1 files changed, 63 insertions, 0 deletions
diff --git a/mem/framer.c b/mem/framer.c
new file mode 100644
index 0000000..9a66feb
--- /dev/null
+++ b/mem/framer.c
@@ -0,0 +1,63 @@
+#include "framer.h"
+
+/* Installs a MemFramer at the specified address */
+MemFramer *mem_framer_install(void *addr, usize end, uint blksz) {
+	MemFramer *self = addr;
+	usize selfend = (usize)(self + 1);
+	usize next = ALIGN_UP(selfend, blksz);
+
+	*self = (MemFramer) {
+		.allocator = (MemAllocator) {
+			.alloc = mem_framer_alloc,
+			.free = mem_framer_free
+		},
+		.next = next,
+		.end = end,
+		.blksz = blksz
+	};
+
+	return self;
+}
+
+/* Allocates a frame */
+void *mem_framer_alloc(MemAllocator *inner, usize n) {
+	/* When allocating a frame, we have two paths:
+	      1. The freelist is not empty: give away
+		     the last freed frame
+		  2. The freelist is empty: bump away the next
+		     frame (pointed at by the next member)
+	   The alloc must fail the freelist is empty and that
+	   the next is beyond the end of the region */
+	
+	MemFramer *self = (MemFramer*)inner;
+
+	/* The implementation does not support more than
+	   one frame */
+	if (n == 0 || n > self->blksz)
+		return nil;
+
+	void *ptr = nil;
+
+	if (self->free) {
+		ptr = self->free;
+		self->free = self->free->next;
+	} else if (self->next + self->blksz <= self->end) {
+		ptr = (void*)self->next;
+		self->next += self->blksz;
+	}
+
+	return ptr;
+}
+
+/* Frees a frame */
+void mem_framer_free(MemAllocator *inner, void *ptr) {
+	/* NOTE: this implementation does make the assumption
+	         that the given pointer is the base of the allocated
+			 region without correction */
+
+	MemFramer *self = (MemFramer*)inner;
+
+	MemFramerFreed *freed = ptr;
+	freed->next = self->free;
+	self->free = freed;
+}
+\ No newline at end of file