ptos: pool: Add pool allocator groundwork

Signed-off-by: Chloe M. <chloe@mensia.org>

service/ptos/head/ex/pool.h

@@ -21,11 +21,20 @@
 #define POOL_LEVEL_GRAN(X) \
     (1 << ((X) + POOL_MIN_LOG2))
 
+/*
+ * Valid types that can be assigned to an allocated region
+ *
+ * @POOL_NON_PAGED:  This type is not paged to disk
+ */
+typedef enum {
+    POOL_NON_PAGED
+} POOL_TYPE;
+
 /*
  * A pool page represents a single allocatable
  * unit within a pool segment.
  *
- * @Bitmap: Bitmap within pool page
+ * @Bitmap: Bitmap within pool page [0=free, 1=allocated]
  * @Next:   Next page within list
  */
 typedef struct _POOL_PAGE {
@@ -37,11 +46,11 @@ typedef struct _POOL_PAGE {
  * A pool segment represents a list of pages at a specific
  * granularity.
  *
- * @LastPage:  Last page in segment
+ * @FirstPage:  Last page in segment
  * @PageCount: Number of pages in this segment
  */
 typedef struct {
-    POOL_PAGE *LastPage;
+    POOL_PAGE *FirstPage;
     USIZE PageCount;
 } POOL_SEGMENT;
 
@@ -62,4 +71,19 @@ typedef struct {
  */
 VOID ExPoolRegionInit(POOL_REGION *Region);
 
+/*
+ * Allocate a memory pool of a specific type and assign a tag
+ * to it for verifying frees among other debugging needs.
+ *
+ * @Type:       Pool type to assign
+ * @ByteCount:  Number of bytes to allocate
+ * @Tag:        Tag to assign to allocated memory
+ *
+ * Returns NULL upon failure.
+ */
+VOID *ExAllocatePoolWithTag(
+    POOL_TYPE Type, USIZE ByteCount,
+    ULONG Tag
+);
+
 #endif  /* !_EX_POOL_H_ */