1 files changed, 61 insertions, 0 deletions
diff --git a/ar/alloca.c b/ar/alloca.c
new file mode 100644
index 0000000..880c100
--- /dev/null
+++ b/ar/alloca.c
@@ -0,0 +1,61 @@
+
+#ifdef __STDC__
+#include <stdlib.h>
+#else
+#include <memory.h>
+#include <string.h>
+#endif
+
+#ifdef __TINYC__
+typedef union mem_cell
+{
+   union mem_cell *next;	/* A pointer to the next mem */
+   unsigned int size;		/* An int >= sizeof pointer */
+   char *depth;			/* For the alloca hack */
+}
+mem;
+
+#define m_size(p)  ((p) [0].size)	/* For malloc */
+#define m_next(p)  ((p) [1].next)	/* For malloc and alloca */
+#define m_deep(p)  ((p) [0].depth)	/* For alloca */
+
+static mem *alloca_stack = 0;
+
+void *
+alloca(size)
+size_t size;
+{
+   auto char probe;		/* Probes stack depth: */
+   register mem *hp;
+
+   /*
+    * Reclaim garbage, defined as all alloca'd storage that was allocated
+    * from deeper in the stack than currently.
+    */
+
+   for (hp = alloca_stack; hp != 0;)
+      if (m_deep(hp) < &probe)
+      {
+	 register mem *np = m_next(hp);
+	 free((void *) hp);	/* Collect garbage.  */
+	 hp = np;		/* -> next header.  */
+      }
+      else
+	 break;			/* Rest are not deeper.  */
+
+   alloca_stack = hp;		/* -> last valid storage.  */
+   if (size == 0)
+      return 0;			/* No allocation required.  */
+
+   hp = (mem *) malloc(sizeof(mem)*2 + size);
+   if (hp == 0)
+      return hp;
+
+   m_next(hp) = alloca_stack;
+   m_deep(hp) = &probe;
+   alloca_stack = hp;
+
+   /* User storage begins just after header.  */
+   return (void *) (hp + 2);
+}
+#endif