X-Git-Url: https://harrygodden.com/git/?p=vg.git;a=blobdiff_plain;f=vg_mem_queue.c;fp=vg_mem_queue.c;h=3b1a9d64ccf80fab6b306a7370ea5cf30310ab16;hp=0000000000000000000000000000000000000000;hb=3b14f3dcd5bf9dd3c85144f2123d667bfa4bb63f;hpb=fce86711735b15bff37de0f70716808410fcf269

diff --git a/vg_mem_queue.c b/vg_mem_queue.c
new file mode 100644
index 0000000..3b1a9d6
--- /dev/null
+++ b/vg_mem_queue.c
@@ -0,0 +1,77 @@
+#include "vg_platform.h"
+#include "vg_mem.h"
+#include "vg_mem_queue.h"
+#include <stddef.h>
+#include <string.h>
+
+/*
+ * Allocate memory on the queue. Returns NULL if allocation failed for any
+ * any reason.
+ */
+vg_queue_frame *vg_queue_alloc( vg_queue *q, u32 size )
+{
+   u32 total = vg_align8(size) + sizeof(vg_queue_frame);
+   vg_queue_frame *frame = NULL;
+
+   if( total > q->size )
+      return NULL;
+
+   if( q->head )
+   {
+      u32 end   = ((u8 *)q->head - q->buffer) + q->head->alloc_size,
+          start = ((u8 *)q->tail - q->buffer),
+          r0    = 0,
+          r1    = 0;
+
+      if( start < end ){
+         r0 = q->size-end;
+         r1 = start;
+      }
+      else 
+         r0 = start - end;
+
+      if( total < r0 ){
+         frame = (vg_queue_frame *)(q->buffer + end);
+      }
+      else {
+         if( total < r1 ){
+            q->head->alloc_size += r0;
+            frame = (vg_queue_frame *)q->buffer;
+         }
+      }
+
+      if( !frame ) return NULL;
+   }
+   else{
+      frame = (vg_queue_frame *)q->buffer;
+      q->tail = frame;
+   }
+
+   memset( frame, 0, sizeof(vg_queue_frame) );
+
+   q->head = frame;
+   frame->alloc_size = total;
+   frame->size = size;
+
+   return frame;
+}
+
+/*
+ * Free last item from queue 
+ */
+void vg_queue_pop( vg_queue *q )
+{
+   if( q->head == q->tail ){
+      q->head = NULL;
+      q->tail = NULL;
+      return;
+   }
+
+   u32 start = ((u8 *)q->tail - q->buffer);
+   start += q->tail->alloc_size;
+
+   if( start == q->size )
+      start = 0;
+
+   q->tail = (vg_queue_frame *)(q->buffer + start);
+}