From 3fa4f2f6ca22e4872b02cd6fb794865257d471be Mon Sep 17 00:00:00 2001
From: Miles Bader <miles@lsi.nec.co.jp>
Date: Mon, 19 Aug 2002 08:46:34 +0000
Subject: Initial checkin.
---
libc/stdlib/malloc/memalign.c | 94 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 94 insertions(+)
create mode 100644 libc/stdlib/malloc/memalign.c
diff --git a/libc/stdlib/malloc/memalign.c b/libc/stdlib/malloc/memalign.c
new file mode 100644
index 000000000..ce13eb99d
--- /dev/null
+++ b/libc/stdlib/malloc/memalign.c
@@ -0,0 +1,94 @@
+/*
+ * libc/stdlib/malloc/memalign.c -- memalign (`aligned malloc') function
+ *
+ * Copyright (C) 2002 NEC Corporation
+ * Copyright (C) 2002 Miles Bader <miles@gnu.org>
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License. See the file COPYING.LIB in the main
+ * directory of this archive for more details.
+ *
+ * Written by Miles Bader <miles@gnu.org>
+ */
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/mman.h>
+
+#include "malloc.h"
+#include "heap.h"
+
+
+#define MAX(x,y) ((x) > (y) ? (x) : (y))
+
+/*
+ ______________________ TOTAL _________________________
+ / \
+ +---------------+-------------------------+--------------+
+ | | | |
+ +---------------+-------------------------+--------------+
+ \____ INIT ____/ \______ RETURNED _______/ \____ END ___/
+*/
+
+void *
+memalign (size_t alignment, size_t size)
+{
+ void *mem, *base;
+ unsigned long tot_addr, tot_end_addr, addr, end_addr;
+ struct heap *heap = &__malloc_heap;
+
+ /* Make SIZE something we like. */
+ size = HEAP_ADJUST_SIZE (size);
+
+ /* Use malloc to do the initial allocation, since it deals with getting
+ system memory. We over-allocate enough to be sure that we'll get
+ enough memory to hold a properly aligned block of size SIZE,
+ _somewhere_ in the result. */
+ mem = malloc (size + 2 * alignment);
+ if (! mem)
+ /* Allocation failed, we can't do anything. */
+ return 0;
+ if (alignment < MALLOC_ALIGNMENT)
+ return mem;
+
+ /* Remember the base-address, of the allocation, although we normally
+ use the user-address for calculations, since that's where the
+ alignment matters. */
+ base = MALLOC_BASE (mem);
+
+ /* The bounds of the initial allocation. */
+ tot_addr = (unsigned long)mem;
+ tot_end_addr = (unsigned long)base + MALLOC_SIZE (mem);
+
+ /* Find a likely place inside MEM with the right alignment. */
+ addr = MALLOC_ROUND_UP (tot_addr, alignment);
+
+ /* Unless TOT_ADDR was already aligned correctly, we need to return the
+ initial part of MEM to the heap. */
+ if (addr != tot_addr)
+ {
+ size_t init_size = addr - tot_addr;
+
+ /* Ensure that memory returned to the heap is large enough. */
+ if (init_size < HEAP_MIN_SIZE)
+ {
+ addr = MALLOC_ROUND_UP (tot_addr + HEAP_MIN_SIZE, alignment);
+ init_size = addr - tot_addr;
+ }
+
+ __heap_free (heap, base, init_size);
+
+ /* Remember that we've freed the initial part of MEM. */
+ base += init_size;
+ }
+
+ /* Return the end part of MEM to the heap, unless it's too small. */
+ end_addr = addr + size;
+ if (end_addr + MALLOC_REALLOC_MIN_FREE_SIZE < tot_end_addr)
+ __heap_free (heap, (void *)end_addr, tot_end_addr - end_addr);
+ else
+ /* We didn't free the end, so include it in the size. */
+ end_addr = tot_end_addr;
+
+ return MALLOC_SETUP (base, end_addr - (unsigned long)base);
+}
--
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