tools/firmware/ihex2fw: Simplify next record offset calculation

This change “tools/firmware/ihex2fw: Simplify next record offset calculation” in Linux kernel is authored by Andrey Smirnov <andrew.smirnov [at] gmail.com> on Thu Dec 20 23:28:40 2018 -0800.

tools/firmware/ihex2fw: Simplify next record offset calculation

We can convert original expression for 'writelen" to use ALIGN as
follows:

    (p->len + 9) & ~3 => (p->len + 6 + 3) & ~3 => ALIGN(p->len + 6, 4)

Now, subsituting "p->len + 6" with "p->len + sizeof(p->addr) +
sizeof(p->len)" we end up with the same expression as used by kernel
couterpart in linux/ihex.h:

    ALIGN(p->len + sizeof(p->addr) + sizeof(p->len), 4)

That is a full size of the record, aligned to 4 bytes. No functional
change intended.

Cc: Chris Healy <cphealy@gmail.com>
Cc: Kyle McMartin <kyle@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-kernel <linux-kernel@vger.kernel.org>
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

This Linux change may have been applied to various maintained Linux releases and you can find Linux releases including commit 2ef8179.

There are 11 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 tools/firmware/ihex2fw.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/tools/firmware/ihex2fw.c b/tools/firmware/ihex2fw.c
index b58dd06..e081cef 100644
--- a/tools/firmware/ihex2fw.c
+++ b/tools/firmware/ihex2fw.c
@@ -24,6 +24,10 @@
 #include <getopt.h>
 
 
+#define __ALIGN_KERNEL_MASK(x, mask)	(((x) + (mask)) & ~(mask))
+#define __ALIGN_KERNEL(x, a)		__ALIGN_KERNEL_MASK(x, (typeof(x))(a) - 1)
+#define ALIGN(x, a)			__ALIGN_KERNEL((x), (a))
+
 struct ihex_binrec {
 	struct ihex_binrec *next; /* not part of the real data structure */
         uint32_t addr;
@@ -259,13 +263,18 @@ static void file_record(struct ihex_binrec *record)
 	*p = record;
 }
 
+static uint16_t ihex_binrec_size(struct ihex_binrec *p)
+{
+	return p->len + sizeof(p->addr) + sizeof(p->len);
+}
+
 static int output_records(int outfd)
 {
 	unsigned char zeroes[6] = {0, 0, 0, 0, 0, 0};
 	struct ihex_binrec *p = records;
 
 	while (p) {
-		uint16_t writelen = (p->len + 9) & ~3;
+		uint16_t writelen = ALIGN(ihex_binrec_size(p), 4);
 
 		p->addr = htonl(p->addr);
 		p->len = htons(p->len);

The commit for this change in Linux stable tree is 2ef8179 (patch).

Leave a Reply

Your email address will not be published. Required fields are marked *