Add pool allocator.

1 files changed, 44 insertions, 0 deletions

diff --git a/source/fitz/pool.c b/source/fitz/pool.c
new file mode 100644
index 00000000..e676947f
--- /dev/null
+++ b/source/fitz/pool.c
@@ -0,0 +1,44 @@
+#include "mupdf/fitz.h"
+
+fz_pool *fz_new_pool(fz_context *ctx)
+{
+	fz_pool *pool = fz_malloc_struct(ctx, fz_pool);
+	fz_pool_node *node = fz_malloc_struct(ctx, fz_pool_node);
+	pool->head = pool->tail = node;
+	pool->pos = node->mem;
+	pool->end = node->mem + sizeof node->mem;
+	return pool;
+}
+
+void *fz_pool_alloc(fz_context *ctx, fz_pool *pool, size_t size)
+{
+	char *ptr;
+
+	/* round size to pointer alignment (we don't expect to use doubles) */
+	size = ((size + sizeof(void*) - 1) / sizeof(void*)) * sizeof(void*);
+
+	if (pool->pos + size > pool->end)
+	{
+		fz_pool_node *node = fz_malloc_struct(ctx, fz_pool_node);
+		pool->tail = pool->tail->next = node;
+		pool->pos = node->mem;
+		pool->end = node->mem + sizeof node->mem;
+		if (pool->pos + size > pool->end)
+			fz_throw(ctx, FZ_ERROR_GENERIC, "out of memory: allocation too large to fit in pool");
+	}
+	ptr = pool->pos;
+	pool->pos += size;
+	return ptr;
+}
+
+void fz_drop_pool(fz_context *ctx, fz_pool *pool)
+{
+	fz_pool_node *node = pool->head;
+	while (node)
+	{
+		fz_pool_node *next = node->next;
+		fz_free(ctx, node);
+		node = next;
+	}
+	fz_free(ctx, pool);
+}