Add FreeRTOS-Plus directory.

FreeRTOS/Demo/uIP_Demo_Rowley_ARM7/uip/memb.c

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+/**
+ * \addtogroup exampleapps
+ * @{
+ */
+
+/**
+ * \file
+ * Memory block allocation routines.
+ * \author Adam Dunkels <adam@sics.se>
+ *
+ * The memory block allocation routines provide a simple yet powerful
+ * set of functions for managing a set of memory blocks of fixed
+ * size. A set of memory blocks is statically declared with the
+ * MEMB() macro. Memory blocks are allocated from the declared
+ * memory by the memb_alloc() function, and are deallocated with the
+ * memb_free() function.
+ *
+ * \note Because of namespace clashes only one MEMB() can be
+ * declared per C module, and the name scope of a MEMB() memory
+ * block is local to each C module.
+ *
+ * The following example shows how to declare and use a memory block
+ * called "cmem" which has 8 chunks of memory with each memory chunk
+ * being 20 bytes large.
+ *
+ \code
+ MEMB(cmem, 20, 8);
+
+ int main(int argc, char *argv[]) {
+    char *ptr;
+    
+    memb_init(&cmem);
+
+    ptr = memb_alloc(&cmem);
+
+    if(ptr != NULL) {
+       do_something(ptr);
+    } else {
+       printf("Could not allocate memory.\n");
+    }
+
+    if(memb_free(ptr) == 0) {
+       printf("Deallocation succeeded.\n");
+    }
+ }
+ \endcode
+ * 
+ */
+
+#include <string.h>
+
+#include "memb.h"
+
+/*------------------------------------------------------------------------------*/
+/**
+ * Initialize a memory block that was declared with MEMB().
+ *
+ * \param m A memory block previosly declared with MEMB().
+ */
+/*------------------------------------------------------------------------------*/
+void
+memb_init(struct memb_blocks *m)
+{
+  memset(m->mem, (m->size + 1) * m->num, 0);
+}
+/*------------------------------------------------------------------------------*/
+/**
+ * Allocate a memory block from a block of memory declared with MEMB().
+ *
+ * \param m A memory block previosly declared with MEMB().
+ */
+/*------------------------------------------------------------------------------*/
+char *
+memb_alloc(struct memb_blocks *m)
+{
+  int i;
+  char *ptr;
+
+  ptr = m->mem;
+  for(i = 0; i < m->num; ++i) {
+    if(*ptr == 0) {
+      /* If this block was unused, we increase the reference count to
+	 indicate that it now is used and return a pointer to the
+	 first byte following the reference counter. */
+      ++*ptr;
+      return ptr + 1;
+    }
+    ptr += m->size + 1;
+  }
+
+  /* No free block was found, so we return NULL to indicate failure to
+     allocate block. */
+  return NULL;
+}
+/*------------------------------------------------------------------------------*/
+/**
+ * Deallocate a memory block from a memory block previously declared
+ * with MEMB().
+ *
+ * \param m m A memory block previosly declared with MEMB().
+ *
+ * \param ptr A pointer to the memory block that is to be deallocated.
+ *
+ * \return The new reference count for the memory block (should be 0
+ * if successfully deallocated) or -1 if the pointer "ptr" did not
+ * point to a legal memory block.
+ */
+/*------------------------------------------------------------------------------*/
+char
+memb_free(struct memb_blocks *m, char *ptr)
+{
+  int i;
+  char *ptr2;
+
+  /* Walk through the list of blocks and try to find the block to
+     which the pointer "ptr" points to. */
+  ptr2 = m->mem;
+  for(i = 0; i < m->num; ++i) {
+    
+    if(ptr2 == ptr - 1) {
+      /* We've found to block to which "ptr" points so we decrease the
+	 reference count and return the new value of it. */      
+      return --*ptr2;
+    }
+    ptr2 += m->size + 1;
+  }
+  return -1;
+}
+/*------------------------------------------------------------------------------*/
+/**
+ * Increase the reference count for a memory chunk.
+ *
+ * \note No sanity checks are currently made.
+ *
+ * \param m m A memory block previosly declared with MEMB().
+ *
+ * \param ptr A pointer to the memory chunk for which the reference
+ * count should be increased.
+ *
+ * \return The new reference count.
+ */
+/*------------------------------------------------------------------------------*/
+char
+memb_ref(struct memb_blocks *m, char *ptr)
+{
+  return ++*(ptr - 1);
+}
+/*------------------------------------------------------------------------------*/
+
+
+
+