[PATCH v2 1/2] lib/vsprintf.c: Simplify uuid_string()

[George Spelvin]

Rather than have a second pass to upcase the buffer, just make the
hex lookup table a variable.

Removing the conditional branch from the inner loop is also a
speedup, but since this is not hot code, the important factor
it shrinks both source and compiled forms:

        Before  After   Delta   Percentage
x86-32  245     199     -46     -18.8%
x86-64  246     186     -60     -24.4%
arm     292     264     -28      -9.6%
thumb   220     160     -60     -27.3%
arm64   296     244     -52     -17.6%

Signed-off-by: George Spelvin <li...@horizon.com>
---
 lib/vsprintf.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 7332a5d7..4ee07e89 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -1316,24 +1316,24 @@ char *uuid_string(char *buf, char *end, const u8 *addr,
        char *p = uuid;
        int i;
        const u8 *index = uuid_be_index;
-       bool uc = false;
+       const char *hex = hex_asc;
 
-       switch (*(++fmt)) {
+       switch (fmt[1]) {
        case 'L':
-               uc = true;              /* fall-through */
+               hex = hex_asc_upper;    /* fall-through */
        case 'l':
                index = uuid_le_index;
                break;
        case 'B':
-               uc = true;
+               hex = hex_asc_upper;
                break;
        }
 
        for (i = 0; i < 16; i++) {
-               if (uc)
-                       p = hex_byte_pack_upper(p, addr[index[i]]);
-               else
-                       p = hex_byte_pack(p, addr[index[i]]);
+               u8 byte = addr[index[i]];
+
+               *p++ = hex[byte >> 4];
+               *p++ = hex[byte & 0x0f];
                switch (i) {
                case 3:
                case 5:
-- 
2.8.1