloc(size_t sz);
     2.9 +void free(void *ptr);
    2.10 +
    2.11  #endif	/* STDLIB_H_ */