linux-kernel - [PATCH 13/15] print_integer, printf: rewrite num_to_str() via print

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Message-Id: <20200420205743.19964-13-adobriyan@gmail.com>
Date:   Mon, 20 Apr 2020 23:57:41 +0300
From:   Alexey Dobriyan <adobriyan@...il.com>
To:     akpm@...ux-foundation.org
Cc:     adobriyan@...il.com, linux-kernel@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, pmladek@...e.com,
        rostedt@...dmis.org, sergey.senozhatsky@...il.com,
        andriy.shevchenko@...ux.intel.com, linux@...musvillemoes.dk
Subject: [PATCH 13/15] print_integer, printf: rewrite num_to_str() via print_integer()

In my opinion, num_to_str() is more understandable this way.

Signed-off-by: Alexey Dobriyan <adobriyan@...il.com>
---
 lib/vsprintf.c | 30 +++++++++++-------------------
 1 file changed, 11 insertions(+), 19 deletions(-)

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 7c488a1ce318..df2b5ce08fe9 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -51,6 +51,7 @@
 
 #include <linux/string_helpers.h>
 #include "kstrtox.h"
+#include "print-integer.h"
 
 /**
  * simple_strtoull - convert a string to an unsigned long long
@@ -343,33 +344,24 @@ char *put_dec(char *buf, unsigned long long n)
  */
 int num_to_str(char *buf, int size, unsigned long long num, unsigned int width)
 {
-	/* put_dec requires 2-byte alignment of the buffer. */
-	char tmp[sizeof(num) * 3] __aligned(2);
-	int idx, len;
+	char tmp[20];
+	char *p = tmp + sizeof(tmp);
+	ptrdiff_t len;
 
-	/* put_dec() may work incorrectly for num = 0 (generate "", not "0") */
-	if (num <= 9) {
-		tmp[0] = '0' + num;
-		len = 1;
-	} else {
-		len = put_dec(tmp, num) - tmp;
-	}
+	p = _print_integer_u64(p, num);
+	len = tmp + sizeof(tmp) - p;
 
 	if (len > size || width > size)
 		return 0;
 
 	if (width > len) {
-		width = width - len;
-		for (idx = 0; idx < width; idx++)
-			buf[idx] = ' ';
+		memset(buf, ' ', width - len);
+		memcpy(buf + width - len, p, len);
+		return width;
 	} else {
-		width = 0;
+		memcpy(buf, p, len);
+		return len;
 	}
-
-	for (idx = 0; idx < len; ++idx)
-		buf[idx + width] = tmp[len - idx - 1];
-
-	return len + width;
 }
 
 #define SIGN	1		/* unsigned/signed, must be 1 */
-- 
2.24.1