[coreboot] New patch to review for coreboot: 876ec78 libpayload: Remove unused FLAG_USED from memory allocator

[Patrick Georgi (patrick@georgi-clan.de)]

Patrick Georgi (patrick at georgi-clan.de) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/1942

-gerrit

commit 876ec78af9f6c9c5251774fbe19cf3ef8769699d
Author: Nico Huber <nico.huber at secunet.com>
Date:   Mon Oct 8 15:03:35 2012 +0200

    libpayload: Remove unused FLAG_USED from memory allocator
    
    The FLAG_USED bit in the memory allocator's header type was never
    read. This removes it to save one bit for the region size so we can
    have heaps of up to 32MiB.
    
    Change-Id: Ibd78e67d79e872d6df426516667c795fd52326d5
    Signed-off-by: Nico Huber <nico.huber at secunet.com>
---
 payloads/libpayload/libc/malloc.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/payloads/libpayload/libc/malloc.c b/payloads/libpayload/libc/malloc.c
index 82bae3c..7756a3b 100644
--- a/payloads/libpayload/libc/malloc.c
+++ b/payloads/libpayload/libc/malloc.c
@@ -37,6 +37,9 @@
  * We're also susceptible to the usual buffer overrun poisoning, though the
  * risk is within acceptable ranges for this implementation (don't overrun
  * your buffers, kids!).
+ *
+ * The header format (hdrtype_t) supports heaps of up to 32MiB (given that int
+ * is 32 bits long).
  */
 
 #define IN_MALLOC_C
@@ -51,14 +54,15 @@ typedef unsigned int hdrtype_t;
 
 #define MAGIC     (0x2a << 26)
 #define FLAG_FREE (1 << 25)
-#define FLAG_USED (1 << 24)
+#define SIZE_BITS 25
+#define MAX_SIZE  ((1 << SIZE_BITS) - 1)
 
-#define SIZE(_h) ((_h) & 0xFFFFFF)
+#define SIZE(_h) ((_h) & MAX_SIZE)
 
-#define _HEADER(_s, _f) ((hdrtype_t) (MAGIC | (_f) | ((_s) & 0xFFFFFF)))
+#define _HEADER(_s, _f) ((hdrtype_t) (MAGIC | (_f) | ((_s) & MAX_SIZE)))
 
 #define FREE_BLOCK(_s) _HEADER(_s, FLAG_FREE)
-#define USED_BLOCK(_s) _HEADER(_s, FLAG_USED)
+#define USED_BLOCK(_s) _HEADER(_s, 0)
 
 #define HDRSIZE (sizeof(hdrtype_t))
 
@@ -91,7 +95,7 @@ static void *alloc(int len)
 	/* Align the size. */
 	len = (len + 3) & ~3;
 
-	if (!len || len > 0xffffff)
+	if (!len || len > MAX_SIZE)
 		return (void *)NULL;
 
 	/* Make sure the region is setup correctly. */