mbed-mruby

Diff: src/pool.c

Revision:

0:158c61bb030f

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/pool.c	Wed Mar 25 17:36:16 2015 +0000
@@ -0,0 +1,195 @@
+/*
+** pool.c - memory pool
+**
+** See Copyright Notice in mruby.h
+*/
+
+#include <stddef.h>
+#include <stdint.h>
+#include <string.h>
+#include "mruby.h"
+
+/* configuration section */
+/* allocated memory address should be multiple of POOL_ALIGNMENT */
+/* or undef it if alignment does not matter */
+#ifndef POOL_ALIGNMENT
+#define POOL_ALIGNMENT 4
+#endif
+/* page size of memory pool */
+#ifndef POOL_PAGE_SIZE
+#define POOL_PAGE_SIZE 16000
+#endif
+/* end of configuration section */
+
+struct mrb_pool_page {
+  struct mrb_pool_page *next;
+  size_t offset;
+  size_t len;
+  void *last;
+  char page[];
+};
+
+struct mrb_pool {
+  mrb_state *mrb;
+  struct mrb_pool_page *pages;
+};
+
+#undef TEST_POOL
+#ifdef TEST_POOL
+
+#define mrb_malloc_simple(m,s) malloc(s)
+#define mrb_free(m,p) free(p)
+#endif
+
+#ifdef POOL_ALIGNMENT
+#  define ALIGN_PADDING(x) ((SIZE_MAX - (x) + 1) & (POOL_ALIGNMENT - 1))
+#else
+#  define ALIGN_PADDING(x) (0)
+#endif
+
+MRB_API mrb_pool*
+mrb_pool_open(mrb_state *mrb)
+{
+  mrb_pool *pool = (mrb_pool *)mrb_malloc_simple(mrb, sizeof(mrb_pool));
+
+  if (pool) {
+    pool->mrb = mrb;
+    pool->pages = NULL;
+  }
+
+  return pool;
+}
+
+MRB_API void
+mrb_pool_close(mrb_pool *pool)
+{
+  struct mrb_pool_page *page, *tmp;
+
+  if (!pool) return;
+  page = pool->pages;
+  while (page) {
+    tmp = page;
+    page = page->next;
+    mrb_free(pool->mrb, tmp);
+  }
+  mrb_free(pool->mrb, pool);
+}
+
+static struct mrb_pool_page*
+page_alloc(mrb_pool *pool, size_t len)
+{
+  struct mrb_pool_page *page;
+
+  if (len < POOL_PAGE_SIZE)
+    len = POOL_PAGE_SIZE;
+  page = (struct mrb_pool_page *)mrb_malloc_simple(pool->mrb, sizeof(struct mrb_pool_page)+len);
+  if (page) {
+    page->offset = 0;
+    page->len = len;
+  }
+
+  return page;
+}
+
+MRB_API void*
+mrb_pool_alloc(mrb_pool *pool, size_t len)
+{
+  struct mrb_pool_page *page;
+  size_t n;
+
+  if (!pool) return NULL;
+  len += ALIGN_PADDING(len);
+  page = pool->pages;
+  while (page) {
+    if (page->offset + len <= page->len) {
+      n = page->offset;
+      page->offset += len;
+      page->last = (char*)page->page+n;
+      return page->last;
+    }
+    page = page->next;
+  }
+  page = page_alloc(pool, len);
+  if (!page) return NULL;
+  page->offset = len;
+  page->next = pool->pages;
+  pool->pages = page;
+
+  page->last = (void*)page->page;
+  return page->last;
+}
+
+MRB_API mrb_bool
+mrb_pool_can_realloc(mrb_pool *pool, void *p, size_t len)
+{
+  struct mrb_pool_page *page;
+
+  if (!pool) return FALSE;
+  len += ALIGN_PADDING(len);
+  page = pool->pages;
+  while (page) {
+    if (page->last == p) {
+      size_t beg;
+
+      beg = (char*)p - page->page;
+      if (beg + len > page->len) return FALSE;
+      return TRUE;
+    }
+    page = page->next;
+  }
+  return FALSE;
+}
+
+MRB_API void*
+mrb_pool_realloc(mrb_pool *pool, void *p, size_t oldlen, size_t newlen)
+{
+  struct mrb_pool_page *page;
+  void *np;
+
+  if (!pool) return NULL;
+  oldlen += ALIGN_PADDING(oldlen);
+  newlen += ALIGN_PADDING(newlen);
+  page = pool->pages;
+  while (page) {
+    if (page->last == p) {
+      size_t beg;
+
+      beg = (char*)p - page->page;
+      if (beg + oldlen != page->offset) break;
+      if (beg + newlen > page->len) {
+        page->offset = beg;
+        break;
+      }
+      page->offset = beg + newlen;
+      return p;
+    }
+    page = page->next;
+  }
+  np = mrb_pool_alloc(pool, newlen);
+  if (np == NULL) {
+    return NULL;
+  }
+  memcpy(np, p, oldlen);
+  return np;
+}
+
+#ifdef TEST_POOL
+int
+main(void)
+{
+  int i, len = 250;
+  mrb_pool *pool;
+  void *p;
+
+  pool = mrb_pool_open(NULL);
+  p = mrb_pool_alloc(pool, len);
+  for (i=1; i<20; i++) {
+    printf("%p (len=%d) %ud\n", p, len, mrb_pool_can_realloc(pool, p, len*2));
+    p = mrb_pool_realloc(pool, p, len, len*2);
+    len *= 2;
+  }
+  mrb_pool_close(pool);
+  return 0;
+}
+#endif
+