Re: [Xen-devel] [PATCH] trivial: Optimize printnum

[Keir Fraser <keir@xxxxxxx>]

Needs a signed-off-by line, but you can also add my:
Acked-by: Keir Fraser <keir@xxxxxxx>

When you resubmit. I don't know why my reply is mangled as below.

 -- Keir


On 14/02/2013 13:09, "Frediano Ziglio" <frediano.ziglio@xxxxxxxxxx> wrote:

> 
Reuse the string of hexadecimal numbers to simplify printnum
> implementation
---
 tools/firmware/hvmloader/util.c |   20
> ++++++--------------
 1 file changed, 6 insertions(+), 14 deletions(-)

diff
> --git a/tools/firmware/hvmloader/util.c
> b/tools/firmware/hvmloader/util.c
index d5cd277..741b9c2 100644
---
> a/tools/firmware/hvmloader/util.c
+++ b/tools/firmware/hvmloader/util.c
@@
> -315,23 +315,15 @@ cpuid(uint32_t idx, uint32_t *eax, uint32_t *ebx, uint32_t
> *ecx, uint32_t *edx)
         : "0" (idx) );
 }
 
+static const char
> hex_digits[] = "0123456789abcdef";
+
 /* Write a two-character hex
> representation of 'byte' to digits[].
    Pre-condition: sizeof(digits) >= 2
> */
 void
 byte_to_hex(char *digits, uint8_t byte)
 {
-    uint8_t nybbel =
> byte >> 4;
-
-    if ( nybbel > 9 )
-        digits[0] = 'a' + nybbel-10;
-
> else
-        digits[0] = '0' + nybbel;
-
-    nybbel = byte & 0x0f;
-    if (
> nybbel > 9 )
-        digits[1] = 'a' + nybbel-10;
-    else
-
> digits[1] = '0' + nybbel;
+    digits[0] = hex_digits[byte >> 4];
+
> digits[1] = hex_digits[byte & 0x0f];
 }
 
 /* Convert an array of 16 unsigned
> bytes to a DCE/OSF formatted UUID
@@ -518,13 +510,13 @@ void
> pci_write(uint32_t devfn, uint32_t reg, uint32_t len, uint32_t val)
     }
 }

> 
-static char *printnum(char *p, unsigned long num, int base)
+static char
> *printnum(char *p, unsigned long num, unsigned base)
 {
     unsigned long n;

> 
     if ( (n = num/base) > 0 )
         p = printnum(p, n, base);
-    *p++ =
> "0123456789abcdef"[(int)(num % base)];
+    *p++ = hex_digits[num % base];

> *p = '\0';
     return p;
 }
-- 
1.7.9.5





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